WO2017035727A1

WO2017035727A1 - Broadcast automatic repeat request

Info

Publication number: WO2017035727A1
Application number: PCT/CN2015/088562
Authority: WO
Inventors: Xipeng Zhu; Xiaoxia Zhang
Original assignee: Qualcomm Incorporated; Wang, Jun
Priority date: 2015-08-31
Filing date: 2015-08-31
Publication date: 2017-03-09

Abstract

A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus may be a user equipment (UE). The apparatus supports an automatic repeat request (ARQ) protocol during a broadcast transmission of data. The apparatus determines that that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs. The apparatus transmits an ARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.

Description

BROADCAST AUTOMATIC REPEAT REQUEST

BACKGROUND Field

The present disclosure relates generally to communication systems, and more particularly, to an automatic repeat request.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE) . LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP) . LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA on the downlink (DL) , SC-FDMA on the uplink (UL) , and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi- access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In an aspect of the disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a user equipment (UE) . The apparatus determines that that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs. The apparatus transmits an automatic repeat request (ARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.

In an aspect of the disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a base station. The apparatus broadcasts at least one PDU. The apparatus receives an ARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received. The apparatus determines to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure in LTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure in LTE.

FIG. 5 is a diagram illustrating an example of a radio protocol architecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B and user equipment in an access network.

FIG. 7A is a diagram illustrating an example of an evolved Multimedia Broadcast Multicast Service channel configuration in a Multicast Broadcast Single Frequency Network.

FIG. 7B is a diagram illustrating an example of a Multicast Broadcast Single Frequency Network area.

FIG. 7C is a diagram illustrating a format of a Multicast Channel Scheduling Information Media Access Control control element.

FIG. 8A is an example diagram illustrating an interaction between a transmitter node and a receiver node, according to an aspect of the disclosure.

FIG. 8B is an example diagram illustrating a broadcast ARQ-based retransmission of repair PDUs, according to an aspect of the disclosure.

FIG. 9 is a flowchart of a method of wireless communication, according to an aspect of the disclosure.

FIG. 10A is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 9, according to an aspect of the disclosure.

FIG. 10B is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 9, according to an aspect of the disclosure.

FIG. 11A is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 9, according to an aspect of the disclosure.

FIG. 11B is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 9, according to an aspect of the disclosure.

FIG. 12 is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 9, according to an aspect of the disclosure.

FIG. 13 is a conceptual data flow diagram illustrating the data flow between different means/components in an exemplary apparatus.

FIG. 14 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

FIG. 15 is a flowchart of a method of wireless communication, according to an aspect of the disclosure.

FIG. 16 is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 13, according to an aspect of the disclosure.

FIG. 17A is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 13, according to an aspect of the disclosure.

FIG. 17B is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 13, according to an aspect of the disclosure.

FIG. 17C is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 13, according to an aspect of the disclosure.

FIG. 18 is a flowchart of a method of wireless communication, expanding from the flowchart of FIG. 13, according to an aspect of the disclosure.

FIG. 19 is a conceptual data flow diagram illustrating the data flow between different means/components in an exemplary apparatus.

FIG. 20 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, those skilled in the art will readily appreciate that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, steps, operations, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an LTE network architecture 100. The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more user equipment (UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, and an Operator’s Internet Protocol (IP) Services 122. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108, and may include a Multicast Coordination Entity (MCE) 128. The eNB 106 provides user and control planes protocol terminations toward the UE 102. The eNB 106 may be connected to the other eNBs 108 via a backhaul (e.g., an X2 interface) . The MCE 128 allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS) , and determines the radio configuration (e.g., a modulation and coding scheme (MCS) ) for the eMBMS. The MCE 128 may be a separate entity or part of the eNB 106. The eNB 106 may also be referred to as a base station, a Node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , or some other suitable terminology. The eNB 106 provides an access point to the EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA) , a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player) , a camera, a game console, a tablet, or any other similar functioning device. The UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include a Mobility Management Entity (MME) 112, a Home Subscriber Server (HSS) 120, other MMEs 114, a Serving Gateway 116, a Multimedia Broadcast Multicast Service (MBMS) Gateway 124, a Broadcast Multicast Service Center (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. The MME 112 is the control node that processes the signaling between the UE 102 and the EPC 110. Generally, the MME 112 provides bearer and connection management. All user IP packets are transferred through the Serving Gateway 116, which itself is connected to the PDN Gateway 118. The PDN Gateway 118 provides UE IP address allocation as well as other functions. The PDN Gateway 118 and the BM-SC 126 are connected to the IP Services 122. The IP Services 122 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service (PSS) , and/or other IP services. The BM-SC 126 may provide functions for MBMS user service provisioning and delivery. The BM-SC 126 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway 124 may be used to distribute MBMS traffic to the eNBs (e.g., 106, 108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

FIG. 2 is a diagram illustrating an example of an access network 200 in an LTE network architecture. In this example, the access network 200 is divided into a number of cellular regions (cells) 202. One or more lower power class eNBs 208 may have cellular regions 210 that overlap with one or more of the cells 202. The lower power class eNB 208 may be a femto cell (e.g., home eNB (HeNB) ) , pico cell, micro cell, or remote radio head (RRH) . The macro eNBs 204 are each assigned to a respective cell 202 and are configured to provide an access point to the EPC 110 for all the UEs 206 in the cells 202. There is no centralized controller in this example of an access network 200, but a centralized controller may be used in alternative configurations. The eNBs 204 are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors) . The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving a particular coverage area. Further, the terms “eNB, ” “base station, ” and “cell” may be used interchangeably herein depending upon the context in which the terms are used.

The modulation and multiple access scheme employed by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplex (FDD) and time division duplex (TDD) . As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB) . EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA； Global System for Mobile Communications (GSM) employing TDMA； and Evolved UTRA (E-UTRA) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs 204 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data streams may be transmitted to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE (s) 206 with different spatial signatures, which enables each of the UE (s) 206 to recover the one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR) .

FIG. 3 is a diagram 300 illustrating an example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, for a normal cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 7 consecutive OFDM symbols in the time domain, for a total of 84 resource elements. For an extended cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 6 consecutive OFDM symbols in the time domain, for a total of 72 resource elements. Some of the resource elements, indicated as

R

302, 304, include DL reference signals (DL-RS) . The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structure in LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned

resource blocks

410a, 410b in the control section to transmit control information to an eNB. The UE may also be assigned

resource blocks

420a, 420b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make a single PRACH attempt per frame (10 ms) .

FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 506. Layer 2 (L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control (MAC) sublayer 510, a radio link control (RLC) sublayer 512, and a packet data convergence protocol (PDCP) 514 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508 including a network layer (e.g., IP layer) that is terminated at the PDN gateway 118 on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc. ) .

The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ) . The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3 layer) . The RRC sublayer 516 is responsible for obtaining radio resources (e.g., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650 in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processing functions for the L1 layer (i.e., physical layer) . The signal processing functions include coding and interleaving to facilitate forward error correction (FEC) at the UE 650 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK) , quadrature phase-shift keying (QPSK) , M-phase-shift keying (M-PSK) , M-quadrature amplitude modulation (M-QAM) ) . The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 674 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 650. Each spatial stream may then be provided to a different antenna 620 via a separate transmitter 618TX. Each transmitter 618TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 656. The RX processor 656 implements various signal processing functions of the L1 layer. The RX processor 656 may perform spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are destined for the UE 650, they may be combined by the RX processor 656 into a single OFDM symbol stream. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 on the physical channel. The data and control signals are then provided to the controller/processor 659.

The controller/processor 659 implements the L2 layer. The controller/processor can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 662 for L3 processing. The controller/processor 659 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659. The data source 667 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB 610. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610 may be used by the TX processor 668 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 668 may be provided to different antenna 652 via separate transmitters 654TX. Each transmitter 654TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar to that described in connection with the receiver function at the UE 650. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to a RX processor 670. The RX processor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the controller/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

FIG. 7A is a diagram 750 illustrating an example of an evolved MBMS (eMBMS) channel configuration in an MBSFN. The eNBs 752 in cells 752' may form a first MBSFN area and the eNBs 754 in cells 754' may form a second MBSFN area. The

eNBs

752, 754 may each be associated with other MBSFN areas, for example, up to a total of eight MBSFN areas. A cell within an MBSFN area may be designated a reserved cell. Reserved cells do not provide multicast/broadcast content, but are time-synchronized to the cells 752', 754' and may have restricted power on MBSFN resources in order to limit interference to the MBSFN areas. Each eNB in an MBSFN area synchronously transmits the same eMBMS control information and data. Each area may support broadcast, multicast, and unicast services. A unicast service is a service intended for a specific user, e.g., a voice call. A multicast service is a service that may be received by a group of users, e.g., a subscription video service. A broadcast service is a service that may be received by all users, e.g., a news broadcast. Referring to FIG. 7A, the first MBSFN area may support a first eMBMS broadcast service, such as by providing a particular news broadcast to UE 770. The second MBSFN area may support a second eMBMS broadcast service, such as by providing a different news broadcast to UE 760. FIG. 7B is a diagram 770 illustrating an example of an MBSFN area. Each MBSFN area supports one or more physical multicast channels (PMCH) (e.g., 15 PMCHs) . Each PMCH corresponds to a multicast channel (MCH) . Each MCH can multiplex a plurality (e.g., 29) of multicast logical channels. Each MBSFN area may have one multicast control channel (MCCH) . As such, one MCH may multiplex one MCCH and a plurality of multicast traffic channels (MTCHs) and the remaining MCHs may multiplex a plurality of MTCHs.

A UE can camp on an LTE cell to discover the availability of eMBMS service access and a corresponding access stratum configuration. Initially, the UE may acquire a system information block (SIB) 13 (SIB13) . Subsequently, based on the SIB13, the UE may acquire an MBSFN Area Configuration message on an MCCH. Subsequently, based on the MBSFN Area Configuration message, the UE may acquire an MCH scheduling information (MSI) MAC control element. The SIB13 may include (1) an MBSFN area identifier of each MBSFN area supported by the cell； (2) information for acquiring the MCCH such as an MCCH repetition period (e.g., 32, 64, …, 256 frames) , an MCCH offset (e.g., 0, 1, …, 10 frames) , an MCCH modification period (e.g., 512, 1024 frames) , a signaling modulation and coding scheme (MCS) , subframe allocation information indicating which subframes of the radio frame as indicated by repetition period and offset can transmit MCCH； and (3) an MCCH change notification configuration. There is one MBSFN Area Configuration message for each MBSFN area. The MBSFN Area Configuration message may indicate (1) a temporary mobile group identity (TMGI) and an optional session identifier of each MTCH identified by a logical channel identifier within the PMCH, and (2) allocated resources (i.e., radio frames and subframes) for transmitting each PMCH of the MBSFN area and the allocation period (e.g., 4, 8, …, 256 frames) of the allocated resources for all the PMCHs in the area, and (3) an MCH scheduling period (MSP) (e.g., 8, 16, 32, …, or 1024 radio frames) over which the MSI MAC control element is transmitted.

FIG. 7Cis a diagram 790 illustrating the format of an MSI MAC control element. The MSI MAC control element may be sent once each MSP. The MSI MAC control element may be sent in the first subframe of each scheduling period of the PMCH. The MSI MAC control element can indicate the stop frame and subframe of each MTCH within the PMCH. There may be one MSI per PMCH per MBSFN area. A logical channel identifier (LCID) field (e.g., LCID 1, LCID 2, …, LCID n) may indicate a logical channel identifier of the MTCH. A Stop MTCH field (e.g., Stop MTCH 1, Stop MTCH 2, …, Stop MTCH n) may indicate the ordinal number of the subframe within the MCH scheduling period counting only the subframes allocated to the MCH, where the corresponding MTCH stops.

An RLC layer (e.g., the RLC sublayer 512) connects a MAC layer (e.g., the MAC sublayer 510) with an RRC layer (e.g., the RRC sublayer 516) , and may work in different modes such as Transparent Mode (TM) , Unacknowledged Mode (UM) and Acknowledged Mode (AM) . The RLC AM mode is associated with retransmission of unsuccessfully received protocol data units (PDUs) . Generally, an automatic repeat request (ARQ) for the RLC protocol is supported in LTE for a unicast AM mode. The ARQ is implemented to provide reliable data traffic, by providing a reception status (feedback) of transmitted data such as an ACK and a NACK. For the RLC ARQ, a PDU reception status is generally triggered by polling, which involves a transmitter node (e.g., a base station) transmitting a poll request to a receiver node (e.g., a UE) and the receiver node sending a status report in response to the poll request. Frequency of the polling may be controlled by at least one of a number of PDUs, a number of bytes of PDUs, or a timer. The receiver node generally sends the status report to the transmitter node on a physical uplink channel such as a PUSCH, where the status report includes an ACK or a NACK. The status report may further include a sequence number up to which the receiver node has successfully received PDUs. For example, if the receiver node has successfully received PDU #1, #2, and #3, then the status report may include the sequence number 3. The status report may include NACK information of all PDUs that have not been successfully received by the receiver node (e.g., missing PDUs) . In LTE, the ARQ is not supported for broadcast communication, such as a single-cell point-to-multipoint (SC-PTM) transmission or an MBSFN transmission. In particular, in LTE, an ARQ protocol has not been developed for a case when a transmitter node communicates to a receiver node via broadcast. In addition, if an RLC layer does not exist, use of another layer such as a MAC layer for broadcast transmission with the ARQ has not been considered. Thus, there is a need to explore these areas in the ARQ and to extend the ARQ protocol to cover such situations.

FIG. 8A is an example diagram 800 illustrating an interaction between a transmitter node and a receiver node, according to an aspect of the disclosure. The example diagram 800 shows an interaction between a base station 802, and a UE 812, where the base station 802 is the transmitter node and the UE 812 is the receiver node. The UE 812 may be in a same group as surrounding

UEs

814 and 816, such that the UE 812 and the surrounding

UEs

814 and 816 may receive the same broadcast transmission from the base station 802. At 822, the base station 802 sends a broadcast transmission of data packets such as PDUs and the UE 812 receives the broadcast transmission from the base station 802. At 824, as an ARQ protocol, the UE 812 determines whether the UE 812 has successfully received the PDUs broadcasted from the base station 802, and generates an ARQ feedback based on such determination. At 826, the UE 812 transmits the ARQ feedback to the base station 802, based on the determination at 824. For example, if the UE 812 determines that the UE 812 has successfully received all of the PDUs, the UE 812 generates and transmits an ARQ feedback including an ACK to the base station 802. If the UE 812 determines that the UE 812 has not successfully received (thus is missing) at least one of the PDUs, the UE 812 generates and transmits an ARQ feedback including a NACK to the base station 802. At 828, if the base station 802 receives an ARQ feedback including a NACK from the UE 812, the base station 802 generates repair PDUs in response to the NACK. At 830, based on the ARQ feedback, the base station 802, rather than performing retransmission of the one of more PDUs that were not unsuccessfully received by the UE 812, instead transmits one or more new repair PDUs generated by the FEC encoder based on the ARQ feedback. In particular, at 830, the transmission of one or more new repair PDUs may be performed via broadcast.

FIG. 8B is an example diagram 850 illustrating a broadcast ARQ-based retransmission according to an aspect of the disclosure illustrating the transmission of new repair PDUs rather than retransmission of missing PDUs in response to a NACK feedback from the UE. The example diagram 850 may provide details about an example of the process taken place at 822, 824, 826, 828, and 830 of the example diagram 800 of FIG. 8A. Referring to the example diagrams 800 and 850, at 822, the base station 802 broadcasts a group of PDUs 852 to the UE 812. The group of PDUs may include K PDUs. After the base station 802 sends the group of PDUs 852, if the UE determines at 824 that one or more PDUs were not successfully received, the UE 812 at 826 sends a NACK 854 to the base station 802. Then, the base station 802 generates at 828 one or more repair PDUs using a FEC encoder. The group of PDUs including K PDUs is used as an input for the FEC encoder to generate the one or more repair PDUs. Thus, the base station 802 transmits at 830 the one or more repair PDUs generated based on the FEC, instead of retransmitting the PDUs that were not successfully received. For example, the FEC may be based on either fountain codes (e.g., RaptorQ, Raptor, LT) or other codes for erasure channel (e.g., Reed-Solomon) . As illustrated in the example diagram 850, in response to receiving the NACK 854, the base station 802 generates the

repair PDUs

856 and 858 using the group of PDUs 852 as an input to the FEC encoder, and transmits the

repair PDUs

856 and 858. If the UE 812 successfully receives the group of PDUs after receiving the

repair PDUs

856 and 858, the UE does not send a NACK. For example, if the UE 812 determines that a sufficient number of PDUs have been received (e.g., based on the number of PDUs initially received and the number of repair PDUs received) to successfully decode data packets, the UE 812 may determine that the UE 812 has successfully received the group of PDUs. If no NACK is received in response to the

repair PDUs

856 and 858, the base station 802 broadcasts the next group of PDUs 860.

In one aspect, in an ARQ feedback, the UE 812 may transmit a NACK (e.g., RLC NACK) when the UE 812 determines that a number of PDUs that were not successfully received (thus missing) and/or a byte size of PDUs that were not successfully received exceeds a preconfigured threshold. In an aspect, if the UE 812 is missing at least n PDUs out of m PDUs that were broadcasted to the UE 812, the UE 812 may transmit a NACK, where m and n are integers, and m is greater than n. Both n and m can be indicated to the UE 812 from the base station 802 through RRC signaling (for example, a SIB) or downlink control information (DCI) carried by the PDCCH. In such an aspect, the UE 812 may determine a number of missing PDUs based on sequence numbers that are missing, where sequence numbers are associated with the PDUs. For example, if 10 PDUs are transmitted to the UE 812 within a receiving window, and the UE 812 has received PDUs with

sequence numbers

1, 2, 4, 5, 6, 7, 9, and 10, then the UE 812 may determine that PDUs with sequence numbers 3 and 8 are missing, and thus may determine two PDUs out of ten PDUs are missing. In another example, the UE 812 may determine a number of missing PDUs based on physical layer packet decoding. In particular, the UE 812 determines a number of total received packets and a number of missing packets through cyclic redundancy check (CRC) . For example, if there are 10 PDUs and 3 PDUs are missing, then the UE will indicate 3 CRC failures and 7 CRC successes.

In an aspect, if the UE 812 does not successfully receive at least n bytes out of m bytes that were broadcasted to the UE 812, the UE 812 may transmit a NACK. In such an aspect, the UE 812 may determine the missing number of bytes based on sequence numbers that are missing and a byte size of each PDU, where sequence numbers are associated with the PDUs and each PDU has a header including a byte size of the PDU. For example, if 10 PDUs are transmitted to the UE 812 within a receiving window and each PDU has a byte size of 1000 bytes, and the UE 812 has received PDUs with

sequence numbers

1, 2, 4, 5, 6, 7, 9, and 10, then the UE 812 may determine that two PDUs with sequence numbers 3 and 8 are missing, and thus 2000 bytes are missing out of 10000 bytes total. In one example, n may be set to 0 by default. If n is set to 0, the UE transmits a NACK whenever there is a missing PDU, regardless of a number of missing PDUs or a byte size of missing PDUs.

In another example, if n is set to 2 PDUs out of 10 total PDUs, the UE 812 transmits a NACK if the UE 812 is missing two or more PDUs out of 10 total PDUs. Yet in another example, the base station 802 can specify multiple n’s (for example, n1 and n2) . For example, in a case where n1 is set to 2 PDUs and n2 is set to 5 PDUs, the UE 812 transmits a NACK in a first radio resource if the UE 812 is missing one or two PDUs out of 10 total PDUs, transmits a NACK in a second radio resource if the UE 812 is missing three or four PDUs, and transmits a NACK in a third radio resource if the UE 812 is missing five or more PDUs, out of 10 total PDUs.

In an aspect, the UE 812 may transmit a NACK (e.g., RLC NACK) periodically based on a preconfigured timer and/or may transmit a NACK based on a RLC polling message and/or may transmit a NACK based on a scheduled grant. For example, a resource and/or a channel for transmitting a NACK may be preconfigured by an RRC subscriber identity module (SIM) or may be indicated by a polling message or a scheduled PDCCH. For example, if a preconfigured timer is used, the UE 812 may transmit the NACK when the preconfigured timer expires, and may reset the preconfigured timer when the preconfigured timer expires.

The UE 812 may provide an ARQ feedback using a group NACK or an individual NACK. If the UE 812 uses the group NACK approach, the UE 812 may transmit a group NACK on a shared common resource. The common resource may be shared among UEs (e.g.,

UEs

812, 814, and 816) within the same group such that the UEs in the same group may send a group NACK to the base station (e.g., 802) via the common resource. The base station 802 may estimate how many UEs in the group of UEs (e.g.,

UEs

812, 814, and 816) did not successfully receive the PDUs based on the power of the signal strength of a group NACK received via the common source. For example, the power of the signal strength of the group NACK is higher for a higher number of UEs sending a group NACK. Thus, higher power of the signal strength of the group NACK may indicate a higher number of UEs not being able to successfully receive the PDUs. Based on the power of the signal strength of the group NACK from the group of the UEs, the base station 802 may be configured for the group of the UEs. For example, if the power of the signal strength of the group NACK is high, the base station 802 may be configured to transmit more repair PDUs.

According to a first approach of the group NACK aspect of the disclosure, when the UE 812 transmits a group NACK on a shared common resource, the UE 812 may transmit the group NACK on a physical uplink channel, such as a PUCCH or a shared PUSCH. The shared resource for the physical uplink channel may be pre-allocated. In an aspect, multiple resources (e.g., radio resources) for the physical uplink channel may be allocated for different types of a group NACK, where each resource indicates a particular range for a number of missing PDUs or a byte size of missing PDUs. For example, if the UE 812 is missing less than three PDUs, the UE may transmit a group NACK on a first resource for the physical uplink channel, and if the UE is missing three or more PDUs, the UE may transmit a group NACK on a second resource for the physical uplink channel. Because each resource for the physical uplink channel corresponds to a specific range for the number of missing PDUs or a byte size of missing PDUs, the base station 802 may determine the range for the number of missing PDUs or a byte size of missing PDUs by examining the resource that was used to transmit the group NACK. In an aspect, the UE 812 may use a particular resource on the physical uplink channel for a group ACK when all PDUs are successfully received, thus having no missing PDUs.

In an aspect, the resource for the physical uplink channel (for example, a PUCCH or a PUSCH) may be assigned by resource assignment information included in DCI carried by a PDCCH or RRC signaling (for example, a SIB) . The PDCCH is identified by scrambling cyclic redundancy check (CRC) with a group radio network temporary identifier (G-RNTI) . The PDCCH or RRC signaling (for example, a SIB) may specify a group NACK triggering configuration for triggering transmission of a group NACK to the base station 802.

If the group NACK is sent over a PUCCH which is a physical layer channel, and the ARQ protocol in this aspect of the disclosure may be performed in an RLC layer. Thus, in this aspect, an RLC layer and a physical layer and/or a MAC layer may communicate with each other. In particular, at the UE 812, an RLC layer of the UE may indicate to a physical layer and/or a MAC layer of the UE to transmit a group NACK. At the base station 802, when a physical layer and/or a MAC layer receives a group NACK, the physical layer and/or the MAC layer indicates to the RLC layer of the base station 802 that the group NACK is received.

According to a second approach of the group NACK aspect of the disclosure, when the UE 812 transmits a group NACK on a shared common resource, the UE 812 may transmit the group NACK on a shared PRACH. Using the shared PRACH to transmit a group NACK may provide an advantage in that, even if the UE 812 is in an RRC idle mode, the UE 812 can still send a group NACK to the base station 802. Thus, the UE 812 may transmit a group NACK on the shared PRACH both in an RRC idle mode and in an RRC connected mode. The UE 812 may receive broadcasted PDUs both in an RRC idle mode and in an RRC connected mode. A resource for the shared PRACH may be indicated by an RLC polling message (e.g., a RLC PDU) and/or the resource may be preconfigured.

In an aspect, the UE 812 may use different preambles on PRACH for a group NACK. Each preamble of the different preambles may be used to indicate different ranges for a number of missing PDUs or different ranges for a byte size of missing PDUs. For example, if the UE 812 is missing less than three PDUs, the UE 812 may transmit a group NACK with a first preamble, and if the UE 812 is missing three or more PDUs, the UE 812 may transmit a group NACK with a second preamble. In an aspect, the UE 812 may also use a preamble to indicate that none of the PDUs were successfully received (e.g., all PDUs are missing) . In an aspect, the UE 812 may use a particular preamble on PRACH for a group ACK when all PDUs are successfully received, thus having no missing PDUs. Because each preamble corresponds to a specific range for the number of missing PDUs or a byte size of missing PDUs, the base station 802 may determine the range for the number of missing PDUs or a byte size of missing PDUs by examining the preamble transmitted in the group NACK. The range may be used to determine the number of repair PDUs to transmit.

In another aspect of the disclosure, the UE 812 transmits an individual NACK (or an individual ACK) to the base station 802 on an unshared resource. The UE may transmit the individual ACK/NACK on an individually scheduled resource on the PUSCH. The individual ACK/NACK may be included in an RLC PDU status report transmitted from the UE 812 to the base station 802. Generally, when a UE sends an individual NACK via unicast, then the UE specifies which PDU is missing, such that the base station will retransmit the specific missing PDUs. However, according to this aspect of the disclosure, the UE 812 may not specify which PDUs are missing, but instead may indicate in the status report to the base station 802 a number of missing PDUs and/or a byte size of missing PDUs. Because, according to such aspect of the disclosure, the UE 812 does not specify which PDUs are missing, the UE 812 is able to provide a faster ARQ response than when each missing PDU is specified.

It is noted that sending an individual NACK includes each UE sending an individual NACK on its own resource, and thus may use more resources than sending a group NACK on a shared resource. Thus, when using the individual NACK approach, a base station 802 may specify a percentage of UEs that should send an RLC PDU status report. Because a percentage of the UEs send an RLC PDU status report, not as many resources are consumed as when all UEs send an RLC PDU status report.

In an aspect of the disclosure involving the network, a network entity (e.g., a base station 802 or an MCE) sends a feedback configuration to the UE 812 for an ARQ feedback transmitted by the UE 812. The network entity may send the feedback configuration via a SIB and/or RRC signaling. The network entity may send the feedback configuration in a message sent to the UE 812 or may send the feedback configuration in an information element within the SIB or the RRC signaling. The feedback configuration may include at least one of: an indication of whether to transmit an ARQ feedback (e.g., a group NACK based on the ARQ) , a HARQ feedback (e.g., a group NACK based on the HARQ) , or both the ARQ feedback and the HARQ feedback, a threshold corresponding to a number of missing PDUs or a byte size corresponding to the missing PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback (e.g., a group NACK based on the ARQ) can be transmitted in an RRC idle state. In particular, as discussed supra, the UE 812 may transmit a NACK when the UE 812 determines that a number of missing PDUs and/or a byte size of missing PDUs exceeds the threshold corresponding to the number of missing PDUs and/or the byte size corresponding to the missing PDUs. It is noted that a determination on whether to transmit an ARQ feedback, a HARQ feedback, or both the ARQ feedback and the HARQ feedback may be based on delay requirements. In particular, each radio bearer is associated with a quality of service (QoS) profile, which determines the delay requirement for a data service. For example, for voice services, the delay requirement may be 100msec, and for other service, the delay requirement may be 300msec. Thus, for example, an ARQ feedback may be used for some delay requirements, while a HARQ feedback may be used for other delay requirements.

Note that a network (e.g., the base station 802) may set an MCS, such that every time the network schedules a transmission, the network indicates the MCS in a PDCCH. For example, for transmission of repair PDUs, the network may set a less aggressive MCS than for the transmission of the initial PDUs, in order to increase a chance of the UE successfully receiving the repair PDUs. In addition, as discussed supra, the network (e.g., the base station 802) applies FEC based on the ARQ feedback to generate repair PDUs. For example, in response to the ARK feedback, the base station may generate repair PDUs based on a RaptorQ FEC code.

In one aspect, an SC-PTM transmission may be used for broadcast. In such an aspect, based on the ARQ feedback, the base station 802 may add FEC redundancy by increasing the number of repair symbols (e.g., repair PDUs) and broadcasts the repair symbols to the UEs (e.g.,

UEs

812, 814, and 816) within a cell operated by the base station 802. In the SC-PTM transmission, a single cell performs broadcasting of data in LTE.

In another aspect, if an MBSFN transmission or a multi-cell PTM transmission is used for broadcast, multiple cells perform broadcasting of data in LTE. Thus, in the MBSFN approach or the multi-cell PTM approach, multiple base stations in the same group (e.g., serving the same MBSFN area) may receive ARQ feedbacks transmitted from different UEs and may forward the ARQ feedbacks to an MCE or a primary base station. In particular, each base station may receive the ARQ feedback from one or more UE’s within the base station’s coverage area (e.g., within a cell operated by the base station) . Each of the base stations may forward an ARQ feedback to the MCE over an eNB-MCE interface (M3 interface) or may forward an ARQ feedback to a primary base station over an eNB-eNB interface (X2 interface) . Thus, for the MBSFN approach or the multi-cell PTM approach, either the MCE or the primary base station may make a decision on the FEC and the transmission of repair PDUs. If a primary base station is used, the primary base station receives the ARQ feedbacks from different UEs via other base stations. Based on all of the ARQ feedbacks, the primary base station may apply FEC redundancy to generate repair symbols (e.g., repair PDUs) , and may send the repair symbols to other base stations (e.g., via the X2 interface) . Then, the primary base station and the other base stations transmit the repair symbols to the UEs within the MBSFN area served by the primary base station and the other base stations. The primary base station and the other base stations may transmit (in synchronized manner) the repair symbols to the UEs via MBMS transmission (e.g., using identical waveform on same resources) .

If an MCE is used, the MCE receives the ARQ feedbacks from different UEs via base stations. Based on all of the ARQ feedbacks, the MCE indicates to each of the base stations to generate repair symbols (e.g., repair PDUs) and to send the repair symbols to the UEs within the MBSFN area served by the base stations. Thus, when base stations serving the MBSFN area receive such indication from the MCE, the base stations generate the repair symbols and send the repair symbols to the UEs within the MBSFN area. The content of the repair symbols may be the same across all base stations within the MBSFN area.

In some cases, the RLC layer may not be available. For example, the RLC layer may be removed from the UE. When the RLC layer is not available, a MAC ARQ may be used when receiving a broadcast transmission. For example, in such a case, the MAC layer may perform concatenation and segmentation. Further, if some packets (e.g., PDUs) are received out of sequence at the UE, the UE performs reordering of the packets. When the RLC layer is not available, a packet data convergence protocol (PDCP) may be utilized for reordering and/or the MAC layer of the UE may perform reordering. Several approaches may be utilized for performing the ARQ protocol when the RLC layer is not available.

According to a first approach, the MAC layer may perform the ARQ protocol and may optionally perform a HARQ protocol. During the HARQ protocol, the UE sends a HARQ feedback with a group NACK to the base station if at least one PDU is missing. The base station may early terminate the HARQ protocol if the base station detects low energy of group NACK (meaning that a small number of UEs are sending NACK) in the HARQ feedback from the UE. With the low energy of group NACK, when the HARQ protocol is terminated, the base station starts ARQ retransmission and transmits repair PDUs generated using the FEC if the base station decides to send extra repair symbols. If the base station does not detect a low energy of group NACK, the base station may perform HARQ retransmission for repair PDUs to the UE. If the HARQ protocol has corrected the transmission errors (e.g., by HARQ retransmission) , the UE does not transmit an ARQ feedback to the base station. Thus, by utilizing the HARQ protocol in addition to the ARQ protocol, feedback latency may be reduced.

According to a second approach, the MAC layer may perform the ARQ protocol without performing the HARQ protocol. In the second approach, the UE may transmit a group NACK or an individual NACK. The approaches used for the RLC ARQ described supra may be used for the second approach.

FIG. 9 is a flowchart 900 of a method of wireless communication, according to an aspect of the disclosure. The method may be performed by a UE. (e.g., the UE 812, the apparatus 1302/1302') . At 902, the UE may receive a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling. The feedback configuration includes at least one of an indication of whether to transmit ARQ feedback, HARQ feedback, or both ARQ and HARQ feedback, a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback can be transmitted in an RRC idle state. For example, as discussed supra, a network entity (e.g., a base station 802 or an MCE) sends a feedback configuration to the UE 812 for an ARQ feedback transmitted by the UE 812, where the network entity may send the feedback configuration via a SIB and/or RRC signaling. For example, as discussed supra, the feedback configuration may include at least one of: an indication of whether to transmit an ARQ feedback (e.g., a group NACK based on the ARQ) , a HARQ feedback (e.g., a group NACK based on the HARQ) , or both the ARQ feedback and the HARQ feedback, a threshold corresponding to a number of missing PDUs or a byte size corresponding to the missing PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback (e.g., a group NACK based on the ARQ) can be transmitted in an RRC idle state.

At 904, the UE determines that at least one broadcasted PDU is unsuccessfully received of one or more broadcasted PDUs. For example, as discussed supra, the UE 812 determines whether the UE 812 has successfully received the PDUs broadcasted from the base station 802, and generates an ARQ feedback based on such determination. At 906, the UE may perform additional features as discussed infra in relation to FIG. 10A or FIG. 10B.

At 908, the UE transmits an ARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received. For example, as discussed supra, if the UE 812 determines that the UE 812 has not successfully received (thus is missing) at least one of the PDUs, the UE 812 generates and transmits an ARQ feedback including a NACK to the base station 802. At 909, the UE may perform additional features as discussed infra in relation to FIG. 11A or FIG. 11B

In an aspect, the ARQ feedback may be transmitted as a group NACK on a shared resource. For example, as discussed supra, if the UE 812 uses the group NACK approach, the UE 812 transmits a group NACK on a shared common resource. Additional features in this aspect are discussed infra in FIGs. 10A and 10B.

In another aspect, the ARQ feedback may be transmitted as an individual NACK on an unshared resource. In such an aspect, the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs. For example, as discussed supra, the UE 812 transmits an individual NACK (or an individual ACK) to the base station 802 on an unshared resource. For example, as discussed supra, the UE 812 may not specify which PDUs are missing, but instead may indicate in the status report to the base station 802 a number of missing PDUs and/or a byte size of missing PDUs.

At 910, the UE receives one or more repair PDUs based on the transmitted ARQ feedback. For example, as discussed supra, the base station 802 performs retransmission for one of more PDUs that were not unsuccessfully received to the UE 812 by transmitting the repair PDUs generated based on the ARQ feedback. At 912, the UE may perform additional features, as discussed infra in relation to FIG. 12.

FIG. 10A is a flowchart 1000 of a method of wireless communication, expanding from the flowchart 900 of FIG. 9, according to an aspect of the disclosure. The method may be performed by a UE. (e.g.， the UE 812, the apparatus 1302/1302') . As discussed supra, in an aspect, the ARQ feedback is transmitted as a group NACK on a shared resource. At 906, the flowchart 1000 expands from 906 of the flowchart 900 of FIG. 9. The flowchart 1000 further describes features in an aspect where the group NACK is transmitted via a physical uplink channel including at least one of a PUCCH or a PUSCH. For example, as discussed supra, when the UE 812 transmits a group NACK on a shared common resource, the UE 812 may transmit the group NACK on a physical uplink channel, such as a PUCCH or a shared PUSCH. In an aspect, at 1002, the UE selects a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource. For example, as discussed supra, multiple resources for the physical uplink channel may be allocated for different types of a group NACK, where each resource indicates a particular range for a number of missing PDUs or a byte size of missing PDUs. After performing the features of 1002, the UE may perform the features of 908 of the flowchart 900 in FIG. 9.

In an aspect, a resource for the physical uplink channel is scheduled based on a PDCCH. For example, as discussed supra, the resource for the physical uplink channel (for example, a PUCCH or a PUSCH) may be assigned by resource assignment information included in DCI carried by a PDCCH or RRC signaling (for example, a SIB) . In an aspect, the ARQ feedback is transmitted based on communication between an RLC layer of the UE and at least one of a physical layer or a media access control (MAC) layer of the UE. For example, as discussed supra, an RLC layer of the UE may indicate to a physical layer and/or a MAC layer of the UE to transmit a group NACK.

FIG. 10B is a flowchart 1050 of a method of wireless communication, expanding from the flowchart 900 of FIG. 9, according to an aspect of the disclosure. The method may be performed by a UE. (e.g., the UE 812, the apparatus 1302/1302') . As discussed supra, in an aspect, the ARQ feedback is transmitted as a group NACK on a shared resource. At 906, the flowchart 1050 expands from 906 of the flowchart 900 of FIG. 9. The flowchart 1000 further describes features in an aspect where the group NACK is transmitted via a shared PRACH. For example, as discussed supra, when the UE 812 transmits a group NACK on a shared common resource, the UE 812 may transmit the group NACK on a shared PRACH. In such an aspect, a resource for the shared PRACH on which the group NACK is transmitted is at least one of preconfigured or indicated through an RLC polling message. For example, as discussed supra, resource for the shared PRACH may be indicated by an RLC polling message (e.g., a RLC PDU) and/or may be preconfigured. In such an aspect, at 1052, the UE selects a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs. For example, as discussed supra, the UE 812 may use different preambles for a group NACK that are used to indicate different ranges for a number of missing PDUs or a byte size of missing PDUs. After performing the features of 1052, the UE may perform the features of 908 of the flowchart 900 in FIG. 9.

FIG. 11A is a flowchart 1100 of a method of wireless communication, expanding from the flowchart 900 of FIG. 9, according to an aspect of the disclosure. The method may be performed by a UE. (e.g., the UE 812, the apparatus 1302/1302') . The UE transmitting the ARQ feedback may include the features of the flowchart 1100. At 909, the flowchart 1100 expands from 909 of the flowchart 900 of FIG. 9. At 1102, the UE determines whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold. At 1104, the UE transmits a NACK based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold. For example, as discussed supra, the UE 812 may transmit a NACK (e.g., RLC NACK) when the UE 812 determines that a number of PDUs that were not successfully received (thus missing) and/or a byte size of PDUs that were not successfully received exceeds a preconfigured threshold. After performing the features of 1104, the UE may perform the features of 910 of the flowchart 900 in FIG. 9.

FIG. 11B is a flowchart 1150 of a method of wireless communication, expanding from the flowchart 900 of FIG. 9, according to an aspect of the disclosure. The method may be performed by a UE. (e.g., the UE 812, the apparatus 1302/1302') . The UE transmitting the ARQ feedback may include the features of the flowchart 1100. At 909, the flowchart 1150 expands from 909 of the flowchart 900 of FIG. 9. At 1152, the UE transmits a NACK when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, an RLC polling message, or a scheduled grant. For example, as discussed supra, the UE 812 may transmit a NACK (e.g., RLC NACK) periodically based on a preconfigured timer and/or may transmit a NACK based on a RLC polling message and/or may transmit a NACK based on a scheduled grant. After performing the features of 1152, the UE may perform the features of 910 of the flowchart 900 in FIG. 9.

FIG. 12 is a flowchart 1200 of a method of wireless communication, expanding from the flowchart 900 of FIG. 9, according to an aspect of the disclosure. The method may be performed by a UE. (e.g., the UE 812, the apparatus 1302/1302') . At 912, the flowchart 1200 expands from 912 of the flowchart 900 of FIG. 9. In this aspect of the disclosure, the RLC layer of the UE may be unavailable. At 1202, the UE transmits a HARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received. For example, as discussed supra, during the HARQ protocol, the UE sends a HARQ feedback with a group NACK to the base station if at least one PDU is missing. At 1204, the UE receives one or more repair PDUs based on the transmitted HARQ feedback. For example, as discussed supra, if the base station does not detect a low energy of group NACK, the base station may perform HARQ retransmission for repair PDUs to the UE. At 1206, the UE determines that the at least one PDU is successfully received based on the one or more repair PDUs. At 1208, the UE refrains from transmitting the ARQ feedback upon determination that the at least one PDU is successfully received. For example, as discussed supra, if the HARQ protocol has corrected the transmission errors (e.g., by HARQ retransmission) , the UE does not transmit an ARQ feedback to the base station.

FIG. 13 is a conceptual data flow diagram 1300 illustrating the data flow between different means/components in an exemplary apparatus 1302. The apparatus may be a UE. The apparatus includes a reception component 1304, a transmission component 1306, a feedback management component 1308, a data management component 1310, and a resource management component 1312.

The feedback management component 1308 receives (e.g., from the base station 1350) via the reception component 1304, at 1372 and 1374, a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling. The feedback configuration includes at least one of an indication of whether to transmit ARQ feedback, HARQ feedback, or both ARQ and HARQ feedback, a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback can be transmitted in an RRC idle state.

The data management component 1310 determines, at 1372 and 1376, that at least one broadcasted PDU is unsuccessfully received (e.g., via the reception component 1304) of one or more broadcasted PDUs.

The feedback management component 1308 transmits via the transmission component 1906, at 1380 and 1382, an ARQ feedback based on the determination at the data management component 1310 (e.g., at 1378) that the at least one broadcasted PDU is unsuccessfully received. In an aspect, the feedback management component 1308 determines whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold, and transmits via the transmission component 1306 a NACK based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold. In another aspect, the feedback management component 1308 transmits via the transmission component 1306 a NACK when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, an RLC polling message, or a scheduled grant.

In an aspect, the ARQ feedback may be transmitted as a group NACK on a shared resource. In one aspect, the group NACK is transmitted via a physical uplink channel including at least one of a PUCCH or a PUSCH. In such an aspect, a resource management component 1312 selects, at 1384, 1386, and 1388, a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource. In such an aspect, a resource for the physical uplink channel is scheduled based on a PDCCH. In such an aspect, the ARQ feedback is transmitted based on communication between an RLC layer of the UE and at least one of a physical layer or a MAC layer of the UE.

In another aspect, the group NACK is transmitted via a shared PRACH. In such an aspect, a resource for the shared PRACH on which the group NACK is transmitted is at least one of preconfigured or indicated through an RLC polling message. In such an aspect, the feedback management component 1308 selects, at 1378, a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs.

In another aspect, the ARQ feedback may be transmitted as an individual NACK on an unshared resource. In such an aspect, the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.

The data management component 1310 receives via the reception component 1304, at 1372 and 1376, one or more repair PDUs based on the transmitted ARQ feedback.

In an aspect, the RLC layer of the UE may be unavailable. In such an aspect, the feedback management component 1308 transmits via the transmission component 1306, at 1380 and 1382, a HARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received. The data management component 1310 receives via the reception component 1304, at 1372 and 1376, one or more repair PDUs based on the transmitted HARQ feedback. The data management component 1310 determines that the at least one PDU is successfully received based on the one or more repair PDUs. The feedback management component 1308 refrains from transmitting the ARQ feedback upon determination at the data management component 1310 (at 1378) that the at least one PDU is successfully received.

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of FIGs. 9-12. As such, each block in the aforementioned flowcharts of FIGs. 9-12 may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 14 is a diagram 1400 illustrating an example of a hardware implementation for an apparatus 1302' employing a processing system 1414. The processing system 1414 may be implemented with a bus architecture, represented generally by the bus 1424. The bus 1424 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1414 and the overall design constraints. The bus 1424 links together various circuits including one or more processors and/or hardware components, represented by the processor 1404, the

components

1304, 1306, 1308, 1310, 1312, and the computer-readable medium /memory 1406. The bus 1424 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1414 may be coupled to a transceiver 1410. The transceiver 1410 is coupled to one or more antennas 1420. The transceiver 1410 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1410 receives a signal from the one or more antennas 1420, extracts information from the received signal, and provides the extracted information to the processing system 1414, specifically the reception component 1304. In addition, the transceiver 1410 receives information from the processing system 1414, specifically the transmission component 1306, and based on the received information, generates a signal to be applied to the one or more antennas 1420. The processing system 1414 includes a processor 1404 coupled to a computer-readable medium /memory 1406. The processor 1404 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 1406. The software, when executed by the processor 1404, causes the processing system 1414 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 1406 may also be used for storing data that is manipulated by the processor 1404 when executing software. The processing system 1414 further includes at least one of the

components

1304, 1306, 1308, 1310, and 1312. The components may be software components running in the processor 1404, resident/stored in the computer readable medium /memory 1406, one or more hardware components coupled to the processor 1404, or some combination thereof. The processing system 1414 may be a component of the UE 650 and may include the memory 660 and/or at least one of the TX processor 668, the RX processor 656, and the controller/processor 659.

In one configuration, the apparatus 1302/1302' for wireless communication includes means for determining that at least one PDU is unsuccessfully received of one or more broadcasted PDUs, means for transmitting an ARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received, and means for receiving one or more repair PDUs based on the transmitted ARQ feedback. In an aspect, the means for transmitting the ARQ feedback is configured to determine whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold and to transmit a NACK based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold. In an aspect, the means for transmitting the ARQ feedback is configured to transmit a NACK when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, an RLC polling message, or a scheduled grant. The apparatus 1302/1302' may further include means for receiving a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling.

In an aspect where the group NACK is transmitted via a physical uplink channel including at least one of a PUCCH or a PUSCH, the apparatus 1302/1302' may further include means for selecting a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource. In an aspect where the group NACK is transmitted via a shared PRACH, the apparatus 1302/1302' may further include means for selecting a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs.

In an aspect where an RLC layer of the UE is unavailable, the apparatus 1302/1302' may further include means for transmitting a HARQ feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received, means for receiving one or more repair PDUs based on the transmitted HARQ feedback, means for determining that the at least one PDU is successfully received based on the one or more repair PDUs, and means for refraining from transmitting the ARQ feedback upon determination that the at least one PDU is successfully received.

The aforementioned means may be one or more of the aforementioned components of the apparatus 1302 and/or the processing system 1414 of the apparatus 1302' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1414 may include the TX Processor 668, the RX Processor 656, and the controller/processor 659. As such, in one configuration, the aforementioned means may be the TX Processor 668, the RX Processor 656, and the controller/processor 659 configured to perform the functions recited by the aforementioned means.

FIG. 15 is a flowchart 1500 of a method of wireless communication, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . At 1502, the eNB may transmit a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling. In an aspect, the feedback configuration includes at least one of: an indication of whether to transmit ARQ feedback, HARQ feedback, or both ARQ and HARQ feedback, a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback can be transmitted in a RRC idle state. For example, as discussed supra, a network entity (e.g., a base station 802 or an MCE) sends a feedback configuration to the UE 812 for an ARQ feedback transmitted by the UE 812, where the network entity may send the feedback configuration via a SIB and/or RRC signaling. For example, as discussed supra, the feedback configuration may include at least one of: an indication of whether to transmit an ARQ feedback (e.g., a group NACK based on the ARQ) , a HARQ feedback (e.g., a group NACK based on the HARQ) , or both the ARQ feedback and the HARQ feedback, a threshold corresponding to a number of missing PDUs or a byte size corresponding to the missing PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback (e.g., a group NACK based on the ARQ) can be transmitted in an RRC idle state.

At 1504, the eNB broadcasts at least one PDU. For example, as discussed supra, at 822, the base station 802 sends a broadcast transmission of data packets such as PDUs and the UE 812 receives the broadcast transmission from the base station 802. At 1506, the eNB receives an ARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received. For example, as discussed supra, if the UE 812 determines that the UE 812 has not successfully received (thus is missing) at least one of the PDUs, the UE 812 generates and transmits an ARQ feedback including a NACK to the base station 802. In an aspect, the ARQ feedback is received based on communication between an RLC layer of the base station and at least one of a physical layer or a MAC layer of the base station. For example, as discussed supra, at the base station 802, when a physical layer and/or a MAC layer receives a group NACK, the physical layer and/or the MAC layer indicates to the RLC layer of the base station 802 that the group NACK is received.

In one aspect, the ARQ feedback is received as a group NACK on a shared resource. In such an aspect, the group NACK is received via a physical uplink channel including at least one of a PUCCH, a PUSCH, or a shared PRACH. For example, as discussed supra, when the UE 812 transmits a group NACK on a shared common resource, the UE 812 may transmit the group NACK on a physical uplink channel, such as a PUCCH or a shared PUSCH, or may transmit the group NACK on a shared PRACH. In another aspect, the ARQ feedback is received as an individual NACK on an unshared resource. In such an aspect, the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs. For example, as discussed supra, the UE 812 transmits an individual NACK (or an individual ACK) to the base station 802 on an unshared resource. For example, as discussed supra, the UE 812 may not specify which PDUs are missing, but instead may indicate in the status report to the base station 802 a number of missing PDUs and/or a byte size of missing PDUs.

At 1508, the eNB may configure an MCS via a PDCCH based on the ARQ feedback. For example, as discussed supra, the network (e.g., the base station 802) may set an MCS, such that every time the network schedules a transmission, the network indicates the MCS in a PDCCH. At 1510, the eNB determines to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback. For example, as discussed supra, based on the ARQ feedback, the base station 802 performs retransmission for one of more PDUs that were not unsuccessfully received to the UE 812 by transmitting the repair PDUs generated based on the ARQ feedback.

At 1512, the eNB may perform additional features as discussed infra.

FIG. 16 is a flowchart 1600 of a method of wireless communication, expanding from the flowchart 1500 of FIG. 15, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . The flowchart 1600 describes features in an aspect where the at least one PDU is broadcasted via a SC-PTM transmission. At 1602, the eNB generates the one or more repair PDUs based on FEC. At 1604, the eNB broadcasts the one or more repair PDUs to one or more UEs in a cell operated by the base station. For example, as discussed supra, if an SC-PTM transmission is used for broadcast, based on the ARQ feedback, the base station 802 may add FEC redundancy for repair symbols (e.g., repair PDUs) and broadcasts the repair symbols to the UEs (e.g.,

UEs

812, 814, and 816) within a cell operated by the base station 802.

FIG. 17A is a flowchart 1700 of a method of wireless communication, expanding from the flowchart 1500 of FIG. 15, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . The flowchart 1700 describes features in an aspect where the at least one PDU is broadcasted via at least one of a MBSFN transmission or a PTM transmission. At 1702, the eNB generates the one or more repair PDUs based on FEC. At 1704, the eNB transmits the one or more repair PDUs to one or more other base stations that are associated with the base station. For example, as discussed supra, based on all of the ARQ feedbacks, the primary base station may apply FEC redundancy to generate repair symbols (e.g., repair PDUs) , and may send the repair symbols to other base stations. At 1706, the eNB broadcasts the one or more repair PDUs to one or more UEs. For example, as discussed supra, the primary base station and the other base stations transmit the repair symbols to the UEs within the MBSFN area served by the primary base station and the other base stations.

FIG. 17B is a flowchart 1730 of a method of wireless communication, expanding from the flowchart 1500 of FIG. 15, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . The flowchart 1730 describes features in an aspect where the at least one PDU is broadcasted via at least one of an MBSFN transmission or a PTM transmission. At 1732, the eNB receives the one or more repair PDUs from at least one other base station that is associated with the base station. For example, as discussed supra, may send the repair symbols to other base stations. At 1743, the eNB broadcasts the one or more repair PDUs to one or more UEs upon receiving the one or more repair PDUs from the at least one other base station. For example, as discussed supra, the primary base station and the other base stations transmit the repair symbols to the UEs within the MBSFN area served by the primary base station and the other base stations

FIG. 17C is a flowchart 1760 of a method of wireless communication, expanding from the flowchart 1500 of FIG. 15, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . The flowchart 1760 describes features in an aspect where the at least one PDU is broadcasted via at least one of an MBSFN transmission or a PTM transmission. At 1762, the eNB forwards the ARQ feedback to an MCE. For example, as discussed supra, if an MCE is used, the MCE receives the ARQ feedbacks from different UEs via base stations. At 1764, the eNB receives from the MCE an indication to generate the one or more repair PDUs based on the ARQ feedback. For example, as discussed supra, based on all of the ARQ feedbacks, the MCE indicates to each of the base stations to generate repair symbols (e.g., repair PDUs) and to send the repair symbols to the UEs within the MBSFN area served by the base stations. At 1766, the eNB generates the one or more repair PDUs based on FEC and based on the indication. At 1768, the eNB broadcasts the one or more repair PDUs to one or more UEs. For example, as discussed supra, when base stations serving the MBSFN area receive such indication from the MCE, the base stations generate the repair symbols and send the repair symbols to the UEs within the MBSFN area.

FIG. 18 is a flowchart 1800 of a method of wireless communication, expanding from the flowchart 1500 of FIG. 15, according to an aspect of the disclosure. The method may be performed by an eNB. (e.g., the base station 802, the apparatus 1902/1902') . In this aspect of the disclosure, the RLC layer of the UE may be unavailable. At 1802, the eNB receives a HARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received. For example, as discussed supra, during the HARQ protocol, the UE sends a HARQ feedback with a group NACK to the base station if at least one PDU is missing. At 1804, the eNB determines to transmit one or more repair PDUs generated in response to the HARQ feedback. At 1806, the eNB determines that a signal energy associated with the HARQ feedback is below an energy threshold. At 1808, the eNB refrains from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold. For example, as discussed supra, the base station may early terminate the HARQ protocol if the base station detects low energy of group NACK (meaning that a small number of UEs are sending NACK) in the HARQ feedback from the UE. For example, as discussed supra, if the base station does not detect a low energy of group NACK, the base station may perform HARQ retransmission for repair PDUs to the UE.

FIG. 19 is a conceptual data flow diagram 1900 illustrating the data flow between different means/components in an exemplary apparatus 1902. The apparatus may be an eNB. The apparatus includes a reception component 1904, a transmission component 1906, a feedback configuration component 1908, a data management component 1910, and a feedback management component 1912.

The feedback configuration component 1908 may transmit via the transmission component 1906, at 1972 and 1974, a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling. In an aspect, the feedback configuration includes at least one of: an indication of whether to transmit ARQ feedback, HARQ feedback, or both ARQ and HARQ feedback, a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, information indicating timing information for sending the ARQ feedback, or an indication whether the ARQ feedback can be transmitted in a RRC idle state.

The data management component 1910 broadcasts via the transmission component 1906, at 1976 and 1974, at least one PDU. The feedback management component 1912 receives via the reception component 1904, at 1978 and 1980, an ARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received. In an aspect, the ARQ feedback is received based on communication between an RLC layer of the eNB and at least one of a physical layer or a MAC layer of the base station. The feedback management component 1912 may configure an MCS via a PDCCH based on the ARQ feedback.

In one aspect, the ARQ feedback is received as a group NACK on a shared resource. In such an aspect, the group NACK is received via a physical uplink channel including at least one of a PUCCH, a PUSCH, or a shared PRACH.

In another aspect, the ARQ feedback is received as an individual NACK on an unshared resource. In such an aspect, the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.

The data management component 1910 determines to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.

In an aspect where the at least one PDU is broadcasted via a SC-PTM transmission, the data management component 1910 generates the one or more repair PDUs based on FEC (e.g., at 1982) , and broadcasts via the transmission component 1906, at 1976 and 1974, the one or more repair PDUs to one or more UEs (e.g., the UE 1950) in a cell operated by the eNB.

According to one approach, in an aspect where the at least one PDU is broadcasted via at least one of a MBSFN transmission or a PTM transmission, the data management component 1910 generates the one or more repair PDUs based on FEC (e.g., at 1982) , and transmits via the transmission component 1906, at 1976 and 1974, the one or more repair PDUs to one or more other base stations (e.g., the base station 1940) that are associated with the eNB. In such an aspect, the data management component 1910 broadcasts the one or more repair PDUs to one or more UEs.

According to another approach, in an aspect where the at least one PDU is broadcasted via at least one of an MBSFN transmission or a PTM transmission, the data management component 1910 receives via the reception component 1904 (e.g., at 1984 and 1986) the one or more repair PDUs from at least one other base station (e.g., the base station 1940) that is associated with the eNB, and broadcasts via the transmission component 1906 at 1976 and 1974 the one or more repair PDUs to one or more UEs (e.g., the UE 1950) upon receiving the one or more repair PDUs from the at least one other base station (e.g., the base station 1940) .

According to another approach, in an aspect where the at least one PDU is broadcasted via at least one of an MBSFN transmission or a PTM transmission, the feedback management component 1912 forwards via the transmission component 1906, at 1988 and 1990, the ARQ feedback to an MCE (e.g., the MCE 1960) . In such an aspect, the data management component 1910 receives from the MCE via the reception component 1904, at 1992 and 1986, an indication to generate the one or more repair PDUs based on the ARQ feedback, and generates the one or more repair PDUs based on FEC and based on the indication. In such an aspect, the data management component 1910 broadcasts via the transmission component 1906, at 1976 and 1974, the one or more repair PDUs to one or more UEs (e.g., the UE 1950) .

In an aspect where the RLC layer of the UE may be unavailable, the feedback management component 1912 receives via the reception component 1904, at 1978 and 1980, a HARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received. In such an aspect, the data management component 1910 at 1982 determines to transmit one or more repair PDUs generated in response to the HARQ feedback. In such an aspect, the feedback management component 1912 at 1982 may determine that a signal energy associated with the HARQ feedback is below an energy threshold, and may refrain from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold.

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of FIGs. 15-18. As such, each block in the aforementioned flowcharts of FIGs. 15-18 may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 20 is a diagram 2000 illustrating an example of a hardware implementation for an apparatus 1902' employing a processing system 2014. The processing system 2014 may be implemented with a bus architecture, represented generally by the bus 2024. The bus 2024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2014 and the overall design constraints. The bus 2024 links together various circuits including one or more processors and/or hardware components, represented by the processor 2004, the

components

1904, 1906, 1908, 1910, 1912, and the computer-readable medium /memory 2006. The bus 2024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2014 may be coupled to a transceiver 2010. The transceiver 2010 is coupled to one or more antennas 2020. The transceiver 2010 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2010 receives a signal from the one or more antennas 2020, extracts information from the received signal, and provides the extracted information to the processing system 2014, specifically the reception component 1904. In addition, the transceiver 2010 receives information from the processing system 2014, specifically the transmission component 1906, and based on the received information, generates a signal to be applied to the one or more antennas 2020. The processing system 2014 includes a processor 2004 coupled to a computer-readable medium /memory 2006. The processor 2004 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 2006. The software, when executed by the processor 2004, causes the processing system 2014 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 2006 may also be used for storing data that is manipulated by the processor 2004 when executing software. The processing system 2014 further includes at least one of the

components

1904, 1906, 1908, 1910, and 1912. The components may be software components running in the processor 2004, resident/stored in the computer readable medium /memory 2006, one or more hardware components coupled to the processor 2004, or some combination thereof. The processing system 2014 may be a component of the eNB 610 and may include the memory 676 and/or at least one of the TX processor 616, the RX processor 670, and the controller/processor 675.

In one configuration, the apparatus 1902/1902' for wireless communication includes means for broadcasting at least one PDU, means for receiving an ARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received, and means for determining to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback. In an aspect, the apparatus 1902/1902' may further include means for transmitting a feedback configuration for the ARQ feedback via at least one SIB or RRC signaling. In an aspect, the apparatus 1902/1902' may further include means for configuring an MCS via a PDCCH based on the ARQ feedback. In an aspect where the at least one PDU is broadcasted via a SC-PTM transmission, the apparatus 1902/1902' may further include means for generating the one or more repair PDUs based on FEC, and means for broadcasting the one or more repair PDUs to one or more UEs in a cell operated by the apparatus 1902/1902'.

In an aspect, the apparatus 1902/1902' may further include means for generating the one or more repair PDUs based on FEC, means for transmitting the one or more repair PDUs to one or more other base stations that are associated with the apparatus 1902/1902', and means for broadcasting the one or more repair PDUs to one or more UEs. In an aspect, the apparatus 1902/1902' may further include means for receiving the one or more repair PDUs from at least one other base station that is associated with the apparatus 1902/1902', and means for broadcasting the one or more repair PDUs to one or more UEs upon receiving the one or more repair PDUs from the at least one other base station. In an aspect, the apparatus 1902/1902' may further include means for forwarding the ARQ feedback to an MCE, means for receiving from the MCE an indication to generate the one or more repair PDUs based on the ARQ feedback, means for generating the one or more repair PDUs based on FEC and based on the indication, and means for broadcasting the one or more repair PDUs to one or more UEs.

In an aspect, the apparatus 1902/1902' may further include means for receiving a HARQ feedback indicating that the at least one broadcasted PDU is unsuccessfully received, and means for determining to transmit one or more repair PDUs generated in response to the HARQ feedback. In such an aspect, the apparatus 1902/1902' may further include means for determining that a signal energy associated with the HARQ feedback is below an energy threshold, and means for refraining from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold.

The aforementioned means may be one or more of the aforementioned components of the apparatus 1902 and/or the processing system 2014 of the apparatus 1902' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 2014 may include the TX Processor 616, the RX Processor 670, and the controller/processor 675. As such, in one configuration, the aforementioned means may be the TX Processor 616, the RX Processor 670, and the controller/processor 675 configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in the processes /flowcharts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “at least one of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “at least one of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

Claims

A method for wireless communication by a user equipment (UE) , comprising:

determining that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs； and

transmitting an automatic repeat request (ARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.
The method of claim 1, further comprising receiving one or more repair PDUs based on the transmitted ARQ feedback.
The method of claim 1, wherein the transmitting the ARQ feedback comprises:

determining whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold； and

transmitting a negative acknowledgement (NACK) based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold.
The method of claim 1, wherein the transmitting the ARQ feedback comprises:

transmitting a negative acknowledgement (NACK) when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, a radio link control (RLC) polling message, or a scheduled grant.
The method of claim 1, further comprising receiving a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The method of claim 5, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The method of claim 1, wherein the ARQ feedback is transmitted as a group negative acknowledgement (NACK) on a shared resource.
The method of claim 7, wherein the group NACK is transmitted via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) .
The method of claim 8, further comprising selecting a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource.
The method of claim 8, wherein a resource for the physical uplink channel is scheduled based on a physical downlink control channel (PDCCH) .
The method of claim 8, wherein the ARQ feedback is transmitted based on communication between a radio link control (RLC) layer of the UE and at least one of a physical layer or a media access control (MAC) layer of the UE.
The method of claim 7, wherein the group NACK is transmitted via a shared physical random access channel (PRACH) .
The method of claim 12, wherein a resource for the shared PRACH on which the group NACK is transmitted is at least one of preconfigured or indicated through a radio link control (RLC) polling message.
The method of claim 12, further comprising selecting a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs.
The method of claim 1, wherein the ARQ feedback is transmitted as an individual NACK on an unshared resource.
The method of claim 15, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The method of claim 1, further comprising:

transmitting a hybrid ARQ (HARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received；

receiving one or more repair PDUs based on the transmitted HARQ feedback；

determining that the at least one PDU is successfully received based on the one or more repair PDUs； and

refraining from transmitting the ARQ feedback upon determination that the at least one PDU is successfully received.
The method of claim 17, wherein a radio link control (RLC) layer of the UE is unavailable.
A method for wireless communication by a base station, comprising:

broadcasting at least one protocol data unit (PDU) ；

receiving an automatic repeat request (ARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

determining to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.
The method of claim 19, further comprising:

transmitting a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The method of claim 19, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The method of claim 19, further comprising:

configuring a modulation and coding scheme (MCS) via a physical downlink control channel (PDCCH) based on the ARQ feedback.
The method of claim 19, wherein the ARQ feedback is received as a group negative acknowledgement (NACK) on a shared resource.
The method of claim 23, wherein the group NACK is received via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) , a physical uplink shared channel (PUSCH) , or a shared physical random access channel (PRACH) .
The method of claim 19, wherein the ARQ feedback is received as an individual negative acknowledgement (NACK) on an unshared resource.
The method of claim 25, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The method of claim 19, wherein the ARQ feedback is received based on communication between a radio link control (RLC) layer of the base station and at least one of a physical layer or a media access control (MAC) layer of the base station.
The method of claim 19, wherein the at least one PDU is broadcasted via a single-cell point-to-multipoint (SC-PTM) transmission, the method further comprising:

generating the one or more repair PDUs based on forward error correction (FEC) ； and

broadcasting the one or more repair PDUs to one or more user equipments (UEs) in a cell operated by the base station.
The method of claim 19, wherein the at least one PDU is broadcasted via at least one of a multicast-broadcast single-frequency network (MBSFN) transmission or a point-to-multipoint (PTM) transmission.
The method of claim 29, further comprising:

generating the one or more repair PDUs based on forward error correction (FEC) ；

transmitting the one or more repair PDUs to one or more other base stations that are associated with the base station； and

broadcasting the one or more repair PDUs to one or more user equipments (UEs) .
The method of claim 29, further comprising:

receiving the one or more repair PDUs from at least one other base station that is associated with the base station； and

broadcasting the one or more repair PDUs to one or more user equipments (UEs) upon receiving the one or more repair PDUs from the at least one other base station.
The method of claim 29, further comprising:

forwarding the ARQ feedback to a multicast coordination entity (MCE) ； and

receiving from the MCE an indication to generate the one or more repair PDUs based on the ARQ feedback；

generating the one or more repair PDUs based on forward error correction (FEC) and based on the indication； and

broadcasting the one or more repair PDUs to one or more user equipments (UEs) .
The method of claim 19, further comprising:

receiving a hybrid ARQ (HARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

determining to transmit one or more repair PDUs generated in response to the HARQ feedback.
The method of claim 33, further comprising:

determining that a signal energy associated with the HARQ feedback is below an energy threshold； and

refraining from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold.
A user equipment (UE) for wireless communication, comprising:

means for determining that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs； and

means for transmitting an automatic repeat request (ARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.
The UE of claim 35, further comprising means for receiving one or more repair PDUs based on the transmitted ARQ feedback.
The UE of claim 35, wherein the means for transmitting the ARQ feedback is configured to:

determine whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold； and

transmit a negative acknowledgement (NACK) based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold.
The UE of claim 35, wherein the means for transmitting the ARQ feedback is configured to:

transmit a negative acknowledgement (NACK) when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, a radio link control (RLC) polling message, or a scheduled grant.
The UE of claim 35, further comprising means for receiving a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The UE of claim 39, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The UE of claim 35, wherein the ARQ feedback is transmitted as a group negative acknowledgement (NACK) on a shared resource.
The UE of claim 41, wherein the group NACK is transmitted via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) .
The UE of claim 42, further comprising means for selecting a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource.
The UE of claim 42, wherein a resource for the physical uplink channel is scheduled based on a physical downlink control channel (PDCCH) .
The UE of claim 42, wherein the ARQ feedback is transmitted based on communication between a radio link control (RLC) layer of the UE and at least one of a physical layer or a media access control (MAC) layer of the UE.
The UE of claim 41, wherein the group NACK is transmitted via a shared physical random access channel (PRACH) .
The UE of claim 46, wherein a resource for the shared PRACH on which the group NACK is transmitted is at least one of preconfigured or indicated through a radio link control (RLC) polling message.
The UE of claim 46, further comprising means for selecting a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs.
The UE of claim 35, wherein the ARQ feedback is transmitted as an individual NACK on an unshared resource.
The UE of claim 49, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The UE of claim 35, further comprising:

means for transmitting a hybrid ARQ (HARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received；

means for receiving one or more repair PDUs based on the transmitted HARQ feedback；

means for determining that the at least one PDU is successfully received based on the one or more repair PDUs； and

means for refraining from transmitting the ARQ feedback upon determination that the at least one PDU is successfully received.
The UE of claim 51, wherein a radio link control (RLC) layer of the UE is unavailable.
A base station for wireless communication, comprising:

means for broadcasting at least one protocol data unit (PDU) ；

means for receiving an automatic repeat request (ARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

means for determining to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.
The base station of claim 53, further comprising:

means for transmitting a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The base station of claim 53, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The base station of claim 53, further comprising:

means for configuring a modulation and coding scheme (MCS) via a physical downlink control channel (PDCCH) based on the ARQ feedback.
The base station of claim 53, wherein the ARQ feedback is received as a group negative acknowledgement (NACK) on a shared resource.
The base station of claim 57, wherein the group NACK is received via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) , a physical uplink shared channel (PUSCH) , or a shared physical random access channel (PRACH) .
The base station of claim 53, wherein the ARQ feedback is received as an individual negative acknowledgement (NACK) on an unshared resource.
The base station of claim 59, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The base station of claim 53, wherein the ARQ feedback is received based on communication between a radio link control (RLC) layer of the base station and at least one of a physical layer or a media access control (MAC) layer of the base station.
The base station of claim 53, wherein the at least one PDU is broadcasted via a single-cell point-to-multipoint (SC-PTM) transmission, the base station further comprising:

means for generating the one or more repair PDUs based on forward error correction (FEC) ； and

means for broadcasting the one or more repair PDUs to one or more user equipments (UEs) in a cell operated by the base station.
The base station of claim 53, wherein the at least one PDU is broadcasted via at least one of a multicast-broadcast single-frequency network (MBSFN) transmission or a point-to-multipoint (PTM) transmission.
The base station of claim 63, further comprising:

means for generating the one or more repair PDUs based on forward error correction (FEC) ；

means for transmitting the one or more repair PDUs to one or more other base stations that are associated with the base station； and

means for broadcasting the one or more repair PDUs to one or more user equipments (UEs) .
The base station of claim 63, further comprising:

means for receiving the one or more repair PDUs from at least one other base station that is associated with the base station； and

means for broadcasting the one or more repair PDUs to one or more user equipments (UEs) upon receiving the one or more repair PDUs from the at least one other base station.
The base station of claim 63, further comprising:

means for forwarding the ARQ feedback to a multicast coordination entity (MCE) ； and

means for receiving from the MCE an indication to generate the one or more repair PDUs based on the ARQ feedback；

means for generating the one or more repair PDUs based on forward error correction (FEC) and based on the indication； and

means for broadcasting the one or more repair PDUs to one or more user equipments (UEs) .
The base station of claim 53, further comprising:

means for receiving a hybrid ARQ (HARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

means for determining to transmit one or more repair PDUs generated in response to the HARQ feedback.
The base station of claim 67, further comprising:

means for determining that a signal energy associated with the HARQ feedback is below an energy threshold； and

means for refraining from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold.
A user equipment (UE) for wireless communication, comprising:

a memory； and

at least one processor coupled to the memory and configured to:

determine that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs； and

transmit an automatic repeat request (ARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.
The UE of claim 69, wherein the at least one processor is further configured to receive one or more repair PDUs based on the transmitted ARQ feedback.
The UE of claim 69, wherein the at least one processor configured to transmit the ARQ feedback is configured to:

determine whether a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs exceeds a threshold； and

transmit a negative acknowledgement (NACK) based on the determination whether the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs exceeds the threshold.
The UE of claim 69, wherein the at least one processor configured to transmit the ARQ feedback is configured to:

transmit a negative acknowledgement (NACK) when one or more of the PDUs is unsuccessfully received, wherein the NACK is transmitted based on at least one of a preconfigured transmission time, a radio link control (RLC) polling message, or a scheduled grant.
The UE of claim 69, wherein the at least one processor is further configured to receive a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The UE of claim 73, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The UE of claim 69, wherein the ARQ feedback is transmitted as a group negative acknowledgement (NACK) on a shared resource.
The UE of claim 75, wherein the group NACK is transmitted via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) .
The UE of claim 76, wherein the at least one processor is further configured to select a radio resource of a plurality of radio resources within the shared resource for transmitting the group NACK based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the group NACK being transmitted on the selected resource.
The UE of claim 76, wherein a resource for the physical uplink channel is scheduled based on a physical downlink control channel (PDCCH) .
The UE of claim 76, wherein the ARQ feedback is transmitted based on communication between a radio link control (RLC) layer of the UE and at least one of a physical layer or a media access control (MAC) layer of the UE.
The UE of claim 75, wherein the group NACK is transmitted via a shared physical random access channel (PRACH) .
The UE of claim 80, wherein a resource for the shared PRACH on which the group NACK is transmitted is at least one of preconfigured or indicated through a radio link control (RLC) polling message.
The UE of claim 80, wherein the at least one processor is further configured to select a preamble of a plurality of preambles based on a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs, the ARQ feedback being transmitted with the selected preamble in order to indicate the number of unsuccessfully received PDUs or the number of bytes corresponding to the unsuccessfully received PDUs.
The UE of claim 69, wherein the ARQ feedback is transmitted as an individual NACK on an unshared resource.
The UE of claim 83, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The UE of claim 69, wherein the at least one processor is further configured to:

transmit a hybrid ARQ (HARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received；

receive one or more repair PDUs based on the transmitted HARQ feedback；

determine that the at least one PDU is successfully received based on the one or more repair PDUs； and

refrain from transmitting the ARQ feedback upon determination that the at least one PDU is successfully received.
The UE of claim 85, wherein a radio link control (RLC) layer of the UE is unavailable.
A base station for wireless communication, comprising:

a memory； and

at least one processor coupled to the memory and configured to:

broadcast at least one protocol data unit (PDU) ；

receive an automatic repeat request (ARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

determine to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.
The base station of claim 87, wherein the at least one processor is configured to:

transmit a feedback configuration for the ARQ feedback via at least one system information block (SIB) or radio resource control (RRC) signaling.
The base station of claim 87, wherein the feedback configuration includes at least one of:

an indication of whether to transmit ARQ feedback, hybrid ARQ (HARQ) feedback, or both ARQ and HARQ feedback,

a threshold corresponding to a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs,

information indicating timing information for sending the ARQ feedback, or

an indication whether the ARQ feedback can be transmitted in a radio control resource (RRC) idle state.
The base station of claim 87, wherein the at least one processor is configured to:

configure a modulation and coding scheme (MCS) via a physical downlink control channel (PDCCH) based on the ARQ feedback.
The base station of claim 87, wherein the ARQ feedback is received as a group negative acknowledgement (NACK) on a shared resource.
The base station of claim 91, wherein the group NACK is received via a physical uplink channel including at least one of a physical uplink control channel (PUCCH) , a physical uplink shared channel (PUSCH) , or a shared physical random access channel (PRACH) .
The base station of claim 87, wherein the ARQ feedback is received as an individual negative acknowledgement (NACK) on an unshared resource.
The base station of claim 93, wherein the individual NACK includes information indicating a number of unsuccessfully received PDUs or a number of bytes corresponding to the unsuccessfully received PDUs.
The base station of claim 87, wherein the ARQ feedback is received based on communication between a radio link control (RLC) layer of the base station and at least one of a physical layer or a media access control (MAC) layer of the base station.
The base station of claim 87, wherein the at least one PDU is broadcasted via a single-cell point-to-multipoint (SC-PTM) transmission, and wherein the at least one processor is configured to:

generate the one or more repair PDUs based on forward error correction (FEC) ； and

broadcast the one or more repair PDUs to one or more user equipments (UEs) in a cell operated by the base station.
The base station of claim 87, wherein the at least one PDU is broadcasted via at least one of a multicast-broadcast single-frequency network (MBSFN) transmission or a point-to-multipoint (PTM) transmission.
The base station of claim 97, wherein the at least one processor is configured to:

generate the one or more repair PDUs based on forward error correction (FEC) ；

transmit the one or more repair PDUs to one or more other base stations that are associated with the base station； and

broadcast the one or more repair PDUs to one or more user equipments (UEs) .
The base station of claim 97, wherein the at least one processor is configured to:

receive the one or more repair PDUs from at least one other base station that is associated with the base station； and

broadcast the one or more repair PDUs to one or more user equipments (UEs) upon receiving the one or more repair PDUs from the at least one other base station.
The base station of claim 97, wherein the at least one processor is configured to:

forward the ARQ feedback to a multicast coordination entity (MCE) ； and

receive from the MCE an indication to generate the one or more repair PDUs based on the ARQ feedback；

generate the one or more repair PDUs based on forward error correction (FEC) and based on the indication； and

broadcast the one or more repair PDUs to one or more user equipments (UEs) .
The base station of claim 87, wherein the at least one processor is configured to:

receive a hybrid ARQ (HARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

determine to transmit one or more repair PDUs generated in response to the HARQ feedback.
The base station of claim 101, wherein the at least one processor is configured to:

determine that a signal energy associated with the HARQ feedback is below an energy threshold； and

refrain from generating a repair PDU associated with the HARQ feedback based on the determination that the signal energy is below the energy threshold.
A computer-readable medium storing computer executable code for wireless communication, for a user equipment (UE) , comprising code for:

determining that at least one broadcasted protocol data unit (PDU) is unsuccessfully received of one or more broadcasted PDUs； and

transmitting an automatic repeat request (ARQ) feedback based on the determination that the at least one broadcasted PDU is unsuccessfully received.
A computer-readable medium storing computer executable code for wireless communication, for a base station, comprising code for:

broadcasting at least one protocol data unit (PDU) ；

receiving an automatic repeat request (ARQ) feedback indicating that the at least one broadcasted PDU is unsuccessfully received； and

determining to broadcast one or more repair PDUs based on the ARQ feedback, the one or more repair PDUs being based on the received ARQ feedback.