US20140348077A1

US20140348077A1 - Control channel design for new carrier type (nct)

Info

Publication number: US20140348077A1
Application number: US14/126,020
Authority: US
Inventors: Xiaogang Chen; Seunghee Han; Yuan Zhu; Jong-Kae Fwu
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 2012-12-03
Filing date: 2013-09-27
Publication date: 2014-11-27
Also published as: JP6579713B2; WO2014088662A1; US20170078909A1; CN104769870B; US20180316371A1; US20150289251A1; WO2014089090A1; EP2926489A4; EP2926477A1; US10277264B2; CN107682099A; CN104769869B; CN104782167A; EP2926588A1; CN104756581A; US20150256279A1; WO2014089110A1; US9900033B2; EP3185446A1; US9723508B2

Abstract

Technology for allocating at least one physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT) is disclosed. In one method, a number of bits associated with channel coding for an acknowledgement (ACK) or negative acknowledgement (NACK) in the EPHICH transmission is determined. A plurality of modulation symbols for each ACK or NACK in the EPHICH transmission is generated based in part on the number of bits associated with the ACK or NACK. The plurality of modulation symbols are mapped as EPHICH quadrants in one or more resource element blocks (REGs), wherein the EPHICH quadrants are mapped to a plurality of physical resource blocks (PRBs) allocated for EPHICH to increase frequency diversity gain.

Description

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Patent Application No. 61/732,851, filed Dec. 3, 2012 with a docket number of P51116Z, the entire specification of which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g. a transmission station or a transceiver node) and a wireless device (e.g. a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in an uplink (UL) transmission. Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3GPP) long term evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as Wi-Fi.
In 3GPP radio access network (RAN) LTE systems, the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). The downlink (DL) transmission can be a communication from the node (e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL) transmission can be a communication from the wireless device to the node.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention; and, wherein:

FIG. 1 illustrates a block diagram of an orthogonal frequency division multiple access (OFDMA) frame structure in accordance with an example;

FIG. 2 illustrates the generation of an enhanced physical hybrid automatic repeat request (ARQ) indicator channel (EPHICH) and EPHICH quadrant to resource element group (REG) mapping in accordance with an example

FIG. 3 illustrates the generation of an enhanced physical hybrid automatic repeat request (ARQ) indicator channel (EPHICH) for frequency division multiplexed (FDMed) or time division multiplexed (TDMed) mapping in accordance with an example

FIGS. 4A and 4B illustrate an enhanced physical hybrid automatic repeat request (ARQ) indicator channel (EPHICH) that is frequency division multiplexed (FDMed) or time division multiplexed (TDMed) being multiplexed with an enhanced physical downlink control channel (EPDCCH) in accordance with an example;

FIG. 5 illustrates an enhanced physical hybrid automatic repeat request (ARQ) indicator channel (EPHICH) multiplexed with an enhanced physical downlink control channels (EPDCCH) with an enhanced resource element group (EREG) granularity in accordance with an example;

FIG. 6 depicts functionality of computer circuitry of an evolved node B (eNB) operable to provide physical broadcast channel (PBCH) transmissions and physical downlink shared channel (PDSCH) transmissions in a New Carrier Type (NCT) in accordance with an example;

FIG. 7 depicts a flow chart of a method for allocating at least one physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT) in accordance with an example;

FIG. 8 depicts functionality of computer circuitry of a node operable to assign a plurality of physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT) in accordance with an example; and

FIG. 9 illustrates a block diagram of a mobile device (e.g., a user equipment) in accordance with an example.

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

DEFINITIONS

As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.

Example Embodiments

An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter. The following definitions are provided for clarity of the overview and embodiments described below.
FIG. 1 illustrates a downlink radio frame structure type 2. In the example, a radio frame 100 of a signal used to transmit the data can be configured to have a duration, T_f, of 10 milliseconds (ms). Each radio frame can be segmented or divided into ten subframes 110 i that are each 1 ms long. Each subframe can be further subdivided into two slots 120 a and 120 b, each with a duration. T_slot, of 0.5 ms. The first slot (#0) 120 a can include a legacy physical downlink control channel (PDCCH) 160 and/or a physical downlink shared channel (PDSCH) 166, and the second slot (#1) 120 b can include data transmitted using the PDSCH.
Each slot for a component carrier (CC) used by the node and the wireless device can include multiple resource blocks (RBs) 130 a, 130 b, 130 i, 130 m, and 130 n based on the CC frequency bandwidth. The CC can have a carrier frequency having a bandwidth and center frequency. Each subframe of the CC can include downlink control information (DCI) found in the legacy PDCCH. The legacy PDCCH in the control region can include one to three columns of the first OFDM symbols in each subframe or RB, when a legacy PDCCH is used. The remaining 11 to 13 OFDM symbols (or 14 OFDM symbols, when legacy PDCCH is not used) in the subframe may be allocated to the PDSCH for data (for short or normal cyclic prefix).
The control region can include physical control format indicator channel (PCFICH), physical hybrid automatic repeat request (hybrid-ARQ) indicator channel (PHICH), and the PDCCH. The control region has a flexible control design to avoid unnecessary overhead. The number of OFDM symbols in the control region used for the PDCCH can be determined by the control channel format indicator (CFI) transmitted in the physical control format indicator channel (PCFICH). The PCFICH can be located in the first OFDM symbol of each subframe. The PCFICH and PHICH can have priority over the PDCCH, so the PCFICH and PHICH are scheduled prior to the PDCCH.
Each RB (physical RB or PRB) 130 i can include 12-15 kHz subcarriers 136 (on the frequency axis) and 6 or 7 orthogonal frequency-division multiplexing (OFDM) symbols 132 (on the time axis) per slot. The RB can use seven OFDM symbols if a short or normal cyclic prefix is employed. The RB can use six OFDM symbols if an extended cyclic prefix is used. The resource block can be mapped to 84 resource elements (REs) 140 i using short or normal cyclic prefixing, or the resource block can be mapped to 72 REs (not shown) using extended cyclic prefixing. The RE can be a unit of one OFDM symbol 142 by one subcarrier (i.e., 15 kHz) 146.
Each RE can transmit two bits 150 a and 150 b of information in the case of quadrature phase-shift keying (QPSK) modulation. Other types of modulation may be used, such as 16 quadrature amplitude modulation (QAM) or 64 QAM to transmit a greater number of bits in each RE, or bi-phase shift keying (BPSK) modulation to transmit a lesser number of bits (a single bit) in each RE. The RB can be configured for a downlink transmission from the eNodeB to the UE, or the RB can be configured for an uplink transmission from the UE to the eNodeB.
Downlink physical channels for transmitting information transferred to a downlink transport channel to a radio interval between the UE and the network include a Physical Broadcast Channel (PBCH) for transmitting BCH information, a Physical Downlink Shared Channel (PDSCH) for transmitting downlink shared channel (SCH) infomnnation, and a Physical Downlink Control Channel (PDCCH) (also called a DL L1/L2 control channel) for transmitting control information, such as DL/UL Scheduling Grant information, received from first and second layers (L1 and L2).
In general, the PBCH may broadcast a limited number of parameters essential for initial access of the cell such as downlink system bandwidth, the Physical Hybrid ARQ Indicator Channel structure, and the most significant eight-bits of the System Frame Number. These parameters may be carried in a Master Information Block which is 14 bits long. The PBCH may be designed to be detectable without prior knowledge of system bandwidth and to be accessible at the cell edge. The MIB can be coded at a very low coding rate and mapped to the 72 center sub-carriers (6 RBs) of the OFDM structure. The PBCH transmission is spread over four 10 ms frames (over subframe #0) to span a 40 ms period.
In general, the PDSCH is the main downlink data-bearing channel in LTE. The PDSCH can be used to transmit all user data, as well as for broadcast system information that is not communicated on the PBCH. In addition, the user data can be mapped to spatial layers according to the type of multi-antenna technique (e.g. closed loop spatial multiplexing, open-loop, spatial multiplexing, transmit diversity, etc.) and then mapped to a modulation symbol which includes Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM) and 64 QAM.
In one example, the PCFICH can communicate the Control Frame Indicator (CFI), which includes the number of OFDM symbols used for control channel transmission in each subframe (typically 1, 2, or 3). The 32-bit long CFI is mapped to 16 Resource Elements in the first OFDM symbol of each downlink frame using QPSK modulation.
In one configuration, the PHICH can communicate the HARQ ACK/NAK, which indicates to the UE whether the eNodeB correctly received uplink user data carried on the PUSCH. In addition. BPSK modulation can be used with a repetition factor of 3 to increase robustness.
In one example, the PDCCH can communicate the resource assignment for UEs which are contained in a Downulink Control Information (DCI) message. Multiple wireless devices can be scheduled in one subframe of a radio frame. Therefore, multiple DCI messages can be sent using multiple PDCCHs. QPSK modulation can be used for the PDCCH. Four QPSK symbols can be mapped to each REG. The DCI information in a PDCCH can be transmitted using one or more control channel elements (CCE). A CCE can be comprised of a group of resource element groups (REGs). A legacy CCE can include up to nine REGs. Each legacy REG can be comprised of four resource elements (REs). Each resource element can include two bits of information when quadrature modulation is used. Therefore, a legacy CCE can include up to 72 bits of information. When more than 72 bits of information are needed to convey the DCI message, multiple CCEs can be employed. The use of multiple CCEs can be referred to as an aggregation level. In one example, the aggregation levels can be defined as 1, 2, 4 or 8 consecutive CCEs allocated to one PDCCH.
The legacy PDCCH can create limitations to advances made in other areas of wireless communication. For example, mapping of CCEs to subframes in OFDM symbols can typically be spread over the control region to provide frequency diversity. However, no beam forming diversity may be possible with the current mapping procedures.
Moreover, the capacity of the legacy PDCCH may not be sufficient for advanced control signaling. For instance, networks may be configured as heterogeneous networks (HetNets) that can include a number of different kinds of nodes in a single macro cell serving area. More wireless devices can be served simultaneously by macro and pico cells in the HetNet. The PDCCH can be designed to demodulate based on cell-specific reference signals (CRS), which can make fully exploring cell splitting gain difficult. The legacy PDCCH may not be adequate to convey the information needed to allow a wireless device to take advantage of the multiple transmission nodes in the HetNet to increase bandwidth and decrease battery usage at the wireless device.
In addition, an increased capacity in the PDCCH can be useful in the use of multi-user multiple-input multiple-output (MU-MIMIO), machine to machine communication (M2M), PDSCH transmission in a multicast\broadcast single-frequency network, and cross carrier scheduling. The use of UE specific reference signals (UERS) in PDCCH demodulation at the wireless device can allow the use of multiple nodes in the HetNet. Rather than relying on a single common reference symbol (e.g., CRS) for an entire cell, each reference symbol can be UE specific (e.g., UERS).
To overcome the limitations of the legacy PDCCH an enhanced PDCCH (EPDCCH) can use the REs in an entire PRB or PRB pair (where a PRB pair is two contiguous PRBs using the same subcarrier's subframe), instead of just the first one to three columns of OFDM symbols in a first slot PRB in a subframe as in the legacy PDCCH. Accordingly, the EPDCCH can be configured with increased capacity to allow advances in the design of cellular networks and to minimize currently known challenges and limitations.
Unlike the legacy PDCCH the EPDCCH can be mapped to the same REs or region in a PRB as the PDSCH, but in different PRBs. In an example, the PDSCH and the EPDCCH may not be multiplexed within a same PRB (or a same PRB pair). Thus if one PRB (or one PRB pair) contains an EPDCCH, the unused REs in the PRB (or PRB pair) may be blanked, since the REs may not be used for the PDSCH.
As the evolution of LTE-advanced (LTE-A) keeps increasing support for multi-user MIMO (MU-MIMO), more UEs can be scheduled per sub-frame for the MU-MIMO operation, which can increase the physical down link control channel (PDCCH) resource demand for downlink scheduling. The legacy PDCCH design (e.g., LTE Rel-8/9/10) with the maximum PDCCH size of 3 OFDM symbols may not meet an increased demand, which can consequently limit the gain from MU-MIMO. The PDCCH extension design, called enhanced PDCCH (EPDCCH or E-PDCCH), can be located in the PDSCH region for an advanced PDCCH (e.g. LTE Release 11 and subsequent releases). The EPDCCH can use a PRB-based (instead of CCE-based PDCCH design) multiplexing scheme to increase the PDCCH capacity and improve enhanced inter-cell interference coordination (eICIC) support in HetNet scenarios. The limitation of the legacy PDCCH design to effectively perform inter-cell interference coordination (ICIC) on the legacy PDCCH can be due to PDCCH interleaving, where the control channel elements (CCEs) used for the transmission of DCI formats in PDCCH are distributed over the entire bandwidth (BW). Conversely, the enhanced PDCCH (EPDCCH) in PDSCH region can be designed using a PRB-based scheme to achieve the benefit to support frequency-domain ICIC.
In some carrier types supporting EPDCCH (e.g. carrier types in LTE-Release 11), the location and size of the EPDCCH regions can be indicated to the user equipment/mobile station (UE/MS) through radio resource control (RRC) signaling, which can use the PDCCH and UE's reading of PDCCH to obtain such RRC configuration from a primary cell (PCell). However, new carrier types (NCT), which may be used by next generation UEs/MSs (e.g., UEs/MSs using LTE-Release 12 and subsequent releases), may use stand-alone carriers without a legacy PDDCH.
In LTE Release 12 or Release 11, the NCT is a non-backward compatible carrier for boosting throughput by reducing the emphasis on common reference symbols (CRS). The NCT can reduce and/or eliminate legacy control signaling and/or CRS. In addition, the density of the CRS may be reduced in both the frequency domain and the time domain. The new carrier type can enhance spectral efficiency, improved support for heterogeneous networks (HetNets), and improve energy efficiency. Either a synchronized or unsynchronized carrier type can support the new carrier type. The new carrier type can be non-stand alone or stand alone
Legacy control channels, such as the physical broadcast channel (PBCH), the physical hybrid automatic repeat request (ARQ) indicator channel (PHICH), the physical control format indicator channel (PCFICH), and the physical downlink control channel (PDCCH) that rely on CRS for demodulation may be optimized for NCT. In LTE Release 11, EPDCCH which was demodulated based on demodulation reference signals (DMRS), was introduced as an enhanced version of legacy PDCCH for UE search space (USS). Similarly, the PHICH, PBCH, PCFICH, and the common search space (CSS) in the PDCCH may be optimized for NCT.
In one configuration, at least three alternatives may be used to indicate the CSS resources for the NCT. In alternative one, a cyclic redundancy check (CRC) scrambling code for the PBCH may be used to indicate the CSS resources. In general, the CRC is used for error detection in DCI messages. Since CRS is not used for demodulation in the NCT, the CRC scrambling code used for the PBCH is not needed to indicate a CRS antenna port. Thus, this signaling may be reused to indicate CSS resources for the user equipment (UE) to monitor for blind decoding. In general, the UE may perform blind decoding when unaware of the detailed control channel structure, including the number of control channels and the number of control channel elements (CCEs) to which each control channel is mapped. In one example, one or more PRB patterns may be hard coded into the 3GPP LTE Technical Specification (TS), and the CRC scrambling code may be used to indicate one or more PRB patterns that are allocated for the CSS resources.
In alternative two, a plurality of bits used to configure the legacy PHICH may be used to indicate the CSS resources. In one example, 3 bits used to configure the legacy PHICH may be reused for the PBCH. If the exclusive PRBs are allocated for EPHICH transmission, then the 3 bits used to indicate the configuration of the PHICH may be reused for indication of the CSS resources.
In alternative three, dummy bits in the PBCH may be used to indicate one or more PRB patterns that are allocated for the CSS resources. In one example, there may be 10 dummy bits out of 24 information bits in the PBCH. Thus, any one, or a combination of, these 10 dummy bits may be used to indicate one or more PRB patterns that are allocated for the CSS resources.
In one example, any combination of alternative one, alternative two, and alternative three may be combined for indicating the CSS resources in the NCT. For example, three bits may be carried by alternative two and two additional bits may be carried by alternative one. Thus, the five combined bits may be used to indicate the CSS resources in the NCT.
In one configuration, demodulation reference signals (DRMS) may be utilized for PBCH transmission in the NCT, as CRS may not be used for PBCH demodulation in the NCT. In general, DMRS can be used to enable coherent signal demodulation at the eNodeB. If random beamforming is used, a precoder may cycle per RB or per several RE within a PRB, including a single RE.
The changes in the NCT have created some potential problems. In one example, the PDSCH may be scheduled to transmit information in PRBs in the same PRBs that the PBCH is to transmit information. However, the same resources cannot be concurrently used to transmit information for both the PDSCH and the PBCH. At least three solutions may be presented to avoid the same PRBs being scheduled for use at the same time for both the PDSCH and the PBCH.
In solution one, the DMRS ports used for PBCH transmission may be hard coded in the 3GPP LTE TS. As an example, DMRS ports 7 and 8 may be reserved for PBCH demodulation. As a result, the DMRS ports reserved for PBCH demodulation may not be scheduled for use by the PDSCH, and therefore, the PDSCH transmission may not conflict with the PBCH transmission.
In solution two, the eNB may transmit information in the PDSCH using a UERS based open loop transmission mode (TM). The UERS based open loop TM may accommodate the UERS based PBCH transmission. Thus, the PDSCH transmission may not conflict with the PBCH transmission.
In solution three, when an open loop TM is used for the PDSCH transmission, the eNB may use a different DMRS port for the PBCH transmission as compared to the PBCH transmission. For example, the PBCH transmission may occur with DMRS ports 7 and 8. The UE may assume an offset is added on top of the DMRS port indicated in the DCI for the PDSCH demodulation. The value of the offset may be the number of DMRS ports used in the PBCH transmission. Thus, if the DMRS port indicated in the DCI is 7 and DMRS ports 7 and 8 are reserved for PBCH demodulation, then the UE may use DMRS port 9 for PDSCH demodulation because 7+2 (the offset value)=9.
FIG. 2 is an example illustrating the generation of an EPHICH and EPHICH quadrant to resource element group (REG) mapping. The EPHICH symbol generation procedure may reuse the legacy PHICH physical layer structure, i.e., constructing the REG and then mapping the EPHICH quadrant to the REG.
In one configuration, exclusive PRBs may be assigned for EPHICH transmissions. In addition, one or more PRBs may be allocated for the EPHICH transmissions using radio resource control (RRC) signaling for the NCT. If the PRBs allocated for the PDSCH transmission overlap with the PRBs allocated for the EPHICH transmission, then rate matching may be applied around the EPHICH PRBs in the PDSCH RE mapping process. In general, the rate matching (RM) process can adapt the code rate of the LTE data transmissions such that the number of information and parity bits to be transmitted matches the resource allocation.
As shown in FIG. 2, channel coding for ACK is 111 (3 bits) and for NAK is 000 (3 bits). In other words. ACK is 1 (1 bit) with a Nx repetition of N=3 and NAK is 0 (1 bit) with a Nx repetition of N=3. The EPHICH may use binary phase shift keying (BPSK) modulation so that 3 modulation symbols are generated for each ACK or NAK. In general, BPSK is a modulation scheme that conveys one bit per symbol, whereby the values of the bit are represented by opposite phases of the carrier. The modulation symbols may be multiplied by an orthogonal cover code with a spreading factor of four (i.e., OCC4) for the normal cyclic prefix, resulting in a total of 12 modulation symbols. Since each REG contains 4 REs and each RE can carry one modulation symbol, 3 REs are needed for a single EPHICH. As shown in FIG. 2. REG0, REG1 and REG2 may be included in EPHICH group 1. In addition. REG3, REG4 and REG5 may be included in EPHICH group 2.
In one configuration, EPHICH quadrant to REG mapping may include distributing the PHICH quadrant to as many PRBs (that are allocated for EPHICH) as possible for reaping financial diversity gain. As shown in FIG. 2, the EPHICH quadrant is mapped to the REG across the frequency domain and then across the time domain. In an alternative configuration, an REG index may be interleaved and then the EPHICH quadrant may be sequentially mapped to the interleaved REG.
In one example, the EPHICH demodulation may be based on the DMRS. Thus, the EPHICH may reuse the same DMRS port as the distributed EPDCCH. In addition, the DMRS sequence scrambling initialization may reuse the conclusion of the EPDCCH, i.e., the virtual cell identifier (ID) may be configured from higher layer signaling. In one example, a per RE/REG cycled random precoding may be applied to the EPHICH demodulation. In addition, DMRS based transmit diversity may be used, but orphan REs may be accounted. Thus, if there is an orphan RE in one REG, the entire REG or the OFDM symbol associated with the REG may not be used for the EPHICH transmission.
In order to indicate the EPHICH resource (e.g. group ID, sequence ID), the implicit PHICH group and sequence indication may be reused from LTE Release 11 and earlier releases. Furthermore, since the EPHICH and the EPDCCH are not multiplexed in the same PRB, at least 3 bits in the PBCH for the indication of the PHICH configuration may be saved. Thus, these 3 bits may be reused for indicating the CSS resources in the NCT.
FIG. 3 illustrates an example of the generation of an enhanced physical hybrid automatic repeat request (ARQ) indicator channel (EPHICH) for frequency division multiplexed (FDMed) or time division multiplexed (TDMed) mapping. The ACK/NAK bit may be repeated N times and then BPSK modulated. A phase rotation process may be added to support additional UEs in a single EPHICH group. In general, N may dominate the spectrum efficiency of the EPHICH. In one example. N=3 results in SE=2 bits/3 REs. M may be the number of UEs supported in the single EPHICH group. M may be the same as the legacy PHICH, i.e., M=8 to facilitate reusing the PHICH group/sequence indication as used in the legacy PHICH.
In the EPICH to RE mapping process, the REs available for the EPHICH may be indexed in a frequency domain or a time domain to generate i(0), i(1), . . . i(N_RE), wherein N_RE is the number of REs available for the EPHICH transmission in one subframe. The indices may be interleaved with an interleaver to generate j(0), j(1), . . . j(N_RE). The EPHICH symbols may be sequentially mapped in one subframe to j(0), j(1), . . . j(N_RE). In one example, the interleaver may reuse the sub-block interleaver in legacy turbo coding or another interleaver.
As shown in FIG. 3, the REs associated with A/N bit 1 & 2 may be mapped to the plurality of PRBs, the REs associated withA/N bit 3 & 4 may be mapped to the plurality of PRBs, and the REs associated with A/N bit M−1 & M may be mapped to the plurality of PRBs. In EPHICH to RE mapping, the EPHICH for one UE may be distributed to as many different PRBs as possible for procuring frequency diversity gain.
FIGS. 4A and 4B illustrate an example of the EPHICH multiplexed with the EPDCCH. In one example. ECCEs (in a distributed EPDCCH set) may be assigned for the EPHICH. In addition, EPHICHs associated with different UEs may be frequency division multiplexed (FDMed) or time division multiplexed (TDMied). In general, FDM relates to multiplexing different data signals for transmission on a single communications channel, whereby each signal is assigned a non-overlapping frequency range within the main channel. In addition, TDM relates to multiplexing different data signals, whereby the channel is divided into multiple time slots and the different signals are mapped to different time slots.
As shown in FIGS. 4A and 4B, EPHICHs associated with different UEs may be FDMed or TDMed and multiplexed with the EPDCCH. Two A/N bits may be transmitted and each of the two A/N bits may be repeated four times (i.e., N=4). In this example, the ECCE which is constructed by EREG 0, 4, 8, and 12 is allocated for the EPHICH transmission. In particular, EREG 0, 4, 8 and 12 may be associated with EPHICH 1 or EPHICH 2. FIGS. 4A and 4B illustrate two types of checkered patterns to indicate the resources for EPHICH 1 and EPHICH 2. A third type of checkered pattern may indicate all resources of one ECCE, which may include the EREGs 0, 4, 8 or 12. The remaining EREGs shown in FIGS. 4A and 4B (i.e. represented by the solid boxes without a checkered pattern) may be associated with the EPDCCH.
In one example, the EECEs allocated for EPHICH transmissions are punctured by the EPHICH. In coding theory, puncturing is the process of removing some of the parity bits after encoding with an error-correction code. Puncturing can have the same effect as encoding with an error-correction code with a higher rate (e.g., modulation and coding scheme (MCS)), or less redundancy. With puncturing a same decoder can be used regardless of how many bits have been punctured, thus puncturing can considerably increase the flexibility of a system without significantly increasing the system's complexity.
For EPHICH resource allocation, the EPHICH may be multiplexed with the EPDCCH in common search space (CSS) or UE search space (USS). The 3 bits that are used in the PBCH to indicate the legacy PHICH configuration may be reused to indicate the EPHICH resources. In addition, 8 ECCE patterns may be predefined and 3 bits may be used to indicate which ECCE pattern is applied in the serving cell. For example, a single bit may indicate that either the CSS or the USS is multiplexed with the EPHICH, and the remaining two bits may be used to select the ECCE pattern.
In one example, the EPHICH demodulation may be based on the DMRS. Thus, the EPHICH may reuse the same DMRS port as the distributed EPDCCH. In addition, the DMRS sequence scrambling initialization may reuse the conclusion of the EPDCCH. i.e., the virtual cell identifier (ID) may be configured from higher layer signaling. In one example, a per RE/REG cycled random precoding may be applied to the EPHICH demodulation. The UE may search ECCEs that are allocated to the EPHICH during EPDCCH blind detection. Alternatively, the UE may not search ECCEs that are allocated to the EPHICH during EPDCCH blind detection. In order to indicate the EPHICH resource (e.g., group ID, sequence ID), the implicit PHICH group and sequence indication may be reused from LTE Release 11 and earlier releases.
In an alternative configuration, the EPHICH may be multiplexed with the EPDCCH, wherein the EECEs (in the distributed EPDCCH set) may be assigned for the EPHICH and EPHICHs of different UEs may be code division multiplexed (CDMed). In general, CDM relates to multiplexing different data signals by means of different codes, rather than different frequencies or timeslots. The codes used for different signals may be orthogonal to each other, or may be pseudo-random and have a wider bandwidth than the data signals. In one example, the EPHICH symbol generation procedure may reuse the legacy PHICH processor for generating symbols. In addition, other procedures may reuse the procedures as previously described.
FIG. 5 illustrates an example of an EPHICH multiplexed with an EPDCCH with an enhanced resource element group (EREG) granularity. The EREGs (in the distributed EPDCCH set) may be assigned for the EPHICH. While in one configuration, the EPHICH may puncture the ECCEs allocated for the EPHICH transmission, in an alternative configuration, all of the ECCEs may be equally punctured with the EPHICH to balance the number of available REs in each ECCE for the EPDCCH transmission. The EPHICH symbol generation procedure may reuse the TDM/FDM procedure or the CDM procedure as previously described. In addition, the resources allocated for the EPHICH transmission may be measured in terms of EREGs. As shown in FIG. 5, each ECCE may be equally punctured. The unfilled EREG may be allocated for the EPHICH transmission, whereas the filled EREG may be allocated for EPDCCH transmission. Subsequently, each ECCE may be equally punctured by the EPHICH. In addition, the PRBs may be assigned to the EPDCCH and can be distributed across an entire bandwidth.
Another example provides functionality 600 of computer circuitry of an evolved node B (eNB) operable to provide physical broadcast channel (PBCH) transmissions and physical downlink shared channel (PDSCH) transmissions in a New Carrier Type (NCT), as shown in the flow chart in FIG. 6. The functionality may be implemented as a method or the functionality may be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The computer circuitry can be configured to determine that the PDSCH is scheduled to transmit information in at least one physical resource block (PRB) that is used to transmit information in the PBCH, as in block 610. The computer circuitry can be configured to determine a reference signal type for communicating the information in the PDSCH and the PBCH, as in block 620. The computer circuitry can be further configured to identify a reference signal location in the NCT for PBCH demodulation so that the PDSCH is not scheduled to transmit information in the same reference signal location as the PBCH, wherein the information in the PDSCH and the PBCH are communicated according to the reference signal type, as in block 630.
In one example, the computer circuitry can be configured to communicate information in the PDSCH, at the eNB, by using user equipment (UE) specific reference signal (UERS) based open loop transmission mode (TM) for accommodating an UERS based PBCH transmission. In addition, the computer circuitry can be configured to utilize demodulation reference signal (DMRS) for communicating information in the PBCH in the NCT.
In one configuration, the computer circuitry can be configured to reserve at least one DMRS port for communicating information in the PBCH in the NCT, such that the reserved DMRS ports for communicating information in the PBCH does not correspond to DMRS ports for communicating information in the PDSCH. In one example, the computer circuitry can be configured to precode at least one resource block (RB) or at least one resource element (RE) included in the physical resource block (PRB) in response to determining that random beamforming is used to communicate information in the PBCH.
In one configuration, the computer circuitry can be configured to determine that a closed loop transmission mode (TM) is being used to communicate information in the PDSCH; and identify, at the eNB, a DMRS port to communicate information in the PDSCH different than the DMRS port used to communicate information in the PBCH. In addition, the computer circuitry can be configured to identify at least one physical resource block (PRB) pattern allocated in a common search space (CSS) resource using a cyclic redundancy check (CRC) scrambling code.
Furthermore, the computer circuitry can be configured to identify common search space (CSS) resources using one or more information bits to indicate at least one physical resource block (PRB) pattern used for the CSS resources. In one example, the one or more information bits are information bits used to indicate a Physical Hybrid-ARQ Indicator Channel (PHICH) configuration in the PBCH. In an alternative example, the one or more information bits are one or more dummy bits in the PBCH.
Another example provides a method 700 for allocating at least one physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT), as shown in the flow chart in FIG. 7. The method may be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The method includes the operation of determining a number of bits associated with channel coding for an acknowledgement (ACK) or negative acknowledgement (NACK) in the EPHICH transmission, as in block 710. The method includes generating a plurality of modulation symbols for each ACK or NACK in the EPHICH transmission based in part on the number of bits associated with the ACK or NACK, as in block 720. The method additionally includes mapping the plurality of modulation symbols as EPHICH quadrants in one or more resource element blocks (REGs), wherein the EPHICH quadrants are mapped to a plurality of physical resource blocks (PRBs) allocated for EPHICH to increase frequency diversity gain, as in block 730.
In one configuration, the method can include mapping the EPHICH quadrants to the REGs across a frequency domain and mapping the EPHICH quadrants to the REGs across a time domain. In addition, the method can include interleaving an REG index and sequentially mapping the EPHICH quadrants to an interleaved REG.
In one example, the method can include allocating the plurality of PRBs for EPHICH transmission by radio resource control (RRC) signaling for the NCT. In addition, the method can include determining that the plurality of PRBs allocated for the EPHICH overlap with at least one PRB allocated for the physical downlink shared channel (PDSCH); and applying rate mapping to the plurality of PRBs allocated for the EPHICH while mapping resource elements (REs) associated with the PDSCH. Furthermore, the method can include identifying an orphan resource element (RE) in the resource element group (REG); and excluding the REG with the orphan RE or an Orthogonal Frequency Division Multiplexing (OFDM) symbol associated with the REG from the EPHICH transmission.
FIG. 8 provides functionality 800 of computer circuitry of a node operable to assign a plurality of physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT). The functionality may be implemented as a method or the functionality may be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The computer circuitry can be configured to generate a plurality of EPHICH modulation symbols for each acknowledgement (ACK) or negative acknowledgement (NACK) in an EPHICH transmission based in part on a number of bits associated with the ACK or NACK, as in block 810. The computer circuitry can be configured to index a plurality of resource elements (REs) in one subframe available for the EPHICH transmission in a frequency or time first order and interleave the REs that are indexed with an interleaver, as in block 820. The computer circuitry can be further configured to allocate EPHICH resources by mapping the plurality of EPHICH modulation symbols in the one subframe to the interleaved indexed REs, wherein the EPHICH modulation symbols are mapped as REs in the plurality of PRBs, wherein a plurality of enhanced control channel elements (ECCEs) associated with the REs are assigned for the EPHICH transmission, as in block 830.
In one example, the ECCEs can be associated with a distributed enhanced Physical Downlink Control Channel (EPDCCH) set. In addition, the computer circuitry can be further configured to perform frequency division multiplexing (FDM) or time division multiplexing (TDM) with the EPHICHs that are associated with at least one user equipment (UE). Furthermore, the computer circuitry can be configured to allocate the EPHICH resources by multiplexing the EPHICH with the EPDCCH in a common search space (CSS) or a UE-specific search space (USS).
In one configuration, the computer circuitry can be further configured to multiplex at least one user equipment (UE) associated with the EPHICHs in a frequency domain or a time domain. In addition, the computer circuitry can be further configured to map the EPHICH used by at least one user equipment (UE) to a plurality of PRBs to increase frequency diversity gain. Furthermore, the computer circuitry can be configured to multiplex at least one user equipment (UE) associated with the EPHICHs using code division multiplexing (CDM).
In one configuration, the computer circuitry can be further configured to assign enhanced resource element groups (EREGs) in a distributed enhanced Physical Downlink Control Channel (EPDCCH) set for the EPHICH. In addition, the computer circuitry can be further configured to puncture the ECCEs equally with the EPHICH for balancing the number of available REs in each ECCE for the EPDCCH transmission. In one example, the node is selected from a group consisting of a base station (BS), a Node B (NB), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), or a remote radio unit (RRU).
FIG. 9 provides an example illustration of the mobile device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, or other type of mobile wireless device. The mobile device can include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or, transmission station, such as a base station (BS), an evolved Node B (eNB), a base band unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), or other type of wireless wide area network (WWAN) access point. The mobile device can be configured to communicate using at least one wireless communication standard including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and Wi-Fi. The mobile device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The mobile device can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.
FIG. 9 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the mobile device. The display screen may be a liquid crystal display (LCD) screen, or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen may use capacitive, resistive, or another type of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. A non-volatile memory port can also be used to provide data input/output options to a user. The non-volatile memory port may also be used to expand the memory capabilities of the mobile device. A keyboard may be integrated with the mobile device or wirelessly connected to the mobile device to provide additional user input. A virtual keyboard may also be provided using the touch screen.
Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e. instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a RAM, EPROM, flash drive, optical drive, magnetic hard drive, or other medium for storing electronic data. The base station and mobile device may also include a transceiver module, a counter module, a processing module, and/or a clock module or timer module. One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.
It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.
Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.
Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The modules may be passive or active, including agents operable to perform desired functions.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of materials, fasteners, sizes, lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

Claims

What is claimed is:

1. An evolved node B (eNB) operable to provide physical broadcast channel (PBCH) transmissions and physical downlink shared channel (PDSCH) transmissions in a New Carrier Type (NCT), the eNB having computer circuitry configured to:

determine that the PDSCH is scheduled to transmit information in at least one physical resource block (PRB) that is used to transmit information in the PBCH;

determine a reference signal type for communicating the information in the PDSCH and the PBCH; and

identify a reference signal location in the NCT for PBCH demodulation so that the PDSCH is not scheduled to transmit information in the same reference signal location as the PBCH, wherein the information in the PDSCH and the PBCH are communicated according to the reference signal type.

2. The computer circuitry of claim 1, further configured to communicate information in the PDSCH, at the eNB, by using user equipment (UE) specific reference signal (UERS) based open loop transmission mode (TM) for accommodating an UERS based PBCH transmission.

3. The computer circuitry of claim 1, further configured to utilize demodulation reference signal (DMRS) for communicating information in the PBCH in the NCT.

4. The computer circuitry of claim 1, further configured to reserve at least one DMRS port for communicating information in the PBCH in the NCT, such that the reserved DMRS ports for communicating information in the PBCH does not correspond to DMRS ports for communicating information in the PDSCH.

5. The computer circuitry of claim 1, further configured to precode at least one resource block (RB) or at least one resource element (RE) included in the physical resource block (PRB) in response to determining that random beamforming is used to communicate information in the PBCH.

6. The computer circuitry of claim 1, further configured to:

determine that a closed loop transmission mode (TM) is being used to communicate information in the PDSCH; and

identify, at the eNB, a DMRS port to communicate information in the PDSCH different than the DMRS port used to communicate information in the PBCH.

7. The computer circuitry of claim 1, further configured to identify at least one physical resource block (PRB) pattern allocated in a common search space (CSS) resource using a cyclic redundancy check (CRC) scrambling code.

8. The computer circuitry of claim 1, further configured to identify common search space (CSS) resources using one or more information bits to indicate at least one physical resource block (PRB) pattern used for the CSS resources.

9. The computer circuitry of claim 8, wherein the one or more information bits are information bits used to indicate a Physical Hybrid-ARQ Indicator Channel (PHICH) configuration in the PBCH.

10. The computer circuitry of claim 8, wherein the one or more information bits are one or more dummy bits in the PBCH.

11. A method for allocating at least one physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT), the method comprising:

determining a number of bits associated with channel coding for an acknowledgement (ACK) or negative acknowledgement (NACK) in the EPHICH transmission;

generating a plurality of modulation symbols for each ACK or NACK in the EPHICH transmission based in part on the number of bits associated with the ACK or NACK; and

mapping the plurality of modulation symbols as EPHICH quadrants in one or more resource element blocks (REGs), wherein the EPHICH quadrants are mapped to a plurality of physical resource blocks (PRBs) allocated for EPHICH to increase frequency diversity gain.

12. The method of claim 11, further comprising mapping the EPHICH quadrants to the REGs across a frequency domain and mapping the EPHICH quadrants to the REGs across a time domain.

13. The method of claim 11, further comprising interleaving an REG index and sequentially mapping the EPHICH quadrants to an interleaved REG.

14. The method of claim 11, further comprising allocating the plurality of PRBs for EPHICH transmission by radio resource control (RRC) signaling for the NCT.

15. The method of claim 11, further comprising:

determining that the plurality of PRBs allocated for the EPHICH overlap with at least one PRB allocated for the physical downlink shared channel (PDSCH); and

applying rate mapping to the plurality of PRBs allocated for the EPHICH while mapping resource elements (REs) associated with the PDSCH.

16. The method of claim 11, further comprising:

identifying an orphan resource element (RE) in the resource element group (REG); and

excluding the REG with the orphan RE or an Orthogonal Frequency Division Multiplexing (OFDM) symbol associated with the REG from the EPHICH transmission.

17. A node operable to assign a plurality of physical resource block (PRB) for an Enhanced Physical Hybrid-ARQ Indicator Channel (EPHICH) transmission for a New Carrier Type (NCT), the node having computer circuitry configured to:

generate a plurality of EPHICH modulation symbols for each acknowledgement (ACK) or negative acknowledgement (NACK) in a EPHICH transmission based in part on a number of bits associated with the ACK or NACK;

index a plurality of resource elements (REs) in one subframe available for the EPHICH transmission in a frequency or time first order and interleave the REs that are indexed with an interleaver; and

allocate EPHICH resources by mapping the plurality of EPHICH modulation symbols in the one subframe to the interleaved indexed REs, wherein the EPHICH modulation symbols are mapped as REs in the plurality of PRBs, wherein a plurality of enhanced control channel elements (ECCEs) associated with the REs are assigned for the EPHICH transmission.

18. The computer circuitry of claim 17, wherein the ECCEs are associated with a distributed enhanced Physical Downlink Control Channel (EPDCCH) set.

19. The computer circuitry of claim 17, further configured to multiplex one or more user equipments (UEs) associated with the EPHICH in a frequency domain or a time domain.

20. The computer circuitry of claim 17, further configured to allocate the EPHICH resources by multiplexing the EPHICH with the EPDCCH in a common search space (CSS) or a UE-specific search space (USS).

21. The computer circuitry of claim 17, further configured to perform frequency division multiplexing (FDM) or time division multiplexing (TDM) with the EPHICHs that are associated with at least one user equipment (UE).

22. The computer circuitry of claim 17, further configured to map the EPHICH used by at least one user equipment (UE) to a plurality of PRBs to increase frequency diversity gain.

23. The computer circuitry of claim 17, further configured to multiplex at least one user equipment (UE) associated with the EPHICHs using code division multiplexing (CDM).

24. The computer circuitry of claim 17, further configured to assign enhanced resource element groups (EREGs) in a distributed enhanced Physical Downlink Control Channel (EPDCCH) set for the EPHICH.

25. The computer circuitry of claim 17, further configured to puncture the ECCEs equally with the EPHICH for balancing the number of available REs in each ECCE for the EPDCCH transmission.

26. The computer circuitry of claim 17, wherein the node is selected from a group consisting of a base station (BS), a Node B (NB), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), or a remote radio unit (RRU).