WO2018150084A1

WO2018150084A1 - Efficient and fast data recovery using network coordination information and harq feedback channel

Info

Publication number: WO2018150084A1
Application number: PCT/FI2018/050078
Authority: WO
Inventors: Saeed Reza KHOSRAVIRAD; Venkatkumar Venkatasubramanian; Anna LUKOWA
Original assignee: Nokia Technologies Oy
Priority date: 2017-02-17
Filing date: 2018-02-05
Publication date: 2018-08-23

Abstract

In accordance with the example embodiments of the invention there is at least a method and apparatus to perform determining physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver are to be retransmitted to the receiver; and based on the determining, initiating, by the network node, the retransmission of the physical resource blocks with the at least one data packet to the receiver. Further, in accordance with the example embodiments of the invention there is at least a method and apparatus to perform determining that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver needs to be retransmitted to the receiver; and based on the determining, sending feedback towards the network node regarding the initial transmission.

Description

EFFICIENT AND FAST DATA RECOVERY USING NETWORK

COORDINATION INFORMATION AND HARQ FEEDBACK CHANNEL

TECHNICAL FIELD:

[0001] The teachings in accordance with the exemplary embodiments of this invention relate generally to wireless communication systems, and more particularly, to effective improvement of channel utilization in strongly interfered cells. BACKGROUND:

[0002] This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.

[0003] Certain abbreviations that may be found in the description and/or in the Figures are herewith defined as follows:

4G: 4^th generation

5G: 5^th generation

ACK: Acknowledgement

AP: access point

DL: downlink

FDD: Frequency division duplex

HARQ: hybrid automatic repeat request

LTE: long term evolution

NACK: Negative acknowledgement

PRB: Physical resource block

QoS: quality of service

SINR: Signal to interference and noise ration TB: Transport block

TDD: time division duplex

TTI: Transmission time interval

UL: uplink

UE: user equipment

URLLC: ultra-reliable low latency communication

[0004] In transmission of large transport blocks (TB's) it is desired to have efficient mechanisms of data recovery in case of decoding failure. Lower layer mechanisms in LTE such as ARQ and HARQ provide high chances of data recovery in case of failure at the expense of using second, third and so on retransmission chances for the failed packet. It is well known that the efficiency of such retransmission mechanisms can be improved by increasing feedback content which will in turn enable focusing the retransmission power and resources only on the failed segments of the failed transport block. It is also known that the feedback bits come at a generally high cost due to an increased repetition order prior to transmission and energy consumption per bit of feedback at the UE side in order to guarantee feedback reliability.

[0005] The example embodiments of the invention as disclosed herein provide novel operations related to efficient data recovery management for UE's which are more prone to interference from other cells (e.g., cell-edge UE's).

SUMMARY:

[0006] In an exemplary aspect of the invention, there is a method comprising determining, by a network node of a communication network, physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver are to be retransmitted to the receiver; and based on the determining, initiating, by the network node, the retransmission of the physical resource blocks with the at least one data packet to the receiver. [0007] In another exemplary aspect of the invention, there is an apparatus comprising at least one processor; and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: determine physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver of a communication network are to be retransmitted to the receiver; and based on the determining, initiate the retransmission of the physical resource blocks with the at least one data packet to the receiver.

[0008] In another exemplary aspect of the invention, there is a method comprising determining, by a network device of a communication network, that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver needs to be retransmitted to the receiver; and based on the determining, sending feedback towards the network node regarding the initial transmission.

[0009] In yet another exemplary aspect of the invention, there is an apparatus comprising at least one processor; and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: determine that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver of a communication network needs to be retransmitted to the receiver; and based on the determining, sending feedback towards the network node regarding the initial transmission. BRIEF DESCRIPTION OF THE DRAWINGS :

[0010] The foregoing and other aspects of embodiments of this invention are made more evident in the following Detailed Description, when read in conjunction with the attached Drawing Figures, wherein:

[0011] Figure 1 shows Two types of information available over an X2 interface;

[0012] Figure 2 shows a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary embodiments of this invention;

[0013] Figure 3 shows pro-active phase and re-active phase subframe operations associated with a possible retransmission; [0014] Figure 4 shows operations associated with the pro-active phase in accordance with example embodiments of the invention; [0015] Figures 5 shows operations associated with a re-active retransmission in accordance with the example embodiments of the invention;

[0016] Figure 6 shows operations associated with a refined regular retransmission in accordance with the example embodiments of the invention; and

[0017] Figures 7a and 7b each show a method that can be performed by an apparatus in accordance with the example embodiments of the invention.

DETAILED DESCRIPTION:

[0018] The example embodiments of the invention relate generally to wireless communication systems, and more particularly, to effective improvement of channel utilization in strongly interfered cells. The invention can be applied to the dynamic TDD scenario (as for LTE/LTE-A as well as emerging for 5G) as well as FDD scenario in wireless network technologies.

[0019] Further, the example embodiments of the invention as described herein can be applied to URLLC scenarios with require low user plane latency in the order of few milliseconds (ms), low control plane latency and also high reliability. Example of such scenarios can be intelligent transport system using V2X or process automation, or other types of machine type communications with the above requirements. Cellular networks may employ reuse patterns for these scenarios, and in both TDD and FDD systems.

[0020] The example embodiments of the invention as disclosed herein provide operations which address efficient data recovery management for UE's which are more prone to interference from other cells (e.g., cell-edge UE's) and refined multi-bit feedback is not a practically feasible idea for them. [0021] For instance in case of cell-edge UE's naturally an extra feedback transmission duration is imposed to a feedback transmission to collect enough energy for detection at an eNB for example. It is noted that the feedback transmission may require more energy and/or demand more time-frequency resource as compared to a UE that is closer to the eNB. Therefore, the feedback message is expected to be a limited length and/or convey limited information for this type of UE. This is however despite the fact that there is other information usually available from the network that can help the eNB provide an efficient retransmission even without receiving multi-bit ACK/NACK from the UE. Among this information there can be the following:

The semi-static DL/UL pattern in flexible TDD scenario and the PRB-reuse pattern in both TDD and FDD scenarios coming from the neighbouring cells which corresponds to the potential interference pattern coming from these cells to the serving cell - The information available at the X2 interface relating to the dynamic pattern of interference coming from the interfering cells

[0022] Figure 1 shows an API and an AP 2 given semi-statically allocated pattern of resources (protected) and dynamically allocated pattern of resources, respectively.

[0023] The example embodiments of the invention propose new methods for better use of this type of network originated information together with single or multi bit FIARQ feedback from the UE in the serving node to provide a timely and efficient retransmission for the failed transport blocks (data packets).

[0024] Before describing in further detail the exemplary embodiments of this invention, reference is made to Figure 2 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 2 a wireless network 1 is adapted for communication over a wireless link 11 with an apparatus, such as a mobile communication device which may be referred to as a UE 10, via a network access node such as a base station, and more specifically an eNB 12. The network 1 may include a network control element (NCE) 14 that may include the MME/SGW functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the internet). The NCE 14 includes a controller, such as a computer or a data processor (DP) 14A, a computer-readable memory medium embodied as a memory (MEM) 14B that stores a program of computer instructions (PROG) 14C, and a suitable data path 13, (e.g., antenna and/or hardwire) for bidirectional wireless communications with the eNB 12.

[0025] The UE 10 includes a controller, such as a computer or a data processor (DP)

10A, a computer-readable memory medium embodied as a memory (MEM) 10B that stores a program of computer instructions (PROG) 10C, and a suitable radio frequency (RF) transceiver 10D for bidirectional wireless communications with the eNB 12 via one or more antennas. The eNB 12 also includes a controller, such as a computer or a data processor (DP) 12 A, a computer-readable memory medium embodied as a memory (MEM) 12B that stores a program of computer instructions (PROG) 12C, and a suitable RF transceiver 12D for communication with the UE 10 via one or more antennas. The eNB 12 is coupled via a data / control path 13 to the NCE 14. The path 13 may be implemented as the S I interface. The eNB 12 may also be coupled to another eNB via data / control path 15, which may be implemented as the X2 interface. [0026] The PROGs IOC, 12C, and/or 14C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 10A of the UE 10 and/or by the DP 12A of the eNB 12, or by hardware, or by a combination of software and hardware (and firmware).

[0027] In general, the various embodiments of the UE 10 can include, but are not limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

[0028] The computer readable MEMs 10B, 12B, and 14B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 10A, 12A, and 14A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi- core processor architectures, as non-limiting examples.

[0029] The example embodiments of the invention as disclosed herein provides procedures for TB recovery for the scenarios where known/un-known pattern of interference can cause a failure in TB decoding. In general a large-enough multi-bit feedback can convey useful information to refine a HARQ retransmission of a large TB in order for a more efficient utilization of the channel resources. Further, the example embodiments of this invention can help a network node such as an eNB to refine the retransmission using network information that are available over the X2 interface. Furthermore, example embodiments of the invention propose timing approaches to lower the experienced latency over the air for an interfered TB. Several procedures for efficient retransmission are described as follows.

[0030] Two types of information available over the X2 interface: [0031] Semi-static PRB-reuse pattern from the interfering cells - The semi- static pattern of PRB-reuse can be shared among neighbouring cells ahead of time. In principle, the decision making and sharing of the patterns can happen in many different ways but as long as the pattern is known by the influenced cells prior to it happening, it can be addressed as a semi- static pattern. In semi-static PRB-reuse, each of the APs can be allocated with a number of semi-statically protected resource blocks. The neighbouring APs can negotiate with each other upon protected resources in a long scale (i.e. periodically every few seconds and/or on demand whenever there is a major change in a cell traffic). The ratio of protected resources can be adopted to the cell traffic demands. The semi-static PRB patterns are exchanged between the cells. Each cell first allocates the downlink data on their statically allocated resources and tries to avoid using the resources which are semi-statically allocated to the neighbouring cells. [0032] Dynamic PRB-reuse pattern from the interfering cells - A dynamic PRB pattern is any pattern other than the known semi-static pattern which may be used by a cell. The dynamic PRB-reuse pattern of the neighboring cell in a time slot are known after an X2 delay or after X2 delay from when the neighboring cell makes the decision on such pattern. [0033] In accordance with the example embodiments the UE can signal, over HARQ feedback, ACK/NACK separately per each set of resources block: semi-statically and dynamically allocated. Thus, in case of retransmission the AP can retransmit only the part of the data from the affected PRBs. [0034] Different Re-Transmission Time Opportunities:

[0035] Based on the timing of the network feedback and HARQ timing the example embodiments of the invention can define different re-transmission opportunities as follows: [0036] Pro-active retransmission (when the network feedback is received at eNB prior to UE ACK/NACK feedback) - Is the retransmission of parts of or the whole of a packet prior to the arrival of the corresponding HARQ feedback of the initial transmission (or the previous retransmission). A pro-active retransmission could for example happen when the eNB is informed through the network of an interference that could potentially cause the decoding of the packet to fail. In such a scenario, eNB can perform the retransmission of the expected failing part(s) or the whole packet prior to receiving the feedback and in turn help the packet decoding with extra redundancy to overcome the effect of interference.

[0037] Re-active retransmission (after receiving UE NACK feedback) - This mechanism takes into account that the UE may perform interference mitigation by using advanced receiver, i.e., the interference that has been caused may not be problematic on all PRBs. In case the information about a potential interference arrives at the cell from the X2 interface after the NACK feedback is received for the interfered packet, the retransmission can use the information from network. In this case the network information helps to resolve the cause for the failures in ACK/NACK. A Dual ACK/NACK with a two-bit or multi-bit NACK for example can be provided to further enhance the re-active retransmission prior to the regular retransmission occurrence. If the NACK is received, the AP can take the advantage of the information about the interference and retransmit only potentially interfered blocks of data.

[0038] Refined regular retransmission - The regular retransmission can take advantage of the dynamic pattern information as well as the semi-static pattern information together with the multi-bit NACK to provide a refined retransmission which is optimally created based on the necessary segments of the TB to be retransmitted.

[0039] Three types of feedback signalling assumed: [0040] Single-bit ACK/NACK - A single-bit Boolean type of feedback will be available naturally to trigger the HARQ retransmissions. In case of single-bit feedback the retransmissions can be refined only based on the network information that eNB has received. The single-bit feedback as the baseline case can trigger the regular retransmission and the reactive retransmission. In cases such as high traffic in the UL, low channel quality in the UL (cell-edge), etc. it is valid to assume that only a single-bit feedback is available for the UE to report HARQ feedback. In cases it is furthermore possible to assume that no feedback will be provided by the UE to the eNB hence the eNB will decide for the retransmissions only based on the feedback from network and therefore only pro-active retransmission decisions will be made in such scenarios.

[0041 ] Dual ACK/NACK - The UE can signal ACK/NACK separately for its semi- static and dynamic PRBs. Here one has to note the following logical set of PRB resources:

a) Semi-static and dynamic PRBs of a victim node; and

b) Semi-static and dynamic PRBs of the dominant strong interferer

Note that the semi-static PRBs of a victim may likely not collide with semi-static PRBs of the dominant neighbour interferer. Because the dynamic PRBs of the victim AP can correspond to the semi-static resources of a dominant neighbour interferer, this type of dual ACK/NACK signalling can allow a victim AP to perform selective automatic re-transmissions. On the other hand, because the semi-static resources of a victim AP are its protected resources, this type of signalling allows to prioritize re-transmission of victim's semi-static.

[0042] The dynamic PRBs of a victim may be interfered by both dynamic PRBs of a neighbour as well as the semi-static PRBs. Thus, the AP can retransmit only the affected PRBs of the dynamic part. The affected PRBs of the dynamic part may most likely correspond to the semi-static PRBs of the dominant interferer. Thus eNB first blindly performs re-transmissions of the data in interferers semi-static PRBs (corresponding to the dominant interferer of the individual UE) in a TTI n. Dynamic PRBs of the interferer are re-transmitted when the information then becomes available to the eNB because of X2.

[0043] Multi-bit ACK/NACK - the multi-bit NACK can contain more detailed information on the segments of each of the semi-static and/or dynamic PRB's. For instance a large enough multi-bit feedback can activate per-CB or per sub band feedback.

[0044] The radio resource management (RRM) configuration of the HARQ retransmission can therefore be any combination of the above defined types of feedback signals, timing opportunities and network signalling. For instance the following two approaches can be chosen based on the overall experience X2 delay:

Completely dynamic RRM - Useful for cases with low X2 delay. The eNB makes a retransmission based on the dynamic scheduling information that is available on the X2 interface in a particular TTI. The retransmission is refined based on the X2 information and can be sent over any of the above defined timing opportunities. In case of availability of multi-bit feedback the dynamic X2 information can help further refine the re-active and/or the regular timing retransmissions. - Semi-static and dynamic - Useful for cases with higher X2 delay. The eNBs may exchange a semi-static priority PRB allocation and signal the semi-static PRB resource map to the UE. Thus eNB first blindly performs re-transmissions of the data in interferers semi-static PRBs (corresponding to the dominant interferer of the individual UE) in a TTI n. Dynamic PRBs of the interferer are re-transmitted when the information then becomes available to the eNB because of X2. [0045] We further consider two different retransmission scheduling methods:

Blind hopping retransmissions - In general, for retransmission the AP can use the same frequency-resource blocks as it has used during the first transmission. However, it is highly probable that the same frequency blocks as during the first transmission would collide by semi-static PRB pattern of strong interferer. Thus, for higher reliability, retransmissions can follow a PRB permutation. In this mechanism, re-transmissions are performed in a separate set of PRBs with a fixed PRB mapping relation to the PRB's in the initial transmission. This allows retransmissions to be performed with a low downlink control overhead. Note that the information about PRBs that are to be re- transmitted is obtained via X2 information or the dual ACK/NACK feedback.

Scheduled retransmissions - Permutation of the PRB's (or segments) based on a common permutation matrix: the example embodiments of the invention provide a method where a one-to-one relation between the position of each PRB in the initial transmission and the following retransmission exist that both communicating nodes are aware of it. The retransmission control channel will only then convey the information about the PRB's where the UE is scheduled in (similar to the adaptive HARQ control channel). The UE will then know implicitly which PRB's from the previous transmission are being retransmitted given that UE is aware of the permutation matrix.

[0046] The example embodiments of the invention provide at least methods of efficient data retransmission. It allows to reduce the retransmission latency with pro-active and re-active retransmission schemes. Proposed solution also allows for better utilization of radio resources by reducing the amount of retransmitted data. Thus, instead of a whole TB retransmission, only the data affected by interference may be retransmitted.

[0047] The adaptive retransmission as generated by the novel approaches as disclosed herein may naturally require extra control signalling as compared to a normal adaptive HARQ where the whole TB is subject to retransmission. For instance, the control signalling should either explicitly or implicitly inform the UE about the PRB ' s (or any other segments o f the TB) that are being retransmitted.

[0048] The explicit signalling is straightforward. However, to reduce the signalling overhead example embodiments of the invention introduce implicit signalling methods as explained herein. The PRB's (or segments) based on a common permutation matrix will be permuted from one transmission to the next (re)transmission. A one-to-one relation between the position of each PRB in the initial transmission and the following retransmission is defined and shared between both communicating nodes. The retransmission control channel will only then convey the information about the PRB's where the UE is scheduled in (similar to the adaptive HARQ control channel). The UE will then know implicitly which PRB's from the previous transmission are being retransmitted given that the permutation matrix is already known at the UE .

[0049] To improve retransmission latency and efficiency the example embodiments of the invention introduce different retransmission opportunities as discussed herein which are depicted in the following figure in regards with the timing relation of each retransmission opportunity to the HARQ feedback timing opportunity.

[0050] In accordance with the example embodiments of the invention the different retransmission opportunities include pro-active phase and a reactive phase retransmissions. Figure 3 shows pro-active phase and re-active phase subframe operations associated with a possible retransmission. As shown in Figure 3 there is a pro-active phase (310) and a re-active phase (320) subframe operations associated with a possible retransmission. As shown in the pro-active phase 310 there is in a first subframe a first data transmission 312. Whereas, in the re-active phase 320 there is an ACK/NACK 322 in a first subframe, and the possible retransmission 324 occurs later.

[0051] A detailed description of the proposed retransmission opportunities in accordance with an example embodiment of the invention are as follows. [0052] Pro-active retransmission

[0053] The retransmission is triggered prior to the UE ACK/NACK feedback based on information from the network. The network can inform the AP about possible interference which might lead to packet decoding failure at the receiving UE. The detailed network information can include indication of exact PRBs on which strong interference took place. The AP might then retransmit the data before receiving the ACK/NACK feedback from the UE. Based on the network feedback, the AP can retransmit whole data or the portions of the data from affected PRBs. The UE might then use the retransmitted portions of the TB to improve its decoding chances.

[0054] As shown in Figure 4 a pro-active phase leading to a pro-active retransmission

430 for a first data transmission 410 can be initiated by network feedback 410 in accordance with the example embodiments as disclosed herein. This first data transmission may be considered an initial transmission in accordance with the embodiments. Then as shown in Figure 4 there is network feedback 410. Then in response to the network feedback 410 there is a pro-active retransmission 430 in accordance with the example embodiments. Further, as shown in Figure 4 following the network feedback 410 there is ACK NACK 440 feedback (e.g., HARQ feedback) for the initial transmission.

[0055] Note that in case of proactive retransmission, the UE feedback (e.g.,

ACK/NACK 440 as in Figure 4) can be shifted in time e.g., by means of control signalling to jointly process the data from the first transmission and pro-active retransmission.

[0056] In accordance with the example embodiments of the invention the feedback may include the multi-bit NACK feedback from the UE that can correspond only to the data sent during the first transmission but with the indication on which PRBs that failed the decoding (strongly interfered). Thus, the AP can decide if the PRBs sent during pro-active retransmission were sufficient and match the ones indicated by the UE.

[0057] In case when only the identity of a strong interferer is known at the AP (the per- PRB scheduling info is not available), affected cell might blindly retransmit the data from the PRBs which were semi-statically allocated to the strong interferer.

[0058] Re-active retransmission

[0059] Note that in case of X2 delay, the network feedback about the strong interference can arrive to the AP after receiving a NACK from the UE. However, the AP can take the advantage of the interference information and, if available, the multi-bit feedback form the UE and retransmit the portions of the data only from affected PRBs.

[0060] Figure 5 shows operations associated with a re-active retransmission in accordance with the example embodiments of the invention. As shown in Figure 5 there is a first data transmission 510. This first data transmission may be considered an initial transmission in accordance with the embodiments. Further, there is shown the Network feedback 530 which arrives after the NACK 520 feedback. The NACK 520 can be a multi-bit NACK in accordance with the example embodiments as disclosed herein. Then, as shown in Figure 5 there is the re-transmission 540. In accordance with the example embodiments the retransmission can use the feedback information from network and/or use the multi-bit NACK feedback to identify physical resource blocks and dynamically allocated physical resource blocks of the initial transmission that need to be retransmitted.

[0061] Refined regular retransmission

[0062] The AP waits for ACK/NACK feedback from the UE. The UE might use multi- bit feedback to indicate which PRBs were affected with interference and need to be retransmitted. Further, in accordance with the example embodiments of the invention this refined regular transmission can use similar Dual ACK NACK operations as at least described above. Particularly, after receiving UE feedback for example, this mechanism can also take into account network information or feedback as described herein to help resolve the cause for the failures in ACK/NACK.

[0063] However, in case of cell edge users the multi-bit feedback might be infeasible. Then the UE might use only two bits to indicate whether the data part which failed to be decoded was send on semi-statically or dynamically allocated PRBs. Thus, the AP might retransmit the data only from affected PRBs. [0064] Figure 6 shows operations associated with a refined regular retransmission in accordance with the example embodiments of the invention. As shown in Figure 6 there is a first data transmission 610. This first data transmission may be considered an initial transmission in accordance with the embodiments. In response, as shown in Figure 6 a NACK 620 is communicated. In accordance with the example embodiments as disclosed herein this NACK 620 can include two bits to indicate data parts that were transmitted on semi-statically or dynamically allocated PRBs but which failed to be decoded. In addition, there may be network feedback 625 which can be used to resolve the cause for the NACK 620 for example. Then as shown in Figure 6 there is a retransmission 630. In accordance with the example embodiments the sender of the retransmission can use the two bit NACK feedback to identify physical resource blocks and dynamically allocated physical resource blocks of the initial transmission that need to be retransmitted.

[0065] With the dual ACK/NACK feedback e.g., a signalling of ACK/NACK separately for its semi-static and dynamic PRBs, the UE can indicate if it failed to decode the data transmitted on semi-statically or dynamically allocated PRBs as shown in the table below:

With only one extra bit of UE feedback, the AP can reduce the amount of retransmitted data and send the data only from failed PRBs. [0066] In general, for retransmission the AP can use the same frequency-resource blocks as it has used during a first transmission. However, it is highly probable that the same frequency blocks as during the first transmission would be affected by a strong interference during the retransmission. Thus, for higher reliability, the PRB data permutation is recommended.

[0067] In regards to Figure 7a there is illustrated a method and the operation of a computer program product in accordance with an exemplary embodiments of the invention which may be performed by a network node, such as the Node B 12 as illustrated in Figure 2. As shown in step 710 of Figure 7a there is determining, by a network node of a communication network, physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver are to be retransmitted to the receiver. Then as shown in step 720 of Figure 7a there is, based on the determining, initiating, by the network node, the retransmission of the physical resource blocks with the at least one data packet to the receiver

[0068] In accordance with the example embodiments as described in the paragraph above, the retransmission is initiated prior to arrival of an acknowledgement from the receiver of the initial transmission.

[0069] In accordance with the example embodiments as described in the paragraphs above, there is, prior to the retransmission, receiving at least one of an acknowledgement and negative acknowledgement, wherein the at least one of an acknowledgement and negative acknowledgement is used to determine particular physical resource blocks of the initial transmission which are retransmitted.

[0070] In accordance with the example embodiments as described in the paragraphs above, each acknowledgement or negative acknowledgement is received separately for a set of semi-static physical resource blocks and a set of dynamic physical resource blocks of the initial transmission.

[0071] In accordance with the example embodiments as described in the paragraphs above, the retransmission is a retransmission of at least one of a set of semi-static physical resource blocks and a set of dynamic physical resource blocks associated with the feedback.

[0072] In accordance with the example embodiments as described in the paragraphs above, the retransmission is initiated after receiving a negative acknowledgement from the receiver, and wherein the negative acknowledgement from the receiver comprises multi-bit feedback to identify at least one of particular segments and physical resource blocks of the initial transmission, that include the at least one packet, to be retransmitted. [0073] In accordance with the example embodiments as described in the paragraphs above, the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted. [0074] In accordance with the example embodiments as described in the paragraphs above, there is, prior to the retransmission, receiving feedback from the communication network regarding interference identified as capable of causing a decoding failure of the initial transmission at the receiver. [0075] In accordance with the example embodiments as described in the paragraphs above, the feedback is received over an X2 interface.

[0076] In accordance with the example embodiments as described in the paragraphs above, the feedback comprises a single bit, and wherein the feedback from the communication network is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

[0077] In accordance with the example embodiments as described in the paragraphs above, the retransmission is performed in physical resource blocks with a mapping relationship that is separate from the initial transmission.

[0078] In accordance with the example embodiments as described in the paragraphs above, the retransmission is performed using a one-to-one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission.

[0079] In accordance with the example embodiments as described in the paragraphs above, the network node comprises a base station of the communication network.

[0080] In the example aspect of the invention according to the paragraphs above, wherein at least the means for configuring and sending comprises a non-transitory computer readable medium [MEM 12B] encoded with a computer program [PROG 12C] executable by at least one processor [DP 12A].

[0081] In accordance with an example embodiment of the invention as described above there is an apparatus comprising: means for determining (DP 12A and/or DP 14A, PROG 12C and/or PROG 14C, and MEM 12B and/or 14B as in Figure 2) by a network node (eNB 12 and/or NCE 14 as in Figure 2) of a communication network (Network 1 as in Figure 2), physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver are to be retransmitted to the receiver; and means, based on the determining, for initiating (DP 12A and/or DP 14A, PROG 12C and/or PROG 14C, and MEM 12B and/or 14B as in Figure 2), by the network node (eNB 12 and/or NCE 14 as in Figure 2), the retransmission of the physical resource blocks with the at least one data packet to the receiver (e.g. UE 10 as in Figure 2).

[0082] Figure 7b illustrates operations which may be performed by a device such as, but not limited to, a device (e.g., the UE 10 as in Figure 2). As shown in step 750 of Figure 7b, there is determining, by a network device of a communication network, that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver needs to be retransmitted to the receiver. As shown in step 760 of Figure 7b there is, based on the determining, sending feedback towards the network node regarding the initial transmission. [0083] In accordance with the example embodiments as described in the paragraph above, the feedback comprises at least one of an acknowledgement and a negative acknowledgement regarding the initial transmission. [0084] In accordance with the example embodiments as described in the paragraph above, the at least one of an acknowledgement and a negative acknowledgement is sent separately for a set of semi-static physical resource blocks and a set of dynamic physical resource blocks of the initial transmission.

[0085] In accordance with the example embodiments as described in the paragraph above, the semi-static physical resource blocks and dynamic physical resource blocks are associated with the receiver and an interferer of the initial transmission.

[0086] In accordance with the example embodiments as described in the paragraph above, the feedback comprises a negative acknowledgement, and wherein the negative acknowledgement comprises multi-bit feedback to identify at least one of particular segments and physical resource blocks of the initial transmission, that include the at least one packet, to be retransmitted.

[0087] In accordance with the example embodiments as described in the paragraph above, the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted.

[0088] In accordance with the example embodiments as described in the paragraph above, the feedback is sent over an X2 interface. [0089] In accordance with the example embodiments as described in the paragraph above, the feedback comprises a single bit, and wherein the feedback is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

[0090] In accordance with the example embodiments as described in the paragraph above there is, in response to the feedback, receiving a retransmission of only particular physical resource blocks of the initial transmission, wherein the particular physical resource blocks of the retransmission are defined based on the feedback. [0091] In accordance with the example embodiments as described in the paragraph above, the retransmission is using physical resource blocks with a mapping relationship that is separate from the initial transmission.

[0092] In accordance with the example embodiments as described in the paragraph above, the retransmission is using a one-to-one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission. [0093] In accordance with the example embodiments as described in the paragraph above, the receiver comprises a user equipment of the communication network.

[0094] In accordance with the example embodiments as described in the paragraph above, the network device is embodied in the user equipment.

[0095] In the example aspect of the invention according to the paragraphs above, wherein at least the means for configuring and sending comprises a non-transitory computer readable medium [MEM 10B] encoded with a computer program [PROG IOC] executable by at least one processor [DP 10A].

[0096] In accordance with an example embodiment of the invention as described above there is an apparatus comprising: means for determining (DP 10A and/or DP 14A, PROG IOC and/or PROG 14C, and MEM 10B and/or 14B as in Figure 2), by a network device (UE 10 as in Figure 2) of a communication network (Network 1 as in Figure 2), that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver needs to be retransmitted to the receiver; and means, based on the determining, for sending (DP 10A and/or DP 14A, PROG IOC and/or PROG 14C, and MEM 10B and/or 14B as in Figure 2) feedback towards the network node (eNB 12 and/or NCE 14 as in Figure 2) regarding the initial transmission.

[0097] In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. [0098] Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0099] The word "exemplary" is may be used herein is to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims.

[00100] The foregoing description has provided by way of exemplary and non- limiting examples a full and informative description of the best method and apparatus presently contemplated by the inventors for carrying out the invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention.

[00101] It should be noted that the terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non- exhaustive examples.

[00102] Furthermore, some of the features of the preferred embodiments of this invention could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the invention, and not in limitation thereof.

Claims

What is claimed is: 1. A method comprising: determining, by a network node of a communication network, physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver are to be retransmitted to the receiver; and based on the determining, initiating, by the network node, the retransmission of the physical resource blocks with the at least one data packet to the receiver.

2. The method of claim 1, wherein the retransmission is initiated prior to arrival of an acknowledgement from the receiver of the initial transmission.

3. The method of claim 1, comprising prior to the retransmission, receiving at least one of an acknowledgement and negative acknowledgement, wherein the at least one of an acknowledgement and negative acknowledgement is used to determine particular physical resource blocks of the initial transmission which are retransmitted.

4. The method of claim 3, wherein each acknowledgement or negative

acknowledgement is received separately for a set of semi-static physical resource blocks and a set of dynamic physical resource blocks of the initial transmission.

5. The method of claim 4, wherein the retransmission is a retransmission of at least one of a set of semi-static physical resource blocks and a set of dynamic physical resource blocks associated with the feedback.

6. The method of claim 1 , wherein the retransmission is initiated after receiving a negative acknowledgement from the receiver, and wherein the negative acknowledgement from the receiver comprises multi-bit feedback to identify at least one of particular segments and physical resource blocks of the initial transmission, that include the at least one packet, to be retransmitted.

7. The method of claim 6, wherein the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted.

8. The method of claim 1, comprising: prior to the retransmission, receiving feedback from the communication network regarding interference identified as capable of causing a decoding failure of the initial transmission at the receiver.

9. The method of claim 8, wherein the feedback comprises a single bit, and wherein the feedback from the communication network is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

10. The method of claim 1, wherein the retransmission is performed in physical resource blocks with a mapping relationship that is separate from the initial transmission.

11. The method of claim 1 , wherein the retransmission is performed using a one-to-one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission.

12. The method of claim 1 , wherein the network node comprises a base station of the communication network.

13. A non-transitory computer-readable medium storing program code, the program code executed by at least one processor to perform the method of claim 1.

14. An apparatus, comprising: at least one processor; and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: determine physical resource blocks with at least one data packet transmitted in an initial transmission to a receiver of a communication network are to be retransmitted to the receiver; and based on the determining, initiate the retransmission of the physical resource blocks with the at least one data packet to the receiver.

15. The apparatus of claim 14, wherein the retransmission is initiated prior to arrival of an acknowledgement from the receiver of the initial transmission.

16. The apparatus of claim 14, wherein the at least one memory including the computer program code is configured with the at least one processor to cause the apparatus, prior to the retransmission, to receive at least one of an acknowledgement and negative

acknowledgement, wherein the at least one of an acknowledgement and negative acknowledgement is used to determine particular physical resource blocks of the initial transmission which are retransmitted.

17. The apparatus of claim 16, wherein each acknowledgement or negative

18. The apparatus of claim 17, wherein the retransmission is a retransmission of at least one of a set of semi-static physical resource blocks and a set of dynamic physical resource blocks associated with the feedback.

19. The apparatus of claim 14, wherein the retransmission is initiated after receiving a negative acknowledgement from the receiver, and wherein the negative acknowledgement from the receiver comprises multi-bit feedback to identify at least one of particular segments and physical resource blocks of the initial transmission, that include the at least one packet, to be retransmitted.

20. The apparatus of claim 19, wherein the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted.

21. The apparatus of claim 14, wherein the at least one memory including the computer program code is configured with the at least one processor to cause the apparatus, prior to the retransmission, to receive feedback from the communication network regarding interference identified as capable of causing a decoding failure of the initial transmission at the receiver.

22. The apparatus of claim 21, wherein the feedback comprises a single bit, and wherein the feedback from the communication network is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

23. The apparatus of claim 14, wherein the retransmission is performed in physical resource blocks with a mapping relationship that is separate from the initial transmission.

24. The apparatus of claim 14, wherein the retransmission is performed using a one-to- one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission.

25. A method comprising:

determining, by a network device of a communication network, that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver needs to be retransmitted to the receiver; and based on the determining, sending feedback towards the network node regarding the initial transmission.

26. The method of claim 25, wherein the feedback comprises at least one of an acknowledgement and a negative acknowledgement regarding the initial transmission.

27. The method of claim 26, wherein the at least one of an acknowledgement and a negative acknowledgement is sent separately for a set of semi-static physical resource blocks and a set of dynamic physical resource blocks of the initial transmission.

28. The method of claim 27, wherein the semi-static physical resource blocks and dynamic physical resource blocks are associated with the receiver and an interferer of the initial transmission.

29. The method of claim 25, wherein the feedback comprises a negative

acknowledgement, and wherein the negative acknowledgement comprises multi-bit feedback to identify at least one of particular segments and physical resource blocks of the initial transmission, that include the at least one packet, to be retransmitted.

30. The method of claim 29, wherein the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted.

31. The method of claim 25, wherein the feedback comprises a single bit, and wherein the feedback is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

32. The method of claim 25, comprising: in response to the feedback, receiving a retransmission of only particular physical resource blocks of the initial transmission, wherein the particular physical resource blocks of the retransmission are defined based on the feedback.

33. The method of claim 32, wherein the retransmission is using physical resource blocks with a mapping relationship that is separate from the initial transmission.

34. The method of claim 33, wherein the retransmission is using a one-to-one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission.

35. An apparatus, comprising : at least one processor; and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: determine that physical resource blocks with at least one data packet of an initial transmission from a network node to a receiver of a communication network needs to be retransmitted to the receiver; and based on the determining, sending feedback towards the network node regarding the initial transmission.

36. The apparatus of claim 35, wherein the feedback comprises at least one of an acknowledgement and a negative acknowledgement regarding the initial transmission.

37. The apparatus of claim 36, wherein the at least one of an acknowledgement and a negative acknowledgement is sent separately for a set of semi-static physical resource blocks and a set of dynamic physical resource blocks of the initial transmission.

38. The apparatus of claim 37, wherein the semi-static physical resource blocks and dynamic physical resource blocks are associated with the receiver and an interferer of the initial transmission.

39. The apparatus of claim 35, wherein the feedback comprises a negative

40. The apparatus of claim 39 wherein the multi-bit feedback comprises at least two bits identifying particular semi-statically allocated physical resource blocks and dynamically allocated physical resource blocks of the initial transmission to be retransmitted.

41. The apparatus of claim 40, wherein the feedback comprises a single bit, and wherein the feedback is used to identify particular segments and physical resource blocks of the initial transmission to be retransmitted.

42. The apparatus of claim 35, wherein the at least one memory including the computer program code is configured with the at least one processor to cause the apparatus to, in response to the feedback, receive a retransmission of only particular physical resource blocks of the initial transmission, wherein the particular physical resource blocks of the retransmission are defined based on the feedback.

43. The apparatus of claim 42, wherein the retransmission is using physical resource blocks with a mapping relationship that is separate from the initial transmission.

44. The apparatus of claim 42, wherein the retransmission is using a one-to-one relationship between the retransmitted physical resource blocks and physical resource blocks of the initial transmission.

45. The apparatus of claim 35, wherein the receiver comprises a user equipment of the communication network.