WO2022096093A1 - Method and apparatus for enhanced harq processing in radio network - Google Patents

Abstract

The present disclosure relates to method and apparatus for enhanced HARQ (Hybrid Automatic Repeat Request) processing in sidelink communication between User Equipments (UEs) as well as in downlink/uplink communication between base station and UE. In particular the disclosure relates to a first device (310, 330), comprising: a processor (301), configured to: obtain a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group; and a transceiver (302), configured to: transmit the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

Description

METHOD AND APPARATUS FOR ENHANCED HARQ PROCESSING IN RADIO NETWORK

TECHNICAL FIELD

The present disclosure relates to method and apparatus for enhanced HARQ (Hybrid Automatic Repeat Request) processing in radio network. The disclosure particularly relates to techniques for enhancing the reliability of the feedback channel for transmitting HARQ response, such as the PSFCH (Physical Sidelink Feedback Channel) and PUCCH (Physical Uplink Control Channel).

BACKGROUND

The 5G mobile radio network is aiming at providing the Ultra Reliable and Low Latency Communication (URLLC) services to the business areas such as Vehicle to Evertying (V2X), Industrial Internet of Things (HOT) and healthcares, etc. The Radio Access Network (RAN) part of the 5G system, relies on the Hybrid Automatic Repeat reQuest (HARQ) as one of the important techniques for achieving reliable data transmission. In HARQ, the original data is encoded with a forward error correction (FEC) code into different redundant versions (RV) which are transmitted progressively upon the HARQ response when a receiver detects an erroneous message.

For achieving the ultra-reliable data transmission, the reception of HARQ response at the data transmitter (Tx) side from the data receiver (Rx) should also be reliable.

SUMMARY

It is the object of this disclosure to provide techniques for providing ultra-reliable data transmission in mobile communication. It is a particular object of this disclosure to improve the reliability of HARQ response in mobile data communication, e.g. for communication over the 5G mobile radio network.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures. A basic idea of this disclosure is to transmit the HARQ response based on a group of physical resource blocks (PRBs) instead of a single PRB. New allocation methods for this concept are provided and described below.

Transmission of the HARQ response as described above can be applied for both, sidelink communication between UEs, as well as downlink/uplink communication (via llu link) between base station and UE.

The new concept can be summarized as follows:

According to a first part, referred to as Part 1 hereinafter, HARQ response is based on a group PRBs instead of single PRB. New features are to provide a UE with the grouping range option by prescription or configuration signaling, in particular configured by Radio Resource Control (RRC) signaling:

(i) within the frequency range of the whole resource pool of the feedback channel for transmitting HARQ response, such as the PSFCH and/or PUCCH; or

(ii) within the frequency range of the same subchannel as the resource unit for transmitting the shared channel, such as the physical sidelink shared channel (PSSCH) or the physical uplink shared channel (PUCCH). The resource unit of the shared channel comprises the minimal granularity of allocating the orthogonal frequency-division multiple access (OFDMA) radio resource in both time and frequency domains, e.g. in one frequency-domain subchannel one time-domain slot.

According to a first method, referred to as Method A hereinafter, of Part 1 , the resource is firstly divided into groups of staggered or non-contiguously staggered PRBs and then the PRB groups are associated with the shared channel resource.

As new features: (i) a UE is provided with the Group Size by prescription or configuration signaling, in particular configured by RRC signaling; (ii) a staggering method for a UE is applied to derive the grouping of the feedback channel’s PRBs within the physical feedback channel’ resource pool.

According to a second method, referred to as Method B hereinafter, of Part 1 , the staggered PRBs are firstly associated to the shared channel resource units and/or the associated PRBs may be divided into groups, group size can be dynamically determined by Tx UE based on channel condition and reliability requirement. As new features: (i) the staggering method for a UE may be applied to derive the association of the shared channel resource unit to the feedback channel PRBs; (ii) for a shared channel transmission, the Group Size may be provided by Tx UE to Rx UE, via SCI format 0-1 or 0- 2 or MAC CE; and (iii) The staggering method for a UE may be applied to derive the grouping of feedback channel PRBs within the associated PRBs to the shared channel transmission.

According to a second part, referred to as Part 2 hereinafter, channel-aware feedback channel transmission comprises: (a) Rx UE may select one or part of the PRBs from a feedback channel PRB group (b) Rx UE can allocate different power level on the selected PRBs; (c) The Tx UE and/or gNB can also indicate to the Rx UE the selection of feedback channel PRBs in a group and optionally a beam indicator based on the detection of previous shared channel transmission via SCI format 0-1 or 0-2 or MAC CE; and (d) An extension to the power allocation and/or PRB selection based shared channel transmission may be to further consider the amplitude and phase changes of the fading channel along the REs in frequency domain.

Resource Unit (RU) is a unit in OFDMA terminology used to denote a set of subcarriers (tones) of a set of OFDM symbols used in both Downlink (DL)/Uplink (UL) and sideling (SL) transmissions. With OFDMA, different transmit powers may be applied to different RUs.

According to a first aspect, the disclosure relates to a first device, comprising: a processor, configured to: obtain a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group; and a transceiver, configured to: transmit the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

This solution is not limited to the sidelink scenario, it can also be applied to the Uu-link scenario or any other radio network where HARQ is used. The first device can be a network device or a user device such as a User Equipment, UE. The second device (which receives the HARQ response) can be a user device.

By transmitting the HARQ response in the PRB group with the size of at least two PRBs, significant improvement in reliability and detection performance compared to the case of one fixed PRB can be achieved. As shown below with respect to Figure 9, when selecting PRB with the best channel gain out of two staggered PRBs in a group, over 6 dB gain can be achieved, for example. With MRT pre-equalization using both PRBs, over 10 dB gain can be achieved, for example.

The term “non-contiguously” or “non-contiguously staggered”, respectively, means in this context that the PRB resources of each PRB group are separated by each other and also separated by other PRB resources of other PRB groups. I.e., resources between the staggered or non-contiguously staggered PRB resources are not belonging to a same PRB group. In addition, the term “staggered” means an arrangement of PRBs so that the PRBs are not positioned in a regular way, in particular so that PRBs are arranged in any of various zigzags or alternations of slot and/or frequency.

In an exemplary implementation of the first device, the processor may be further configured to: obtain an index of the PRB group, wherein the index of the PRB group is used to determine the PRB resources of each PRB group.

By obtaining the index of the PRB group, the PRB resources of each PRB group can be efficiently determined by the processor.

In an exemplary implementation of the first device, the processor may be further configured to: obtain a resource pool for transmission of a HARQ response, wherein the resource pool is used to be allocated into PRB group according to the size of the PRB group.

This provides the advantage that an efficient resource utilization can be achieved.

In an exemplary implementation of the first device, the PRB resources of each PRB group may be staggered with one or more of PRB resources of another PRB group.

The word “staggered” means in this context, as already described above, that the PRB resources of each PRB group are separated by each other and also separated by other PRB resources of other PRB groups.

This provides the advantage that a good resource diversity can be obtained.

In an exemplary implementation of the first device, the transceiver may be configured to: transmit the size of a Physical Resource Block, PRB group to a second device. This provides the advantage that the second device is informed about the size of the PRB group and thus can efficiently implement its HARQ scheme.

In an exemplary implementation of the first device, the transceiver may be configured to transmit the HARQ response in a Physical Sidelink Feedback Channel, PSFCH, to another UE; or in a Physical Uplink Control Channel, PUCCH, to a base station.

This provides the advantage that HARQ reliability can be improved for both scenarios, sidelink transmission and Uu-link transmission.

In an exemplary implementation of the first device, according to a first option the at least two PRBs of the PRB group may be staggered within a frequency range of the resource pool; or according to a second option the at least two PRBs of the PRB group may be staggered within the same frequency range.

This provides the advantage that frequency distance of the PRBs in a group can be maximized and hence the frequency diversity gain; or channel-aware transmission can be improved by exploring the reciprocity of the channel.

In an exemplary implementation of the first device, the processor may be configured to first divide a PRB resource into fixed groups of staggered PRBs and then associate the PRB groups with resource units, wherein the PRB groups have a fixed group size R.

This provides the advantage that frequency diversity can be improved.

This implementation is corresponding to Method A referred to in the disclosure.

In an exemplary implementation of the first device, the group size R may be prescribed or configured, in particular configured by Radio Resource Control, RRC, signaling.

This provides the advantage of flexibility in configuration.

This implementation is corresponding to Method A, Step 1 referred to in the disclosure.

In an exemplary implementation of the first device, the frequency range of the resource pool according to the first option or the frequency range according to the second option may be prescribed or configured, in particular configured by RRC signaling. This provides the advantage of flexibility in configuration.

This implementation is corresponding to Method A, Step 1 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to determine a grouping configuration of the group of PRBs based on a staggering operation.

This provides the advantage of maximizing the spreading of PRBs

This implementation is corresponding to Method A, Step 2 referred to in the disclosure.

The staggering operation can, for example, be implemented by: filling elements of a first sequence one by one along one dimension of a matrix, and generating a second sequence by taking elements one by one from the other dimension of the matrix. Other ways to perform the staggering operation can be implemented, as well.

The above-described matrix can have a size of M/R times R, wherein R represents a fixed group size and M represents a total number of feedback channel PRBs.

The first sequence can be associated with a logical index of the PRBs within the resource pool, and the second sequence can be associated with a staggered physical index of the PRBs according to the logical index of the PRBs.

In an exemplary implementation of the first device, the processor may be configured to associate the PRB groups with the resource units based on a pre-defined indexing.

This provides the advantage of an easy implementation when indexing is pre-defined.

This implementation is corresponding to Method A, Step 3 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to determine the PRB group which transmits the HARQ response based on the grouping configuration of the group of PRBs.

This provides the advantage of high reliability since the grouping configuration is known to the processor. This implementation is corresponding to Method A, Step 4 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to first associate staggered PRBs to resource units and then divide the associated PRBs into groups.

This provides the advantage of increasing the frequency diversity.

This implementation is corresponding to Method B referred to in the disclosure.

In an exemplary implementation of the first device, the frequency range of the resource pool according to the first option or the frequency range according to the second option may be prescribed or configured, in particular configured by RRC signaling.

This provides the advantage of flexibility in configuration.

This implementation is corresponding to Method B, Step 1 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to associate staggered PRBs to resource units based on a staggering operation.

This provides the advantage of maximizing the spreading of PRBs.

This implementation is corresponding to Method B, Step 2 referred to in the disclosure.

The staggering operation can be implemented by filling elements of a first sequence one by one along one dimension of the matrix, and generating a second sequence by taking elements one by one from the other dimension of the matrix.

The matrix can have a size of N times K, wherein N represents a number of PRBs per resource unit and K represents a number of resource units within a resource pool.

The first sequence can be associated with a logical index of the PRBs within the resource pool, and the second sequence can be associated with a staggered physical index of the PRBs according to the logical index of the PRBs. In an exemplary implementation of the first device, the processor may be configured to group the PRBs which are associated to the resource units of a transmission based on a transmission-specific group size R, wherein the transceiver is configured to transmit the transmission-specific group size R to at least one UE.

This provides the advantage of easy implementation since the group size R is transmission specific and known to the UE.

This implementation is corresponding to Method B, Step 3 and 4 referred to in the disclosure.

The method described above with respect to Claim 11 can be used for grouping the PRBs associated to the resource units of a transmission.

In an exemplary implementation of the first device, the processor may be configured to determine the PRB group which transmits the HARQ response based on the transmissionspecific group size R.

This provides the advantage of high reliability since the transmission-specific group size is known to the processor.

This implementation is corresponding to Method B, Step 5 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to select at least one PRB from the PRB group based on a selection by the first device and/or the one or more second devices, wherein the selection may be determined by the first device and/or the one or more second devices.

This provides the advantage of high flexibility due to the selection operation.

This implementation is corresponding to Part 2 referred to in the disclosure.

In an exemplary implementation of the first device, power levels of the selected PRBs may be based on an allocation by the first device and/or the one or more second devices, wherein the allocation may be based on a channel quality in each PRB. This provides the advantage of high reliability since the power levels can be efficiently allocated.

This implementation is corresponding to Part 2 referred to in the disclosure.

In an exemplary implementation of the first device, the processor may be configured to select the at least one PRBs of the PRB group based on a channel condition.

This provides the advantage of high reliability since the channel condition is considered.

The channel condition may be determined from observation of a previous reception of feedback channel (e.g. PSFCH) and/or shared channel (e.g. PSSCH, PDSCH) and/or control channel (e.g. PSCCH, PDCCH).

This implementation is corresponding to Part 2 referred to in the disclosure.

In an exemplary implementation of the first device, the processor is configured to select the at least one PRBs of the PRB group and power levels of the selected PRBs based on signaling in PSCCH with SCI Format 0-1 or PSSCH with SCI Format 0-2 or MAC CE, based on channel condition from a previous reception of feedback channel (e.g. PSFCH) and/or shared channel (e.g. PSSCH, PDSCH) and/or control channel (e.g. PSCCH, PDCCH)..

This provides the advantage of high reliability since the channel condition is considered.

This implementation is corresponding to Part 2 referred to in the disclosure.

In an exemplary implementation of the first device, the selection of the PRBs and/or an allocation of power levels of the selected PRBs may be based on applying a preequalization vector with specific amplitude and/or phase values on the resource elements of the selected at least one PRB.

This provides the advantage of high reliability due to the user of the pre-equalization vector.

This implementation is corresponding to Extension of Part 2 referred to in the disclosure.

According to a second aspect, the disclosure relates to a method for HARQ transmission, the method comprising: obtaining a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group; and transmitting the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

This provides the same advantages as described above for the first aspect.

As described above, this solution is not limited to the sidelink scenario, it can also be applied to the Uu-link scenario or any other radio network where HARQ is used. The method can be applied for HARQ transmission between a network device and a user device or for HARQ transmission between two user devices.

According to a third aspect, the disclosure relates to a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method according to the second aspect. Such a computer program product may include a non-transient readable storage medium storing program code thereon for use by a processor, the program code comprising instructions for performing the methods or the computing blocks as described hereinafter.

The computer program product may run on the components of a communication system described below with respect to Figure 11. For example, the computer program product may run on a first user device 1101 a as shown in Figure 11 . Such a first user device may comprises a processing circuitry 1103a for instance, a processor 1103a, for processing and generating data, e.g. the program code described above, a transceiver 1105a, including, for instance, an transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 1100, and a non-transitory memory 1107a for storing data, e.g. the program code described above.

Using such a computer program product improves reliability of HARQ transmission in radio communication networks, e.g. such as transmission over the 5G radio network.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which: Fig. 1 shows a schematic diagram illustrating a wireless channel with frequency-selective fading;

Fig. 2 shows a time-frequency diagram illustrating resources for transmission over a wireless channel;

Fig. 3 shows a schematic diagram of a communication system 300 with a network device 310;

Fig. 4 shows a schematic diagram illustrating the setting of frequency location for allocated PRBs in a group according to a first option (Option 1);

Fig. 5 shows a schematic diagram illustrating the setting of frequency location for allocated PRBs in a group according to a second option (Option 2);

Fig. 6 shows a sequence chart illustrating message signaling between the network device and the group of user devices;

Fig. 7 shows a sequence chart illustrating message signaling between the network device and the group of user devices;

Fig. 8 shows a schematic diagram illustrating channel-aware PRB selection and power allocation;

Fig. 9 shows a performance diagram illustrating detection performance when using two staggered PRBs instead of a single PRB; and

Fig. 10 shows a schematic diagram illustrating a method for transmitting a HARQ response in a PRB group with a size of at least two PRBs; and

Fig. 11 shows a schematic diagram illustrating a communication system according to the disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

UE User Equipment

PSFCH Physical Sidelink Feedback Channel

PUCCH Physical Uplink Control Channel

HARQ Hybrid Automatic Repeat reQuest

NACK Not-Acknowledged

ACK Acknowledged

RE Resource Element

RU Resource Unit

RV Redundant Version

DTX Discontinuous Transmission

CS Cyclic Shift

RRC Radio Resource Control

MAC Media Access Control

CE Control Element

PRB Physical Resource Block

DL Downlink

UL Uplink

SL Sidelink

MAC Media Access Control

CE Control Element

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The methods, devices and systems described herein may be implemented in radio network, in particular long term evolution, LTE, 5G, or 5G beyond. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender). However, devices described herein are not limited to transmit and/or receive radio signals, also other signals designed for transmission in deterministic communication networks may be transmitted and/or received.

The devices and systems described herein may include processors or processing devices, memories and transceivers, i.e. transmitters and/or receivers. The term “processor” or “processing device” describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multicore processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc.

The devices and systems described herein may include transceivers or transceiver devices. A transceiver is a device that is able to both transmit and receive information or signal through a transmission medium, e.g. a radio channel. It is a combination of a transmitter and a receiver, hence the name transceiver. Transmission is usually accomplished via radio waves. By combining a receiver and transmitter in one consolidated device, a transceiver allows for greater flexibility than what either of these could provide individually.

As described above, the solution presented in this disclosure can be designed progressively into two parts. Part 1 addresses staggered grouping of the PRBs for PSFCH. There are two optional allocation methods: Method A: firstly divide the PSFCH resources into fixed groups of staggered PRBs and then associate the PRB groups with PSSCH resource units; the PRBs of each group are staggered.

Method B: firstly allocate staggered PRBs to PSSCH resource units and then divide the allocated PRBs into groups. This method allows for adjustable group size for each transmission.

Part 2 addresses channel-aware PRB selection and power allocation based on the PSFCH PRB grouping in Part 1 considering the both Methods A and B, with an extension of preequalization based transmission.

Fig. 1 shows a schematic diagram illustrating a wireless channel 100 with frequency- selective fading. The frequency selective fading is shown by reference sign 102: The channel is changing with frequency f. When a sequence 101 is based on PSFCH with only one physical resource block, PSFCH reception 103 is very weak as can be seen from Figure 1.

Present disclosure will use sidelink HAQR as example, but it should be understood that the method and/or devices shall not be limited to sidelink and it may be used for any radio network for example evolved LTE, 5G or 5G beyond.

When using a first device according to the first aspect of the disclosure as described above, the following negative consequences of the detection failure of HARQ response (in sidelink communication between UEs as an example) can be overcome due to transmission of the HARQ response in the PRB group with a size of at least two PRBs:

Misdetection of NACK (Not-Acknowledged) as ACK (Acknowedged) which may result in missing retransmission to Receiver (Rx) UE, which may reduce the reliability of the transmission. On the other hand, misdetection of ACK as NACK may result in unnecessary retransmission from Tx UE, which leads to waste of resources.

Misdetection of NACK as Discontinuous Transmission (DTX) which may result in retransmission of suboptimal Redundant Version (RV) to Rx UE, which leads to degraded reliability. Failure to identify NACK in sidelink Groupcast Option 1 (only transmit NACK) which may result in missing retransmission to the failed Rx UE, which may reduce the reliability of the transmission over the sidelink.

It should be understood that the first device in some scenarios acts as transmitting device, but in some other scenarios acts as receiving device in particularly for sidelink case. In some scenarios, the first device may act as both transmitting device and receiving device. The present disclosure may treat the first device as both transmitting device and receiving device, but it should be understood that the first device may act as only transmitting device or receiving device. The transmitting device may refer as transmit UE and receiving device may refer as receive UE in the present disclosure.

In 5G RAN, the HARQ response may be carried by the Physical Uplink Control Channel (PUCCH), the Physical Sidelink Feedback Channel (PSFCH) for the cellular link and sidelink communication respectively. In current Release-16 (R16) of 5G, the PSFCH and PUCCH Format 0 occupy only a single Physical Resource Block (PRB) at a pre-allocated frequency domain location. When using the first device according to the first aspect of the disclosure, reliable detection of HARQ response can be provided, in particular in the following scenarios:

(1) The PSFCH and PUCCH Format 0 are narrow band signals, which occupy only 12 consecutive Resource Element (REs). The bandwidth is only 720kHz at its maximum for the subcarrier spacing of 60kHz. Due to its narrowband nature, the detection performance suffers severely from the frequency selective fading of wireless channel.

For example, the coherent bandwidth of the 3GPP TDL-C UMi (Tapped Delay Line profile C, Urban Microcells) Street-canyon with long delay is up to 4.42MHz. As a result, the narrow band signal falls easily into a fading notch in frequency domain leading to weak reception at the receiver.

By using the first device according to the disclosure such problems due to frequency selective fading channel can be overcome, since the HARQ response in the PRB group is transmitted with a size of at least two PRBs.

(2) The transmitting power is subject to power control when in coverage, which may further limit its reliable detection. By using the first device according to the disclosure such problems related to power control can be overcome. (3) The transmission of PSFCH or PLICCH format 0 at a pre-allocated frequency location is not channel-aware and adaptive. By using the first device according to the disclosure such problems related to power control can be overcome.

It should be understood that the scenarios above are just for example. The method and/or devices in the present disclosure may also be used for other scenarios where HAQRQ response is received.

Fig. 2 shows a time-frequency diagram illustrating resources 200 for transmission over a wireless channel.

In current design of 5G HARQ for example sidelink, only one PRB is used in PSFCH and PLICCH for example format 0 for the HARQ response to a data transmission carried in the Physical Sidelink Shared Channel (PSSCH), which is unreliable in frequency-selective fading channel as shown above with respect to Figure 1 . This unreliability can be overcome by using a first device according to the first aspect of the disclosure as described above due to transmission of the HARQ response in the PRB group with a size of at least two PRBs.

A further problem with data transmission using only one PRB in PSFCH as described below can also be overcome by using the first device according to the first aspect of the disclosure. The problem is that the available PRBs e.g. for PSFCH are highly redundant, as illustrated in the following example:

Example: The sidelink radio resource may be split in frequency domain into Subchannels with several options of SubchannelSize: 10, 15, 20, 25, 50, 75, or 100 PRBs. The number of Subchannels within the resource pool is: /V_subch. PSFCH resource exists periodically with the period Npfs^H = {0,1 , 2, 4} PSSCH time slot(s). The zero means no PSFCH resource, thus HARQ response may be turned off. The total number of PSFCH PRBs in a resource pool is: Mpp ^c _s ^H _ct , its maximum value is: SubchannelSize x /V_subch. One PSSCH resource unit ( 'i.e. one subchannel in one slot) ' is associated with M s^Pu^b^Fc^h,^H s,lo „t PRBs of PSFCH :

_MPSFCH _ | _MPS

^Msubch, slot - [^MPR

[(SubchannelSize

As a result, the available PSFCH PRBs associated with a PSSCH resource unit ranges from 2 up to 100. Besides the available PSFCH resources can scale up further: One PSSCH transmission can use multiple PSSCH resource units. Then the available PSFCH PRBs for a PSSCH transmission can scale up further. Multiple Cyclic Shift (CS) pairs (1 ,2,3 or 6) can be used for code domain multiplexing in the same PSFCH PRB, which further scales up available PSFCH PRBs for a PSSCH transmission.

Since an Rx UE transmits PSFCH with only one PRB, the actual utilization of the PSFCH resource is quite low: For Unicast: only one PRB is used by the single Rx UE; For Groupcast Option 1 : only the Rx UE(s) which failed to decode PSSCH transmit NACK; For Groupcast Option 2: all Rx UEs transmit ACK/NACK. By using transmission of the HARQ response based on a group of physical resource blocks (PRBs) according to the concept of this disclosure, instead of a single PRB, the PSFCH resource can be better utilized resulting in a higher reliability.

A specific example to further illustrate the high redundancy of PSFCH resource is shown in Figure 2, where an exemplary number of four PSSCH resources 202, 203, 204, 205 are illustrated, early PSSCH resources are referred to by 201 , an exemplary period of PSFCH resource 211 is set to 2, minimum time gap 212 of PSFCH is shown and an exemplary subchannel size 213 of 20 is given: The following parameters apply in Figure 2:

SubchannelSize: 20 PRBs, periodPSFCHresource: 2 slots, the number of PSFCH PRBs associated with one PSSCH resource unit is:

1°- Assume for a PSSCH transmission, 2 PSSCH resource units are used and the code domain multiplexing with 2 CS pairs is allowed. Then as a result: the resource utilization per UE is only: 1 1 (10*2*2) = 2.5%; and for groupcast, it means that high up to 40 Rx UEs in a group are supported.

In conclusion, the PSFCH transmission with only one PRB transmitted by a UE is unreliable and the redundant PSFCH resources can be utilized for enhancing the reliability of HARQ response. As indicated above, this unreliability can be overcome by using a first device according to the first aspect of the disclosure as described above due to transmission of the HARQ response in the PRB group with a size of at least two PRBs.

Fig. 3 shows a schematic diagram of a communication system 300 with a network device 310, e.g. gNB and Core Network, and a group of user devices, a first user device 330 denoted as receive UE (Rx UE) and a second user device 320 denoted as transmit UE (Tx UE) according to the disclosure. Each device 310, 320, 330 shown in Figure 3 can include a processor 301 and a transceiver 302 as illustrated on the right-hand side of Figure 3 illustrating the structure of a first device 310, 330 or a second device 320.

The network device 310 provides configuration information 311 , 312 of UEs including resource pool, grouping parameters, etc. to the Tx UE 320 and the Rx UE 330. In the sidelink scenario, Tx UE 320 may send data and/or control information 321 in PSSCH as well as control information 321 in PSCCH to Rx UE 330. Rx UE 330 responds by sending HARQ response 331 in PSFCH to Tx UE 320.

In the Uu link scenario, network device 310 may send data and/or control information 321 in PSSCH as well as control information 321 in PSCCH to Rx UE 330 (not shown in Fig. 3). Rx UE 330 responds by sending HARQ response 331 to network device 310 (not shown in Fig. 3). The Uu link is also known as cellular link and alternative one may be used in the present disclosure.

In the general case including both scenarios, sidelink and Uu link, the first device 310, 330 comprises a processor 301 , configured to: obtain a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group; and a transceiver 302, configured to: transmit the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

The processor 301 may further be configured to obtain an index of the PRB group, wherein the index of the PRB group is used to determine the PRB resources of each PRB group.

The processor 301 may further be configured to obtain a resource pool for transmission of a HARQ response, wherein the resource pool is used to be allocated into PRB group according to the size of the PRB group.

The PRB resources of each PRB group may be staggered with one or more of PRB resources of another PRB group.

The transceiver 302 may be configured to transmit the size of a Physical Resource Block, PRB group to a second device 320. The transceiver 302 may be configured to transmit the HARQ response in a Physical Sidelink Feedback Channel, PSFCH, to another UE; or in a Physical Uplink Control Channel, PUCCH, to a base station.

According to a first option the at least two PRBs of the PRB group may be non-contiguous within a frequency range of the resource pool, e.g. as illustrated in Figure 4, and may be staggered with the PRB resources of other PRB groups; or according to a second option the at least two PRBs of the PRB group may be non-contiguous within the same frequency range, e.g. as illustrated in Figure 5, and may be staggered with the PRB resources of other PRB groups.

The frequency range of the resource pool denotes the frequency range of the whole resource pool, including all subchannels of the resource pool, as shown in Figure 4, for example. The same frequency range denotes the frequency range of the same subchannel, e.g. of subchannel s, as shown in Figure 5.

The processor 301 may further be configured to first divide a PRB resource into fixed groups and the PRB resources of different groups staggered each other. Then associate the PRB groups with resource units, wherein the PRB groups have a fixed group size R, e.g. corresponding to Method A described in this disclosure.

The group size R may be prescribed or configured, in particular configured by Radio Resource Control, RRC, signaling, e.g. corresponding to Method A, step 1 described in this disclosure.

The frequency range of the resource pool according to the first option or the frequency range according to the second option may be prescribed or configured, in particular configured by RRC signaling, e.g. corresponding to Method A, step 1 described in this disclosure.

The processor 301 may further be configured to determine a grouping configuration of the group of PRBs based on a staggering operation, e.g. corresponding to Method A, step 2 described in this disclosure.

The processor 301 may further be configured to associate the PRB groups with the resource units based on a pre-defined indexing, e.g. corresponding to Method A, step 3 described in this disclosure. The processor 301 may further be configured to determine the PRB group which transmits the HARQ response based on the grouping configuration of the group of PRBs, e.g. corresponding to Method A, step 4 described in this disclosure.

The processor 301 may further be configured to first associate staggered PRBs to a resource units and then divide the associated PRBs into groups, e.g. corresponding to Method B described in this disclosure.

The frequency range of the resource pool according to the first option or the frequency range according to the second option may be prescribed or configured, in particular configured by RRC signaling, e.g. corresponding to Method B, step 1 described in this disclosure.

The processor 301 may further be configured to associate staggered PRBs to resource units based on a staggering operation, e.g. corresponding to Method B, step 2 described in this disclosure.

The processor 301 may further be configured to group the PRBs which are associated to the resource units of a transmission based on a transmission-specific group size R. The transceiver 302 may further be configured to transmit the transmission-specific group size R to at least one UE, e.g. corresponding to Method B, step 3 and 4 described in this disclosure.

The processor 301 may further be configured to determine the PRB group which transmits the HARQ response based on the transmission-specific group size R, e.g. corresponding to Method B, step 5 described in this disclosure.

The processor 301 may further be configured to select at least one PRB from the PRB group based on a selection by the first device and/or the one or more second devices, wherein the selection is determined by the first device and/or the one or more second devices, e.g. corresponding to Part 2 described in this disclosure.

Power levels of the selected PRBs may be based on a power allocation by the first device and/or the one or more second devices, wherein the power allocation is based on a channel quality in each PRB, e.g. corresponding to Part 2 described in this disclosure. The processor 301 may further be configured to select the at least one PRBs of the PRB group based on a channel condition, e.g. corresponding to Part 2 described in this disclosure.

The processor 301 may further be configured to select the at least one PRBs of the PRB group and power levels of the selected PRBs based on signaling in PSCCH for example with SCI Format 0-1 or PSSCH with SCI Format 0-2 or MAC CE, based on channel condition from a previous reception of PSFCH and/or PSSCH and/or PSCCH signal, e.g. corresponding to Part 2 described in this disclosure.

The selection of the PRBs and/or an allocation of power levels of the selected PRBs may be based on applying a pre-equalization vector with specific amplitude and/or phase values on the resource elements of the selected at least one PRB, e.g. corresponding to Extension of Part 2 described in this disclosure.

In the following, in particular with reference to Figures 4 to 9, the sidelink scenario is described in more detail.

In the sidelink scenario, a group of UEs 320, 330, configured by the network 310 or preconfigured by certain default rules, communicates with each other directly via the Sidelink. A Tx UE 320 transmits data carried in PSSCH and/or control information 321 carried in PSCCH to one or multiple Rx UE(s) 330.

Based on the results (succesfull or failed) of decoding the PSSCH, the Rx UE(s) 330 send the HARQ response 331 to the Tx UE 320 in the PSFCH which includes a group of at least two PRBs. The PRBs in each group may be staggered or non-contiguously allocated with possibly large frequency distance so that the frequency diversity can be utilized for enhancing the reliability of detecting the HARQ response 331 at the Tx UE side 320.

There are two options for setting the frequency location of the PSFCH PRBs of a group.

According to a first option, also referred to as “Frequency Range Option 1”, the allocated PRBs in a group may be within the frequency range of the whole PSFCH resource pool, as shown in Figure 4. This option can maximize the frequency distance of the PRBs in a group and hence maximize the frequency diversity gain. According to a second option, also referred to as “Frequency Range Option 2”, the allocated PRBs in a group may be within the frequency range of the same subchannel as the group’s associated PSSCH resource unit(s), as shown in Figure 5. This option can enable the channel-aware transmission of HARQ response by exploring the reciprocity of the wireless channel, which will be further described below with respect to Part 2 of this disclosure.

The selection between the two Options can be configured by high layer.

Fig. 4 shows a schematic diagram illustrating the setting of frequency location for allocated PRBs in a group according to a first option (Option 1) 400 or example. In Figure 4, resources are shown over subchannels 403, 402, 401 and time.

According to the first option (Frequency Range Option 1), the allocated PRBs 411 , 412, 413, 414 in a group are within the frequency range 420 of the whole PSFCH resource pool, as shown in Figure 4. This option can maximize the frequency distance of the PRBs 411 , 412, 413, 414 in a group and hence maximize the frequency diversity gain.

Fig. 5 shows a schematic diagram illustrating the setting of frequency location for allocated PRBs in a group according to a second option (Option 2) 500 or example. In Figure 5, resources are shown over subchannels 403, 402, 401 and time.

According to the second option (Frequency Range Option 2), the allocated PRBs 511 , 512, 513, 514 in a group may be within the frequency range 520 of the same subchannel, e.g. subchannel 402 as shown in Fig. 5, as the group’s associated PSSCH resource unit(s) 410. This option can enable the channel-aware transmission of HARQ response by exploring the reciprocity of the wireless channel, which will be further described below with respect to Part 2 of this disclosure.

Fig. 6 shows a sequence chart 600 illustrating message signaling between the network device 310 and the group of user devices 320, 330 shown in Figure 3 according to a first method, referred to as Method A in this disclosure. The network device 310 and the group of user devices 320, 330 may correspond to the respective devices shown in Figure 3.

In a first step 601 , the fixed group size R is either prescribed or configured (e.g. by RRC signaling) for a UE 320, 330. The grouping frequency range (options 1 or 2 as illustrated in Figures 4 and 5) of the PRBs is either prescribed or configured (e.g. by RRC signaling) for a UE 320, 330. PSFCH and PSSCH resource pool is provided from the network (gNB and core network) 310 to a UE 320, 330.

In a second step and third step 602, based on the known {group size, grouping range, PSFCH resource pool allocation}, UEs 320, 330 may derive the grouping configuration (Step 2). The UEs 320, 330 may derive an association relations between PSFCH PRB groups with PSSCH resource (Step 3).

It follows PSSCH transmission from Tx UE 320 to Rx UE 330.

In a fourth step 604, PSFCH is transmitted from Rx UE 330 to Tx UE 320 using the derived PRB group.

Method A of Part 1 first divides the PSFCH resource into fixed groups of staggered PRBs and then associates the PRB groups with PSSCH resource units.

In the method A, the resource of PSFCH may be divided into PRB groups with a fixed group size R. The grouping of PSFCH PRBs may be commonly known among the UEs sharing the same resource pool. The groups may be associated with the PSSCH resource units (i.e. one subchannel in one slot) with a predetermined rule.

The Rx UE can derive the selection of PSFCH PRB group according to the parameters such as time and frequency location of the PSSCH it receives and the UE’s ID, etc. A grouping method of the PSFCH PRBs in a resource pool with fixed group size based on the staggering operation with a matrix is presented below with respect to Step 4, which is able to maximize the frequency diversity. The following parameters are defined for illustrating this method A:

• K: number of PSSCH resource units within a resource pool (Option 7) or within a subchannel (Option 2 ,

• N: number of PSFCH PRBs per PSSCH resource unit;

• M = N x K: total number of PSFCH PRBs;

• R: group size, G = N/R: number of groups per resource unit.

The procedures of PSFCH PRB Grouping and association are described in the following with respect to the four steps 601 , 602, 604 shown in Figure 6:

Step 1 : Tx UE 320 and Rx UE 330 may obtain the parameters of grouping: o The fixed Group Size R is either prescribed or configured (e.g. by Radio Resource Control (RRC) signaling) for a Tx UE 320 and Rx UE 330; o The grouping frequency range (Option 1 or 2) of the PRBs is either prescribed or configured (e.g. by RRC signaling) for a Tx UE 320 and Rx UE 330; o PSFCH and PSSCH resource pool is provided from the network 310 (gNB and core network) to a Tx UE 320 and Rx UE 330.

Step 2: Tx UE 320 and Rx UE 330 may derive the grouping configuration:

The PSFCH resource is divided into groups of staggered PRB. A specific grouping method which can maximize the frequency diversity is described as follows:

M o Tx UE 320 and Rx UE 330 may compose a matrix with the size of — x R; fill the elements of the sequence m = (0, 1 , M-1) one by one along one dimension of the matrix (e.g. column wise), as shown in Table 1.

Table 1: Matrix for PRB Grouping with Group Size R

o Tx UE 320 and Rx UE 330 may generate another sequence by taking the elements one by one from the other dimension of the matrix (e.g. row wise): n_m = (0, M/R, 2M/R, ... , (R-1)M/R, 1 , M/R+1, 2M/R+1, ... , (R-1)M/R+1 , ... , M-1). o Sequence m is regarded as the logical index of the PRBs within the PSFCH resource pool; sequence n_m is regarded as the staggered physical index of the PRBs according to the logical index m. o The elements in the sequence (n_m) are then grouped (using group size R) into the physical PRB index sets y_g o Resource 0, Group 0: y₀ = (n₀,n₁,n₂,

o Resource 0, Group 1: y = (n_R, n_R+1, n_R+2, ...n_2fi-i) o Resource 0, Group

o

Step 3: Rx UE may associate the PRB groups with PSSCH resource unit using a predefined indexing method.

Step 4: The Rx UE 330 can derive the PSFCH PRB group for transmitting HARQ response 604 according to the parameters such as the time and frequency location of the PSSCH it receives and the UE’s ID, etc.

In Table 2 below, an example is presented with K = 4 PSSCH resource units and M = 16 PSFCH PRBs which are divided into groups of size R = 2. With the grouping Method A, each PSSCH resource unit is associated with two PSFCH PRB groups, each of which has two PRBs with the possibly large frequency distance of up to 8 PRBs, thus half of the total bandwidth of all PSFCH PRBs.

Table 2: Example with four PSSCH resource units and 16 PRBs

Res 0 Res 0 Res 1 Res 1 Res 2 Res 2 Res 3 Res 3

Group 0 Group 1 Group 0 Group 1 Group 0 Group 1 Group 0 Group 1

The new signaling can be described by the following example:

In Step 1 , The Group Size R and/or the grouping frequency range options can be configured via RRC signaling. For example, two additional fields, sl-PSFCH-RB- GroupSize with integer data type and sl-PSFCH-RB-GroupRangelsLocal with boolean data type (‘true’ denotes Option 2 and ‘false’ denotes Option 1) can be added to the existing SL-PSFCH-Config RRC Information Element (IE), as shown below:

Fig. 7 shows a sequence chart 700 illustrating message signaling between the network device 310 and the group of user devices 320, 330 shown in Figure 3 according to a second method, referred to as Method B in this disclosure. The network device 310 and the group of user devices 320, 330 may correspond to the respective devices shown in Figure 3.

In a first step 701 , the grouping range (options 1 or 2 as illustrated in Figures 4 and 5) of the PRBs may be either prescribed or configured (e.g. by RRC signaling) for a UE, i.e. Tx UE 320 and Rx UE 330. The PSSCH and PSFCH resource pool may be provided to a UE, i.e. Tx UE 320 and Rx UE 330 by the network (gNB and core network) 310.

In a second step 702, based on the knowledge of {grouping range, PSFCH resource pool allocation}, Tx UE 320 and Rx UE 330 may derive the configuration of associating PSSCH with staggered PRBs.

In a third step 703, Tx UE 320 may determine the grouping setup and group size.

In a fourth step 704, PSSCH (and optionally PSCCH) including a dedicated group size may be transmitted from Tx UE 320 to Rx UE 330.

In a fifth step 705, PSFCH may be transmitted from Rx UE 330 to Tx UE 320 using the derived PRB group.

Method B of Part 1 firstly allocates staggered PRBs to PSSCH resource units and then divides the allocated PRBs into groups.

In this method B, firstly the PSFCH PRBs associated to PSSCH resource unit(s) may be staggered or allocated non-contiguously for getting increased frequency diversity. The rule of staggering or non-contiguous allocation of PSFCH PRBs may be commonly known to all the UEs sharing the resource.

The allocated PSFCH PRBs for a PSSCH may be divided into groups with adjustable group size according to reliability requirement. The group size may be made known to the Rx UE 330 which can derive the PSFCH PRB group for transmitting HARQ response 705 according to the parameters such as the dedicated group size for the PSSCH, the time and frequency location of the PSSCH and the UE’s ID, etc.

The following parameters are defined for illustrating this method:

• K: number of PSSCH resource units within a resource pool (Option 7) or within a subchannel (Option 2)

• N: number of PSFCH PRBs per PSSCH resource unit

• M = N x K: total number of PSFCH PRBs

The procedures of PSFCH PRB Grouping and association can be described as follows with respect to the five steps 701 , 702, 703, 704, 705 shown in Figure 6:

Step 1 : The grouping range (Option 1 or 2) of the PRBs may be either prescribed or configured (e.g. by RRC signaling) for a UE. The PSSCH and/or PSFCH resource pool may be provided to a UE, i.e. Tx UE 320 and Rx UE 330 by the network 310 (gNB & core).

Step 2: PSSCH resource unit is associated with staggered PRBs. A specific associating method which can maximize the frequency diversity is described as follows: o Tx UE 320 and Rx UE 330 may compose a matrix as shown in Table 3 below with the size of K x M; fill the elements of the sequence m = (0, 1 , ... , M-1) one by one along one dimension of the matrix (e.g. column wise)

Table 3: Matrix for the staggered association of PRB with PSSCH resource unit

o Tx UE 320 and Rx UE 330 may generate another sequence by taking the elements one by one from the other dimension of the matrix (e.g. row wise): n_m = (0, K, 2K, ... , (N - 1)K, 1, K + 1,2K + 1, ... , (N - 1)K + 1, ... , M - 1) o Sequence m is regarded as the logical index of the PRBs within the PSFCH resource pool; sequence n_m is regarded as the staggered physical index of the PRBs according to the logical index m o Associate the re-index PRBs by n_m with PSSCH resource unit.

Step 3: the PRBs associated to a PSSCH transmission (not all PRBs within a resource pool) may be grouped with a transmission specific group size R using the same method described in Part 1 - Method A (see Figure 6) with the purpose of maximizing the PRB’s frequency distance with in a group.

It should be noted that when the PSSCH transmission takes multiple adjacent (in frequency and/or in time domain) resource units (i.e. one subchannel in one slot), the PSFCH PRBs associated to each of the resource units may be combined to form a larger set of PRB for grouping, which leads to increased frequency distance and diversity. The group size may be determined by Tx UE based on, for example, the reliability requirement of PSFCH and the amount of available PSFCH resource which is associated to the transmitted PSSCH resource from the Tx UE. The grouped PRBs may be indexed with n_m' which are assigned to different groups y_s.

Step 4: PSSCH (and optionally PSCCH) transmission including a specific group size R provided by Tx UE to Rx UE. The specific group size can be carried in PSCCH (SCI Format 0-1) or PSSCH (e.g. SCI Format 0-2 or Media Access Control (MAC) Control Element (CE)).

Step 5: The Rx UE can derive the PSFCH PRB group for transmitting HARQ response according to the parameters such as the dedicated group size for the PSSCH obtained in Step 5, the time and frequency location of the PSSCH and the UE’s ID, etc.

In the following, an example is described with K = 4 PSSCH resource units and M = 16 PSFCH PRBs (see Table 4 below). With the grouping Method B, each PSSCH resource unit is associated with K=4 PRBs with large frequency distance of up to 4 PRBs. For PSSCH resource unit 0 and 2, the four PRBs are further split into two groups with group size R = 2. While for PSSCH resource unit 1 and 3, the four PRBs are taken as a single group with group size R = 4. By reusing the grouping method A (Method A shown above in Figure 6), the possibly maximum frequency distance of the PRBs in a group may be achieved, thus the distance of 8 PRBs for group size 2 and the distance of 4 PRBs for group size 4.

Table 4: Example with K = 4 PSSCH resource units and M = 16 PSFCH PRBs

The new signaling can be summarized as follows:

In Step 1 , the grouping frequency range options can be configured via RRC signaling, which may be the same as in Method A. For example, an additional field sl-PSFCH-RB- GroupRangelsLocal with boolean data type (‘true’ denotes Option 2 and ‘false’ denotes Option 1) can be added to the existing SL-PSFCH-Config RRC Information Element (IE).

The group size which is specific to a PSSCH transmission can be carried in the following possible ways:

(a) In the PSCCH, for example as an additional field called “PSFCH PRB group size” in SCI Format 0-1 ;

(b) In the PSSCH, for example as an additional field called “PSFCH PRB group size” in SCI Format 0-2; or

(c) In a new type of MAC CE with a new reserved (Logical Channel Identity) LCID value.

Fig. 8 shows a schematic diagram illustrating channel-aware PRB selection and power allocation 800 according to the disclosure. Channel-aware PRB selection and power allocation for PSFCH transmission 811 is related to Part 2 of this disclosure as mentioned above. Rx UE 330 can estimate the channel information 810 based on the PSSCH/PSCCH 803 and their reference signal 804. Part 1 of this disclosure presents the allocation and grouping methods of PSFCH PRBs for enhancing the frequency diversity gain. Utilizing the group based PSFCH resource, this part 2 further introduces the channel-aware transmission method for PSFCH which can further enhance the HARQ response’s reliability.

This method is particularly effective combining the Frequency Range Option 2 of Part 1 by which the reciprocity of wireless channel can be made used of. The following are the key aspect of Part 2.

The channel information may be obtained 810 by Rx UE 330 (see Figure 3) based on the signal transmitted by Tx UE 320 in PSSCH/PSCCH 803 and their reference signal 804 (e.g. demodulation reference signal (DMRS)). With the channel information, the Rx UE 330 can select 811 (one or more) most favorable PRBs from the PSFCH PRB group for transmitting the HARQ response.

The power allocation may be conducted according to the channel quality in each PRB:

(a) Maximum Ratio Transmission: higher power may be allocated to the PRB(s) with higher channel gain.

(b) Select the Strongest Transmission: Based on the channel status, select one or part of the PRBs in a group with the strongest channel gain and transmit the PSFCH only with the selected PRB(s), while all other PRBs in the group may be not used for transmission. It should be noted that the total transmitting power and the transmitting power in each PRB should subject to the constraints of the power control limit set by the network’s configuration as well as the UE’s maximum transmitting power.

(c) The following Table 5 gives an example for power allocation selection, in which PRB 0 and 2 of the same group may be selected and/or transmitted with signal amplitude of a and b for the REs of the two PRBs (u is the index of REs): Table 5: Example for power allocation selection

The selection of PSFCH PRB(s) and/or power allocation in a group for HARQ response can also be determined by Tx UE 320 and signaled in PSCCH (SCI Format 0-1) or PSSCH (SCI Format 0-2 or MAC CE), based on, e.g.: the observed channel condition by Tx UE 320 from previous reception of PSFCH and/or PSSCH and/or PSCCH signal.

An extension to the power allocation and/or PRB selection based PSFCH transmission may be to further consider the amplitude and phase changes of the fading channel along the REs in frequency domain. A pre-equalization vector may be generated for the selected PRBs:

(i) Original RE values of the PSFCH PRB(s) with length U used in PSFCH: x(u), u = 0,1, ..., U - 1., in which u is the index of REs.

(ii) A vector may be used to pre-equalize the REs of PSFCH: x'(u) = x(u)p(u).

(iii) The pre-equalization vector may be generated based on the channel information h(u) at the Rx UE side. An option of generating the pre-equalizaiton vector may be to apply the maximum ratio transmission principal for each RE: p(u) =

in which “*” denotes the complex conjugate operation.

Fig. 9 shows a performance diagram illustrating detection performance when using two staggered or non-contiguous PRBs according to the disclosure instead of a single PRB.

Table 6 below illustrates the parameters applied in this numerical evaluation:

Table 6: Parameters for numerical evaluation

Graph 901 represents missed ACK/NACK, 1RB, AWGN.

Graph 902 represents NACK ACK, 1RB, AWGN.

Graph 903 represents missed ACK/NACK, 1 RB, TDL-C.

Graph 904 represents NACK ACK, 1 RB, TDL-C.

Graph 905 represents missed ACK/NACK, select 1RB from 2, TDL-C.

Graph 906 represents NACK - ACK, select 1RB from 2, TDL-C.

Graph 907 represents missed ACK/NACK, 2RB, RE pre-EQ, TDL-C.

Graph 908 represents NACK - ACK, 2RB, RE pre-EQ, TDL-C.

Frequency diversity gain is illustrated by reference sign 910 and pre-equalization gain is illustrated by reference sign 911.

Numerical evaluation shows that by using one group of two staggered PRBs instead of single PRB, significant improvement of the detection performance for PSFCH compared to the case of one fixed PRB is achieved:

(i) When selecting PRB with the best channel gain out of two staggered PRBs in a group, over 6 dB gain can be achieved.

(ii) With MRT pre-equalization using both PRBs, over 10 dB gain can be achieved. Fig. 10 shows a schematic diagram illustrating a method 1000 for transmitting a HARQ response in a PRB group with a size of at least two PRBs according to the disclosure.

The method 1000 comprises obtaining 1001 a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group.

The method 1000 comprises transmitting 1002 the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

The method 1000 may correspond to the functionality of the first device 310, 320, 330 as described above with respect to Figure 3.

Fig. 11 shows a schematic diagram illustrating a communication system 1100 according to the disclosure.

The communication system 1100, includes a first user device 1101a or UE, respectively, according to an embodiment, a plurality of neighboring user devices 1101 b,c of the first user device 1101a and a base station 1120. In the embodiment shown in figure 11 , the first user device 1101a and one of the neighboring user devices 1101c are, by way of example, portable devices, in particular smartphones 1101a,c, while another neighboring user device is, by way of example, a laptop computer 1101 b. The first user device 1101a, and the neighboring user devices 1101 b,c may be configured to communicate with the base station 1120, for instance, via llu channel. The first user device 1101a, and the neighboring user devices 1101 b, c may also be configured to communicate with each other by sidelink channel without the base station 1120.

As can be taken from figure 11 , the first user device 1101a may comprises a processing circuitry 1103a for instance, a processor 1103a, for processing and generating data, a transceiver 1105a, including, for instance, an transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 1100, and a non- transitory memory 1107a for storing data. The processor 1103a of the first user device 1101a may be implemented in hardware and/or software.

The hardware may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The non-transitory memory 1107a may store data as well as executable program code which, when executed by the processor 1103a, causes the first user device 1101a to perform the functions, operations and methods described in this disclosure.

In an embodiment, the neighboring user devices 1101b, c of the first user device 1101a may have a similar architecture as the first user device 101a, i.e. may comprise a processor for processing and generating data, a transceiver for exchanging data with the other components of the communication system 1100 as well as a memory for storing data. Likewise, as illustrated in figure 11 , the base station 1120 may comprise a processor 1113 for processing and generating data, a transceiver 1115 for exchanging data with the other components of the communication system 1100 as well as a non-transitory memory 1117 for storing data.

As described above, the processor 1103a of the first user device 1101a may be configured to: obtain a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group. The transceiver 1105a of the first user device 1101a may be configured to transmit the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the methods and procedures described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the methods and procedures described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1 . A first device (310, 330), comprising: a processor (301), configured to: obtain a size of a Physical Resource Block, PRB group, wherein the PBR group is used for transmission of HARQ response, and wherein the size of PRB group is used to determine the PRB resources of each PRB group; and a transceiver (302), configured to: transmit the hybrid automatic repeat request, HARQ, response in the PRB group with the size of at least two PRBs.

2. The first device (310, 330) according to claim 1 , the processor (301) is further configured to: obtain an index of the PRB group, wherein the index of the PRB group is used to determine the PRB resources of each PRB group.

3. The first device (310, 330) according to claim 1 or 2, the processor (301) is further configured to: obtain a resource pool for transmission of a HARQ response, wherein the resource pool is used to be allocated into PRB group according to the size of the PRB group.

4. The first device (310, 330) according to any one of claims 1 to 3, wherein the PRB resources of each PRB group are staggered with one or more of PRB resources of another PRB group.

5. The first device (310, 330) according to any one of claims 1 to 3, the transceiver (302) is configured to: transmit the size of a Physical Resource Block, PRB group to a second device

(320).

36

6. The first device (310, 330) of one of the preceding claims, wherein the transceiver (302) is configured to transmit the HARQ response in a Physical Sidelink Feedback Channel, PSFCH, to another UE; or in a Physical Uplink Control Channel, PUCCH, to a base station.

7. The first device (310, 330) of claim 3, wherein according to a first option the at least two PRBs of the PRB group are non-contiguous within a frequency range of the resource pool; or wherein according to a second option the at least two PRBs of the PRB group are non-contiguous within the same frequency range.

8. The first device (310, 330) of claim 7, wherein the processor (301) is configured to first divide a PRB resource into fixed groups of staggered PRBs and then associate the PRB groups with resource units, wherein the PRB groups have a fixed group size R.

9. The first device (310, 330) of claim 8, wherein the group size R is prescribed or configured, in particular configured by Radio Resource Control, RRC, signaling.

10. The first device (310, 330) of one of claims 8 to 9, wherein the frequency range of the resource pool according to the first option or the frequency range according to the second option is prescribed or configured, in particular configured by RRC signaling.

11. The first device (310, 330) of one of claims 8 to 10, wherein the processor (301) is configured to determine a grouping configuration of the group of PRBs based on a staggering operation.

12. The first device (310, 330) of claim 11, wherein the processor (301) is configured to associate the PRB groups with the resource units based on a pre-defined indexing.

13. The first device (310, 330) of claim 11 or 12,

37 wherein the processor (301) is configured to determine the PRB group which transmits the HARQ response based on the grouping configuration of the group of PRBs.

14. The first device (310, 330) of claim 7, wherein the processor (301) is configured to first associate staggered PRBs to resource units and then divide the associated PRBs into groups.

15. The first device (310, 330) of claim 14, wherein the frequency range of the resource pool according to the first option or the frequency range according to the second option is prescribed or configured, in particular configured by RRC signaling.

16. The first device (310, 330) of claim 14 or 15, wherein the processor (301) is configured to associate staggered PRBs to resource units based on a staggering operation.

17. The first device (310, 330) of claim 16, wherein the processor (301) is configured to group the PRBs which are associated to the resource units of a transmission based on a transmission-specific group size R, wherein the transceiver is configured to transmit the transmission-specific group size R to at least one UE.

18. The first device (310, 330) of claim 17, wherein the processor (301) is configured to determine the PRB group which transmits the HARQ response based on the transmission-specific group size R.

19. The first device (310, 330) of one of the preceding claims, wherein the processor (301) is configured to select at least one PRB from the PRB group based on a selection by the first device (310, 330) and/or the one or more second devices (320), wherein the selection is determined by the first device (310, 330) and/or the one or more second devices (320).

20. The first device (310, 330) of claim 19, wherein power levels of the selected PRBs are based on an allocation by the first device and/or the one or more second devices (320), wherein the allocation is based on a channel quality in each PRB.

21 . The first device (310, 330) of one of the preceding claims, wherein the processor (301) is configured to select the at least one PRBs of the

PRB group based on a channel condition.

22. The first device (310, 330) of claim 21 , wherein the processor (301) is configured to select the at least one PRBs of the PRB group and power levels of the selected PRBs based on signaling in PSCCH with SCI Format 0-1 or PSSCH with SCI Format 0-2 or MAC CE, based on channel condition from a previous reception of PSFCH and/or PSSCH and/or PSCCH signal.

23. The first device (310, 330) of one of claims 19 to 22, wherein the selection of the PRBs and/or an allocation of power levels of the selected PRBs is based on applying a pre-equalization vector with specific amplitude and/or phase values on the resource elements of the selected at least one PRB.