WO2021016882A1

WO2021016882A1 - Resource configuration of feedback channel for device-to-device communication

Info

Publication number: WO2021016882A1
Application number: PCT/CN2019/098429
Authority: WO
Inventors: Yong Liu; Dong Li; Torsten WILDSCHEK; Jun Tan
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-07-30
Filing date: 2019-07-30
Publication date: 2021-02-04
Also published as: CN114175693A

Abstract

Embodiments of the present disclosure relate to devices, methods, apparatuses and computer readable storage media of resource configuration of a feedback channel for a device-to-device communication. In example embodiments, if device-to-device data is to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, a first terminal device selects a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period. The first terminal device selects, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel. The first terminal device further sends, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

Description

RESOURCE CONFIGURATION OF FEEDBACK CHANNEL FOR DEVICE-TO-DEVICE COMMUNICATION

FIELD

Embodiments of the present disclosure generally relate to the field of communications, and in particular, to devices, methods, apparatuses and computer readable storage media of resource configuration of a feedback channel for a device-to-device communication.

BACKGROUND

New Radio (NR) vehicle-to-everything (V2X) is being developed to provide advanced V2X services in a NR system. In Long Term Evolution (LTE) V2X, only a broadcast mode is specified at a physical (PHY) layer for sidelink communications. Unicast and groupcast modes need to be implemented at higher layers. For NR V2X sidelink communication, it is considered that unicast and groupcast communications are implemented directly at the PHY layer under standardization in the 3rd Generation Partnership Project (3GPP) Release 16.

In order to enable hybrid automatic repeat quest (HARQ) at the PHY layer, an acknowledgement or non-acknowledgement (ACK/NACK) needs to be fed back from a receiver to a transmitter. It is required to configure relevant feedback resources, and it is desirable to multiplex feedbacks from multiple user equipment (UEs) to improve feedback efficiency.

SUMMARY

In general, example embodiments of the present disclosure provide devices, methods, apparatuses and computer readable storage media of resource configuration of a feedback channel for a device-to-device communication.

In a first aspect, a first terminal device provided comprising at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the first terminal device to in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, select a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period. The first terminal device is further caused to select, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel. The first terminal device is further caused to send, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

In a second aspect, a second terminal device is provided comprising at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the second terminal device to decode device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period. The second terminal device is caused to receive, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel. The second terminal device is further caused to determine, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences. The second terminal device is then caused to send, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.

In a third aspect, a network device is provided comprising at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to allocate a plurality of feedback time periods to a device-to-device feedback channel in a resource pool. The network device is caused to allocate a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods. The network device is further caused to determine a delay range between a device-to-device data channel and the device-to-device feedback channel. The network device is then caused to associate, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.

In a fourth aspect, a method is provided. In the method, in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, a first terminal device selects a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period. The first terminal device selects, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel. The first terminal device further sends, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

In a fifth aspect, a method is provided. In the method, a second terminal device decodes device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period. The second terminal device receives, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel. The second terminal device determines, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences. The second terminal device sends, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.

In a sixth aspect, a method is provided. In the method, a network device allocates a plurality of feedback time periods to a device-to-device feedback channel in a resource pool. The network device allocates a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods. The network device determines a delay range between a device-to-device data channel and the device-to-device feedback channel. The network device associates, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.

In a seventh aspect, there is provided an apparatus comprising means for performing the method according to the fourth, fifth or sixth aspect.

In an eighth aspect, there is provided a computer readable storage medium that stores a computer program thereon. The computer program, when executed by a processor of a device, causes the device to perform the method according to the fourth, fifth or sixth aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

FIG. 1 illustrates example resource configuration for a short PSFCH in a resource pool;

FIG. 2 illustrates an example environment in which embodiments of the present disclosure can be implemented;

FIG. 3 illustrates an example structure of a resource pool according to some example embodiments of the present disclosure;

FIG. 4 illustrates example extended resource configuration in the resource pool according to some example embodiments of the present disclosure;

FIG. 5 illustrates a signaling flow between the network device and the two terminal devices according to some example embodiments of the present disclosure;

FIG. 6 illustrates example resource configuration in the resource pool for D2D communications according to some example embodiments of the present disclosure;

FIG. 7 illustrates an example structure of a D2D feedback channel according to some example embodiments of the present disclosure;

FIG. 8 illustrates example configuration of a delay range according to some example embodiments of the present disclosure;

FIG. 9 illustrates example association between a D2D data channel and a D2D feedback channel according to some example embodiments of the present disclosure;

FIG. 10 illustrates example selection of D2D resource according to some example embodiments of the present disclosure;

FIG. 11 illustrates a signaling flow between the network device and the two terminal devices according to some other example embodiments of the present disclosure;

FIG. 12 illustrates example configuration of a delay range according to some other example embodiments of the present disclosure;

FIG. 13 illustrates example association between a D2D data channel and a D2D feedback channel according to some example embodiments of the present disclosure;

FIG. 14 illustrates example selection of a feedback time period of a D2D feedback channel according to some example embodiments of the present disclosure;

FIG. 15 illustrates a flowchart of an example method according to some example embodiments of the present disclosure;

FIG. 16 illustrates a flowchart of an example method according to some other example embodiments of the present disclosure; ;

FIG. 17 illustrates a flowchart of an example method according to yet other example embodiments of the present disclosure; and

FIG. 18 illustrates a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term “network device” refers to a device via which services can be provided to a terminal device in a communication network. Examples of the network device may include a relay, an access point (AP) , a transmission point (TRP) , a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a New Radio (NR) NodeB (gNB) , a Remote Radio Module (RRU) , a radio header (RH) , a remote radio head (RRH) , a low power node such as a femto, a pico, and the like.

As used herein, the term “terminal device” or “user equipment” (UE) refers to any terminal device capable of wireless communications with each other or with the base station. The communications may involve transmitting and/or receiving wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for conveying information over air. In some example embodiments, the UE may be configured to transmit and/or receive information without direct human interaction. For example, the UE may transmit information to the network device on predetermined schedules, when triggered by an internal or external event, or in response to requests from the network side.

Examples of the UE include, but are not limited to, user equipment (UE) such as smart phones, wireless-enabled tablet computers, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , wireless customer-premises equipment (CPE) , sensors, metering devices, personal wearables such as watches etc., and/or vehicles that are capable of communication. The terminal device may also include vehicles in V2X communications via D2D sidelink. For the purpose of discussion, some example embodiments will be described with reference to UEs as examples of the terminal devices, and the terms “terminal device” and “user equipment” (UE) may be used interchangeably in the context of the present disclosure.

As used herein, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) : (i) a combination of analog and/or digital hardware circuit (s) with software/firmware and (ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

As used herein, the singular forms “a” , “an” , and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to” . The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.

As used herein, the terms “first” , “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

Different from LTE V2X, both unicast and groupcast communications need to be directly implemented at the PHY layer to improve transmission efficiency of these communications. More advanced schemes need to be designed to enable the direct communications at the PHY layer. For example, a short physical sidelink feedback channel (PSFCH) is specified for acknowledgement feedbacks in the sidelink communication.

FIG. 1 shows example resource configuration for a short PSFCH in a resource pool 100. As shown, in every N slots 105-1, …, 105-N, where N represents a positive integer, one slot 105-N is configured for a short PSFCH 110 which occupies the last three (or more) symbols in the slot 105-N (totally 14 symbols per slot) within a period of N slots. The short PSFCH 110 occupies the whole frequency band 115 in the resource pool 100. Typically, the first symbol of the short PSFCH 110 is used for automatic gain control (AGC) , and the last symbol is used for transmitting and receiving (T/R) switch. Only the symbol (s) in the middle is practically used to convey HARQ feedback.

The inventor notices that the scheme of using the short PSFCH has the following drawbacks. First, the feasibility of this scheme is subject to a half-duplex constraint. For example, when there are bidirectional unicast communications between two UEs, both the two UEs may need to feedback ACK/NACK in the same PSFCH slot to meet the respective latency requirements. However, due to the half-duplex constraint, this is not feasible since a UE cannot transmit and receive at the same time. Moreover, stringent latency requirement may not be met because a UE has to wait for a PSFCH slot to feedback ACK/NACK.

The inventor also notices that one approach to alleviate the above two issues may be reducing the period of N slots. However, a small period of the short PSFCH may cause substantial resource consumption because the short PSFCHs occupy the whole frequency band of a configured resource pool as shown in FIG. 1.

Embodiments of the present disclosure provide a feasible and efficient resource configuration scheme for a feedback channel (for example, hybrid configuration of a HARQ feedback channel such as a PSFCH) in device-to-device (D2D) communications (for example, sidelink communications) . According to this scheme, a feedback channel is configured with a plurality of feedback time periods (such as time slots or subframes) in a time domain. The feedback time periods may be continuous. The feedback channel may occupy one or more PRBs configured by a network in a frequency domain. When a terminal device is intended to initiate D2D transmission, the terminal device selects one of plurality of feedback time periods for receiving acknowledgement from a receiving party. The determination is based on a predetermined delay range between a D2D data channel, such as a physical sidelink shared channel (PSSCH) , and the D2D feedback channel. The delay range may be configured dynamically, or preconfigured semi-statically or statically by the network or predefined in the 3GPP specifications. The terminal device indicates the selected feedback time period to the receiving party to enable the receiving party to feed ACK/NACK back.

In addition, association between a plurality of orthogonal code sequences and the D2D data channel is configured, preconfigured or predefined. The orthogonal code sequences may be generated by a base sequence (such as a Zadoff-Chu sequence) with different code division multiplexing (CDM) signatures. The CDM signature may be a combination of a cyclic shift and an orthogonal cover code (OCC) . For example, each subchannel of the D2D data channel in one or more transmission time periods (for example, time slots) is configured with a unique CDM signature for HARQ feedback in the corresponding feedback channel. Such resource configuration of the feedback channel can provide prompt HARQ feedback for services with the stringent latency requirement and alleviate the half-duplex constraint efficiently.

FIG. 2 shows an example environment 200 in which embodiments of the present disclosure can be implemented. The environment 200, which is a part of a communication network, comprises two terminal devices 210 and 220 (referred to as a first terminal device 210 and a second terminal device 220, respectively) and a network device 230. It is to be understood that two terminal devices and one network device are shown in FIG. 1 only for the purpose of illustration without suggesting any limitations.

The two

terminal devices

210 and 220 can communicate directly via a D2D connection or via the network device 230. The two

terminal devices

210 and 220 can also communicate with other terminal devices (not shown) directly or via the network device 230. The communications in the environment 200 may follow any suitable communication standards or protocols such as Universal Mobile Telecommunications System (UMTS) , long term evolution (LTE) , LTE-Advanced (LTE-A) , the fifth generation (5G) NR, Wireless Fidelity (Wi-Fi) and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employ any suitable communication technologies, including, for example, Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiplexing (OFDM) , time division multiplexing (TDM) , frequency division multiplexing (FDM) , code division multiplexing (CDM) , Bluetooth, ZigBee, machine type communication (MTC) , enhanced mobile broadband (eMBB) , massive machine type communication (mMTC) , ultra-reliable low latency communication (URLLC) , Carrier Aggregation (CA) , Dual Connection (DC) , New Radio Unlicensed (NR-U) and V2X technologies.

For the D2D communication between the two

terminal devices

210 and 220, the network device 230 configures a resource pool. In the resource pool, in addition to a D2D data channel, the network device 230 configures resources for a D2D feedback channel for HARQ feedbacks.

FIG. 3 shows an example structure of a resource pool 300 according to some example embodiments of the present disclosure.

The resource pool 300 comprises a plurality of time periods 305-1, 305-2, …, 305-N (collectively or individually referred to as a time period 305) in the time domain, where N represents any suitable positive integer. The time period 305 may have any suitable time length. For example, the time period 305 may comprise a time slot in a NR network or a time subframe in a LTE network. Moreover, the resource pool 300 comprises a plurality of subchannels 310-1, …, 310-M (collectively or individually referred to as a subchannel 310) in the frequency domain, where M represents any suitable positive integer. The subchannel 310 may comprise one or more PRBs depending on the system configuration.

In the resource pool 300, a D2D data channel 315 is configured with a plurality of time periods 305 in the time domain and a plurality of subchannels 310 in the frequency domain. The D2D data channel 315 may be implemented by a PSSCH. The resources for the D2D data channel 315 may also be used for a D2D control channel such as a physical sidelink control channel (PSCCH) .

Moreover, a D2D feedback channel 320 is configured in the resource pool 300 which occupies a plurality of continuous time periods in the time domain. For the purpose of discussion, a time period in the D2D data channel 315 will be referred to as a transmission time period, and a time period in the D2D feedback channel 320 will be referred to as a feedback time period. In this example, the D2D feedback channel 320 occupies 1 PRB (or more PRBs configured by the network device 230) in every time period 305 of the resource pool 300. The D2D feedback channel 320 may be implemented by a PSFCH. The D2D feedback channel 320 can provide prompt HARQ feedback for services with the stringent latency requirement and alleviate the half-duplex constraint.

In addition, as shown, a short D2D feedback channel 325 is also configured with time duration shorter than one time period. As an example, the short D2D feedback channel 325 may be implemented by the short PSFCH 110 as shown in FIG. 1. In some example embodiments, the continuous feedback time periods of the D2D feedback channel 320 may exclude a time period 330 where the short D2D feedback channel 325 is configured since the receiving party can use the short D2D feedback channel 325 for HARQ feedback in the time period 330.

Alternatively, the D2D feedback channel 320 is configured in the resource pool 300 which may not occupy a plurality of continuous time periods in the time domain. As an example, as shown in FIG. 3, the time period 305-3 may be excluded from the D2D feedback channel 320. The first terminal device won’t select the time period 305-3 for acknowledgement feedback. As another example, as shown in FIG. 3, the D2D feedback channel 320 may occupy a time period every K (for example, K=2) time periods. K may be set to be a positive integer smaller than N, which means that the D2D feedback channel 320 has shorter periodicity than that of the short PSFCH.

With the resource configuration in the resource pool 300, when the first terminal device 210 performs a D2D transmission to the second terminal device 220 on the D2D data channel 315, the second terminal device 220 can use the D2D feedback channel 320 for acknowledgement feedback to the D2D transmission.

The network device 230 also configures a delay range 335 between the D2D data channel 315 and the D2D feedback channel 320. In this example, as shown in FIG. 3, the delay range 335 is configured to be [1, 2] . That is, for D2D transmission in a time period t ₁ (for example, the time period 305-1) of the D2D data channel 315, a time period t ₁+1 and t ₁+2 (for example, the time periods 305-2 and 305-3) of the D2D feedback channel 320 can be used for feedback. Accordingly, a time period t ₂ (for example, the time period 305-3) of the D2D feedback channel 320 can be used for feedback to data transmission in the time periods t ₂-1 and t ₂-2 (represented by time periods 305-1 and 305-2, respectively) on the D2D data channel 315.

Within a time period, different receiving terminal devices may use different orthogonal code sequences for ACK/NACK feedbacks. In some example embodiments, the same Zadoff-Chu sequence may be used to generate the orthogonal code sequences using the same base sequence such as a Zadoff-Chu sequence with different CDM signatures. Different CDM signatures may be implemented by different combinations of cyclic shifts and orthogonal cover codes (OCCs) .

Furthermore, the network device 230 configures association between the orthogonal code sequences (for example, CDM signatures) for the D2D feedback channel 320 and the D2D data channel 315 in the delay range 335. For example, in the delay range 335, each subchannel 310 of the D2D data channel 315 is provided with a unique CDM signature for HARQ feedback on the D2D feedback channel 320. A CDM signature used in a time period t ₂ on the D2D feedback channel 320 associated with a time period t ₂-Δt on the D2D data channel 315 can be determined by (Δt, l) where l represents an index of a subchannel in the time period t ₂-Δt.

If the first terminal device 210 is to initiate D2D data transmission to the second terminal device 220, the first terminal device 210 may select a subchannel 310 in a transmission time period t ₁ on the D2D data channel 315. Based on the delay range 335 and the association between the D2D data channel 315 and the D2D feedback channel 320 which is (pre) configured by the network device 230, the first terminal device 210 may select a feedback time period t ₁ + Δt on the D2D feedback channel 320 for ACK/NACK feedback from the second terminal device 220.

The first terminal device 210 sends an indication of the selected feedback time period of the D2D feedback channel 320 to the second terminal device 220. The indication may be sent in sidelink control information (SCI) on a D2D control channel (such as PSCCH) associated with the D2D data channel 315. Accordingly, based on the indication, the second terminal device 220 may identify the feedback time period of the D2D feedback channel 320 and determine the code sequence (such as the CDM signature) for ACK/NACK feedback. Alternatively, the indication may be sent in the D2D data channel 315. For example, the indication may be sent together with the data in the D2D data channel 315 to further reduce signaling overhead.

Due to the limitation of the number of orthogonal code sequences (such as CDM signatures) , in some example embodiments, an extended scheme of the resource configuration for the D2D feedback channel 320 can be employed to reduce the number of different CDM signatures required on the D2D feedback channel. With the extended scheme, the delay range 335 may be divided into a plurality of delay sub-ranges, represented by n sub-ranges, where n represents a positive integer. The association between the orthogonal code sequences and the D2D data channel 315 is repeatedly used in the n sub-ranges.

FIG. 4 shows example extended resource configuration in the resource pool 300 according to some example embodiments of the present disclosure.

In this example, a delay range 335 between the D2D data channel 315 and the D2D feedback channel 320 is configured to be [1, 4] . This delay range 335 is divided into two sub-ranges [1, 2] and [3, 4] , represented as a sub-range 405 and a sub-range 410, respectively. In a sub-range 405 or 410, each subchannel 310 of the D2D data channel 315 is provided with a unique CDM signature for HARQ feedback in a feedback time period 305-5 on the D2D feedback channel 320.

The reuse of the CDM signatures in n sub-ranges may significantly reduce the number of required CDM signatures for the D2D feedback channel 320. Accordingly, a feedback time period of the D2D feedback channel 320 may be used for ACK/NACK feedback to the data transmitted on more subchannels of the D2D data channel 315, and therefore resource consumption of the D2D feedback channel 320 may be reduced.

In the case of the reuse of CDM signatures, as shown in FIG. 4, subchannels 310 at time periods 305-1 and 305-3 may be mapped to the same time period 305-5 of the D2D feedback channel 320 and use the same CDM signatures. In order to further enhance the feedback efficiency, when selecting a feedback time period for ACK/NACK feedback to data transmission, the first terminal device 210 may select a feedback time period with unused CDM signatures based on detection or decoding of the D2D control information on the D2D data channel 315 in previous time periods 305.

FIG. 5 shows a signaling flow 500 between the network device 230 and the two

terminal devices

210 and 220 according to some example embodiments of the present disclosure. In this example, the network device 230 is implemented by a gNB, and the two

terminal devices

210 and 220 are implemented by UEs. The network device 230 communicates with the first and second

terminal devices

210 and 220 via a Uu interface, and the two

terminal devices

210 and 220 can communicate in a D2D link.

As shown in FIG. 5, the network device 230 determines (505) a time and frequency resource for the short D2D feedback channel 325 such as the short PSFCH 110 as shown in FIG. 1. The configuration of the short D2D feedback channel 325 is optionally. In some example embodiments, there may be no such a short feedback channel configured. The network device 230 determines (510) a time and frequency resource for the long D2D feedback channel 320.

The resources determination will be described below with reference to FIG. 6 which shows example resource configuration in the resource pool 300 for D2D communications according to some example embodiments of the present disclosure.

As shown in FIG. 6, in the time domain of the resource pool 300, the time resource for the short D2D feedback channel 325 occupies last symbols in a time period 305-N (for example, a time slot or subframe) with the periodicity of N time periods. In the frequency domain, the frequency resource occupies the whole frequency band 605 of the subchannels 310 in the resource pool 300.

For the long D2D feedback channel 320, the frequency resource in the frequency domain occupies 1 PRB (or more PRBs configured by the network device 230) in every time period of the resource pool 300. In the hybrid resource configuration of the short and long

D2D feedback channels

325 and 320, the time period 330 with the short D2D feedback channel 325 configured may be excluded from the D2D feedback channel 320 since the receiving party can use the short D2D feedback channel 325 when needed for prompt HARQ feedbacks.

The D2D feedback channel 320 may occupy the whole period of each time period in the time domain. FIG. 7 shows an example structure of the D2D feedback channel 320 according to some example embodiments of the present disclosure. In this example, as shown in FIG. 7, the D2D feedback channel 320 occupies 12 subcarriers in the frequency domain. Moreover, in the time domain, the D2D feedback channel 320 occupies all symbols (for example, 14 OFDM symbols) in a time slot 705. Among the 14 symbols, the 1st symbol 710 is used for AGC, and the last symbol 715 is used as a guard symbol (or GP) . The middle 12 symbols 720 are used to carry ACK/NACK information.

The orthogonal code sequences are allocated to the D2D feedback channel 320 in the time slot 705. For example, BPSK modulation is used, and the modulated symbol is spread with a Zadoff-Chu sequence, represented by r _u, v, with different cyclic shifts (represented by α) as well as orthogonal cover codes (OCC) , represented by w (1) ～w (6) .

In some example embodiments, in the resource pool 300, the same Zadoff-Chu sequence is employed for the D2D feedback channel 320. In the D2D feedback channel 320, different receiving terminal devices may employ the same sequence but different CDM signatures for ACK/NACK feedbacks. A CDM signature is the combination of a cyclic shift and an OCC. Hence, the multiplexing between HARQ feedbacks from multiple terminal devices is achieved. In addition, a plurality of resource pools in a zone or cell or a plurality of zones or cells may employ different Zadoff-Chu sequences to randomize mutual interference.

Alternatively, in the resource pool 300, non-orthogonal code sequences but with low cross-correlation may be employed for the D2D feedback channel 320. For example, the non-orthogonal code sequences may be generated by different base sequences (such as Zadoff-Chu sequences with low cross-correlation) .

Still with reference to FIG. 5, the network device 230 determines (515) a delay range [a, b] of Δt between the D2D data channel 315 and the D2D feedback channel 320 for HARQ feedback. The delay Δt between a time period t ₁ on the D2D data channel 315 and a time period t ₂ on the D2D feedback channel 320 is t ₂ -t ₁. The delay range can be set based on such factors as the number of subchannels in the resource pool 300, the periodicity N of the short D2D feedback channel 325, the number of PRBs for the D2D feedback channel 320. Some example values of the delay range may include [2, 4] , [2, 2] , [1, 3] , [1, 1] .

The network device 230 associates (520) a plurality of orthogonal code sequences with a plurality of subchannels 310 of the D2D data channel 315 in the delay range 335. In some example embodiments, the same Zadoff-Chu sequence is used in the resource pool 300. Different CDM signatures are associated with subchannels 310 in the delay range 335. In this way, each subchannel 310 in the delay range is provided a unique CDM signature for HARQ feedback in the corresponding feedback time period on the D2D feedback channel 320.

The CDM signature of the time period t ₂ on the D2D feedback channel 320 associated with a subchannel l in a time period t ₁ on the D2D data channel 315 is determined by (Δt, l) where Δt = t ₂-t ₁, and l represents an index of a subchannel 310 of the D2D data channel 315. If the D2D data channel 315 occupies multiple (more than one) subchannels 310, l may represent an index of a starting subchannel of the D2D data channel 315.

FIG. 8 shows example configuration of the delay range 335 according to some example embodiments of the present disclosure. In this example, the delay range 335 is configured as [1, 2] . Subchannels 310 in the time periods 305-1 and 305-2 (represented by t ₂-2 and t ₂-1) have different CDM signatures for their respective HARQ feedbacks in the corresponding time period 305-3 (represented by a time period t ₂) on the D2D feedback channel 320.

FIG. 9 shows example association between the D2D data channel 315 and the D2D feedback channel 320 according to some example embodiments of the present disclosure. In this example, while one terminal device (for example, the first terminal device 210) transmits D2D data at a time period 305-1 (represented by a time period t ₂-2) and a subchannel 310 (represented by a subchannel l) , the other terminal device (for example, the second terminal device 220) transmits D2D data at a time period 305-2 (represented by a time period t ₂-1) and the subchannel 310 (represented by the subchannel l) . Their corresponding receiving terminal devices can feedback ACK/NACKs in the feedback time period 305-3 (represented by a time period t ₂) on the D2D feedback channel 320 but with different CDM signatures for multiplexing.

Still with reference to FIG. 5, the network device 230 sends (525) an indication of a resource configuration for the D2D feedback channel 320 to both the first and second

terminal devices

210 and 220. As an example, the indication may be sent in a broadcast or multicast message such as a system information block (SIB) or master information block (MIB) . As an alternative example, the indication may be sent in a dedicated message such as radio resource control (RRC) signaling.

The network device 230 sends (530) an indication of the delay range and the resource association to both the first and second

terminal devices

210 and 220. The indication may also be sent in a broadcast message such as a SIB or MIB, or in a dedicated message such as the RRC signaling. The delay range and/or resource association may be configured by the network device 230 dynamically, semi-statically or statically. Alternatively, the configuration may be predefined in the related 3GPP specification.

It is to be understood that the delay range may be configured or predefined to be a certain single value such as [2, 2] , for example. In this case, there is no need for the first terminal device 210 to indicate the feedback time period to the second terminal device 220.

With the association between the D2D data channel 315 and the D2D feedback channel 320 (pre) configured by the network device 230 or predefined and the delay range set by the network device 230, the first and second

terminal devices

210 and 220 can perform D2D communication. As shown, the first terminal device 210 selects (535) one or more subchannel (s) of the D2D data channel 315 for D2D communication with the second terminal device 220. For example, the selected subchannel may be represented by (t ₁, l) where t ₁ represents the time period and l represents an index of a subchannel in the frequency domain.

Based on the delay range, the first terminal device 210 selects (540) a time period t ₁+Δt on the D2D feedback channel 320 for ACK/NACK feedback from the second terminal device 220. In addition to the delay range, the selection of the time period on the D2D feedback channel 320 may be implemented by considering any other suitable factors such as the latency requirements and the half duplex constraints.

FIG. 10 shows example selection of the D2D resource according to some example embodiments of the present disclosure. In this example, as shown, the delay range is configured as [1, 2] . The first terminal device 210 selects a subchannel 310 at a time period 305-1 for D2D transmission. In this case, there are two potential time periods 305-2 and 305-3 on the D2D feedback channel 320. The first terminal device 210 can select one of the two time periods 305-2 and 305-3 for the feedback.

Still with reference to FIG. 5, the first terminal device 210 sends (545) an indication of the feedback time period to the second terminal device 220 over a D2D control channel (such as a PSCCH) . For example, the first terminal device 210 may include the feedback delay information Δt as the indication in the SCI of the PSCCH associated with the PSSCH. The first terminal device 210 also sends (550) the data to the second terminal device 220 on the selected subchannel 310 of the D2D data channel 315.

The second terminal device 220 decodes (555) data on the subchannel 310 of the D2D data channel 315. Based on the predetermined association between the subchannels of the D2D data channel 315 and a plurality of orthogonal code sequences, the second terminal device 220 determines (560) a code sequence from the plurality of orthogonal code sequences. For example, in the example embodiments where the same base sequence (such as the same Zadoff-Chu sequence) , the second terminal device 220 determines a CDM signature based on (Δt, l) and (pre) configured/predefined association between the D2D data channel 315 and the D2D feedback channel 320. The second terminal device 220 sends (565) ACK/NACK in the feedback time period on the D2D feedback channel 320 by employing the determined CDM signature.

FIG. 11 shows an example signaling flow 1100 between the network device 230 and two

terminal devices

210 and 220 according to some other embodiments of the present disclosure. In this example, extended association between the D2D data channel 315 and the D2D feedback channel 320 is configured to reduce the resource consumption for HARQ feedback.

As shown, the network device 230 determines (1105) a time and frequency resource for the short D2D feedback channel 325. The network device 230 determines (1110) a time and frequency resource for the long D2D feedback channel 320. The network device 230 configures (1115) the delay range [a, b] of Δt between the D2D data channel 315 and the D2D feedback channel 320 for HARQ feedback. The determinations of the resources for the short and long

D2D feedback channels

315 and 320 and the delay range are similar to the determinations of the resources for the short and long

D2D feedback channels

315 and 320 and the delay range as described above with reference to FIG. 5. For the purpose of simplicity, the details will not be repeated.

The network device 230 associates (1120) a plurality of orthogonal code sequences for the D2D feedback channel 320 with a plurality of subchannels of the D2D data channel 315. In this example, the delay range is divided into n sub-ranges: [a, a+m-1] , [a+m, a+2m-1] , …, [a+ (n-1) m, a+nm-1] , where b-a+1=nm. The association between the D2D data channel 315 and the D2D feedback channel 320 is repeatedly used for n sub-ranges. For example, the same CDM signature used in a time period t ₂ on the D2D feedback channel 320 is associated with a subchannel (t ₂ -Δt, l) and a subchannel (t ₂ -Δt-km, l) on the D2D data channel 315. In a sub-range, a unique CDM signature is provided for HARQ feedback on the D2D feedback channel. The association can be preconfigured semi-statically or statically by the network device 230 or dynamically configured by the network device 230 or predefined in the network.

The repetition of the association can reduce the number of different CDM signatures required by the D2D feedback channel 320. The larger the required number of different CDM signatures is, the wider (more PRBs) the D2D feedback channel 320 is. Hence the extended association can eventually reduce resource consumption of the D2D feedback channel 320.

FIG. 12 shows example configuration of a delay range 335 according to some other example embodiments of the present disclosure. In this example, the delay range 335 is configured as [1, 4] . The associations between the D2D data channel 315 and the D2D feedback channel 320 in the two

sub-ranges

405 and 410, represented as [1, 2] and [3, 4] , are the same.

Still with reference to FIG. 11, the network device 230 sends (1125) an indication of a resource configuration for the D2D feedback channel 320 to both the first and second

terminal devices

210 and 220. The network device 230 also sends (1130) an indication of the delay range and the resource association to both the first and second

terminal devices

210 and 220.

In order to avoid the collision caused by the repeated use of a CDM signature, enhanced sensing of control information on the D2D data channel 315 is enabled at the first terminal device 210. As shown in FIG. 11, the first terminal device 210 decodes (1135) control information from other terminal devices on the D2D data channel 315. Based on the indication of the time period t ₂ to be used for the feedback on the D2D feedback channel 320 (for example, the information about the feedback delay Δt included in the control information on the D2D data channel 315) , the first terminal device 210 identifies (1140) the time period t ₂ and the CDM signatures to be used for HARQ feedback on the D2D feedback channel 320.

The first terminal device 210 selects (1145) subchannel (s) represented by (t ₁, l) for the D2D transmission.

The first terminal device 210 selects (1150) a feedback time period of the D2D feedback channel 320. In some example embodiments, based on the range/sub-range information, the latency requirements and half duplex constraints, the first terminal device 210 selects a time period t ₁+Δt with unused CDM signatures. For example, if the time period t ₁+Δt is not selected by other terminal devices for sending ACK/NACK corresponding to the data transmitted at a subchannel l and in a time period t ₁-km, the time period t ₁+Δt can be selected by the first terminal device 210.

In the example embodiments where the CDM signatures are reused for n sub-ranges of the delay range, the feedback time period may be selected from candidate feedback time periods based on the delay range [a, b] , the latency requirements and the half-duplex constraints by the detection of the feedback time periods of the D2D feedback channel 320 to be used by other terminal devices.

FIG. 13 shows example association between the D2D data channel 315 and the D2D feedback channel 320 according to some example embodiments of the present disclosure. While another terminal device transmits D2D data to the second terminal device 220 at a subchannel 310 in a time period 305-1 (represented by a time period t ₁, a subchannel l) of the D2D data channel 315, the first terminal device transmits D2D data at the subchannel 310 in the time period 305-3 (represented by a time period t ₁+2, a subchannel l) . If the first terminal device 210 determines that a time period 305-5 (represented by a time period t ₁+4) of the D2D feedback channel 320 has been selected by the other terminal device for the feedback, the first terminal device 210 selects a feedback time period of the D2D feedback channel 320 with an unused CDM signature to avoid collisions. The feedback time period may be selected from candidate feedback time periods based on the delay range [a, b] , the latency requirements and the half-duplex constraints by the detection of the feedback time periods to be used by other terminal devices previously.

FIG. 14 shows example selection of a feedback time period of the D2D feedback channel 320 according to some example embodiments of the present disclosure.

In this example, the delay range is configured as [1, 4] , which is divided into two sub-ranges [1, 2] and [3, 4] . If the first terminal device 210 selects a subchannel 310 in a time period 305-1 (represented by a time period t ₁, a subchannel l) for D2D transmission, there are four potential resource blocks at time periods 305-2 to 305-5 (represented by time periods t ₁+1, t ₁+2, t ₁+3 and t ₁+4) on the D2D feedback channel 320.

Still with reference to FIG. 11, the first terminal device 210 sends (1155) an indication of the selected resource block on the D2D feedback channel 320 to the second terminal device 220 via a D2D control channel such as the PSCCH. The first terminal device 210 transmits (1160) the D2D data to the second terminal device 220. The second terminal device 220 decodes (1165) the D2D data. Then, the second terminal device 220 determines the CDM signature for ACK/NACK feedback. The second terminal device 220 sends (1175) ACK/NACK at the feedback time period by employing the determined CDM signature.

FIG. 15 shows a flowchart of an example method 1500 of resource configuration according to some example embodiments of the present disclosure. The method 1500 can be implemented by the network device 230 as shown in FIG. 2. For the purpose of discussion, the method 1500 will be described with reference to FIG. 2.

At block 1505, the network device 230 allocates a plurality of feedback time periods to a D2D feedback channel in a resource pool. At block 1510, the network device 230 allocates a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods. At block 1515, the network device 230 determines a delay range between a D2D data channel and the D2D feedback channel. At block 1520, the network device 230 associates, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the D2D data channel in a transmission time period.

In some example embodiments, the network device 230 sends an indication of the delay range to at least the first terminal device 210.

In some example embodiments, the network device 230 associates the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period. In some example embodiments, the delay range comprises at least a first delay sub-range and a second delay sub-range. A time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.

In some example embodiments, the network device 230 sends an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device 210 and a different second terminal device 220.

In some example embodiments, the network device 230 allocates a frequency band to the device to device feedback channel in the resource pool. In some example embodiments, the allocated frequency band comprises one or more physical resource blocks. Alternatively, the network device 230 may allocate different physical resource blocks in a plurality of time periods to the device to device feedback channel.

In some example embodiments, the time period comprises a time slot. In some example embodiments, the D2D data channel comprises a physical sidelink shared channel, and the D2D feedback channel comprises a physical sidelink feedback channel.

FIG. 16 shows a flowchart of an example method 1600 according to some example embodiments of the present disclosure. The method 1600 can be implemented by the first terminal device 210 as shown in FIG. 2. For the purpose of discussion, the method 1600 will be described with reference to FIG. 2.

At block 1605, in response to D2D data to be transmitted to the second terminal device 220 in a transmission time period on a D2D data channel, the first terminal device 210 selects a subchannel from a plurality of subchannels of the D2D data channel in the transmission time period. At block 1610, the first terminal device 210 selects, based on the transmission time period and a predetermined delay range between the D2D data channel and a D2D feedback channel, a feedback time period from a plurality of feedback time periods on a D2D feedback channel. At block 1615, the first terminal device 210 sends, to the second terminal device 220, an indication of the feedback time period to enable the second terminal device 220 to send acknowledgement for the D2D data in the feedback time period on the D2D feedback channel.

In some example embodiments, the first terminal device 210 determines, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel from the plurality of orthogonal code sequences. The first terminal device 210 determines whether the code sequence is to be used to acknowledge further D2D data. If it is determined that the code sequence is to be used for acknowledging the further D2D data, the first terminal device 210 selects a further subchannel from the plurality of subchannels for transmitting the D2D data to the second terminal device in the transmission time period.

In some example embodiments, the first terminal device 210 detects an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further D2D data. Upon the detection of the indication, the first terminal device 210 determines whether the code sequence is to be used for acknowledging the further D2D data.

In some example embodiments, the plurality of orthogonal code sequences are associated with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.

In some example embodiments, the delay range comprises at least a first delay sub-range and a second delay sub-range. A time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.

In some example embodiments, the first terminal device 210 receives, from the network device 230, an indication of the predetermined association.

In some example embodiments, the first terminal device 210 selects a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel. Then, based on the further transmission time period and the predetermined delay range, the first terminal device 210 selects a feedback time period from the plurality of feedback time periods. Based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, the first terminal device 210 determines a code sequence associated with the further subchannel from the plurality of orthogonal code sequences. Further, the first terminal device 210 determines whether the code sequence is to be used to acknowledge further device-to-device data. If it is determined that the code sequence is to be used for acknowledging the further device-to-device data, the first terminal device 210 determines that the device-to-device data is to be transmitted in the transmission time period. Further, the first terminal device 210 selects the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, the first terminal device 210 selects, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods. A time difference between each candidate feedback time period and the transmission time period is within the predetermined delay range. The first terminal device 210 selects the feedback time period from the set of candidate feedback time periods.

In some example embodiments, the first terminal device 210 receives, from the network device 230, an indication of a time and frequency resource of the D2D feedback channel. The first terminal device 210 determines the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the first terminal device 210 receives, from the network device 230, an indication of the predetermined delay range.

In some example embodiments, the time period comprises a time slot. In some example embodiments, the D2D data channel comprises a physical sidelink shared channel, and the D2D feedback channel comprises a physical sidelink feedback channel. In some example embodiments, the first terminal device 210 sends the indication of the feedback time period to the second terminal device 220 on a physical sidelink control channel.

FIG. 17 shows a flowchart of an example method 1700 according to some other example embodiments of the present disclosure. The method 1700 can be implemented by the second terminal device 220 as shown in FIG. 2. For the purpose of discussion, the method 1700 will be described with reference to FIG. 2.

At block 1705, the second terminal device 220 decodes D2D data from the first terminal device 210 at a subchannel of a plurality of subchannels of a D2D data channel in a transmission time period. At block 1710, the second terminal device 220 receives, from the first terminal device 210, an indication of a feedback time period of a plurality of feedback time periods on a D2D feedback channel. At block 1715, the second terminal device 220 determines, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences. At block 1720, the second terminal device 220 sends, to the first terminal device 210 acknowledgement for the D2D data using the selected code sequence in the feedback time period on the D2D feedback channel.

In some example embodiments, the second terminal device 220 receives, from the network device 230, an indication of the predetermined association.

In some example embodiments, the second terminal device 220 receives, from the network device 230, an indication of a time and frequency resource of the D2D feedback channel. The second terminal device 220 determines the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the time period comprises a time slot. In some example embodiments, the D2D data channel comprises a physical sidelink shared channel, and the D2D feedback channel comprises a physical sidelink feedback channel. In some example embodiments, the second terminal device 220 receives the indication of the feedback time period from the first terminal device on a physical sidelink control channel.

All operations and features as described above with reference to FIGS. 2-14 are likewise applicable to the methods 1500-1700 and have similar effects. For the purpose of simplification, the details will be omitted.

FIG. 18 is a simplified block diagram of a device 1800 that is suitable for implementing embodiments of the present disclosure. The device 1800 can be implemented at the network device 230 or the first terminal device 210 or the second terminal device 220 as shown in FIG. 2.

As shown, the device 1800 includes a processor 1810, a memory 1820 coupled to the processor 1810, a communication module 1830 coupled to the processor 1810, and a communication interface (not shown) coupled to the communication module 1830. The memory 1820 stores at least a program 1840. The communication module 1830 is for bidirectional communications, for example, via multiple antennas. The communication interface may represent any interface that is necessary for communication.

The program 1840 is assumed to include program instructions that, when executed by the associated processor 1810, enable the device 1800 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 2-17. The embodiments herein may be implemented by computer software executable by the processor 1810 of the device 1800, or by hardware, or by a combination of software and hardware. The processor 1810 may be configured to implement various embodiments of the present disclosure.

The memory 1820 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1820 is shown in the device 1800, there may be several physically distinct memory modules in the device 1800. The processor 1810 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

When the device 1800 acts as the network device 230 or a part of the network device 230, the processor 1810 and the communication module 1830 may cooperate to implement the method 1500 as described above with reference to FIG. 15. When the device 1800 acts as the first terminal device 210 or a part of the first terminal device 210, the processor 1810 and the communication module 1830 may cooperate to implement the method 1600 as described above with reference to FIG. 16. When the device 1800 acts as the second terminal device 220 or a part of the second terminal device 220, the processor 1810 and the communication module 1830 may cooperate to implement the method 1700 as described above with reference to FIG. 17. All operations and features as described above with reference to FIGS. 2-17 are likewise applicable to the device 1800 and have similar effects. For the purpose of simplification, the details will be omitted.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. 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. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method 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.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the

processes

500 and 1100 and the methods 1500-1700 as described above with reference to FIGS. 2-17. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable media and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , Digital Versatile Disc (DVD) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Various embodiments of the techniques have been described. In addition to or as an alternative to the above, the following examples are described. The features described in any of the following examples may be utilized with any of the other examples described herein.

In some aspects, a first terminal device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the first terminal device to: in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, select a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period; select, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and send, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the first terminal device is further caused to: determine, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel from the plurality of orthogonal code sequences; determine whether the code sequence is to be used to acknowledge further device-to-device data; in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, select a further subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, the first terminal device is caused to determine whether the code sequence is to be used for acknowledging the further device-to-device data by: detecting an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further device-to-device data; and in response to detecting the indication, determining whether the code sequence is to be used for acknowledging the further device-to-device data.

In some example embodiments, the delay range comprises at least a first delay sub-range and a second delay sub-range, and a time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.

In some example embodiments, the first terminal device is further caused to: receive, from a network device, an indication of the predetermined association.

In some example embodiments, the first terminal device is caused to select the subchannel from the plurality of subchannels by: selecting a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel; selecting, based on the further transmission time period and the predetermined delay range, a feedback time period from the plurality of feedback time periods; determining, based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, a code sequence associated with the further subchannel from the plurality of orthogonal code sequences; determining whether the code sequence is to be used to acknowledge further device-to-device data; in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, determining that the device-to-device data is to be transmitted in the transmission time period; and selecting the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, the first terminal device is caused to select the feedback time period from the plurality of feedback time periods comprises: select, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods, a time difference between each candidate feedback time period and the transmission time period being within the predetermined delay range; and select the feedback time period from the set of candidate feedback time periods.

In some example embodiments, the first terminal device is further caused to: receive, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and determine the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the first terminal device is further caused to: receive, from a network device, an indication of the predetermined delay range.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.

In some example embodiments, the first terminal device is caused to send the indication of the feedback time period to the second terminal device by: sending the indication of the feedback time period to the second terminal device on a physical sidelink control channel.

In some aspects, a second terminal device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the second terminal device to: decode device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period; receive, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel; determine, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and send, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the second terminal device is further caused to: receive, from a network device, an indication of the predetermined association.

In some example embodiments, the second terminal device is further caused to: receive, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and determine the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, the second terminal device is caused to receive the indication of the feedback time period from the first terminal device by: receiving the indication of the feedback time period from the first terminal device on a physical sidelink control channel.

In some aspects, a network device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the network device to: allocate a plurality of feedback time periods to a device-to-device feedback channel in a resource pool; allocate a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods; determine a delay range between a device-to-device data channel and the device-to-device feedback channel; and associate, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.

In some example embodiments, the network device is further caused to: send an indication of the delay range to at least a first terminal device.

In some example embodiments, the network device is caused to associate the plurality of orthogonal code sequences with at least the plurality of subchannels by: associating the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.

In some example embodiments, the network device is further caused to: send an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device and a different second terminal device.

In some example embodiments, the network device is further caused to: allocate a frequency band to the device to device feedback channel in the resource pool.

In some example embodiments, the allocated frequency band comprises one or more physical resource blocks.

In some example embodiments, the time period comprises a time slot.

In some aspects, a method implemented at a first terminal device, comprising: in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, selecting a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period; selecting, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and sending, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the method further comprises: determining, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel among from the plurality of orthogonal code sequences; determining whether the code sequence is to be used to acknowledge further device-to-device data; in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, selecting a further subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, determining whether the code sequence is to be used for acknowledging the further device-to-device data comprises: detecting an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further device-to-device data; and in response to detecting the indication, determining whether the code sequence is to be used for acknowledging the further device-to-device data.

In some example embodiments, the method further comprises: receiving, from a network device, an indication of the predetermined association.

In some example embodiments, selecting the subchannel from the plurality of subchannels comprises: selecting a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel; selecting, based on the further transmission time period and the predetermined delay range, a feedback time period from the plurality of feedback time periods; determining, based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, a code sequence associated with the further subchannel from the plurality of orthogonal code sequences; determining whether the code sequence is to be used to acknowledge further device-to-device data; in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, determining that the device-to-device data is to be transmitted in the transmission time period; and selecting the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, selecting the feedback time period from the plurality of feedback time periods comprises: selecting, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods, a time difference between each candidate feedback time period and the transmission time period being within the predetermined delay range; and selecting the feedback time period from the set of candidate feedback time periods.

In some example embodiments, the method further comprises: receiving, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and determining the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the method further comprises: receiving, from a network device, an indication of the predetermined delay range.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, sending the indication of the feedback time period to the second terminal device comprises: sending the indication of the feedback time period to the second terminal device on a physical sidelink control channel.

In some aspects, a method implemented at a second terminal device, comprising: decoding device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period; receiving, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel; determining, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and sending, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, receiving the indication of the feedback time period from the first terminal device comprises: receiving the indication of the feedback time period from the first terminal device on a physical sidelink control channel.

In some aspects, a method implemented at a network device, comprising: allocating a plurality of feedback time periods to a device-to-device feedback channel in a resource pool; allocating a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods; determining a delay range between a device-to-device data channel and the device-to-device feedback channel; and associating, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.

In some example embodiments, the method further comprises: sending an indication of the delay range to at least a first terminal device.

In some example embodiments, associating the plurality of orthogonal code sequences with at least the plurality of subchannels comprises: associating the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.

In some example embodiments, the method further comprises: sending an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device and a different second terminal device.

In some example embodiments, the method further comprises: allocating a frequency band to the device to device feedback channel in the resource pool.

In some example embodiments, the time period comprises a time slot.

In some aspects, an apparatus implemented at a first terminal device, comprising: means for in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, selecting a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period; means for selecting, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and means for sending, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the apparatus further comprises: means for determining, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel among from the plurality of orthogonal code sequences; means for determining whether the code sequence is to be used to acknowledge further device-to-device data; means for in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, selecting a further subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, the means for determining whether the code sequence is to be used for acknowledging the further device-to-device data comprises: means for detecting an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further device-to-device data; and means for in response to detecting the indication, determining whether the code sequence is to be used for acknowledging the further device-to-device data.

In some example embodiments, the apparatus further comprises: means for receiving, from a network device, an indication of the predetermined association.

In some example embodiments, means for selecting the subchannel from the plurality of subchannels comprises: means for selecting a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel; means for selecting, based on the further transmission time period and the predetermined delay range, a feedback time period from the plurality of feedback time periods; means for determining, based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, a code sequence associated with the further subchannel from the plurality of orthogonal code sequences; means for determining whether the code sequence is to be used to acknowledge further device-to-device data; means for in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, determining that the device-to-device data is to be transmitted in the transmission time period; and means for selecting the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.

In some example embodiments, the means for selecting the feedback time period from the plurality of feedback time periods comprises: means for selecting, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods, a time difference between each candidate feedback time period and the transmission time period being within the predetermined delay range; and means for selecting the feedback time period from the set of candidate feedback time periods.

In some example embodiments, the apparatus further comprises: means for receiving, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and determining the plurality of feedback time periods in the time and frequency resource.

In some example embodiments, the apparatus further comprises: means for receiving, from a network device, an indication of the predetermined delay range.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, the means for sending the indication of the feedback time period to the second terminal device comprises: means for sending the indication of the feedback time period to the second terminal device on a physical sidelink control channel.

In some aspects, an apparatus implemented at a second terminal device, comprising: means for decoding device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period; means for receiving, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel; means for determining, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and means for sending, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.

In some example embodiments, the time period comprises a time slot.

In some example embodiments, the means for receiving the indication of the feedback time period from the first terminal device comprises: means for receiving the indication of the feedback time period from the first terminal device on a physical sidelink control channel.

In some aspects, an apparatus implemented at a network device, comprising: means for allocating a plurality of feedback time periods to a device-to-device feedback channel in a resource pool; means for allocating a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods; means for determining a delay range between a device-to-device data channel and the device-to-device feedback channel; and means for associating, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.

In some example embodiments, the apparatus further comprises: means for sending an indication of the delay range to at least a first terminal device.

In some example embodiments, the means for associating the plurality of orthogonal code sequences with at least the plurality of subchannels comprises: means for associating the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.

In some example embodiments, the apparatus further comprises: means for sending an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device and a different second terminal device.

In some example embodiments, the apparatus further comprises: means for allocating a frequency band to the device to device feedback channel in the resource pool.

In some example embodiments, the time period comprises a time slot.

In some aspects, a computer readable storage medium comprises program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method according to some example embodiments of the present disclosure.

Claims

A first terminal device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the first terminal device to:

in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, select a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period;

select, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and

send, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.
The first terminal device of claim 1, wherein the first terminal device is further caused to:

determine, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel from the plurality of orthogonal code sequences;

determine whether the code sequence is to be used to acknowledge further device-to-device data;

in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, select a further subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.
The first terminal device of claim 2, wherein the first terminal device is caused to determine whether the code sequence is to be used for acknowledging the further device-to-device data by:

detecting an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further device-to-device data; and

in response to detecting the indication, determining whether the code sequence is to be used for acknowledging the further device-to-device data.
The first terminal device of claim 2, wherein the plurality of orthogonal code sequences are associated with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The first terminal device of claim 4, wherein

the delay range comprises at least a first delay sub-range and a second delay sub-range, and

a time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.
The first terminal device of claim 2, wherein the first terminal device is further caused to:

receive, from a network device, an indication of the predetermined association.
The first terminal device of claim 1, wherein the first terminal device is caused to select the subchannel from the plurality of subchannels by:

selecting a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel;

selecting, based on the further transmission time period and the predetermined delay range, a feedback time period from the plurality of feedback time periods;

determining, based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, a code sequence associated with the further subchannel from the plurality of orthogonal code sequences;

determining whether the code sequence is to be used to acknowledge further device-to-device data;

in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, determining that the device-to-device data is to be transmitted in the transmission time period; and

selecting the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.
The first terminal device of claim 1, wherein the first terminal device is caused to select the feedback time period from the plurality of feedback time periods comprises:

select, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods, a time difference between each candidate feedback time period and the transmission time period being within the predetermined delay range; and

select the feedback time period from the set of candidate feedback time periods.
The first terminal device of claim 1, wherein the first terminal device is further caused to:

receive, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and

determine the plurality of feedback time periods in the time and frequency resource.
The first terminal device of claim 1, wherein the first terminal device is further caused to:

receive, from a network device, an indication of the predetermined delay range.
The first terminal device of claim 1, wherein the time period comprises a time slot.
The first terminal device of claim 1, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
The first terminal device of claim 12, wherein the first terminal device is caused to send the indication of the feedback time period to the second terminal device by:

sending the indication of the feedback time period to the second terminal device on a physical sidelink control channel.
A second terminal device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the second terminal device to:

decode device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period;

receive, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel;

determine, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and

send, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.
The second terminal device of claim 14, wherein the plurality of orthogonal code sequences are associated with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The second terminal device of claim 14, wherein the second terminal device is further caused to:

receive, from a network device, an indication of the predetermined association.
The second terminal device of claim 14, wherein the second terminal device is further caused to:

receive, from a network device, an indication of a time and frequency resource of the device-to-device feedback channel; and

determine the plurality of feedback time periods in the time and frequency resource.
The second terminal device of claim 14, wherein the time period comprises a time slot.
The second terminal device of claim 14, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
The second terminal device of claim 19, wherein the second terminal device is caused to receive the indication of the feedback time period from the first terminal device by:

receiving the indication of the feedback time period from the first terminal device on a physical sidelink control channel.
A network device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the network device to:

allocate a plurality of feedback time periods to a device-to-device feedback channel in a resource pool;

allocate a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods;

determine a delay range between a device-to-device data channel and the device-to-device feedback channel; and

associate, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.
The method of claim 21, wherein the network device is further caused to:

send an indication of the delay range to at least a first terminal device.
The network device of claim 21, wherein the network device is caused to associate the plurality of orthogonal code sequences with at least the plurality of subchannels by:

associating the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The network device of claim 23, wherein

the delay range comprises at least a first delay sub-range and a second delay sub-range, and

a time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.
The network device of claim 21, wherein the network device is further caused to:

send an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device and a different second terminal device.
The network device of claim 21, wherein the network device is further caused to:

allocate a frequency band to the device to device feedback channel in the resource pool.
The network device of claim 21, wherein the allocated frequency band comprises one or more physical resource blocks.
The network device of claim 21, wherein the time period comprises a time slot.
The network device of claim 21, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
A method implemented at a first terminal device, comprising:

in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, selecting a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period;

selecting, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and

sending, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.
The method of claim 30, further comprising:

determining, based on predetermined association between a plurality of orthogonal code sequences for the feedback time period and at least the plurality of subchannels, a code sequence associated with the selected subchannel from the plurality of orthogonal code sequences;

determining whether the code sequence is to be used to acknowledge further device-to-device data;

in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, selecting a further subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.
The method of claim 31, wherein determining whether the code sequence is to be used for acknowledging the further device-to-device data comprises:

detecting an indication from a third terminal device to indicate that the feedback time period is to be used for acknowledging the further device-to-device data; and

in response to detecting the indication, determining whether the code sequence is to be used for acknowledging the further device-to-device data.
The method of claim 31, wherein the plurality of orthogonal code sequences are associated with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The method of claim 33, wherein

the delay range comprises at least a first delay sub-range and a second delay sub-range, and

a time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.
The method of claim 31, further comprising:

receiving, from a network device, an indication of the predetermined association.
The method of claim 30, wherein selecting the subchannel from the plurality of subchannels comprises:

selecting a further subchannel from a plurality of other subchannels in a further transmission time period for transmitting the device-to-device data on the device-to-device data channel;

selecting, based on the further transmission time period and the predetermined delay range, a feedback time period from the plurality of feedback time periods;

determining, based on predetermined association between a plurality of orthogonal code sequences for the selected feedback time period and the plurality of other subchannels, a code sequence associated with the further subchannel from the plurality of orthogonal code sequences;

determining whether the code sequence is to be used to acknowledge further device-to-device data;

in response to determining that the code sequence is to be used for acknowledging the further device-to-device data, determining that the device-to-device data is to be transmitted in the transmission time period; and

selecting the subchannel from the plurality of subchannels for transmitting the device-to-device data to the second terminal device in the transmission time period.
The method of claim 30, wherein selecting the feedback time period from the plurality of feedback time periods comprises:

selecting, based on the transmission time period and the predetermined delay range, a set of candidate feedback time periods from the plurality of feedback time periods, a time difference between each candidate feedback time period and the transmission time period being within the predetermined delay range; and

selecting the feedback time period from the set of candidate feedback time periods.
The method of claim 30, further comprising:

receiving, from a network device, an indication of a time and frequency resource of on the device-to-device feedback channel; and

determining the plurality of feedback time periods in the time and frequency resource.
The method of claim 30, further comprising:

receiving, from a network device, an indication of the predetermined delay range.
The method of claim 30, wherein the time period comprises a time slot.
The method of claim 30, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
The method of claim 41, wherein sending the indication of the feedback time period to the second terminal device comprises:

sending the indication of the feedback time period to the second terminal device on a physical sidelink control channel.
A method implemented at a second terminal device, comprising:

decoding device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period;

receiving, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel;

determining, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and

sending, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.
The method of claim 43, wherein the plurality of orthogonal code sequences are associated with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The method of claim 43, further comprising:

receiving, from a network device, an indication of the predetermined association.
The method of claim 43, further comprising:

receiving, from a network device, an indication of a time and frequency resource of on the device-to-device feedback channel; and

determining the plurality of feedback time periods in the time and frequency resource.
The method of claim 43, wherein the time period comprises a time slot.
The method of claim 43, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
The method of claim 48, wherein receiving the indication of the feedback time period from the first terminal device comprises:

receiving the indication of the feedback time period from the first terminal device on a physical sidelink control channel.
A method implemented at a network device, comprising:

allocating a plurality of feedback time periods to a device-to-device feedback channel in a resource pool;

allocating a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods;

determining a delay range between a device-to-device data channel and the device-to-device feedback channel; and

associating, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.
The method of claim 50, further comprising:

sending an indication of the delay range to at least a first terminal device.
The method of claim 50, wherein associating the plurality of orthogonal code sequences with at least the plurality of subchannels comprises:

associating the plurality of orthogonal code sequences with at least the plurality of subchannels in the transmission time period and a plurality of other subchannels in a further transmission time period.
The method of claim 52, wherein

the delay range comprises at least a first delay sub-range and a second delay sub-range, and

a time difference between the transmission time period and the feedback time period is within the first delay sub-range, and a time difference between the further transmission time period and the feedback time period is within the second delay sub-range.
The method of claim 50, further comprising:

sending an indication of the association between the plurality of orthogonal code sequences and the plurality of subchannels to at least the first terminal device and a different second terminal device.
The method of claim 50, further comprising:

allocating a frequency band to the device to device feedback channel in the resource pool.
The method of claim 55, wherein the allocated frequency band comprises one or more physical resource blocks.
The method of claim 50, wherein the time period comprises a time slot.
The method of claim 50, wherein the device-to-device data channel comprises a physical sidelink shared channel, and the device-to-device feedback channel comprises a physical sidelink feedback channel.
An apparatus comprising:

means for in response to device-to-device data to be transmitted to a second terminal device in a transmission time period on a device-to-device data channel, selecting a subchannel from a plurality of subchannels of the device-to-device data channel in the transmission time period;

means for selecting, based on the transmission time period and a predetermined delay range between the device-to-device data channel and a device-to-device feedback channel, a feedback time period from a plurality of feedback time periods on a device-to-device feedback channel; and

means for sending, to the second terminal device, an indication of the feedback time period to enable the second terminal device to send acknowledgement for the device-to-device data in the feedback time period on the device-to-device feedback channel.
An apparatus comprising:

means for decoding device-to-device data from a first terminal device at a subchannel of a plurality of subchannels of a device-to-device data channel in a transmission time period;

means for receiving, from the first terminal device, an indication of a feedback time period of a plurality of feedback time periods on a device-to-device feedback channel;

means for determining, based on predetermined association between the plurality of subchannels and a plurality of orthogonal code sequences for the feedback time period, a code sequence from the plurality of orthogonal code sequences; and

means for sending, to the first terminal device, acknowledgement for the device-to-device data using the selected code sequence in the feedback time period on the device-to-device feedback channel.
An apparatus comprising:

means for allocating a plurality of feedback time periods to a device-to-device feedback channel in a resource pool;

means for allocating a plurality of orthogonal code sequences for a feedback time period of the plurality of feedback time periods;

means for determining a delay range between a device-to-device data channel and the device-to-device feedback channel; and

means for associating, based on the delay range, the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel in a transmission time period.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 30-42.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 43-49.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 50-58.