CN114175693A

CN114175693A - Resource allocation for feedback channel for device-to-device communication

Info

Publication number: CN114175693A
Application number: CN201980098927.4A
Authority: CN
Inventors: 刘勇; 李栋; T·维尔德斯彻克; 谭钧
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2019-07-30
Filing date: 2019-07-30
Publication date: 2022-03-11
Also published as: WO2021016882A1

Abstract

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

Description

Resource allocation for feedback channel for device-to-device communication

Technical Field

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

Background

New Radio (NR) internet of vehicles (V2X) are being developed to provide advanced V2X services in NR systems. In Long Term Evolution (LTE) V2X, the broadcast mode is specified for side-chain communication only at the Physical (PHY) layer. Unicast and multicast modes need to be implemented at a higher level. For NR V2X side chain communications, unicast and multicast communications are considered to be implemented directly at the PHY layer under standardization in 3 rd generation partnership project (3GPP) release 16.

In order to enable hybrid automatic repeat request (HARQ) at the PHY layer, it is necessary to feed back an acknowledgement or non-acknowledgement (ACK/NACK) from the receiver to the transmitter. There is a need to configure related feedback resources and to multiplex feedback from multiple User Equipments (UEs) to improve feedback efficiency.

Disclosure of Invention

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

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

In a second aspect, a second terminal device is provided, the 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 are configured to, with the at least one processor, cause the second terminal device to decode device-to-device data from the first terminal device at a sub-channel of a plurality of sub-channels of a device-to-device data channel during a transmission time period. The second terminal device is caused to receive an indication of a feedback time period of the plurality of feedback time periods from the first terminal device on a device-to-device feedback channel. The second terminal device is further caused to determine a code sequence from the plurality of orthogonal code sequences based on predetermined associations between the plurality of subchannels and the plurality of orthogonal code sequences for the feedback period. The second terminal device is further caused to transmit an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for a feedback time period on a device-to-device feedback channel.

In a third aspect, a network device is provided that includes 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 a plurality of feedback time periods. The network device is also caused to determine a delay range between the device-to-device data channel and the device-to-device feedback channel. The network device is further caused to associate the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel over a transmission time period based on the delay range.

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

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

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, a computer-readable storage medium having a computer program stored thereon is provided. The computer program, when executed by a processor of an apparatus, causes the apparatus to perform the method according to the fourth, fifth or sixth aspect.

It should be understood that the summary is not intended to identify key or essential features of embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

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

fig. 1 illustrates an example resource configuration of a short PSFCH in a resource pool;

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

FIG. 3 illustrates an example structure of a resource pool in accordance with some example embodiments of the present disclosure;

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

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

fig. 6 illustrates example resource configurations in a resource pool for D2D communication, 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 an example configuration of delay ranges in accordance with some example embodiments of the present disclosure;

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

fig. 10 illustrates an example selection of a D2D resource, according to some example embodiments of the present disclosure;

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

fig. 12 illustrates an example configuration of delay ranges according to some other example embodiments of the present disclosure;

fig. 13 illustrates an example association between a D2D data channel and a D2D feedback channel, in accordance with some example embodiments of the present disclosure;

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

fig. 15 shows a flow diagram of an example method according to some example embodiments of the present disclosure;

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

fig. 17 shows a flowchart of an example method according to other example embodiments of the present disclosure; and

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

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is to be understood that these examples are described solely for the purpose of illustration and to aid those skilled in the art in understanding and practicing the invention, and are not intended to limit the scope of the present disclosure in any way. The disclosure described herein may be implemented in various ways other than those 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 skill in the art to which this disclosure belongs.

As used herein, the term "network device" refers to a device via which services may be provided to terminal devices in a communication network. Examples of network devices may include relays, Access Points (APs), transmission points (TRPs), node bs (NodeB or NB), evolved NodeB (eNodeB or eNB), New Radio (NR) NodeB (gnb), remote radio modules (RRUs), Radio Headers (RH), Remote Radio Heads (RRHs), low power nodes (such as femto, pico), and so forth.

As used herein, the term "terminal device" or "user equipment" (UE) refers to any terminal device capable of wireless communication with each other or a base station. Communication may involve the transmission and/or reception of wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for the transmission of information over the air. In some example embodiments, the UE may be configured to transmit and/or receive information without direct human-machine interaction. For example, the UE may transmit information to the network device according to a predetermined schedule, when triggered by an internal or external event, or in response to a request from the network side.

Examples of UEs include, but are not limited to, User Equipment (UE), such as smart phones, wireless-enabled tablets, laptop embedded devices (LEEs), laptop installed devices (LMEs), wireless Customer Premise Equipment (CPEs), sensors, metering devices, personal wearable devices such as watches, and/or vehicles capable of communication. The terminal devices may also include vehicles that communicate V2X via a D2D sidechain. For purposes of discussion, some example embodiments will be described with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably in the context of this disclosure.

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

(a) a purely hardware circuit implementation (such as an implementation in analog and/or digital circuitry only), and

(b) a combination of hardware circuitry and software, such as (as applicable): (i) (a plurality of)

A combination of analog and/or digital hardware circuitry and software/firmware, and (ii) any portion of a hardware processor with software (including digital signal processor(s), and memory(s) that cooperate to cause a device, such as a mobile phone or server, to perform various functions), and

(c) hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware)

The operation is performed but the software may not be present at the operation.

The definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also encompasses implementations of only 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. For example, the term circuitry, if applicable to a particular claim element, also encompasses 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 "include" and its variants should be understood as open-ended terms meaning "including, but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood 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, which 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.

Unlike LTE V2X, both unicast and multicast communications need to be implemented directly at the PHY layer to improve the transmission efficiency of these communications. More advanced schemes need to be designed to enable direct communication at the PHY layer. For example, a short Physical Sidelink Feedback Channel (PSFCH) is specified for acknowledgement feedback in sidelink communications.

Fig. 1 shows an example resource configuration of 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 the short PSFCH 110, the short PSFCH 110 occupying the last three (or more) symbols in the slot 105-N (total 14 symbols per slot) within a period of N slots. The short PSFCH 110 occupies the entire 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 transmission and reception (T/R) switching. Only the middle symbol(s) is actually used to convey HARQ feedback.

The inventors have noted that the scheme using short PSFCH has the following disadvantages. First, the feasibility of this approach is constrained by half-duplex. For example, when there is a bi-directional unicast communication between two UEs, both UEs may need to feed back ACK/NACK in the same PSFCH slot to meet the respective delay requirements. However, this is not feasible due to half-duplex constraints, since the UE cannot transmit and receive simultaneously. Furthermore, strict delay requirements may not be met because the UE must wait for the PSFCH slot to feed back the ACK/NACK.

The inventors have also noted that one approach to alleviating the above two problems may be to reduce the period of the N time slots. However, a short small period of PSFCH may result in a large resource consumption, since the short PSFCH occupies the entire frequency band of the configured resource pool, as shown in fig. 1.

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

Further, associations between the plurality of orthogonal code sequences and the D2D data channel are configured, preconfigured, or predefined. The orthogonal code sequences may be generated from base sequences with different Code Division Multiplexing (CDM) signatures, such as Zadoff-Chu sequences. The CDM signature may be a combination of cyclic shifts and Orthogonal Cover Codes (OCCs). For example, each subchannel of the D2D data channel in one or more transmission time periods (e.g., slots) is configured with a unique CDM signature for HARQ feedback in the corresponding feedback channel. Such resource configuration of the feedback channel may provide timely HARQ feedback for services with strict delay requirements and may effectively alleviate half-duplex constraints.

FIG. 2 illustrates an example environment 200 in which embodiments of the present disclosure may be implemented. The environment 200, which is 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 should be understood that two terminal devices and one network device are shown in fig. 2 for illustrative purposes only and do not imply any limitation.

The two

terminal devices

210 and 220 may be connected directly via D2D or communicate via network device 230. The two

terminal devices

210 and 220 may also communicate with other terminal devices (not shown) directly or via the network device 230. Communications in environment 200 may follow any suitable communication standard or protocol, such as Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), LTE-advanced (LTE-a), fifth generation (5G) NR, wireless fidelity (Wi-Fi), and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employ any suitable communication technology 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), mass Machine Type Communication (MTC), ultra-reliable low delay communication (URLLC), Carrier Aggregation (CA), Dual Connectivity (DC), new radio unlicensed (NR-U), and V2X technologies.

For D2D communication between the two

terminal devices

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

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

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

In the resource pool 300, the D2D data channel 315 is configured to have 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 the psch. The resources of the D2D data channel 315 may also be used for D2D control channels, such as Physical Sidelink Control Channels (PSCCHs).

Further, the D2D feedback channel 320 is configured in the resource pool 300, the D2D feedback channel 320 occupying a plurality of consecutive time periods in the time domain. For ease of discussion, the time periods in the D2D data channel 315 are referred to as transmission time periods, while the time periods in the D2D feedback channel 320 are referred to as feedback time periods. In this example, the D2D feedback channel 320 occupies 1 PRB (or multiple PRBs configured by the network device 230) in each time segment 305 of the resource pool 300. The D2D feedback channel 320 may be implemented by a PSFCH. The D2D feedback channel 320 may provide timely HARQ feedback for services with strict delay requirements and may alleviate half-duplex constraints.

Further, as shown, the short D2D feedback channel 325 is also configured to have a duration that is shorter than a 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 period of the D2D feedback channel 320 may not include the time period 330 in which the short D2D feedback channel 325 is configured, as the recipient may use the short D2D feedback channel 325 for HARQ feedback within the time period 330.

Alternatively, the D2D feedback channel 320 is configured in the resource pool 300, the D2D feedback channel 320 may not occupy multiple consecutive time periods in the time domain. As one example, as shown in fig. 3, the time period 305-3 may be excluded from the D2D feedback channel 320. The first terminal device does not select time period 305-3 for acknowledging the feedback. As another example, as shown in fig. 3, the D2D feedback channel 320 may occupy one time period every K (e.g., K-2) time periods. K may be set to a positive integer less than N, which means that the period of the D2D feedback channel 320 is shorter than the period of the short PSFCH.

With the resource configuration in the resource pool 300, when the first terminal device 210 performs D2D transmission to the second terminal device 220 on the D2D data channel 315, the second terminal device 220 may use the D2D feedback channel 320 for acknowledgment feedback for 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 as [1, 2]]. That is, for time period t of D2D data channel 315₁D2D transmissions within (e.g., time period 305-1), time periods Δ +1 and t of the D2D feedback channel 320₁+2 (e.g., time periods 305-2 and 305-3) may be used for feedback. Thus, the time period t of the D2D feedback channel 320₂(e.g., time period 305-3) may be used for counting at D2DOn data channel 315 for a time period t₂-1 and t₂-2 (represented by time periods 305-1 and 305-2, respectively) for data transmission.

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

Further, the network device 230 configures an association between the orthogonal code sequence (e.g., CDM signature) of the D2D feedback channel 320 and the D2D data channel 315 within the delay range 335. For example, within 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. On the D2D data channel 315 with a time period t₂Δ t associated on the D2D feedback channel 320 for a time period t₂The CDM signature used may be determined by (Δ t, l), where l represents the time period t₂-index of sub-channel within Δ t.

If the first terminal device 210 were to initiate a D2D data transmission to the second terminal device 220, the first terminal device 210 may transmit for a transmission time period t on the D2D data channel 315₁The inner selection sub-channel 310. Based on the delay range 335 and the association between the D2D data channel 315 and the D2D feedback channel 320 (pre) configured by the network device 230, the first terminal device 210 may select the feedback time period t on the D2D feedback channel 320₁+ Δ t is used for ACK/NACK feedback from the second terminal device 220.

The first terminal device 210 sends an indication of the feedback time period of the selected D2D feedback channel 320 to the second terminal device 220. The indication may be sent in the Sidechain 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 period of the D2D feedback channel 320 and determine a code sequence (such as a 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 in the D2D data channel 315 along with the data to further reduce signaling overhead.

Due to the limitation of the number of orthogonal code sequences (such as CDM signatures), in some example embodiments, a spreading scheme of the resource configuration of the D2D feedback channel 320 may be employed to reduce the number of different CDM signatures required on the D2D feedback channel. By extension, 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 reused in n sub-ranges.

Fig. 4 illustrates an example extended resource configuration in a resource pool 300 according to some example embodiments of the present disclosure.

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

Reusing CDM signatures in n subranges can significantly reduce the number of CDM signatures required for D2D feedback channel 320. Accordingly, the feedback period of the D2D feedback channel 320 may be used for ACK/NACK feedback of data transmitted on multiple sub-channels of the D2D data channel 315, and thus resource consumption of the D2D feedback channel 320 may be reduced.

In the case of reusing CDM signatures, as shown in FIG. 4, the subchannels 310 of 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 signature. To further improve feedback efficiency, in selecting a feedback period for ACK/NACK feedback to data transmission, the first terminal device 210 may select a feedback period with an unused CDM signature based on detection or decoding of D2D control information on the D2D data channel 315 in the previous period 305.

Fig. 5 illustrates a signaling flow 500 between a network device 230 and 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 a UE. The network device 230 communicates with the first terminal device 210 and the second terminal device 220 via the Uu interface, and the two

terminal devices

210 and 220 can communicate over a D2D link.

As shown in fig. 5, the network device 230 determines 505 the time and frequency resources of a short D2D feedback channel 325, such as the short PSFCH 110 shown in fig. 1. The configuration of the short D2D feedback channel 325 is optional. In some example embodiments, such short feedback channels may not be configured. The network device 230 determines (510) the time and frequency resources of the long D2D feedback channel 320.

Resource determination will be described below with reference to fig. 6, which fig. 6 illustrates an example resource configuration in a resource pool 300 for D2D communication, 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 of the short D2D feedback channel 325 occupies the last symbol in a time period 305-N (e.g., a slot or subframe) with a period of N time periods. In the frequency domain, the frequency resources occupy the entire frequency band 605 of the sub-channel 310 in the resource pool 300.

For the long D2D feedback channel 320, the frequency resources in the frequency domain occupy 1 PRB (or multiple PRBs configured by the network device 230) in each time segment of the resource pool 300. In a hybrid resource configuration of the short D2D feedback channel 325 and the long D2D feedback channel 320, the time period 330 configured with the short D2D feedback channel 325 may be excluded from the D2D feedback channel 320 because the receiver may use the short D2D feedback channel 325 when timely HARQ feedback is needed.

The D2D feedback channel 320 may occupy the entire period of each time period in the time domain. Fig. 7 illustrates an example structure of a 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. Further, in the time domain, the D2D feedback channel 320 occupies all symbols (e.g., 14 OFDM symbols) in the time slot 705. Of the 14 symbols, the first 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.

In time slot 705, an orthogonal code sequence is allocated to D2D feedback channel 320. For example, BPSK modulation is used, and modulation symbols are spread with a Zadoff-Chu sequence (denoted by ru, v, with different cyclic shifts (denoted by α)) and an Orthogonal Cover Code (OCC) (denoted by w (1) to w (6)).

In some example embodiments, in the resource pool 300, the same Zadoff-Chu sequence is used 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 feedback. The CDM signature is a combination of cyclic shift and OCC. Thus, multiplexing between HARQ feedback from multiple terminal devices is achieved. Furthermore, multiple resource pools in one or more regions or cells may employ different Zadoff-Chu sequences to randomize mutual interference.

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

Still referring to fig. 5, the network device 230 determines (515) a delay range [ a, b ] of Δ t between the D2D data channel 315 and the D2D feedback channel 320 for HARQ feedback]. Time period t on D2D data channel 315₁And the time period t on the D2D feedback channel 320₂The delay Δ t therebetween is t₂-t₁. The delay range may be set based on factors such as the number of subchannels in the resource pool 300, the number of PRBs of the periodic N, D2D feedback channel 320 of the short D2D feedback channel 325, and the like. Some example values for the delay range may include [2, 4]]、[2，2]、[1，3]、[1，1]。

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

Over the D2D data channel 315 for a time period t₁Time period t on D2D feedback channel 320 associated with subchannel l₂Is determined by (Δ t, l), where t ═ t₂-t₁And l denotes an index of the subchannel 310 of the D2D data channel 315. If the D2D data channel 315 occupies multiple (more than one) sub-channel 310, then l may represent the index of the starting sub-channel of the D2D data channel 315.

Fig. 8 illustrates an example configuration of a delay range 335, according to some example embodiments of the present disclosure. In this example, delay range 335 is configured as [1, 2]]. Time periods 305-1 and 305-2 (from t)₂-2 and t₂-1) on the D2D feedback channel 320 for a corresponding time period 305-3 (represented by time period t)₂Representation) have different CDM signatures for their respective HARQ feedback.

Fig. 9 illustrates an 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, although one terminal device (e.g., the first terminal device 210) is in time period 305-1 (by time period t)₂2) and subchannel 310 (represented by subchannel l), but another terminal device (e.g., second terminal device 220) transmits D2D data during time period 305-2 (represented by time period t)₂-1) and subchannel 310 (represented by subchannel l) transmits D2D data. Its corresponding receiving terminal device may be on the D2D feedback channel 320 for the feedback period 305-3 (defined by the period t₂Representation), but with different CDM signatures for multiplexing.

Still referring to fig. 5, the network device 230 sends (525) an indication of the resource configuration of the D2D feedback channel 320 to both the first terminal device 210 and the second terminal device 220. The indication may be sent in a broadcast or multicast message, such as a System Information Block (SIB) or a Master Information Block (MIB), as examples. 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 bound and the resource association to both the first terminal device 210 and the second terminal device 220. The indication may also be sent in a broadcast message, such as SIB or MIB, or in a dedicated message, such as RRC signaling. The delay bounds and/or resource associations may be dynamically, semi-statically, or statically configured by network device 230. Alternatively, the configuration may be predefined in the relevant 3GPP specifications.

It should be understood that the delay range may be configured or predefined to some single value, such as [2, 2 ]. In this case, the first terminal device 210 does not need to indicate the feedback period to the second terminal device 220.

The first terminal device 210 and the second terminal device 220 may perform D2D communications through the association between the D2D data channel 315 and the D2D feedback channel 320 configured or predefined by the network device 230, and the delay range set by the network device 230. As shown, the first terminal device 210 selects 535 one or more sub-channels of the D2D data channel 315 for communication with the D2D of the second terminal device 220. For example, the selected sub-channel may be represented by (t)₁L) represents, wherein t₁Denotes a time period, and l denotes 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 on the D2D feedback channel 320₁+ Δ t is used 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 accomplished by considering any other suitable factors such as delay requirements and half-duplex constraints.

Fig. 10 illustrates an example selection of a D2D resource, according to some example embodiments of the present disclosure. In this example, the delay range is configured as [1, 2] as shown. The first terminal device 210 selects the sub-channel 310 for D2D transmission during time period 305-1. 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 may select one of the two time periods 305-2 and 305-3 for feedback.

Still referring 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 Δ t as an indication in the SCI of the PSCCH associated with the PSCCH. The first terminal device 210 also transmits (550) data to the second terminal device 220 on the selected sub-channel 310 of the D2D data channel 315.

The second terminal device 220 decodes (555) the data on the sub-channel 310 of the D2D data channel 315. The second terminal device 220 determines (560) a code sequence from the plurality of orthogonal code sequences based on a predetermined association between the sub-channel of the D2D data channel 315 and the plurality of orthogonal code sequences. For example, in example embodiments in which the same base sequence, such as the same Zadoff-Chu sequence, the second terminal device 220 determines the CDM signature based on (Δ t, l) and the (pre) configured/predefined association between the D2D data channel 315 and the D2D feedback channel 320. The second terminal device 220 sends (565) an ACK/NACK on the D2D feedback channel 320 within the feedback period with the determined CDM signature.

Fig. 11 illustrates an example signaling flow 1100 between the network device 230 and the two

terminal devices

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

As shown, the network device 230 determines 1105 the time and frequency resources of the short D2D feedback channel 325. The network device 230 determines (1110) the time and frequency resources of the long D2D feedback channel 320. The network device 230 configures 1115 a delay range [ a, b ] of Δ t between the D2D data channel 315 and the D2D feedback channel 320 for HARQ feedback. The determination of the resources and delay ranges of the short feedback channel 315 and the long D2D feedback channel 320 is similar to the determination of the resources and delay ranges of the short feedback channel 315 and the long D2D feedback channel 320 described above with reference to fig. 5. For simplicity, further description will not be provided.

The network device 230 associates 1120 the plurality of orthogonal code sequences of the D2D feedback channel 320 with the 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]Wherein b-a +1 ═ nm. The association between the D2D data channel 315 and the D2D feedback channel 320 is repeated for nAnd (4) a sub-range. For example, over the D2D feedback channel 320 for a time period t₂With the same CDM signature used with subchannels (t) on D2D data channel 315₂- Δ t, l) and subchannels (t)₂- Δ t-km, l). Within a sub-range, a unique CDM signature is provided for HARQ feedback on the D2D feedback channel. The association may be semi-statically or statically pre-configured by the network device 230, or dynamically configured by the network device 230, or predefined in the network.

The repetition of the association may reduce the number of different CDM signatures required for D2D feedback channel 320. The larger the number of different CDM signatures required, the wider (more PRBs) the D2D feedback channel 320. Thus, the extended association may ultimately reduce the resource consumption of the D2D feedback channel 320.

Fig. 12 illustrates an 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 association between the D2D data channel 315 and the D2D feedback channel 320 is the same in the two

sub-ranges

405 and 410 denoted as [1, 2] and [3, 4 ].

Still referring to fig. 11, the network device 230 sends (1125) an indication of the resource configuration of the D2D feedback channel 320 to both the first terminal device 210 and the second terminal device 220. The network device 230 also sends (1130) an indication of the delay bound and resource association to both the first terminal device 210 and the second terminal device 220.

To avoid collisions caused by the reuse of CDM signatures, 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) the control information from the other terminal devices on the D2D data channel 315. Based on a time period t to be used for feedback on the D2D feedback channel 320₂Indicating (e.g., information about the feedback delay Δ t included in the control information on the D2D data channel 315), the first terminal device 210 identifies (1140) a time period t to be used for HARQ feedback on the D2D feedback channel 320₂And a CDM signature.

The first terminal device 210 selects (1145) the channel (t)₁And l) the sub-channel represented by l) is used for D2D transmission.

The first terminal device 210 selects 1150 a feedback period of the D2D feedback channel 320. In some example embodiments, based on the range/sub-range information, the delay requirement and the half-duplex constraint, the first terminal device 210 selects a time period t with an unused CDM signature₁+ Δ t. For example, if the time period t₁+ Δ t is not selected by other terminal devices for transmission and at subchannel l for a time period t₁ACK/NACK for data transmitted in km, time period t₁+ Δ t may be selected by the first terminal device 210.

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

Fig. 13 illustrates an example association between the D2D data channel 315 and the D2D feedback channel 320, according to some example embodiments of the present disclosure. When another terminal device is at the sub-channel 310 for the time period 305-1 of the D2D data channel 315 (by time period t)₁Meaning, subchannel l) to transmit D2D data to the second terminal device 220, the first terminal device is at subchannel 310 for time period 305-3 (by time period t)₁+2 denotes, subchannel l) transmits D2D data. If the first terminal device 210 determines the time period 305-5 of the D2D feedback channel 320 (by time period t)₁+ 4) has been selected for feedback by another terminal device, the first terminal device 210 selects a feedback period of the D2D feedback channel 320 with an unused CDM signature to avoid collisions. The feedback period may be based on the delay range [ a, b ] by detecting a feedback period to be previously used by the other terminal device]Delay requirements, and half-duplex constraints to select from among the candidate feedback time periods.

Fig. 14 illustrates an example selection of a feedback time period for 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]]，[1，4]Is divided into [1, 2]]And [3, 4]]Two sub-ranges. If the first terminal is setThe device 210 selects the sub-channel 310 during time period 305-1 (from time period t)₁Meaning, subchannel l) is used for D2D transmissions, then the time periods 305-2 through 305-5 (from time period t) are on the D2D feedback channel 320₁+1、t₁+2、t₁+3 and t₁+ 4) has four potential resource blocks.

Still referring to fig. 11, the first terminal device 210 sends (1155) an indication of the resource blocks selected on the D2D feedback channel 320 to the second terminal device 220 via a D2D control channel, such as 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 a CDM signature for ACK/NACK feedback. The second terminal device 220 sends 1175 the ACK/NACK in the feedback period with 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 may be implemented by the network device 230 shown in fig. 2. For purposes 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 the D2D feedback channel in the resource pool. At block 1510, the network device 230 allocates a plurality of orthogonal code sequences for a feedback time period of a plurality of feedback time periods. At block 1515, the network device 230 determines a delay range between the D2D data channel and the D2D feedback channel. At block 1520, the network device 230 associates the plurality of orthogonal code sequences with at least a plurality of subchannels of the D2D data channel for the transmission time period based on the delay range.

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

In some example embodiments, the network device 230 sends an indication of associations 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 for the device-to-device feedback channel in a 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 multiple 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 may be implemented by the first terminal device 210 shown in fig. 2. For discussion purposes, the method 1600 will be described with reference to fig. 2.

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

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

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

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

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

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

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

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

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

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

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 an indication of the feedback time period to the second terminal device 220 on the 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 may be implemented by the second terminal device 220 shown in fig. 2. For discussion purposes, the method 1700 will be described with reference to fig. 2.

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

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

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

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 an indication of the feedback time period from the first terminal device on the physical sidelink control channel.

All of the operations and features described above with reference to fig. 2-14 are equally applicable to the method 1500-1700 and have similar effects. Details will be omitted for simplicity.

Fig. 18 is a simplified block diagram of a device 1800 suitable for implementing embodiments of the present disclosure. The device 1800 may 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 communications module 1830 coupled to the processor 1810, and a communications interface (not shown) coupled to the communications module 1830. The memory 1820 stores at least programs 1840. The communication module 1830 is used for bi-directional communication, e.g., via multiple antennas. The communication interface may represent any interface required for communication.

The programs 1840 are assumed to include program instructions that, when executed by the associated processor 1810, enable the device 1800 to operate in accordance with embodiments of the disclosure, as discussed herein with reference to fig. 2-17. Embodiments herein may be implemented by computer software executable by a 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 technology network, and may be implemented using any suitable data storage technology, such as non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 1820 is shown in the device 1800, there can be several memory modules physically distinct in the device 1800. Processor 1810 may be of any type suitable for a local technology network, and may include, by way of non-limiting example, one or more of the following: general purpose computers, special purpose computers, microprocessors, Digital Signal Processors (DSPs), and processors based on a multi-core processor architecture. The device 1800 may have multiple processors, such as application specific integrated circuit chips that are time-dependent from a clock synchronized to the host processor.

When the device 1800 is used as the network device 230 or as 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 is used as the first terminal device 210 or as 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 is used as the second terminal device 220 or as 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 of the operations and features described above with reference to fig. 2-17 are equally applicable to the device 1800 and have similar effects. Details will be omitted for simplicity.

In general, the various embodiments of the 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 the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the block diagrams, apparatus, systems, techniques or methods described herein may be implemented in 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, that execute in the device on the target real or virtual processor to perform the

processes

500 and 1100 and the

method

1500 and 1700 described above with reference to fig. 2-17. Generally, program modules include routines, programs, libraries, objects, classes, components, data types, etc. 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 local or distributed devices. In a distributed facility, program modules may be located in both local and remote memory storage media.

Program code for performing the 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 execution of the program codes by the processor or controller causes the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the 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, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of a carrier include a signal, computer readable medium, 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 is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of a computer-readable storage medium 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), a Digital Versatile Disc (DVD), an optical storage device, a magnetic storage device, or any suitable combination thereof.

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 some cases, multitasking and parallel processing may be advantageous. Also, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the 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 can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the 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 in place of the foregoing, the following examples are described. Features described in any of the following examples may be used with any other example described herein.

In some aspects, a first terminal device includes: 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: selecting a sub-channel from a plurality of sub-channels of a device-to-device data channel during a transmission time period in response to device-to-device data to be transmitted to a second terminal device during the transmission time period on the device-to-device data channel; selecting a feedback time period on a device-to-device feedback channel from a plurality of feedback time periods based on the transmission time period and a predetermined delay range between the device-to-device data channel and the device-to-device feedback channel; and sending an indication of the feedback time period to the second terminal device to enable the second terminal device to send an acknowledgement of the device-to-device data within the feedback time period on the device-to-device feedback channel.

In some example embodiments, the first terminal device is further caused to: determining a code sequence associated with the selected subchannel from among a plurality of orthogonal code sequences of the feedback time period based on a predetermined association between the plurality of orthogonal code sequences and at least the plurality of subchannels; 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 to acknowledge the further device-to-device data, selecting a further sub-channel from the plurality of sub-channels for transmitting the device-to-device data to the second terminal device within 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 indicating 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 plurality of orthogonal code sequences are associated with at least the plurality of subchannels during the transmission time period and with a plurality of other subchannels during further transmission time periods.

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: receiving an indication of the predetermined association from a network device.

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

In some example embodiments, the first terminal device being caused to select the feedback time period from the plurality of feedback time periods comprises: selecting a set of candidate feedback time periods from the plurality of feedback time periods based on the transmission time period and the predetermined delay range, 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 first terminal device is further caused to: receiving, from a network device, an indication of time and frequency resources of the device-to-device feedback channel; and determining the plurality of feedback time periods in the time and frequency resources.

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

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 transmit the indication of the feedback time period to the second terminal device by: transmitting 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 includes: 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: 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 over a transmission time period; receiving an indication of a feedback time period of a plurality of feedback time periods from the first terminal device on a device-to-device feedback channel; determining a code sequence from a plurality of orthogonal code sequences of the feedback time period based on predetermined associations between the plurality of subchannels and the plurality of orthogonal code sequences; and transmitting an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for the feedback time period on the device-to-device feedback channel.

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

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

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: 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 the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel for a transmission time period based on the delay range.

In some example embodiments, the network device is further caused to: transmitting an indication of the delay range to at least the 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 with a plurality of other subchannels in a further transmission time period.

In some example embodiments, the network device is further caused to: transmitting 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: allocating a frequency band for 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, comprises: selecting a sub-channel from a plurality of sub-channels of a device-to-device data channel during a transmission time period in response to device-to-device data to be transmitted to a second terminal device during the transmission time period on the device-to-device data channel; selecting a feedback time period on a device-to-device feedback channel from a plurality of feedback time periods based on the transmission time period and a predetermined delay range between the device-to-device data channel and the device-to-device feedback channel; and sending an indication of the feedback time period to the second terminal device to enable the second terminal device to send an acknowledgement of the device-to-device data within the feedback time period on the device-to-device feedback channel.

In some example embodiments, the method further comprises: determining a code sequence associated with the selected subchannel from among a plurality of orthogonal code sequences of the feedback time period based on a predetermined association between the plurality of orthogonal code sequences and at least the plurality of subchannels; 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 to acknowledge the further device-to-device data, selecting a further sub-channel from the plurality of sub-channels for transmitting the device-to-device data to the second terminal device within 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 indicating 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 an indication of the predetermined association from a network device.

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

In some example embodiments, selecting the feedback time period from the plurality of feedback time periods comprises: selecting a set of candidate feedback time periods from the plurality of feedback time periods based on the transmission time period and the predetermined delay range, 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 time and frequency resources of the device-to-device feedback channel; and determining the plurality of feedback time periods in the time and frequency resources.

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

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: transmitting 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, comprises: 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 over a transmission time period; receiving an indication of a feedback time period of a plurality of feedback time periods from the first terminal device on a device-to-device feedback channel; determining a code sequence from a plurality of orthogonal code sequences of the feedback time period based on predetermined associations between the plurality of subchannels and the plurality of orthogonal code sequences; and transmitting an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for 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 the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel for a transmission time period based on the delay range.

In some example embodiments, the method further comprises: transmitting an indication of the delay range to at least the 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 with a plurality of other subchannels in a further transmission time period.

In some example embodiments, the method further comprises: transmitting 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 for 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 selecting a sub-channel from a plurality of sub-channels of a device-to-device data channel for a transmission time period in response to device-to-device data to be transmitted to a second terminal device for the transmission time period on a device-to-device data channel; means for selecting a feedback time period on a device-to-device feedback channel from a plurality of feedback time periods based on the transmission time period and a predetermined delay range between the device-to-device data channel and the device-to-device feedback channel; and means for transmitting an indication of the feedback time period to the second terminal device to enable the second terminal device to transmit an acknowledgement of the device-to-device data within the feedback time period on the device-to-device feedback channel.

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

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 indicating that the feedback time period is to be used for acknowledging the further device-to-device data; and means for determining whether the code sequence is to be used for acknowledging the further device-to-device data in response to detecting the indication.

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

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

In some example embodiments, the apparatus further includes means for selecting a set of candidate feedback time periods from the plurality of feedback time periods based on the transmission time period and the predetermined delay range, 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 time and frequency resources of the device-to-device feedback channel; and means for determining the plurality of feedback time periods in the time and frequency resources.

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

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

In some example embodiments, the means for transmitting the indication of the feedback time period to the second terminal device comprises: means for transmitting 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 during a transmission time period; means for receiving an indication of a feedback time period of a plurality of feedback time periods from the first terminal device on a device-to-device feedback channel; means for determining a code sequence from a plurality of orthogonal code sequences of the feedback time period based on predetermined associations between the plurality of subchannels and the plurality of orthogonal code sequences; and means for transmitting an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for 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 the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel for a transmission time period based on the delay range.

In some example embodiments, the apparatus further comprises: means for transmitting 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 with a plurality of other subchannels in a further transmission time period.

In some example embodiments, the apparatus further comprises: means for transmitting 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 for 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 includes program instructions stored thereon that, when executed by a processor of a device, cause the device to perform a method according to some example embodiments of the present disclosure.

Claims

1. 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:

selecting a sub-channel from a plurality of sub-channels of a device-to-device data channel during a transmission time period in response to device-to-device data to be transmitted to a second terminal device during the transmission time period on the device-to-device data channel;

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

sending an indication of the feedback time period to the second terminal device to enable the second terminal device to send an acknowledgement of the device-to-device data within the feedback time period on the device-to-device feedback channel.

2. The first terminal device of claim 1, wherein the first terminal device is further caused to:

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

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 to acknowledge the further device-to-device data, selecting a further sub-channel from the plurality of sub-channels for transmitting the device-to-device data to the second terminal device within the transmission time period.

3. The first terminal device of claim 2, wherein the first terminal device is caused to determine whether the code sequence is to be used to acknowledge the further device-to-device data by:

detecting an indication from a third terminal device indicating 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.

4. 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 with a plurality of other subchannels in a further transmission time period.

5. 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, an

The time difference between the transmission time period and the feedback time period is within the first delay sub-range and the time difference between the further transmission time period and the feedback time period is within the second delay sub-range.

6. The first terminal device of claim 2, wherein the first terminal device is further caused to:

receiving an indication of the predetermined association from a network device.

7. 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 sub-channel from a plurality of further sub-channels for a further transmission time period for transmitting the device-to-device data on the device-to-device data channel;

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

determining a code sequence associated with the further sub-channel from a plurality of orthogonal code sequences of the selected feedback time period based on predetermined associations between the plurality of orthogonal code sequences and the plurality of other sub-channels;

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

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

selecting the subchannel from the plurality of subchannels for transmission of the device-to-device data to the second terminal device within the transmission time period.

8. The first terminal device of claim 1, wherein the first terminal device being caused to select the feedback time period from the plurality of feedback time periods comprises:

selecting a set of candidate feedback time periods from the plurality of feedback time periods based on the transmission time period and the predetermined delay range, 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.

9. The first terminal device of claim 1, wherein the first terminal device is further caused to:

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

determining the plurality of feedback time periods in the time and frequency resources.

10. The first terminal device of claim 1, wherein the first terminal device is further caused to:

receiving an indication of the predetermined delay range from a network device.

11. The first terminal device of claim 1, wherein the time period comprises a time slot.

12. 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.

13. 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:

transmitting the indication of the feedback time period to the second terminal device on a physical sidelink control channel.

14. 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:

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 over a transmission time period;

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

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

transmitting an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for the feedback time period on the device-to-device feedback channel.

15. 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 with a plurality of other subchannels in a further transmission time period.

16. The second terminal device of claim 14, wherein the second terminal device is further caused to:

receiving an indication of the predetermined association from a network device.

17. The second terminal device of claim 14, wherein the second terminal device is further caused to:

18. The second terminal device of claim 14, wherein the time period comprises a time slot.

19. 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.

20. 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.

21. 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:

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 the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel for a transmission time period based on the delay range.

22. The method of claim 21, wherein the network device is further caused to:

transmitting an indication of the delay range to at least the first terminal device.

23. 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 with a plurality of other subchannels in a further transmission time period.

24. The network device of claim 23, wherein

25. The network device of claim 21, wherein the network device is further caused to:

transmitting 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.

26. The network device of claim 21, wherein the network device is further caused to:

allocating a frequency band for the device-to-device feedback channel in the resource pool.

27. The network device of claim 21, wherein the allocated frequency band comprises one or more physical resource blocks.

28. The network device of claim 21, wherein the time period comprises a time slot.

29. 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.

30. A method implemented at a first terminal device, comprising:

31. The method of claim 30, further comprising:

32. The method of claim 31, wherein determining whether the code sequence is to be used to acknowledge the additional device-to-device data comprises:

33. 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 are associated with a plurality of other subchannels in a further transmission time period.

34. The method of claim 33, wherein

35. The method of claim 31, further comprising:

receiving an indication of the predetermined association from a network device.

36. The method of claim 30, wherein selecting the subchannel from the plurality of subchannels comprises:

37. The method of claim 30, wherein selecting the feedback time period from the plurality of feedback time periods comprises:

38. The method of claim 30, further comprising:

39. The method of claim 30, further comprising:

receiving an indication of the predetermined delay range from a network device.

40. The method of claim 30, wherein the time period comprises a time slot.

41. 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.

42. The method of claim 41, wherein sending the indication of the feedback time period to the second terminal device comprises:

43. A method implemented at a second terminal device, comprising:

44. 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 are associated with a plurality of other subchannels in a further transmission time period.

45. The method of claim 43, further comprising:

receiving an indication of the predetermined association from a network device.

46. The method of claim 43, further comprising:

47. The method of claim 43, wherein the time period comprises a time slot.

48. 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.

49. The method of claim 48, wherein receiving the indication of the feedback time period from the first terminal device comprises:

50. A method implemented at a network device, comprising:

51. The method of claim 50, further comprising:

52. The method of claim 50, wherein associating the plurality of orthogonal code sequences with at least the plurality of subchannels comprises:

53. The method of claim 52, wherein

54. The method of claim 50, further comprising:

55. The method of claim 50, further comprising:

56. The method of claim 55, wherein the allocated frequency band comprises one or more physical resource blocks.

57. The method of claim 50, wherein the time period comprises a time slot.

58. 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.

59. An apparatus, comprising:

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

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

means for transmitting an indication of the feedback time period to the second terminal device to enable the second terminal device to transmit an acknowledgement of the device-to-device data within the feedback time period on the device-to-device feedback channel.

60. 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 during a transmission time period;

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

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

means for transmitting an acknowledgement of the device-to-device data to the first terminal device using the selected code sequence for the feedback time period on the device-to-device feedback channel.

61. 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 the delay range associating the plurality of orthogonal code sequences with at least a plurality of subchannels of the device-to-device data channel over a transmission time period.

62. A computer readable storage medium comprising program instructions stored thereon which, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 30 to 42.

63. A computer readable storage medium comprising program instructions stored thereon that, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 43 to 49.

64. A computer readable storage medium comprising program instructions stored thereon that, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 50-58.