WO2024065790A1

WO2024065790A1 - Sidelink subchannel frequency mapping

Info

Publication number: WO2024065790A1
Application number: PCT/CN2022/123542
Authority: WO
Inventors: Nuno Manuel KIILERICH PRATAS; Renato Barbosa ABREU; Thomas Haaning Jacobsen; Takayuki Shimizu; Claude Arzelier; Timo Erkki Lunttila; Laura Luque SANCHEZ; Berthold PANZNER; Naizheng ZHENG; Yong Liu
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2024-04-04

Abstract

Embodiments of the present disclosure relate to sidelink subchannel frequency mapping. A terminal device is provided comprising at least one processor and at least one memory storing instructions. The instructions, when executed by the at least one processor, cause the terminal device at least to: determine subchannel indexing schemes supported by a resource pool; determine SCI to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a FRIV that is applied using at least one of the subchannel indexing schemes; and transmit the SCI to the second terminal device. As such, a terminal device can reach all useful resource allocation patterns of subchannels in a resource pool.

Description

SIDELINK SUBCHANNEL FREQUENCY MAPPING

TECHNICAL FIELD

Various example embodiments relate to the field of communication, and in particular, to devices, methods, apparatuses and computer readable storage media for sidelink subchannel frequency mapping.

BACKGROUND

New radio (NR) sidelink (SL) has been designed to facilitate a user equipment (UE) to communicate with other nearby UE (s) via direct/SL communication. Two resource allocation modes have been specified, and a SL transmitter (TX) UE is configured with one of them to perform its NR SL transmissions. These modes are denoted as NR SL mode 1 and NR SL mode 2. In mode 1, a sidelink transmission resource is assigned (scheduled) by the network (NW) to the SL TX UE, while a SL TX UE in mode 2 autonomously selects its SL transmission resources. Sidelink control information (SCI) is also needed for a SL transmission.

SUMMARY

In general, example embodiments of the present disclosure provide devices, methods, apparatuses and computer readable storage media for sidelink subchannel frequency mapping.

In a first aspect, there is provided a first terminal device. The first terminal device comprises at least one processor, and at least one memory storing instructions. The instructions, when executed by the at least one processor, cause the first terminal device at least to: determine subchannel indexing schemes supported by a resource pool; determine sidelink control information (SCI) , to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a frequency resource indicator value (FRIV) , wherein the FRIV is applied using at least one of the subchannel indexing schemes; and transmit the SCI to the second terminal device.

In a second aspect, there is provided a second terminal device. The second terminal device comprises at least one processor, and at least one memory storing instructions. The instructions, when executed by the at least one processor, cause the second terminal device at least to: determine subchannel indexing schemes supported by a resource pool; receive, from a first terminal device, sidelink control information (SCI) , the SCI comprising a frequency resource indicator value (FRIV) , wherein the FRIV is applied using at least one of the subchannel indexing schemes; determine using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and receive the at least one sidelink transmission from the first terminal device on the set of resources.

In a third aspect, there is provided a method. The method comprises: determining, at a first terminal device, subchannel indexing schemes supported by a resource pool; determining SCI to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; and transmitting the SCI to the second terminal device.

In a fourth aspect, there is provided a method. The method comprises determining, at a second terminal device, subchannel indexing schemes supported by a resource pool; receiving, from a first terminal device, SCI, the SCI comprising a FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; determining using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and receiving the at least one sidelink transmission from the first terminal device on the set of resources.

In a fifth aspect, there is provided an apparatus. The apparatus comprises means for performing the method according to the third or fourth aspect.

In a sixth aspect, there is provided a computer readable medium comprising program instructions. The instructions, when executed by an apparatus, cause the apparatus to perform the method according to the third or fourth aspect.

In a seventh aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to perform the method according to the third or fourth aspect.

In an eighth aspect, there is provided a device. The device comprises circuitries for performing the method according to the third or fourth aspect.

Other features and advantages of the embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure are presented in the sense of examples and their advantages are explained in greater detail below, with reference to the accompanying drawings, where

FIG. 1A illustrates an example diagram of acquisition of the Channel Occupancy Time (COT) by an initiating device via Listen Before Talking (LBT) Type 1;

FIG. 1B illustrates an example diagram of the allowed gaps for which LBT Type 2 variant to be applicable;

FIG. 1C illustrates an example diagram of NR SL resource allocation Mode 1;

FIG. 1D illustrates an example diagram of NR SL resource allocation Mode 2;

FIG. 1E illustrates an example diagram of SL slot formats;

FIG. 1F illustrates an example diagram of two reserved resources indicated by an SCI format 1-A;

FIG. 2 illustrates an example communication system in which implementations of the present disclosure can be implemented;

FIG. 3 illustrates an example flowchart showing an example process of sidelink subchannel frequency mapping, in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates an example diagram showing that subchannels are composed by interlaced RBs and the subchannels are numbered/indexed either with sub-channel first or with RB set first, in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates an example diagram showing that subchannels are composed by contiguous RBs, in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates an example diagram showing that interlaced RB based subchannels numbering/indexing schemes are applied to subchannels composed by contiguous RBs, in accordance with some embodiments of the present disclosure;

FIG. 7 illustrates a flowchart of an example method implemented at a first terminal device in accordance with some embodiments of the present disclosure;

FIG. 8 illustrates a flowchart of an example method implemented at a second terminal device in accordance with some embodiments of the present disclosure;

FIG. 9 shows a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 10 shows a block diagram of an example computer readable medium in accordance with some embodiments of the present disclosure.

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

DETAILED DESCRIPTION

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

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

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish functionalities of various elements. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. 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. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

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

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

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

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

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

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as fifth generation (5G) systems, Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communication between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G) , 4.5G, the future fifth generation (5G) new radio (NR) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communication, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR Next Generation NodeB (gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. A RAN split architecture comprises a gNB-CU (Centralized unit, hosting RRC, SDAP and PDCP) controlling a plurality of gNB-DUs (Distributed unit, hosting RLC, MAC and PHY) . A relay node may correspond to DU part of the IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a subscriber station (SS) , a portable subscriber station, a mobile station (MS) , or an access terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to Mobile Termination (MT) part of the integrated access and backhaul (IAB) node (a.k.a. a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

Although functionalities described herein can be performed, in various example embodiments, in a fixed and/or a wireless network node, in other example embodiments, functionalities may be implemented in a user equipment apparatus (such as a cell phone or tablet computer or laptop computer or desktop computer or mobile IoT device or fixed IoT device) . This user equipment apparatus can, for example, be furnished with corresponding capabilities as described in connection with the fixed and/or the wireless network node (s) , as appropriate. The user equipment apparatus may be the user equipment and/or or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functionalities include the bootstrapping server function and/or the home subscriber server, which may be implemented in the user equipment apparatus by providing the user equipment apparatus with software configured to cause the user equipment apparatus to perform from the point of view of these functions/nodes.

Some embodiments of the present disclosure may relate to standardization objectives, which are introduced below. In recent RAN1#94e meeting, the R18 work item (RP-213678) on sidelink enhancements (SL-U is one critical part) was approved with the following objectives related to SL-U:

In RAN1 Meeting #109-e, the following agreement was made in agenda item 9.4.1.2 regarding the SL resource pool configuration, where it was confirmed “that a SL resource pool can be (pre-) configured to include integer number of RB sets” . This implies that a SL resource pool can contain RB spanning multiple RB sets (i.e. 20 MHz LBT bandwidths) .

In RAN1 Meeting #110-e, the following agreement was made in agenda item 9.4.1.2 regarding the use of interlaced RB-based transmission to meet the OCB and PSD requirements.

In RAN 1 Meeting #110-e, the following agreement was made in agenda item 9.4.1.2 regarding the support of both contiguous RB-based and interlaced RB-based transmissions.

Finally, also in RAN1 Meeting #110-e, the following agreement was made in agenda item 9.4.1.2 regarding the need to redefine the resource indication in the frequency domain (i.e. redefine the FRIV) namely due to the need to operate across multiple RB sets and the relation between sub-channel and RB interlaces.

Some embodiments of the present disclosure may relate to unlicensed operations, which are introduced below. ETSI EN 301 893 V2.1.1 (2017-05) : RLAN Harmonised Standard covering the essential requirements of article 3.2 of Directive 2014/53/EU is considered as the main reference.

In sub-7GHz unlicensed bands, the new radio (NR) coexistence with other systems (e.g. IEEE 802.11) is ensured via a Listen Before Talking (LBT) channel access mechanism. Where, a user equipment (UE) intending to perform a sidelink (SL) transmission needs first to successfully complete an LBT check, before being able to initiate that same transmission.

For a UE to pass an LBT check then it must observe the channel as available for a number of consecutive Clear Channel Assessment (CCA) slots. In sub-7GHz the duration of these slots is 9 μs. The UE deems the channel as available in a CCA slot if the measured power (i.e. the collected energy during the CCA slot) is below a regulatory specified threshold (which can depend on the operating band and geographical region) .

When a UE initiates the communication (i.e. the UE takes the role of initiating device) , then this UE has to acquire the “right” to access the channel for a certain period of time –denoted in the regulations as the Channel Occupancy Time (COT) –by applying an “extended” LBT procedure where the channel must be deemed as free for the entire duration of the backoff procedure determined by the Contention Window (CW) . This “extended” LBT procedure, is commonly known as LBT Type 1 as specified in TS 37.213. This procedure is shown in FIG. 1, which illustrates acquisition of the COT by an initiating device via LBT Type 1.

The duration of both the COT and CW depends on the Channel Access Priority Class (CAPC) associated with the UE’s traffic, as shown in Table 1. Control plane traffic is transmitted with p=1, while user plane traffic has p>1. In Table 1, the LBT Type 1 details are described for the Uu uplink (UL) case, but note that the downlink (DL) case LBT Type 1 parameters could also in principle be adopted in SL.

Table 1: Channel Access Priority Class (CAPC) for UL". The contention window length in CCA slots associated with each CAPC has a minimum (CW _min, p) and maximum (CW _max, p) . The duration of the COT is given by T _ulm cot, p.

The UE initiating the transmission (the initiating device) upon successfully completing the LBT Type 1 and performing a transmission, acquires the COT with duration associated with the corresponding CAPC. The acquired COT is valid even in the case where the initiating device pauses its transmission, although if the initiating device wants to perform a new transmission (within the COT) it is still required to perform a “reduced” LBT procedure. This “reduced” LBT procedure, is commonly known as LBT Type 2 [TS 37.213] , with the following variants:

● Type 2A (25 μs LBT) –for SL transmissions within the initiating device acquired COT (in case the gap between two SL transmissions is ≥ 25 μs, as well for SL transmissions following another SL transmission) , depicted in FIG. 1B (c) and (f) ;

● Type 2B (16 μs LBT) –for SL transmission within the initiating device acquired COT (can only be used for SL transmissions following another SL with gap exactly equal to 16 μs) , depicted in FIG. 1B (b) and (e) ;

● Type 2C (no LBT) –can only be used for SL transmission following another SL, with a gap < 16 μs and the allowed duration of the SL transmission ≤ 584 μs) , depicted in FIG. 1B (a) and (d) .

As shown, FIG. 1B illustrates the allowed gaps for which LBT Type 2 variant to be applicable: (a) and (d) LBT Type 2C; (b) and (e) LBT Type 2B; (c) and (f) LBT Type 2A. (a) , (b) and (c) shows the case where the gap is between the two transmissions both from the initiating UE, while (d) , (e) and (f) show the case that the gap is between the two different transmissions from the initiating UE and the responding UE correspondingly.

The initiating device can share its acquired COT with its intended receiver (the responding device) . For this purpose, the initiating device shall inform (e.g. via control signaling) the responding device about the duration of this COT. The responding device uses then this information to decide which type of LBT it should apply upon performing a transmission for which the intended receiver is the initiating device. In case the responding device transmission falls outside the COT, then the responding device will have to acquire a new COT using the LBT Type 1 with the appropriate CAPC.

Some embodiments of the present disclosure may relate to NR SL communications, which are introduced below. During 3GPP Rel-16, NR sidelink (SL) has been designed to facilitate a user equipment (UE) to communicate with other nearby UE (s) via direct/SL communication. Two resource allocation modes have been specified, and a SL transmitter (TX) UE is configured with one of them to perform its NR SL transmissions. These modes are denoted as NR SL mode 1 and NR SL mode 2. In mode 1, a sidelink transmission resource is assigned (scheduled) by the network (NW) to the SL TX UE, while a SL TX UE in mode 2 autonomously selects its SL transmission resources.

In Mode 1, where the gNB is responsible for the SL resource allocation, the configuration and operation is similar to the one over the Uu interface, which is depicted in FIG. 1C. The MAC level details of this procedure are given in section 5.8.3 of 38.321.

FIG. 1D illustrates an example diagram of NR SL resource allocation Mode 2. In Mode 2, the SL UEs perform autonomously the resource selection with the aid of a sensing procedure. More specifically, a SL TX UE in NR SL Mode 2 first performs a sensing procedure over the configured SL transmission resource pool (s) , in order to obtain the knowledge of the reserved resource (s) by other nearby SL TX UE (s) . Based on the knowledge obtained from sensing, the SL TX UE may select resource (s) from the available SL resources, accordingly. In order for a SL UE to perform sensing and obtain the necessary information to receive a SL transmission, it needs to decode the sidelink control information (SCI) . In release 16, the SCI associated with a data transmission includes a 1 ^st-stage SCI and 2 ^nd-stage SCI, and their contents are standardized in 3GPP TS 38.212.

Some embodiments of the present disclosure may relate to SCI, which are introduced below. The SCI follows a 2-stage SCI structure, whose main motivation is to support the size difference between the SCIs for various NR-V2X SL service types (e.g., broadcast, groupcast and unicast) .

The 1 ^st-stage SCI, SCI format 1-A, is carried by PSCCH and contains:

● information to enable sensing operations

● information needed to determine resource allocation of the PSSCH and to decode 2 ^nd-stage SCI

As per Rel-16, the contents of the 1 ^st-stage SCI are the following:

The 2 ^nd-stage SCI, SCI format 2-A and 2-B, carried by PSSCH (multiplexed with SL-SCH) and contains:

● Source and destination identities

● information to identify and decode the associated SL-SCH TB

● control of HARQ feedback in unicast/groupcast

● trigger for CSI feedback in unicast

As per Rel-16, the contents of the 2 ^nd-stage SCI are provided in Table 2:

Table 2: 2 ^nd-stage SCI formats.

Some embodiments of the present disclosure may relate to SCI, which are introduced below. The configuration of the resources in the sidelink resource pool defines the minimum information required for an RX UE to be able to decode a transmission, which includes the number of sub-channels, the number of PRBs per sub-channels, the number of symbols in the PSCCH, which slots have a PSFCH and other configuration aspects not relevant to this invention.

However, the details of the actual sidelink transmission (i.e., the payload) are provided in the PSCCH (1 ^st-stage SCI) for each individual transmission, which includes: The time and frequency resources, the DMRS configuration of the PSSCH, the MCS, PSFCH, among others.

An example of the SL slot structure is depicted in FIG. 1E, where it is shown a slot with PSCCH/PSSCH (FIG. 1E (a) ) and a slot with PSCCH/PSSCH where the last symbols are used for PSFCH (FIG. 1E (b) ) .

The configuration of the PSCCH (e.g., DMRS, MCS, number of symbols used) is part of the resource pool configuration. Furthermore, the indication of which slots have PSFCH symbols is also part of the resource pool configuration. However, the configuration of the PSSCH (e.g., the number of symbols used, the DMRS pattern and the MCS) is provided by the 1 ^st-stage SCI which is the payload sent within the PSCCH.

Some embodiments of the present disclosure may relate to resource indication in time and frequency, which are introduced below. In Rel-16 NR Sidelink, a 1 ^st-stage SCI (Sidelink Control Information) (specified as SCI format 1-A) conveys resource allocation information for reserving up to k=2 future resources within a time window consisting of T=31 logical slots of a resource pool, starting from the logical slot next to that in which the SCI is transmitted, as shown in FIG. 1F.

The resource allocation information carried by an SCI format 1-A consists of two fields:

- a time resource assignment in the form of a Time Resource Indication Value (TRIV) , and

- a frequency resource assignment in the form of a Frequency Resource Indication Value (FRIV) .

The TRIV field conveys the logical slot offsets of the reserved resources with respect to the slot in which the SCI is transmitted. In the case of two reserved resources (k=2) , the two offsets t ₁ and t ₂ (with 1≤t ₁<t ₂≤31) are encoded by the TRIV field as follows (see 3GPP TS 38.214, Section 8.1.5) :

Note: in TS 38.214, N is used as the number of reserved resources, where N=1 refers to the reservation in the slot where SCI was received, and hence k=2 would be similar to N=3.

As there are

possible ways of choosing (t ₁, t ₂) , the TRIV field in this case incurs an overhead of

bits, as indicated in 3GPP TS 38.212, Section 8.3.1.1. Note that the two reserved resources cannot be in the same slot, since t ₁<t ₂.

The FRIV field conveys the starting subchannel indices of the reserved resources within the resource pool (comprising a total of

subchannels) , as well as the resource size L _subCH (i.e., length of contiguous subchannels) . In the case of two reserved resources (k=2) , the two starting subchannel indices

and

are encoded along with the resource size L _subCH by the FRIV field as follows (see 3GPP TS 38.214, Section 8.1.5) :

Where,

●

–denotes the starting sub-channel index for the second resource;

●

–denotes the starting sub-channel index for the third resource;

●

–is the number of sub-channels in a resource pool provided according to the higher layer parameter slNumSubchannel.

As there are

possible FRIV values, the FRIV field in this case incurs an overhead of

bits, as indicated in 3GPP TS 38.212, Section 8.3.1.1.

As described above, in RAN1 Meeting #110-e, the following agreement was made in agenda item 9.4.1.2 regarding the need to redefine the resource indication in the frequency domain (i.e. redefine the FRIV) namely due to the need to operate across multiple RB sets and the relation between sub-channel and RB interlaces.

The NR-SL Rel. 16 FRIV design assumed that when a UE selects a number of sub-channels that these are contiguous in frequency. However, for SL-U it was agreed that a resource pool contains an integer number of RB sets (i.e. multiple 20 MHz LBT bandwidths) and therefore it opens for the possibility of a UE allocating a non-contiguous sub-channels. This is the case either if the sub-channels are composed by contiguous RBs (as in NR-SL Rel. 16) or by K interlaced RBs. Therefore, depending on how the sub-channels in each RB set of the resource pool are numbered, then the current FRIV design will only be able to address a limited number of resource allocation patterns. Hence there are resources in frequency domain that remain unused as those resources are not addressable by any FRIV value.

According to embodiments of the present disclosure, there is providing enhanced schemes for sidelink subchannel frequency mapping. In some embodiments, the present disclosure propose some solutions on how to update the FRIV so that a device can reach all useful resource allocation patterns in a resource pool with resources spread across an integer number of RB sets. Details of the solutions proposed will be described with reference to FIGS. 2-10 below.

FIG. 2 illustrates an example communication system 200 in which implementations of the present disclosure can be implemented. As shown in FIG. 2, the communication network 200 may include a first terminal device (e.g., a UE) 210, a second terminal device (e.g., a UE) 220, and a network device (e.g., a base station, such as a gNB) 230. The network device 230 may communicate with the first terminal device 210 and the second terminal device 220 via respective wireless communication channels. The first terminal device 210 and the second terminal device 220 may communicate with each other via SL channels.

It is to be understood that the number of devices in FIG. 2 is given for the purpose of illustration without suggesting any limitations to the present disclosure. Communications in the system 200 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Divided Multiple Address (CDMA) , Frequency Divided Multiple Address (FDMA) , Time Divided Multiple Address (TDMA) , Frequency Divided Duplexer (FDD) , Time Divided Duplexer (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Divided Multiple Access (OFDMA) and/or any other technologies currently known or to be developed in the future.

FIG. 3 illustrates an example flowchart showing an example process 300 of sidelink subchannel frequency mapping in accordance with some embodiments of the present disclosure. For the purpose of discussion, the process 300 will be described with reference to FIG. 2. The process 300 may involve the first terminal device (e.g., a UE) 210 and the second terminal device (e.g., a UE) 220.

As shown in FIG. 3, the first terminal device 210 determines 310 subchannel indexing schemes supported by a resource pool, then determines 312 SCI to indicate a set of resources in a resource pool for at least one sidelink transmission to the second terminal device 220. The SCI comprises a FRIV that is applied using at least one of the subchannel indexing schemes. The first terminal device 210 transmits 314 the SCI to the second terminal device 220.

The second terminal device 220 also determines 310 subchannel indexing schemes supported by a resource pool. The second terminal device 220 receives 318 the SCI from the first terminal device 210 and determines 320 using the SCI the set of resources in the resource pool for at least one sidelink transmission from the first terminal device 210. Then, the second terminal device 220 receives 322 the at least one sidelink transmission 324 from the first terminal device 210 on the set of resources.

The example process 300 can be applied to a case where the sub-channels are composed by interlaced RBs. In this case, the resource pool may include a configuration information element where it can be configured whether the resource allocations/reservations done in the resource pool support simultaneously different sub-channel numbering/indexing schemes, such as sub-channel first, RB set first sub-channel numbering/indexing scheme or bitmap based. Additionally, UE indicates in the SCI (e.g., its 1 ^st stage SCI or equivalent) which subchannel numbering/indexing scheme does its FRIV refer to, e.g. a sub-channel first, RB set first sub-channel numbering/indexing or bitmap based.

FIG. 4 illustrates an example diagram showing that subchannels are composed by interlaced RBs and the subchannels are numbered/indexed either with sub-channel first or with RB set first. It can be observed that each sub-channel numbering/indexing approach leads to a different resource allocation pattern. Therefore, when the UE indicates in its 1 ^st stage SCI that it uses sub-channel first indexing, then it assumes the mapping as in FIG. 4 (a) , while if it uses RB set first then the mapping is provided in FIG. 4 (b) .

As shown in FIG. 4, For interlaced RB based sub-channels, the two possible mappings of 3 sub-channels (i.e. 3 groups of K interlaces) across 2 RB sets, where the first selected sub-channel is allocated in the RB Set 0: (a) sub-channel first, where the sub-channel 1 to 3 are in RB set 0 and the sub-channels 4 to 6 are in RB set 1; (b) RB set first, where the

sub-channel

1, 3 and 5 are in RB set 0 and the

sub-channel

2, 4 and 6 are in RB set 1.

Note that, in the example depicted in FIG. 4, it is assumed that the resource pool consists of 2 RB sets with 3 groups of K interlaces. Then from these groups of K interlaces, 3 sub-channels are defined at each RB set (e.g.,

subchannels #

1, 3, and 5 for RB set 0 and

subchannels #

2, 4, and 6 for RB set 1) . In other words, a sub-channel is contained in a RB set and is composed by the RBs of the K interlaces which intersect with the RBs of the RB set (in this example, each sub-channel is composed by the RBs of 1 interlace in 1 RB set) .

In Table 3, the present disclosure provides, for a selected number of sub-channels per RB set for 2 RB sets where the first selected sub-channel is allocated in the RB Set 0, an example of the impact of addressable resource patterns versus the total number of possible resource patterns. From this example, it can be observed that the number of un-addressed resource patterns when only one of the sub-channel numbering/indexing schemes is used increases with the number sub-channels per RB set, as well as the number of RB sets. This is problematic from a resource utilization point of view and it will have severe implications in overall resource allocation as it will prevent the UEs to be spread uniformly across the resources and therefore induce additional interference. However, with the proposed solution, a UE can select the appropriate mapping/indexing so that it can obtain the intended resource pattern.

Table 3: addressable resource patterns with either sub-channel or RB set first number schemes only versus with the proposed approach.

One of the advantages of the above proposed solution is that the full resource allocation patterns can be addressed.

The following shows an example specification impact in 38.212:

The following shows an example specification impact in 38.214:

Additionally, it is expected that the resource pool configuration as defined in 3GPP TS 38.331 will be impacted in regard to the indication if the resource pool supports simultaneously sub-channel first and RB set first sub-channel numbering, or any other mapping/indexing scheme or one of those.

The example process 300 can be applied to a case where the sub-channels are composed by contiguous RBs. In this case, a resource pool is configured to allow a UE to reserve sub-channels within a resource pool belonging to different RB sets. Additionally, a UE transmits a 1 ^st stage SCI (or equivalent) in at least one of the (most likely all) RB sets where it has at least one sub-channel allocation. For example, the 1 ^st stage SCI (or equivalent) is transmitted in the PSCCH resources associated with the lowest sub-channel allocated in the RB set.

The UE indicates in its 1 ^st stage SCI (or equivalent) an indication (e.g. a bitmap) of RB sets where it has a transmission (for the current transmission, e.g. during an ongoing channel occupancy) and/or RB sets where it will reserve a resource. Additionally, the UE indicates in its 1 ^st stage SCI (or equivalent) the FRIV. In some embodiments, the FRIV is common to all RB sets, and therefore the selected sub-channels in one RB set are replicated in all indicated RB sets. Additionally or alternatively, the FRIV is a separate FRIV per RB set.

Note that, in order to limit the number of bits spent in the FRIV, when the UE transmits in multiple RB sets, the number of reserved resource reserved in time can be restricted. For example, if a UE activates a single RB set, then it is allowed to indicate up to two future resource reservations in the RB set’s FRIV. While, if a UE activates two or more RB sets then it is only allowed to indicate one future resource. The TRIV is then limited in the same way.

Additionally, when there is a separate FRIV per RB set, then the resource size L _subCH can be also different per RB set.

FIG. 5 illustrates an example diagram showing that subchannels are composed by contiguous RBs. As shown in FIG. 5, for contiguous RB based sub-channels with 3 sub-channels across 2 RB sets, FIG. 5 (a) shows that the sub-channels are indexed separately per RB set; FIG. 5 (b) shows a common FRIV to all RB sets, so the same sub-channels are selected across the indicated RB set; FIG. 5 (c) shows a separate FRIV per RB set, so in each RB set different sub-channels can be reserved by the UE; and FIG. 5 (d) shows a separate FRIV and resource size per RB set.

In some embodiments, the proposed approach for interlace RB based sub-channels can also be applied to the contiguous RB based sub-channels. FIG. 6 illustrates an example diagram showing that interlaced RB based subchannels numbering/indexing schemes are applied to subchannels composed by contiguous RBs.

As shown in FIG. 6, for contiguous RB based sub-channels with 3 sub-channels across 2 RB sets, where the first selected sub-channel is allocated in the RB Set 0, FIG. 6 (a) shows sub-channel first, where the sub-channel 1 to 3 are in RB set 0 and the sub-channels 4 to 6 are in RB set 1; FIG. 6 (b) shows RB set first, where the

sub-channel

1, 3 and 5 are in RB set 0 and the

sub-channel

2, 4 and 6 are in RB set 1.

The advantage of this approach is that the FRIV design itself is not impacted, besides the inclusion of the indication of which sub-channel numbering/indexing is being applied at.

The following shows an example specification impact in 38.212:

It is also expected impact on 38.214 and 38.331.

In some embodiments, the RB set of which the subchannel belongs to is explicitly indicated in the SCI format 1-A or equivalent. When sl-MaxNumPerReserve is 2 only one RB-Set index is needed (or an offset from the RB-Set of which the SCI is received) . When sl-MaxNumPerReserve is 3 two RB-Set indices are provided (or two RB-Set offsets) . If sl-MaxNumPerReserve is 3 but only one RB-Set offset is delivered, the FRIV allocations are derived based on that RB-Set. This is particular useful if the number of subchannels the FRIV should indicate

gets large as it would need to cover the total number of subchannels.

In some embodiments, a UE indicates in its 1 ^st stage SCI (or equivalent) the resource allocation order in terms of RB Sets (e.g., RB Set x -> RB Set y -> RB Set z) , where for “N” RB Sets, ceil (log2 (permutation (N) ) ) [bit] are required. Alternatively, the SL UEs are (pre) configured with the order in which the RB sets are allocated.

In some embodiments, if the UE does not indicate which resource allocation pattern it applies and if the resource allocation is not (pre) configured, the SL UEs assumes a bitmap-based allocation, i.e. the FRIV should become a bitmap for each resource reservation indicating which specific subchannels from which RB sets are being allocated. This option allows the most flexible allocation, as allocation may not be necessarily contiguous (e.g., the UE could indicate the sub-channel 1 from RB-set0 and sub-channels 2 and 3 from RB-set 1) . However, it has the largest overhead in number of bits for FRIV.

In some embodiments, it is possible to configure more than two RB sets with this scheme. So, compared with the implementation examples above, it is possible that three (or more) RB sets are covered by using the embodiments in this document.

It would be understood that, while some embodiments relate to Sidelink NR, the embodiments are by no means limited to this example, and may apply to other systems or Radio Access Technologies (for example, IEEE, or 3GPP 6G) .

FIG. 7 illustrates a flowchart of an example method 700 implemented at a first terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the first network device 210 as shown in, e.g., FIGS. 2 and 3.

At block 710, the first terminal device 210 determines subchannel indexing schemes supported by a resource pool. At block 720, the first terminal device 210 determines SCI to indicate a set of resources in a resource pool for at least one sidelink transmission to a second terminal device 220. The SCI comprises a FRIV, and the FRIV is applied using at least one of the subchannel indexing scheme. At block 730, the first terminal device 210 transmits the SCI to the second terminal device 220.

In some embodiments, the first terminal device 210 may include in the SCI an indication of the at least one of the subchannel indexing schemes. In some embodiments, the first terminal device 210 may define a plurality of subchannels at at least one RB set of the resource pool based on a number of interlaced RBs corresponding to one of the plurality of subchannels. In some embodiments, the number of the interlaced RBs may be configured by upper layers or pre-configured.

In some embodiments, the first terminal device 210 may indicate at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes. In some embodiments, the indication of the at least one of the subchannel indexing schemes may indicate at least one of: a subchannel first scheme; or a RB set first scheme. In some embodiments, the indication of the at least one of the subchannel indexing schemes may indicate a bitmap based scheme. In some embodiments, the first terminal device 210 may determine the subchannel indexing schemes based on a configuration information element in the resource pool.

In some embodiments, the SCI may further comprise an indication of a plurality of used RB sets. In some embodiments, the FRIV may comprise a common FRIV indicating the same subchannel, composed by contiguous RBs, at the plurality of used RB sets. Additionally or alternatively, the FRIV may comprise separate FRIVs, each of the separate FRIVs indicating one or more subchannels, composed by contiguous RBs, at one of the plurality of used RB sets. In some embodiments, the SCI may further comprise a parameter indicating a number of the one or more subchannels at one of the used RB sets.

In some embodiments, the plurality of used RB sets may comprise at least one of: a first number of RB sets for a current transmission; or a second number of RB sets reserved for a future transmission. The second number of RB sets may be restricted based on the first number of RB sets. In some embodiments, the first terminal device 210 may define a plurality of subchannels at the plurality of used RB sets. Additionally, the first terminal device 210 may indicate at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes.

FIG. 8 illustrates a flowchart of an example method 800 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the second network device 220 as shown in, e.g., FIGS. 2 and 3.

At block 810, the second network device 220 determines subchannel indexing schemes supported by a resource pool. At block 820, the second network device 220 receives, from a first terminal device 210, SCI. The SCI comprises a FRIV, and the FRIV is applied using at least one of the subchannel indexing schemes. At block 830, the second network device 220 determines using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device. At block 830, the second network device 220 receives the at least one sidelink transmission from the first terminal device on the set of resources.

In some embodiments, the second network device 220 may use the indicated subchannel indexing scheme and the FRIV to determine the set of resources, if an indication of a subchannel indexing scheme of the subchannel indexing schemes is provided in the SCI. Additionally or alternatively, the second network device 220 may use a default subchannel indexing scheme and the FRIV to determine the set of resources, if an indication of a subchannel indexing scheme of the subchannel indexing schemes is not provided in the SCI.

In some embodiments, the indication of the subchannel indexing scheme may indicate at least one of: a subchannel first scheme; or a RB set first scheme. In some embodiments, the indication of the subchannel indexing scheme may indicate a bitmap based scheme. In some embodiments, the default subchannel indexing scheme may comprise at least one of: a subchannel first scheme; a RB set first scheme; or a bitmap based scheme.

In some embodiments, the second network device 220 may determine at least part of a plurality of subchannels at at least one RB set of the resource pool. The plurality of subchannels may be defined by the first terminal device based on a number of interlaced RBs corresponding to one of the plurality of subchannels. In some embodiments, the second network device 220 may determine subchannel indexing schemes based on a configuration information element in the resource pool.

In some embodiments, the plurality of used RB sets may comprise at least one of: a first number of RB sets for a current transmission; or a second number of RB sets reserved for a future transmission. The second number of RB sets may be restricted based on the first number of RB sets. In some embodiments, the second terminal device 220 may determine at least part of a plurality of subchannels based on the FRIV and at least one of the default subchannel indexing scheme or the indication of the subchannel indexing scheme. The plurality of subchannels may be defined by the first terminal device 210 at the plurality of used RB sets.

In some embodiments, an apparatus capable of performing any of the method 700 (for example, the first terminal device 210) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises means for: determining, at a first terminal device, subchannel indexing schemes supported by a resource pool; determining sidelink control information, SCI, to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; and transmitting the SCI to the second terminal device..

In some embodiments, the apparatus further comprises means for: including in the SCI an indication of the at least one of the subchannel indexing schemes. In some embodiments, the apparatus further comprises means for: defining a plurality of subchannels at at least one resource block, RB, set of the resource pool based on a number of interlaced RBs corresponding to one of the plurality of subchannels. In some embodiments, the number of the interlaced RBs is configured by upper layers or pre-configured.

In some embodiments, the means for determining the SCI to indicate the set of resources comprises means for: indicating at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes. In some embodiments, the indication of the at least one of the subchannel indexing schemes indicates at least one of: a subchannel first scheme; or a RB set first scheme. In some embodiments, the indication of the at least one of the subchannel indexing schemes indicates a bitmap based scheme.

In some embodiments, the means for determining the subchannel indexing schemes comprises means for: determining the subchannel indexing schemes based on a configuration information element in the resource pool.

In some embodiments, the SCI further comprises an indication of a plurality of used RB sets. In some embodiments, the FRIV comprises a common FRIV indicating the same subchannel, composed by contiguous RBs, at the plurality of used RB sets. In some embodiments, the FRIV comprises separate FRIVs, each of the separate FRIVs indicating one or more subchannels, composed by contiguous RBs, at one of the plurality of used RB sets. In some embodiments, the SCI further comprises a parameter indicating a number of the one or more subchannels at one of the used RB sets.

In some embodiments, the plurality of used RB sets comprise at least one of: a first number of RB sets for a current transmission; or a second number of RB sets reserved for a future transmission. In some embodiments, the second number of RB sets is restricted based on the first number of RB sets.

In some embodiments, the apparatus further comprises means for: defining a plurality of subchannels at the plurality of used RB sets; and indicating at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 700. In some embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

In some embodiments, an apparatus capable of performing any of the method 800 (for example, the second terminal device 220) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises means for: determining, at a second terminal device, subchannel indexing schemes supported by a resource pool; receiving, from a first terminal device, sidelink control information, SCI, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; determining using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and receiving the at least one sidelink transmission from the first terminal device on the set of resources.

In some embodiments, the means for determining the set of resources comprises means for: if an indication of a subchannel indexing scheme of the subchannel indexing schemes is provided in the SCI, using the indicated subchannel indexing scheme and the FRIV to determine the set of resources; or if an indication of a subchannel indexing scheme of the subchannel indexing schemes is not provided in the SCI, using a default subchannel indexing scheme and the FRIV to determine the set of resources.

In some embodiments, the indication of the subchannel indexing scheme indicates at least one of: a subchannel first scheme; or a RB set first scheme. In some embodiments, the indication of the subchannel indexing scheme indicates a bitmap based scheme. In some embodiments, the default subchannel indexing scheme comprises at least one of: a subchannel first scheme; a RB set first scheme; or a bitmap based scheme.

In some embodiments, the means for determining the set of resources comprises means for: determining at least part of a plurality of subchannels at at least one resource block, RB, set of the resource pool, wherein the plurality of subchannels is defined by the first terminal device based on a number of interlaced RBs corresponding to one of the plurality of subchannels. In some embodiments, the means for determining the subchannel indexing schemes comprises means for: determining the subchannel indexing schemes based on a configuration information element in the resource pool.

In some embodiments, the second number of RB sets is restricted based on the first number of RB sets. In some embodiments, the means for determining the set of resources comprises means for: determining at least part of a plurality of subchannels based on the FRIV and at least one of the default subchannel indexing scheme or the indication of the subchannel indexing scheme, wherein the plurality of subchannels are defined by the first terminal device at the plurality of used RB sets.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 800. In some embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

FIG. 9 is a simplified block diagram of a device 900 that is suitable for implementing embodiments of the present disclosure. The device 900 may be provided to implement the communication device, for example the first terminal device 210, the second terminal device 220 and the network device 230 as shown in FIG. 2. As shown, the device 900 includes one or more processors 910, one or more memories 940 coupled to the processor 910, and one or more communication modules (TX/RX) 940 coupled to the processor 910.

The TX/RX 940 is for bidirectional communications. The TX/RX 940 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 910 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 900 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 920 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 924, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 922 and other volatile memories that will not last in the power-down duration.

A computer program 930 includes computer executable instructions that are executed by the associated processor 910. The program 930 may be stored in the ROM 920. The processor 910 may perform any suitable actions and processing by loading the program 930 into the RAM 920.

The embodiments of the present disclosure may be implemented by means of the program 930 so that the device 900 may perform any process of the disclosure as discussed with reference to FIGS. 2 to 8. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some embodiments, the program 930 may be tangibly contained in a computer readable medium which may be included in the device 900 (such as in the memory 920) or other storage devices that are accessible by the device 900. The device 900 may load the program 930 from the computer readable medium to the RAM 922 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. FIG. 10 shows an example of the computer readable medium 1000 in form of CD or DVD. The computer readable medium has the program 930 stored thereon.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, device, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a transitory or non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods 700-800 as described above with reference to FIGS. 7 to 8. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

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

In the context of the present disclosure, the instructions or related data may be carried by any suitable carrier to enable the device, device or processor to perform various processes and operations as described above. Examples of the 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 not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

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

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

Claims

A first terminal device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first terminal device at least to:

determine subchannel indexing schemes supported by a resource pool;

determine sidelink control information, SCI, to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; and

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

include in the SCI an indication of the at least one of the subchannel indexing schemes.
The first terminal device of claim 1 or 2, wherein the first terminal device is further caused to:

define a plurality of subchannels at at least one resource block, RB, set of the resource pool based on a number of interlaced RBs corresponding to one of the plurality of subchannels.
The first terminal device of claim 3, wherein the number of the interlaced RBs is configured by upper layers or pre-configured.
The first terminal device of any one of claims 1-4, wherein the first terminal device is caused to determine the SCI to indicate the set of resources by:

indicating at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes.
The first terminal device of claim 5, wherein the indication of the at least one of the subchannel indexing schemes indicates at least one of:

a subchannel first scheme; or

a RB set first scheme.
The first terminal device of claim 5 or 6, wherein the indication of the at least one of the subchannel indexing schemes indicates a bitmap based scheme.
The first terminal device of any one of claims 1-7, wherein the first terminal device is caused to determine the subchannel indexing schemes based on a configuration information element in the resource pool.
The first terminal device of claim 1 or 2, wherein the SCI further comprises an indication of a plurality of used RB sets.
The first terminal device of claim 9, wherein the FRIV comprises a common FRIV indicating the same subchannel, composed by contiguous RBs, at the plurality of used RB sets.
The first terminal device of claim 9 or 10, wherein the FRIV comprises separate FRIVs, each of the separate FRIVs indicating one or more subchannels, composed by contiguous RBs, at one of the plurality of used RB sets.
The first terminal device of claim 11, wherein the SCI further comprises a parameter indicating a number of the one or more subchannels at one of the used RB sets.
The first terminal device of any one of claims 8-12, wherein the plurality of used RB sets comprise at least one of:

a first number of RB sets for a current transmission; or

a second number of RB sets reserved for a future transmission.
The first terminal device of claim 13, wherein the second number of RB sets is restricted based on the first number of RB sets.
The first terminal device of any one of claims 9-14, wherein the first terminal device is further caused to:

define a plurality of subchannels at the plurality of used RB sets; and

indicate at least part of the plurality of subchannels by the FRIV and the indication of the at least one of the subchannel indexing schemes.
A second terminal device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the second terminal device at least to:

determine subchannel indexing schemes supported by a resource pool;

receive, from a first terminal device, sidelink control information, SCI, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes;

determine using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and

receive the at least one sidelink transmission from the first terminal device on the set of resources.
The second terminal device of claim 16, wherein the second terminal device is caused to determine the set of resources by at least one of:

if an indication of a subchannel indexing scheme of the subchannel indexing schemes is provided in the SCI, using the indicated subchannel indexing scheme and the FRIV to determine the set of resources; or

if an indication of a subchannel indexing scheme of the subchannel indexing schemes is not provided in the SCI, using a default subchannel indexing scheme and the FRIV to determine the set of resources.
The second terminal device of 17, wherein the indication of the subchannel indexing scheme indicates at least one of:

a subchannel first scheme; or

a RB set first scheme.
The second terminal device of claim 17 or 18, wherein the indication of the subchannel indexing scheme indicates a bitmap based scheme.
The second terminal device of any one of claims 17-19, wherein the default subchannel indexing scheme comprises at least one of:

a subchannel first scheme;

a RB set first scheme; or

a bitmap based scheme.
The second terminal device of any one of claims 16-20, wherein the second terminal device is caused to determine the set of resources by:

determining at least part of a plurality of subchannels at at least one resource block, RB, set of the resource pool, wherein the plurality of subchannels is defined by the first terminal device based on a number of interlaced RBs corresponding to one of the plurality of subchannels.
The second terminal device of any one of claims 16-21, wherein the second terminal device is caused to determine the subchannel indexing schemes based on a configuration information element in the resource pool.
The second terminal device of claim 16 or 17, wherein the SCI further comprises an indication of a plurality of used RB sets.
The second terminal device of claim 23, wherein the FRIV comprises a common FRIV indicating the same subchannel, composed by contiguous RBs, at the plurality of used RB sets.
The second terminal device of claim 23 or 24, wherein the FRIV comprises separate FRIVs, each of the separate FRIVs indicating one or more subchannels, composed by contiguous RBs, at one of the plurality of used RB sets.
The second terminal device of claim 25, wherein the SCI further comprises a parameter indicating a number of the one or more subchannels at one of the used RB sets.
The second terminal device of any one of claims 23-26, wherein the plurality of used RB sets comprise at least one of:

a first number of RB sets for a current transmission; or

a second number of RB sets reserved for a future transmission.
The second terminal device of claim 27, wherein the second number of RB sets is restricted based on the first number of RB sets.
The second terminal device of any one of claims 23-28, wherein the second terminal device is caused to determine the set of resources by:

determining at least part of a plurality of subchannels based on the FRIV and at least one of the default subchannel indexing scheme or the indication of the subchannel indexing scheme, wherein the plurality of subchannels are defined by the first terminal device at the plurality of used RB sets.
A method comprising:

determining, at a first terminal device, subchannel indexing schemes supported by a resource pool;

determining sidelink control information, SCI, to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; and

transmitting the SCI to the second terminal device.
A method comprising:

determining, at a second terminal device, subchannel indexing schemes supported by a resource pool;

receiving, from a first terminal device, sidelink control information, SCI, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes;

determining using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and

receiving the at least one sidelink transmission from the first terminal device on the set of resources.
An apparatus comprising means for:

determining, at a first terminal device, subchannel indexing schemes supported by a resource pool;

determining sidelink control information, SCI, to indicate a set of resources in the resource pool for at least one sidelink transmission to a second terminal device, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes; and

transmitting the SCI to the second terminal device.
An apparatus comprising means for:

determining, at a second terminal device, subchannel indexing schemes supported by a resource pool;

receiving, from a first terminal device, sidelink control information, SCI, the SCI comprising a frequency resource indicator value, FRIV, wherein the FRIV is applied using at least one of the subchannel indexing schemes;

determining using the SCI a set of resources in the resource pool for at least one sidelink transmission from the first terminal device; and

receiving the at least one sidelink transmission from the first terminal device on the set of resources.
A computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least one of the methods of claims 30-31.