Terminal device and method

Abstract

The present disclosure relates to a method, an apparatus, and a computer-readable medium for sidelink communication, the method including: determining, in a second terminal device, based on detecting sidelink control information (SCI) transmitted from a first starting point within a slot, whether to perform a second sidelink transmission from a second starting point within the slot subsequent to the first starting point; and, if the second sidelink transmission is to be performed, performing the second sidelink transmission from the second starting point.

Description

[Technical Field]

[0001] Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, apparatus, and computer-readable media for sidelink communications. [Background technology]

[0002] Sidelink in unlicensed spectrum or band (SL-U) is a major topic of 3GPP (3rd Generation Partnership Project) Release 18. SL-U should be based on New Radio (NR) sidelink and NR-U.

[0003] In the case of SL-U, two or more transmission start points may be used within a slot, i.e., a first start point and one or more additional start points. Each terminal device may access the channel and transmit sidelink signals based on a different start point. For sidelink transmissions from additional start points, related modifications to the SL channel structure and transmission scheme need to be studied and specified. Summary of the Invention [Problem to be solved by the invention]

[0004] In general, the exemplary embodiments of the present disclosure provide a method, apparatus, and computer-readable medium for sidelink communications. [Means for solving the problem]

[0005] In a first aspect, a method for sidelink communication is provided, comprising: determining, in a second terminal device, based on detection of sidelink control information (SCI) transmitted from a first starting point within a slot, whether to perform a second sidelink transmission from a second starting point within the slot subsequent to the first starting point; and performing the second sidelink transmission from the second starting point in accordance with the determination that the second sidelink transmission is to be performed.

[0006] In a second aspect, a method for sidelink communication is provided, comprising: obtaining, in a first terminal device, a configuration of a second starting point in a slot subsequent to a first starting point in the slot; and performing a first sidelink transmission from the first sidelink starting point based on the configuration.

[0007] In a third aspect, there is provided a terminal device, the terminal device comprising a processor and a memory storing instructions, the memory and the instructions configured to cause the terminal device, using the processor, to perform a method according to the first aspect.

[0008] In a fourth aspect, there is provided a terminal device, the terminal device including a processor and a memory storing instructions, the memory and the instructions configured to cause the terminal device, using the processor, to perform a method according to the second aspect.

[0009] In a fifth aspect, there is provided a computer readable medium storing instructions which, when executed on at least one processor of a device, cause the device to perform a method according to the first aspect.

[0010] In a sixth aspect, there is provided a computer readable medium storing instructions which, when executed on at least one processor of a device, cause the device to perform a method according to the second aspect.

[0011] It should be understood that this Summary of the Invention is not intended to identify key or essential features of the embodiments of the present disclosure, nor to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description. [Brief explanation of the drawings]

[0012] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description of several embodiments of the present disclosure in the accompanying drawings.

[0013] [Figure 1] FIG. 1 illustrates an exemplary communication network in which embodiments of the present disclosure may be implemented.

[0014] [Figure 2] FIG. 1 illustrates an example of temporal resource allocation in a sidelink resource pool, in accordance with some embodiments of the present disclosure.

[0015] [Figure 3] FIG. 10 illustrates an example of symbol allocation in a sidelink slot in accordance with some embodiments of the present disclosure.

[0016] [Figure 4] FIG. 1 illustrates an example of frequency resource allocation in a sidelink resource pool in accordance with some embodiments of the present disclosure.

[0017] [Figure 5] FIG. 1 illustrates an example of a sidelink channel in the time domain, in accordance with some embodiments of the present disclosure.

[0018] [Figure 6] FIG. 10 is a diagram illustrating an example of symbol allocation in a sidelink subframe according to another embodiment of the present disclosure.

[0019] [Figure 7]FIG. 10 illustrates an example of feedback channel resources in the time domain, in accordance with some embodiments of the present disclosure.

[0020] [Figure 8] FIG. 1 illustrates an example of an IRB in an NR-U IRB scheme according to some embodiments of the present disclosure.

[0021] [Figure 9] 1 is a flowchart of an exemplary method according to some embodiments of the present disclosure.

[0022] [Figure 10A] FIG. 10 illustrates two example starting points, according to some embodiments of the present disclosure. [Figure 10B] FIG. 10 illustrates two example starting points, according to some embodiments of the present disclosure.

[0023] [Figure 11] 10 is a flowchart of an example method for determining whether to perform a second sidelink transmission from a second starting point, in accordance with some embodiments of the present disclosure.

[0024] [Figure 12] 10 is a flowchart of an example method for determining whether to perform a second sidelink transmission from a second starting point, in accordance with some other embodiments of the present disclosure.

[0025] [Figure 13] 10 is a flowchart of an example method for determining whether to perform a second sidelink transmission from a second starting point, in accordance with some other embodiments of the present disclosure.

[0026] [Figure 14A] FIG. 10 illustrates an example of symbol repetition for a second starting symbol in accordance with some embodiments of the present disclosure.

[0027] [Figure 14B] FIG. 10 illustrates an example of an extension signal for a second starting symbol in accordance with some embodiments of the present disclosure.

[0028] [Figure 15A] FIG. 10 illustrates an example of a PSCCH resource associated with a second starting point, in accordance with some embodiments of the present disclosure. [Figure 15B] FIG. 10 illustrates an example of a PSCCH resource associated with a second starting point, in accordance with some embodiments of the present disclosure.

[0029] [Figure 16A] FIG. 10 illustrates an example of symbol repetition for a second starting symbol in accordance with some embodiments of the present disclosure. [Figure 16B] FIG. 10 illustrates an example of symbol repetition for a second starting symbol in accordance with some embodiments of the present disclosure. [Figure 16C] FIG. 10 illustrates an example of symbol repetition for a second starting symbol in accordance with some embodiments of the present disclosure. [Figure 16D] FIG. 10 illustrates an example of symbol repetition for a second starting symbol in accordance with some embodiments of the present disclosure.

[0030] [Figure 17] 10 is a flowchart of an exemplary method according to another embodiment of the present disclosure.

[0031] [Figure 18] 10 is a flowchart of an exemplary method according to another embodiment of the present disclosure.

[0032] [Figure 19] FIG. 1 is a schematic block diagram of an apparatus suitable for implementing embodiments of the present disclosure.

[0033] In the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0034] The principles of the present disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are provided for illustrative purposes only to aid those skilled in the art in understanding and practicing the present disclosure, and do not imply any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways different from those described below.

[0035] 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.

[0036] As used herein, the term "terminal device" means any device with wireless or wired communication capabilities. Examples of terminal devices include user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communication (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, in-vehicle devices for V2X communications where X stands for pedestrian, vehicle, or infrastructure / network, devices for Integrated Access and Backhaul (IAB), Small Data Transmission (SDT), mobility, Multicast and Broadcast Services (MBS), positioning, dynamic / flexible duplication in commercial networks, reduced capability (RedCap), High Altitude Platforms (HAP) including satellites and Unmanned Aircraft Systems (UAS). Spaceborne vehicles or airborne vehicles in non-terrestrial networks (NTNs) including the ISS Platform, and extended reality (XR) including different types of reality such as augmented reality (AR), mixed reality (MR), and virtual reality (VR).These include, but are not limited to, reality devices, unmanned aerial vehicles (UAVs), aircraft without a human pilot, commonly referred to as drones, devices on high-speed trains (HSTs), image capture devices such as digital cameras, sensor gaming devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing. A "terminal device" may also have "multicast / broadcast" capabilities to support public safety and mission-critical applications, V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, over-the-air software distribution, group communication, and IoT applications. A terminal device may also incorporate one or more subscriber identity modules (SIMs), known as multi-SIMs. The term "terminal device" may be used interchangeably with UE, mobile station, subscriber station, mobile terminal, user terminal, or wireless device.

[0037] The term "network device" means a device that can provide or host a cell or coverage area in which terminal devices can communicate. Examples of network devices include, but are not limited to, a Node B (Node B or NB), an evolved Node B (eNode B or eNB), a next generation Node B (gNB), a transmission reception point (TRP), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), an IAB node, a low-power node such as a femto node or a pico node, a reconfigurable intelligent surface (RIS), and a network-controlled repeater.

[0038] A terminal device or a network device may have artificial intelligence (AI) or machine learning capabilities, which generally include a model trained from a large amount of data collected for a specific function and can be used to predict some information.

[0039] The terminal device or network device may operate in several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands above 100 GHz, and Terahertz (THz). It can also operate on licensed, unlicensed, and shared spectrum. The terminal device may have two or more connections with the network device under a Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or network device can operate in full duplex, flexible duplex, and cross-division duplex modes.

[0040] The network device may have a function of network energy saving, self-organizing networks (SON) / minimization of drive test (MDT). The terminal may have a function of power saving.

[0041] Embodiments of the present disclosure may be implemented in test equipment such as, for example, a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal device, a test network device, a channel emulator, and the like.

[0042] Embodiments of the present disclosure may be performed in accordance with any currently known or future developed generation of communication protocols, including, but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0043] As used herein, the singular forms "a," "an," and "said" include the plural forms unless the context clearly indicates otherwise. The term "comprises" and variations thereof 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 "some embodiments" and "embodiments" should be understood as "at least some embodiments." The term "another embodiment" should be understood as "at least one other embodiment." Terms such as "first," "second," etc. may refer to different or the same object. The following may include other explicit and implicit definitions.

[0044] In some instances, values, procedures, or devices are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to illustrate that choices may be made from among many functional alternatives used, and that such choices are not necessarily better, smaller, higher, or otherwise more preferred than other choices.

[0045] 1 is a schematic diagram of an exemplary communication network 100 in which embodiments of the present disclosure may be implemented. As shown in FIG. 1, communication network 100 may include a first terminal device 110, a second terminal device 120, a third terminal device 130, and network devices 140 and 150. Network devices 140 and 150 may communicate with terminal device 110, terminal device 120, and terminal device 130 via respective wireless communication channels.

[0046] In some embodiments, the network device 140 may be a gNB in ​​the NR. Accordingly, the network device 140 may be referred to as an NR network device 140.

[0047] In some embodiments, the network device 150 may be an eNB in ​​a Long Term Evolution (LTE) system. Therefore, the network device 150 may be referred to as an LTE network device 150.

[0048] 1 is provided for illustrative purposes only and does not imply any limitations on the present disclosure. Communications network 100 may include any suitable number of network devices and / or terminal devices suitable for implementing embodiments of the present disclosure.

[0049] Communications in communication network 100 may conform to any suitable standard, including, but not limited to, Global System for Mobile Communications (GSM), LTE, LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communication (MTC), etc. Furthermore, communications may be performed according to any currently known or future-developed generation of communication protocols. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communication protocols.

[0050] In some embodiments, communications in communication network 100 may include sidelink communications. Sidelink communications are direct wireless radio communications between two or more terminal devices, e.g., terminal device 110, terminal device 120, and terminal device 130. In this type of communication, two or more terminal devices in close geographic proximity can communicate directly without going through network device 140 or 150 or the core network. Thus, data transmission in sidelink communications differs from typical cellular network communications in which a terminal device transmits data to or receives data from network device 140 or 150 (i.e., uplink transmission). As shown in FIG. 1, in sidelink communications, data is transmitted directly from a source terminal device (e.g., terminal device 110) to a target terminal device (e.g., terminal device 120) over a unified air interface, e.g., a PC5 interface (i.e., sidelink transmission).

[0051] Sidelink communication can provide several advantages, including reducing data transmission load on the core network, system resource consumption, transmission power consumption and network operation costs, conserving radio spectrum resources and improving the spectral efficiency of cellular wireless communication systems.

[0052] In a sidelink communication system, sidelink resources are used to transmit information between terminal devices. Depending on application scenarios, service types, etc., sidelink communication methods include, but are not limited to, device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, etc.

[0053] V2X communication enables vehicles to communicate with other vehicles (i.e., vehicle-to-vehicle (V2V) communication), infrastructure (i.e., vehicle-to-infrastructure (V2I) communication), wireless networks (i.e., vehicle-to-network (V2N) communication), pedestrians (i.e., vehicle-to-pedestrian (V2P) communication), and even with the owner's home (i.e., vehicle-to-home (V2H) communication). Examples of infrastructure include roadside devices such as traffic lights and toll booths. V2X communication can be used in a wide range of scenarios, including accident prevention, safety, convenience, traffic efficiency, and accident-free driving, ultimately leading to autonomous driving and self-driving vehicles.

[0054] For sidelink communication, the terminal device transmits or receives signals using resources in a sidelink resource pool. The sidelink resource pool includes resources in the time and frequency domains that are either dedicated to sidelink communication or shared between sidelink communication and the cellular link. For sidelink communication, two resource assignment modes may be used for the sidelink: a mode in which the network device schedules sidelink resources for the terminal device to transmit sidelink signals, referred to as a Mode 1 resource scheme for the NR sidelink or a Mode 3 resource scheme for the LTE sidelink; and a mode in which the terminal device itself selects sidelink resources for transmitting sidelink signals, referred to as a Mode 2 resource scheme for the NR sidelink or a Mode 4 resource scheme for the LTE sidelink.

[0055] FIG. 2 illustrates an example of timing resource allocation in a sidelink resource pool according to some embodiments of the present disclosure. In some embodiments, the sidelink resource pool may include an NR sidelink resource pool. In such embodiments, the sidelink resource pool may be defined within a sidelink bandwidth part (sidelink BWP). Terminal device 110, terminal device 120, and terminal device 130 may use uplink (UL) resources for sidelink communications. Two or more sidelink resource pools may be configured for one of terminal device 110, terminal device 120, and terminal device 130. A dedicated resource pool may be used for Mode 1 resource scheme or Mode 2 resource scheme, and may be referred to as Mode 1 resource pool or Mode 2 resource pool for short. For the LTE sidelink, a dedicated resource pool may be used for Mode 3 resource scheme or Mode 4 resource scheme, and may be referred to as Mode 3 resource pool or Mode 4 resource pool for short. The resources in the sidelink resource pool may include physical sidelink control channel (PSCCH) resources, physical sidelink shared channel (PSSCH) resources, and physical sidelink feedback channel (PSFCH) resources. A bitmap may be used to indicate which UL slots are configured as sidelink slots. The length of the bitmap may range from 10 to 160.

[0056] Figure 3 illustrates an example of symbol allocation in a sidelink slot according to some embodiments of the present disclosure. A sidelink resource pool may include multiple slots and resource blocks (RBs), and all or some of the symbols in a slot may be used for sidelink transmission. Within the resource pool, the first symbol (i.e., the start symbol) of all symbols configured for sidelink use in each slot is used as an automatic gain control (AGC) symbol, and the last symbol is used as a guard period (GP) symbol. The AGC and GP symbols may be considered as fixed overhead within the sidelink resource pool. In the following description of the embodiments, as shown in Figure 3, the AGC and GP symbols are included in the sidelink symbols indicated by the sidelink channel resource configuration, and the AGC symbols carry redundant sidelink information, while the GP symbols are not used to carry sidelink information.

[0057] Terminal device 110, terminal device 120, and terminal device 130 may transmit sidelink signaling or information using sidelink channels, including at least one of PSCCH resources used to carry sidelink control information (SCI), PSSCH resources used to carry sidelink data service information, PSFCH resources used to carry sidelink Hybrid Automatic Repeat Request (HARQ) feedback information, physical sidelink broadcast channel (PSBCH) resources used to carry sidelink broadcast information, and physical sidelink discovery channel (PSDCH) resources used to carry sidelink discovery signals.

[0058] FIG. 4 illustrates an example of frequency resource allocation in a sidelink resource pool according to some embodiments of the present disclosure. In some embodiments, the sidelink resource pool may be an NR sidelink resource pool. As shown in FIG. 4, the sidelink resource pool may be configured within a SL Bandwidth Part (Sidelink BWP). The resource pool configuration may include sl-StartRB-Subchannel and sl-RB-Number. The sl-StartRB-Subchannel may indicate the lowest resource block (RB) of the resource pool. The lowest RB is also referred to as the start RB. The sl-RB-Number may indicate the total number of RBs in the resource pool.

[0059] The RBs in the resource pool may be divided into consecutive subchannels. A subchannel is a frequency resource unit of the PSSCH. Each subchannel includes consecutive RBs. The terminal devices 110, 120, and 130 may transmit sidelink data using one or more consecutive subchannels as PSSCH resources. The subchannel configuration of the resource pool may include sl-SubchannelSize, which indicates the number of RBs included in one subchannel. SubchannelSize may be equal to 10, 12, 15, 20, 25, 50, 75, or 100.

[0060] FIG. 5 illustrates an example of sidelink channels in the time domain according to some embodiments of the present disclosure. In the example of FIG. 5, the sidelink channels include a PSCCH and a PSSCH. The PSCCH may carry SCI format 1. One PSCCH may be defined in each subchannel. Each PSCCH resource may include t consecutive symbols in the time domain and k consecutive RBs in the frequency domain. The t symbols start from the first available symbol in the time domain, where t = 2 or 3. The k RBs start from the first RB in the corresponding subchannel, where k = 10, 12, 15, 20, or 25. The PSSCH may carry SCI format 2A / 2B, and the sidelink data PSSCH uses subchannels as frequency units. The terminal devices 110, 120, and 130 may transmit sidelink data using one or more consecutive subchannels as PSSCH resources.

[0061] Similar to the NR sidelink resource pool, in the LTE sidelink resource pool, the terminal device 110, the terminal device 120, or the terminal device 130 may use uplink (UL) resources for sidelink communication. Two or more sidelink resource pools may be configured for the terminal device 110, the terminal device 120, or the terminal device 130. The resources in the LTE sidelink resource pool may include a PSCCH resource pool and a PSSCH resource pool. A bitmap may be used to indicate which UL subframes are configured as sidelink subframes.

[0062] Figure 6 illustrates an example of symbol allocation in a sidelink subframe according to another embodiment of the present disclosure. In some embodiments, the sidelink subframe in Figure 6 may be an LTE sidelink subframe. As shown in Figure 6, all symbols in the subframe are used as sidelink resources. Within the subframe, the first symbol is used as AGC and the last symbol is used as GP.

[0063] LTE sidelink channels may include a PSCCH and a PSSCH. The PSCCH may carry SCI format 1. One PSCCH is associated with one subchannel. Each PSCCH resource has a fixed size. For example, each PSCCH resource may include two consecutive PRBs and all symbols in a sidelink subframe. The PSSCH carries sidelink data and may use subchannels as frequency units. The terminal device 110, terminal device 120, or terminal device 130 may use one or more consecutive subchannels as PSSCH resources to transmit sidelink data. The relationship between the PSCCH and the PSSCH may be a one-to-one mapping relationship.

[0064] In a resource pool, whether a PSFCH resource is available or not needs to be configured or pre-configured. In the time domain, one slot out of every N slots in the resource pool contains a PSFCH resource according to the resource pool configuration or pre-configuration, where N = [0, 1, 2, 4]. In the sidelink resource pool, a PSCCH / PSSCH resource exists in each slot and is used to transmit sidelink data packets. As shown in Figure 7, in a slot containing a PSFCH resource, the last three SL symbols (AGC + PSFCH + GP) are used for PSFCH-related purposes.

[0065] A PSFCH resource may include one RB in the frequency domain and one symbol in the time domain (with repeated AGC symbols). Furthermore, a PSFCH resource may carry one bit of ACK / NACK information. Furthermore, a PSFCH resource may be associated with one subchannel within one slot.

[0066] An IRB is used as a frequency resource unit for the NR-U uplink. FIG. 8 illustrates an example of RB sets and IRBs in the NR-U IRB scheme according to some embodiments of the present disclosure. As shown in FIG. 8, each RB set may be defined as 20 MHz. For a 15 kHz subcarrier spacing (SCS), each RB set may include 100 to 110 RBs. For a 30 kHz SCS, each RB set may include 50 to 55 RBs. A guard band may exist between two adjacent RB sets.

[0067] BWPs #1 and #2 are defined within the system carrier. BWP #1 includes RB sets #0 and #1. BWP #2 includes RB sets #2 and #3. Note that although each BWP includes multiple RB sets as shown in Figure 8, in some embodiments, one or more BWPs may include a single RB set.

[0068] In this disclosure, the terms "IRB" and "interlace" may be used interchangeably. An IRB or interlace is defined within a system carrier. IRBs with index 0 start with a Common Resource Block (CRB) with index 0 (i.e., CRB#0). As shown in Figure 8, for a 30 kHz SCS, five interlaces may be defined within a system carrier. For a 15 kHz SCS, ten interlaces may be defined within a system carrier.

[0069] In the case of SL-U, a terminal device may access a channel using a channel access procedure and transmit a sidelink signal if the channel access procedure is successful. When a terminal device transmits on a channel, other terminal devices identify the channel as occupied and cannot perform transmission. If a terminal device transmits a signal on a channel that has only a portion of the frequency domain resources, the remaining frequency resources may be wasted, reducing resource efficiency.

[0070] To solve the above and other potential problems, embodiments of the present disclosure provide a solution for sidelink communication. In this solution, a second terminal device determines whether to perform a second sidelink transmission from a second starting point within a slot, subsequent to the first starting point, based on the detection of an SCI transmitted from a first starting point within the slot. If a second sidelink transmission is to be performed, the second terminal device performs the second sidelink transmission from the second starting point. This can improve sidelink communication efficiency and channel access success rate.

[0071] Hereinafter, several embodiments of the present disclosure according to the first aspect will be described with reference to FIGS. Terminal transmission procedure from any starting point

[0072] 9 is a signaling diagram illustrating a process 900 for sidelink communication in accordance with some implementations of the present disclosure. For illustrative purposes, process 900 is described with reference to FIG. 1. Process 900 may involve first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. Although process 900 is described in the context of communication network 100 of FIG. 1, this process is applicable to other communication scenarios as well.

[0073] In some embodiments, two or more starting points may be configured or pre-configured for sidelink transmission within a slot. The first point within the slot may be designated as the first starting point, and other points may be designated as additional starting points. The additional starting points follow the first starting point. The additional starting points may also be referred to as second starting points. One of the second starting points will be described below by way of example. It should be understood that two or more second starting points may be applied to the present disclosure.

[0074] In some embodiments, the first starting point is defined as the first sidelink symbol in a slot in the sidelink communication system, and the second starting point is defined as symbol #s in a slot in the sidelink communication system, where #s is fixed. In other words, the symbol positions of the first starting point or the second starting point are predefined, and no configuration or indication signaling for the starting points is required.

[0075] 9, the first terminal device 110 obtains a setting for a second starting point within a slot (910). The second starting point follows the first starting point within the slot.

[0076] The first terminal device 110 performs a first sidelink transmission from a first sidelink start point based on the configuration.

[0077] In some embodiments, the setting is: The second starting symbol index, the symbol offset between the first and second starting points; a first indication of whether the second starting point is enabled; a second indication of whether symbol repetition for the second starting point is enabled; a third indication indicating that the second starting point is not used in the slot containing the PSFCH resource; a priority threshold associated with the second starting point; a Channel Access Priority Class (CAPC) threshold associated with the second starting point; a first ratio threshold associated with a second starting point; a second ratio threshold associated with a second starting point; a third ratio threshold associated with the second starting point; the duration of the extension signal associated with the second starting point, or a first number of consecutive symbols in a slot for transmitting the second SCI by the second terminal device 120.

[0078] To perform a first sidelink transmission, first terminal device 110 performs a channel access (CA) procedure (920). As the CA procedure progresses, first terminal device 110 performs a first sidelink transmission from a first starting point (930). From the first starting point, first terminal device 110 may transmit an SCI on a PSCCH and sidelink data on a PSSCH. For example, first terminal device 110 may broadcast the SCI and sidelink data so that second terminal device 120 and third terminal device 130 can receive the SCI and sidelink data.

[0079] On the other hand, if the CA procedure fails, the first terminal device 110 drops the first sidelink transmission.

[0080] The second terminal device 120 detects the SCI transmitted from the first starting point and determines whether to perform a second sidelink transmission from a second starting point based on the detection of the SCI (940).

[0081] In some embodiments, the second terminal device 110 may determine whether to perform a second sidelink transmission from the second starting point based on the detection of the SCI and the setting of the second starting point.

[0082] If it is determined that the second sidelink transmission is to be performed, the second terminal device 120 performs the second sidelink transmission from the second starting point.

[0083] Specifically, the second terminal device 120 performs a CA procedure (950). As the CA procedure progresses, the second terminal device 120 performs a second sidelink transmission from a second starting point (960). From the second starting point, the second terminal device 120 may transmit a second SCI on the PSCCH and transmit sidelink data on the PSSCH. For example, the second terminal device 120 may broadcast the second SCI and data so that the first terminal device 110 and the third terminal device 130 can receive the second SCI and sidelink data.

[0084] On the other hand, if the CA procedure fails, the second terminal device 120 drops the second sidelink transmission.

[0085] If the second terminal device 120 determines that a second sidelink transmission is to be performed, the second terminal device 120 may drop reception of the signal from the first terminal device 110 and switch to a transmit mode, and then perform the second sidelink transmission from the second starting point.

[0086] The process 900 can improve sidelink communication efficiency and channel access success rate, and does not affect sidelink HARQ feedback.

[0087] 10A and 10B illustrate two example starting points, respectively, according to some embodiments of the present disclosure. In the examples of FIG. 10A and FIG. 10B, for simplicity, first terminal device 110 is also referred to as first UE 110, and second terminal device 110 is also referred to as second UE 120.

[0088] In the example of Figure 10A, two starting points are configured for sidelink communication within a slot. Symbols are used as the unit of starting points. The first starting point is symbol #0 within the slot, and the second starting point is symbol #7 within the slot.

[0089] In accordance with the sidelink grant on the unlicensed spectrum, the first terminal device 110 performs a Type 1 CA procedure to occupy the channel. If the Type 1 CA procedure is successful, the first terminal device 110 performs a first sidelink transmission from the first starting symbol in the slot using subchannels #1 and #2. For example, the first terminal device 110 transmits SCI on the PSCCH using subchannel #1 and transmits sidelink data on the PSSCH using subchannels #1 and #2.

[0090] On the other hand, if the CA procedure fails, the first terminal device 110 drops the first sidelink transmission.

[0091] The second terminal device 120 detects the SCI of the first terminal device 110 and identifies that subchannel #0 is not being used by the first terminal device 110. Therefore, the second terminal device 120 decides to perform a second sidelink transmission from a second starting point.

[0092] Optionally, if the second terminal device 120 determines that a second sidelink transmission is to be performed, the second terminal device 120 may switch from a receive mode to a transmit mode.

[0093] Optionally, the second terminal device 120 performs a type 2 CA procedure to occupy the channel.

[0094] If the Type 2 CA procedure is successful, the second terminal device 120 performs a second sidelink transmission using subchannel #0 from the second start symbol in the same slot.

[0095] On the other hand, if the CA procedure fails, the second terminal device 120 drops the second sidelink transmission.

[0096] The example of Figure 10B is similar to the example of Figure 10A, but differs from the example of Figure 10A in that the second starting point is symbol #5 and the sidelink resource pool includes two RB sets in the frequency domain.

[0097] If the Type 1 CA procedure is successful, the first terminal device 110 performs a first sidelink transmission from the first starting symbol in the slot using subchannels in RB set #1.

[0098] The second terminal device 120 detects the SCI of the first terminal device 110 and identifies that the resources of RB set #0 are not being used by the first terminal device 110. The second terminal device 120 then decides to perform a second sidelink transmission from a second starting point.

[0099] Specifically, the second terminal device 120 performs a Type 2 CA procedure, and the Type 2 CA procedure is successful. Then, the second terminal device 120 performs a second sidelink transmission from a second start symbol in the same slot using subchannels in RB set #0.

[0100] Note that the second start symbol should be assigned to a symbol index greater than (equal to) #4. Considering the processing time for decoding the SCI from the first terminal device 110, it should not be assigned before the symbol used for the PSCCH. Determining Whether to Perform a Second Sidelink Transmission from a Second Starting Point

[0101] 11 is a flowchart of an example method 1100 for determining whether to perform a second sidelink transmission from a second starting point according to some embodiments of the present disclosure. Method 1100 may be implemented in a terminal device, such as one of first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. For illustrative purposes, and without loss of generality, method 1100 will be described with reference to FIG. 1 as being performed by second terminal device 120.

[0102] Generally, in method 1100, the second terminal device 120 may determine whether to perform a second sidelink transmission from a second starting point based on the SCI detection and the information indicated in the SCI.

[0103] In the method 1100, the first starting point and the second starting point may be configured or pre-configured for the sidelink transmission within slot #n.

[0104] In block 1110, the second terminal device 120 blindly detects the SCI from the first starting point in slot #n.

[0105] In block 1120, the second terminal device 120 determines whether an SCI from the first starting point is detected.

[0106] If the SCI transmitted from the first starting point is not detected, the second terminal device 120 may determine in block 1130 to perform a second sidelink transmission from a second starting point within slot #n.

[0107] On the other hand, if at least one of the SCIs transmitted from the first starting point is detected in block 1120, the second terminal device 120 determines in block 1140 based on the at least one of the SCIs whether there are available resources in the frequency domain in the sidelink resource pool.

[0108] For example, the available resources in the frequency domain may include at least one of a subchannel, an IRB, an RB set, or an RB.

[0109] If there are available resources in the frequency domain, the second terminal device 120 may determine in block 1130 to perform a second sidelink transmission from a second starting point within slot #n.

[0110] On the other hand, if there are no available resources in the frequency domain, the second terminal device 120 may decide in block 1150 not to perform the second sidelink transmission from the second starting point within slot #n.

[0111] 12 is a flowchart of an example method 1200 for determining whether to perform a second sidelink transmission from a second starting point according to some other embodiments of the present disclosure. Method 1200 may be implemented in a terminal device, such as one of first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. For illustrative purposes, and without loss of generality, method 1200 will be described as being performed by second terminal device 120 with reference to FIG. 1.

[0112] In method 1200, the first and second starting points may be configured or pre-configured for sidelink transmission within slot #n. For simplicity, first terminal device 110 may also be referred to as first UE 110, and second terminal device 110 may also be referred to as second UE 120.

[0113] In block 1210, the second terminal device 120 blindly detects the SCI from the first starting point in slot #n.

[0114] In block 1220, the second terminal device 120 determines whether SCIs from the first starting point are detected and, based on at least one of the SCIs, determines whether there are available resources in the frequency domain in the sidelink resource pool.

[0115] If an SCI from the first starting point is detected and there are available resources in the frequency domain, the second terminal device 120 determines in block 1230 whether the second terminal device 120 is not a target receiving device for the first sidelink transmission from the first terminal device 110 and whether the first terminal device 110 is not a target receiving device for the second sidelink transmission from the second terminal device 120.

[0116] If the second terminal device 120 is not a target receiving device for the first sidelink transmission from the first terminal device 110 and the first terminal device 110 is not a target receiving device for the second sidelink transmission from the second terminal device 120, the second terminal device 120 may determine in block 1240 to perform the second sidelink transmission from a second starting point on at least one of the available resources.

[0117] On the other hand, if the second terminal device 120 determines in block 1220 that no SCI from the first starting point has been detected and / or that there are no available resources in the frequency domain, the second terminal device 120 may determine in block 1250 not to perform a second sidelink transmission from the second starting point on at least one of the available resources.

[0118] Furthermore, if the second terminal device 120 determines in block 1230 that the second terminal device 120 is the target receiving device for the first sidelink transmission or that the first terminal device 110 is the target receiving device for the second sidelink transmission, the second terminal device 120 may determine in block 1250 not to perform the second sidelink transmission from a second starting point on at least one of the available resources.

[0119] According to the method 1200, the influence on the transmission of the first terminal device 110 and the influence on the transmission of the second terminal device 120 can be avoided.

[0120] 13 is a flowchart of an example method 1300 for determining whether to perform a second sidelink transmission from a second starting point according to some other embodiments of the present disclosure. Method 1300 may be implemented in a terminal device, such as one of first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. For illustrative purposes, and without loss of generality, method 1300 will be described as being performed by second terminal device 120 with reference to FIG. 1.

[0121] In method 1300, the first and second starting points may be configured or pre-configured for sidelink transmission within slot #n. For simplicity, first terminal device 110 may also be referred to as first UE 110, second terminal device 110 may also be referred to as second UE 120, and third terminal device 130 may also be referred to as third UE 130.

[0122] In block 1310, the second terminal device 120 blindly detects the SCI from the first starting point in slot #n.

[0123] In block 1320, the second terminal device 120 determines whether a first SCI transmitted by the first terminal device 110 from the first starting point and a third SCI transmitted by the third terminal device 130 from the first starting point are detected, and determines whether there are available resources in the frequency domain in the sidelink resource pool based on at least one of the SCIs.

[0124] In some embodiments, the first SCI may indicate a first priority of a first sidelink transmission from the first terminal device 110.

[0125] In some embodiments, the third SCI may indicate a third priority of a third sidelink transmission from the third terminal device 130.

[0126] If the first SCI and the third SCI from the first starting point are detected and there are available resources in the frequency domain, the second terminal device 120 determines in block 1330 whether the second priority of the second sidelink transmission is greater than or equal to the first priority and whether the second priority is greater than or equal to the third priority.

[0127] If the second priority is greater than or equal to the first priority and if the second priority is greater than or equal to the third priority, the second terminal device 120 may determine in block 1340 to perform a second sidelink transmission from a second starting point on at least one of the available resources.

[0128] On the other hand, if the second terminal device 120 determines in block 1330 that the second priority is lower than the first priority and / or that the second priority is lower than the third priority, the second terminal device 120 may determine in block 1350 not to perform the second sidelink transmission from the second starting point on at least one of the available resources.

[0129] Furthermore, if the second terminal device 120 determines in block 1320 that the first SCI and the third SCI from the first starting point have not been detected and / or there are no available resources in the frequency domain, the second terminal device 120 may determine in block 1350 not to perform a second sidelink transmission from the second starting point on at least one of the available resources.

[0130] The method 1300 can ensure sidelink transmissions with higher priority.

[0131] In some embodiments, if the second priority of the second sidelink transmission is greater than or equal to the priority threshold, the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on at least one of the available resources.

[0132] In some embodiments, the second terminal device 120 may determine to perform a second sidelink transmission from a second starting point on at least one of the available resources if the first ratio is equal to or greater than a first ratio threshold. The first ratio is equal to the number of available resources divided by the number of frequency-domain resources in the sidelink resource pool. For example, the first ratio threshold may be equal to 20%. Such embodiments provide greater flexibility in controlling transmissions on additional starting points.

[0133] In some embodiments, the second terminal device 120 may determine to perform a second sidelink transmission from a second starting point on at least one of the available resources if the second ratio is greater than or equal to a second ratio threshold. The second ratio is equal to the number of available resources divided by the number of occupied resources in the frequency domain in the sidelink resource pool. Such embodiments provide more flexibility in controlling transmissions on additional starting points.

[0134] In some embodiments, the second terminal device 120 may determine to perform a second sidelink transmission from a second starting point on at least one of the available resources if the third ratio is less than or equal to a third ratio threshold. The third ratio is equal to the number of occupied resources divided by the number of frequency-domain resources in the sidelink resource pool. Such embodiments provide more flexibility in controlling transmissions on additional starting points.

[0135] In some embodiments, a first of the at least one of the SCIs includes a first indication indicating whether a second starting point is enabled. In such embodiments, if the first indication indicates that the second starting point is enabled, the second terminal device 120 may determine to perform a second sidelink transmission from the second starting point on at least one of the available resources, thereby ensuring a higher priority sidelink transmission.

[0136] In some embodiments, the first SCI may use SCI format 1-B, which may include an "additional start symbol enable" indicator (i.e., a first indication) as shown in Table 1. [Table 1]

[0137] As shown in Table 1, the overhead of the "enable additional start symbols" indicator is 1 bit. If the "enable additional start symbols" indicator is set to "1", the additional start symbols can be used by other terminal devices. If the "enable additional start symbols" indicator is set to "0", sidelink transmissions from the additional start symbols (i.e., the second start symbol) in the slot are not allowed. Operation of a second terminal device transmitting from an additional origin

[0138] As noted above, in some embodiments, the second starting point is the second starting symbol in the slot, and in such embodiments, the second terminal 120 may perform symbol repetition for the second starting symbol.

[0139] In some embodiments, to perform symbol repetition for the second start symbol, second terminal device 120 may repeat a signal on the fourth symbol immediately following the second start symbol with the second start symbol. If the second start symbol is symbol #n and the fourth symbol is symbol #n+1, second terminal device 120 may repeat a signal on symbol #n+1 with symbol #n. "Repeat" means that resource elements used for the PSCCH / PSSCH of second terminal device 120 on symbol #n+1, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n+1, should be duplicated on the immediately preceding symbol #n. This will be described with reference to FIG. 14A.

[0140] 14A illustrates an example of symbol repetition for a second start symbol according to some embodiments of the present disclosure. In the example of FIG. 14A, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #5.

[0141] The second terminal device 120 determines to transmit from the second start symbol, i.e., symbol #5. The second terminal device 120 uses the second start symbol as an AGC symbol. That is, the second terminal device 120 repeats the signal on symbol #6, including the PSCCH and PSSCH, at symbol #5.

[0142] In some embodiments, to perform symbol repetition for the second starting symbol, second terminal device 120 may repeat the signal on the second starting symbol with the third symbol immediately preceding the second starting symbol. If the second starting symbol is symbol #n and the third symbol is symbol #n-1, second terminal device 120 may repeat the signal on symbol #n with symbol #n-1. "Repeat" means that resource elements used for the PSCCH / PSSCH of second terminal device 120 on symbol #n, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n, should be duplicated on the immediately preceding symbol #n-1.

[0143] In some embodiments, to perform a second sidelink transmission from a second starting point, the second terminal device 120 may transmit an extension signal on a third symbol immediately preceding the second starting symbol, as will be described with reference to FIG. 14B.

[0144] 14B shows an example of an extended signal for a second start symbol according to some embodiments of the present disclosure. In the example of FIG. 14B, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #5.

[0145] The second terminal device 120 may attempt to perform a Type 2A CA procedure to access the channel before the second start symbol, i.e., symbol #5. If the CA is successful, the second terminal device 120 performs a second sidelink transmission with a Cyclic Prefix Extension (CPE) signal from symbol #5. The duration of the CPE signal is equal to (symbol length - 25 μs).

[0146] If the CA procedure fails, the second terminal device 120 drops the second sidelink transmission.

[0147] In some embodiments, the second terminal device 120 determines the duration of the extended signal as: configuration, Pre-configuration, the type of channel access procedure used by the second terminal device 120; the duration of the second start symbol, or a time gap associated with the channel access procedure.

[0148] In some embodiments, the second terminal device 120 may transmit the second SCI on a PSCCH resource associated with the second starting point.

[0149] In some embodiments, the PSCCH resource includes a first number of consecutive symbols in a slot. The first number of consecutive symbols may start from a second starting point. Alternatively, the first number of consecutive symbols may start from the fourth symbol immediately after the second starting point. In the following, this first number may be represented by m.

[0150] In some embodiments, the first number (m) may be configured or preset, for example, m equals the number of symbols for the PSCCH resources used by first terminal device 110, i.e., the legacy PSCCH resources.

[0151] In some embodiments, the PSCCH resource includes a fourth number of RBs in a slot, which may start with the lowest RB of each subchannel, and hereinafter this fourth number may be denoted by s.

[0152] In some embodiments, the fourth number (s) may be configured or preset, for example, s may be equal to the number of RBs for the PSCCH resources used by first terminal device 110, i.e., the legacy PSCCH resources.

[0153] 15A and 15B each show an example of a PSCCH resource associated with a second starting symbol according to some embodiments of the present disclosure. In the examples of FIGS. 15A and 15B, M represents the number of symbols for the PSCCH resource associated with the first starting symbol, S represents the number of RBs for the PSCCH resource associated with the first starting symbol, m represents the number of symbols for the PSCCH resource associated with the second starting symbol, and s represents the number of RBs for the PSCCH resource associated with the second starting symbol. m = M = 3, and s = S = 15. The second starting symbol is symbol #7. Second terminal device 120 transmits SCI format 1 (i.e., the second SCI) using the PSCCH resource associated with the second starting symbol.

[0154] In the example of Figure 15A, the PSCCH resource associated with the second starting symbol (also referred to as the "additional PSCCH") includes symbols #8 to #10, with the signal on symbol #7 being duplicated from symbol #8.

[0155] In the example of Figure 15B, the PSCCH resource associated with the second starting symbol (also referred to as the "additional PSCCH") includes symbols #7 to #9, with the signal on symbol #6 being duplicated from symbol #7.

[0156] The examples of Figures 15A and 15B define PSCCH resources used by the second terminal device 120 and reuse the legacy sidelink scheme to show sidelink control information by the second terminal device 120.

[0157] In some embodiments, the second terminal device 120 may determine a second number of resource elements (RE) allocated for the second sidelink transmission within the physical resource block as: the number of subcarriers in a physical resource block; the number of Sidelink symbols in the slot, Physical sidelink feedback channel (PSFCH) resource overhead, the symbol offset between the first and second starting points; Channel-state information Reference Signal (CSI-RS) and Phase-tracking reference signal (PT-RS) overhead, or Demodulation Reference Signal (DM-RS) overhead.

[0158] For example, the second terminal device 120 may determine the second number of REs as follows.

number

[0159] The second terminal device 120 may then determine the total number of REs allocated for the second sidelink transmission based on the second number of REs.

[0160] For example, the second terminal device 120 may determine the total number of REs allocated for the second sidelink transmission as follows:

[0161]

number

[0162] Consider an example of determining the total number of REs allocated for the second sidelink transmission. In this example, the first starting symbol is set as symbol #0 and the second starting symbol is set as symbol #5. If there are no PSFCH resources configured in the sidelink resource pool, i.e., N symb PSFCH = 0. The second terminal device 120 may use the number of symbols available for the PSSCH to determine the total number of REs allocated for the second sidelink transmission (i.e., the TB size transmitted on the slot), i.e., N, as follows:

number

[0163] As mentioned above, in some embodiments, the second starting point is the second starting symbol in the slot. In such embodiments, the first terminal device 110 may perform symbol repetition, which can avoid AGC problems caused by the second starting symbol.

[0164] In some embodiments, to perform symbol repetition, first terminal device 110 may repeat the signal on the third symbol to the second starting symbol. The third symbol is immediately before the second starting symbol. If the second starting symbol is symbol #n and the third symbol is symbol #n-1, first terminal device 110 may repeat the signal on symbol #n-1 to symbol #n. By "repeat," we mean that resource elements used for the PSCCH / PSSCH of first terminal device 110 on symbol #n-1, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n-1, should be duplicated to symbol #n. This will be described with reference to FIG. 16A.

[0165] FIG. 16A shows an example of symbol repetition for a second start symbol according to some embodiments of the present disclosure. In the example of FIG. 16A, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #7. The first terminal device 110 may repeat the signal on symbol #6 to symbol #7. The second start symbol is a repetition of the previous symbol.

[0166] In some embodiments, to perform symbol repetition, the first terminal device 110 may repeat the signal on the second starting symbol to the third symbol. The third symbol is located immediately before the second starting symbol. If the second starting symbol is symbol #n and the third symbol is symbol #n-1, the first terminal device 110 may repeat the signal on symbol #n to symbol #n-1. By "repeat," we mean that the resource elements used for the PSCCH / PSSCH of the first terminal device 110 on symbol #n, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n, should be duplicated in the immediately preceding symbol #n-1. This will be described with reference to FIG. 16B.

[0167] 16B shows an example of symbol repetition for the second start symbol according to some other embodiments of the present disclosure. In the example of FIG. 16B, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #7. The first terminal device 110 may repeat the signal on symbol #7 to symbol #6.

[0168] In some embodiments, to perform symbol repetition, first terminal device 110 may repeat the signal on the second starting symbol to the fourth symbol immediately following the second starting symbol. If the second starting symbol is symbol #n and the fourth symbol is symbol #n+1, first terminal device 110 may repeat the signal on symbol #n to symbol #n+1. By "repeat," we mean that resource elements used for the PSCCH / PSSCH of first terminal device 110 on symbol #n, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n, should be duplicated on symbol #n+1. This will be described with reference to FIG. 16C.

[0169] 16C shows an example of symbol repetition for a second start symbol according to yet another embodiment of the present disclosure. In the example of FIG. 16C, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #5. The first terminal device 110 may repeat the signal on symbol #5 to symbol #6. The second start symbol is duplicated to the next symbol.

[0170] In some embodiments, to perform symbol repetition, first terminal device 110 may repeat the signal on the fourth symbol to the second start symbol. The fourth symbol immediately follows the second start symbol. If the second start symbol is symbol #n and the fourth symbol is symbol #n+1, first terminal device 110 may repeat the signal on symbol #n+1 to symbol #n. By "repeat," we mean that resource elements used for the PSCCH / PSSCH of first terminal device 110 on symbol #n+1, including any DM-RS, PT-RS, or CSI-RS occurring on symbol #n+1, should be duplicated to symbol #n. This will be described with reference to FIG. 16D.

[0171] 16D shows an example of symbol repetition for a second start symbol according to yet another embodiment of the present disclosure. In the example of FIG. 16D, two start symbols are set or preset within a slot. The first start symbol is symbol #0. The second start symbol is symbol #5. The first terminal device 110 may repeat the signal on symbol #6 to symbol #5.

[0172] In some embodiments, the first terminal device 110 may transmit an SCI on a PSCCH resource associated with the first starting point. a first indication of whether the second starting point is enabled; or a second indication of whether symbol repetition for the second starting point is enabled or not.

[0173] In some embodiments, the SCI may use SCI Format 1x or SCI Format 2x. For example, as shown in Table 2, SCI Format 1-B may include a "repeat indicator" (i.e., the second instruction) and an "enable additional start symbol" indicator (i.e., the first instruction). [Table 2]

[0174] In Table 2, the overhead of the "Repetition Indicator" is 1 bit. When the "Repetition Indicator" is set to "1", symbol repetition for the second starting point is enabled, i.e., symbol repetition for the second starting point is performed by the first terminal device 110. When the "Repetition Indicator" is set to "0", symbol repetition for the second starting point is disabled, i.e., symbol repetition for the second starting point is not performed by the first terminal device 110.

[0175] Furthermore, in Table 2, the overhead of the "enable additional start symbols" indicator is 1 bit. If the "enable additional start symbols" indicator is set to "1", the additional start symbols can be used by other terminal devices. If the "enable additional start symbols" indicator is set to "0", no sidelink transmission is allowed from the additional start symbols (i.e., the second start symbol) in the slot.

[0176] As shown in Table 2, the first terminal device 110 indicates that the second starting symbol is unavailable and that repetition will not be performed for the second starting symbol, which provides flexibility in processing additional starting symbols depending on the requirements of the first terminal device 110 and the channel conditions.

[0177] As mentioned above, first terminal device 110 may perform symbol repetition. When symbol repetition is performed, it means that the actual number of symbols for transmission of first terminal device 110 is changed (decremented by 1). Therefore, the TB size determination of first terminal device 110 should be modified accordingly.

[0178] In some embodiments, the first terminal device 110 may determine a third number of REs allocated for the first sidelink transmission in the physical resource block as: the number of subcarriers in a physical resource block; the number of Sidelink symbols in the slot, PSFCH resource overhead, the overhead of the second starting point in slots, CSI-RS and PT-RS overhead, or the overhead of the DM-RS.

[0179] For example, the first terminal device 110 may determine the third number of REs as follows.

number

[0180] The first terminal device 110 may then determine the total number of REs allocated for the first sidelink transmission based on the third number of REs, thereby ensuring that the sidelink TB sizing scheme is consistent with the additional starting symbol allocation and associated repetitions for the additional symbols.

[0181] For example, the first terminal device 110 may determine the total number of REs allocated for the first sidelink transmission as follows:

number

[0182] Consider an example of determining the total number of REs used for a first sidelink transmission. In this example, two start symbols are configured in one slot, i.e., k=1. The SCI format 1-B of the first terminal device 110 indicates that symbol repetition of the second start symbol is enabled.

[0183] The first terminal device 110 may then use the number of symbols available for the PSSCH to determine the total number of REs used for the first sidelink transmission in the slot, i.e., N, as follows:

number

[0184] 17 is a flowchart of an exemplary method according to some embodiments of the present disclosure. In some embodiments, method 1700 may be implemented in a communications device, such as one of first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. For purposes of illustration, and without loss of generality, method 1700 will be described as being performed by second terminal device 120 with reference to FIG. 1.

[0185] In block 1710, the second terminal device 120 determines whether to perform a second sidelink transmission from a second starting point within the slot based on the detection of the SCI transmitted from the first starting point within the slot, the second starting point following the first starting point.

[0186] In block 1720, if a second sidelink transmission is to be performed, the second terminal device 120 performs the second sidelink transmission from a second starting point.

[0187] In some embodiments, the determining whether to perform the second sidelink transmission from the second starting point may involve the second terminal device 120 determining to perform the second sidelink transmission from the second starting point if the SCI transmitted from the first starting point is not detected.

[0188] In some embodiments, the second terminal device 120 may determine whether to perform the second sidelink transmission from the second starting point including, if at least one of the SCIs transmitted from the first starting point is detected and there are available resources in the frequency domain in the sidelink resource pool based on the at least one of the SCIs, the second terminal device 120 may determine to perform the second sidelink transmission from the second starting point on at least one of the available resources.

[0189] In some embodiments, the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on the at least one of the available resources including determining to perform the second sidelink transmission from a second starting point on the at least one of the available resources if the second terminal device 120 is not a target receiving device for the first sidelink transmission from the first terminal device 110 and the first terminal device 110 is not a target receiving device for the second sidelink transmission.

[0190] In some embodiments, the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on the at least one of the available resources if a second priority of the second sidelink transmission is equal to or greater than the first priority of the first sidelink transmission from the first terminal device 110.

[0191] In some embodiments, the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on the at least one of the available resources if a second priority of the second sidelink transmission is greater than or equal to a priority threshold.

[0192] In some embodiments, the determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources may include determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources if the first ratio is greater than or equal to a first ratio threshold. In some embodiments, the first ratio is equal to the number of available resources divided by the number of resources in the frequency domain in the sidelink resource pool.

[0193] In some embodiments, the determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources may include determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources if the second ratio is greater than or equal to a second ratio threshold. In some embodiments, the second ratio is equal to the number of available resources divided by the number of occupied resources in the frequency domain in the sidelink resource pool.

[0194] In some embodiments, the determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources may include determining by the second terminal device 120 to perform the second sidelink transmission from the second starting point on the at least one of the available resources if a third ratio is less than or equal to a third ratio threshold. In some embodiments, the third ratio is equal to the number of occupied resources divided by the number of resources in the frequency domain in the sidelink resource pool.

[0195] In some embodiments, a first SCI of the at least one of the SCIs includes a first indication of whether the second starting point is enabled.

[0196] In some embodiments, the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on the at least one of the available resources includes the second terminal device 120 may determine to perform the second sidelink transmission from a second starting point on the at least one of the available resources if the first indication indicates that the second starting point is enabled.

[0197] In some embodiments, the second starting point is the second starting symbol in the slot.

[0198] In some embodiments, performing the second sidelink transmission from the second starting point includes performing symbol repetition for the second starting symbol.

[0199] In some embodiments, performing symbol repetition for the second starting symbol includes at least one of repeating a signal on the second starting symbol with a third symbol immediately preceding the second starting symbol, or repeating a signal on a fourth symbol immediately following the second starting symbol with the second starting symbol.

[0200] In some embodiments, performing the second sidelink transmission from the second starting point includes transmitting the extension signal on a third symbol immediately preceding the second starting symbol.

[0201] In some embodiments, the duration of the expansion signal is: · setting, Pre-configuration, the type of channel access procedure used by the second terminal device 120; the duration of the second start symbol, or a time gap associated with the channel access procedure.

[0202] In some embodiments, performing the second sidelink transmission from the second starting point includes transmitting the second SCI on Physical Sidelink Control Channel (PSCCH) resources associated with the second starting point.

[0203] In some embodiments, the PSCCH resource includes a first number of consecutive symbols in a slot. In some embodiments, the first number of consecutive symbols begins at a second starting point. In some embodiments, the first number of consecutive symbols begins at the fourth symbol immediately after the second starting point.

[0204] In some embodiments, performing the second sidelink transmission from the second starting point comprises: the number of subcarriers in a physical resource block; the number of Sidelink symbols in the slot, Physical sidelink feedback channel (PSFCH) resource overhead, the symbol offset between the first and second starting points; Channel state information reference signal and phase tracking reference signal overhead, or demodulation reference signal overhead.

[0205] In such embodiments, performing the second sidelink transmission from the second starting point includes determining a total number of resource elements allocated for the second sidelink transmission based on the second number of resource elements.

[0206] In some embodiments, the second terminal device 120 may determine whether to perform the second sidelink transmission based on the configuration.

[0207] In some embodiments, the setting is: The second starting symbol index, the symbol offset between the first and second starting points; a first indication of whether the second starting point is enabled; a second indication of whether symbol repetition for the second starting point is enabled; a third indication indicating that the second starting point is not used in a slot that includes a Physical Sidelink Feedback Channel (PSFCH) resource; a priority threshold associated with the second starting point; a Channel Access Priority Class (CAPC) threshold associated with the second starting point; a first ratio threshold associated with a second starting point; a second ratio threshold associated with a second starting point; a third ratio threshold associated with the second starting point; the duration of the extension signal associated with the second starting point, or a first number of consecutive symbols in a slot for transmitting a second SCI by a second terminal device.

[0208] 18 is a flowchart of an exemplary method according to some embodiments of the present disclosure. In some embodiments, method 1800 may be implemented in a communications device, such as one of first terminal device 110, second terminal device 120, and third terminal device 130 as shown in FIG. 1. For purposes of explanation, and without loss of generality, method 1800 will be described with reference to FIG. 1 as being performed by first terminal device 110.

[0209] In block 1810, the first terminal device 110 obtains a setting for a second starting point within the slot, the second starting point following the first starting point within the slot.

[0210] In block 1820, the first terminal device 110 performs a first sidelink transmission from a first sidelink starting point based on the configuration.

[0211] In some embodiments, the setting is: The second starting symbol index, the symbol offset between the first and second starting points; a first indication of whether the second starting point is enabled; a second indication of whether symbol repetition for the second starting point is enabled; a third indication indicating that the second starting point is not used in a slot that includes a Physical Sidelink Feedback Channel (PSFCH) resource; a priority threshold associated with the second starting point; a Channel Access Priority Class (CAPC) threshold associated with the second starting point; a first ratio threshold associated with a second starting point; a second ratio threshold associated with a second starting point; a third ratio threshold associated with the second starting point; the duration of the extension signal associated with the second starting point, or a first number of consecutive symbols in a slot for transmitting the second SCI by the second terminal device.

[0212] In some embodiments, the second starting point is the second starting symbol in the slot.

[0213] In some embodiments, performing the first sidelink transmission comprises performing symbol repetition, wherein the performing symbol repetition comprises: Repeating the signal on the third symbol immediately preceding the second starting symbol into the second starting symbol; Repeating the signal on the second starting symbol into the third symbol; Repeating the signal on the second starting symbol into the fourth symbol immediately following the second starting symbol, or repeating the signal on the fourth symbol to the second starting symbol.

[0214] In some embodiments, performing the first sidelink transmission from the first starting point includes transmitting an SCI on Physical Sidelink Control Channel (PSCCH) resources associated with the first starting point. In some embodiments, the SCI includes at least one of: a first indication indicating whether a second starting point is enabled; or a second indication indicating whether symbol repetition for the second starting point is enabled.

[0215] In some embodiments, performing the first sidelink transmission comprises: the number of subcarriers in a physical resource block; the number of Sidelink symbols in the slot, Physical sidelink feedback channel (PSFCH) overhead, the overhead of the second starting point in slots, Channel state information reference signal and phase tracking reference signal overhead, or demodulation reference signal overhead.

[0216] In such embodiments, performing the first sidelink transmission includes determining a total number of resource elements allocated for the first sidelink transmission based on the third number of resource elements.

[0217] 19 is a schematic block diagram of an apparatus 1900 suitable for implementing some embodiments of the present disclosure. The apparatus 1900 may be considered as another exemplary embodiment of one of the terminal devices 110, 120, and 130 or one of the network devices 140 and 150 shown in FIG. 1. Thus, the apparatus 1900 may be implemented in, or as at least a part of, one of the terminal devices 110, 120, and 130 or one of the network devices 140 and 150.

[0218] As shown, the apparatus 1900 comprises a processor 1910, a memory 1920 coupled to the processor 1910, a suitable transmitter (TX) and receiver (RX) 1940 coupled to the processor 1910, and a communication interface coupled to the TX / RX 1940. The memory 1920 stores at least a portion of a program 1930. The TX / RX 1940 is used for bidirectional communication. The TX / RX 1940 has at least one antenna to facilitate communication, although the access nodes referred to herein may in practice have multiple antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between gNBs or eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, an Un interface for communication between a gNB or eNB and a relay node (RN), or an Un interface for communication between a gNB or eNB and a terminal device.

[0219] The program 1930 is envisioned to include program instructions that, when executed by an associated processor 1910, enable the device 1900 to operate according to embodiments of the present disclosure, as described herein with reference to FIGS. 1-18 . The embodiments herein may be implemented by computer software executable by the processor 1910 of the device 1900, by hardware, or by a combination of software and hardware. The processor 1910 may be configured to implement various embodiments of the present disclosure. Furthermore, the combination of the processor 1910 and the memory 1920 may form a processing means 1950 suitable for implementing various embodiments of the present disclosure.

[0220] Memory 1920 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, including, by way of non-limiting example, 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. While only one memory 1920 is shown in device 1900, there may be several physically distinct memory modules within device 1900. Processor 1910 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 1900 may have multiple processors, for example, application-specific integrated circuit chips time-slaved to a clock that synchronizes the main processor.

[0221] Components included in the devices and / or apparatus of the present disclosure may be implemented in various ways, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be implemented using software and / or firmware, such as machine-executable instructions stored on a storage medium. In addition to, or instead of, machine-executable instructions, some or all of the units in the devices and / or apparatus may be implemented, at least in part, by one or more hardware logic components. By way of example and not limitation, exemplary types of hardware logic components that may be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-chips (SOCs), complex programmable logic devices (CPLDs), etc.

Claims

1. A method of communication comprising: determining, in the second terminal device, based on detection of sidelink control information (SCI) transmitted from a first starting point within a slot, whether to perform a second sidelink transmission from a second starting point within the slot subsequent to the first starting point; performing the second sidelink transmission from the second starting point in accordance with the determination that the second sidelink transmission is to be performed; and A method comprising:

2. determining whether to perform the second sidelink transmission from the second starting point comprises: determining, in accordance with determining that the SCI transmitted from the first starting point has not been detected, to perform the second sidelink transmission from the second starting point. The method of claim 1.

3. determining whether to perform the second sidelink transmission from the second starting point comprises: and upon determining that at least one of the SCIs transmitted from the first starting point is detected and that there are available resources in the frequency domain in a sidelink resource pool based on the at least one of the SCIs, determining to perform the second sidelink transmission from the second starting point on at least one of the available resources. The method of claim 1.

4. determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources comprises: upon determining that the second terminal device is not a target receiver of a first sidelink transmission from a first terminal device and that the first terminal device is not a target receiver of the second sidelink transmission, determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources. The method of claim 3.

5. determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources comprises: upon determining that the second priority of the second sidelink transmission is equal to or greater than the first priority of the first sidelink transmission from the first terminal device, determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources. The method of claim 3.

6. determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources comprises: upon determining that the second priority of the second sidelink transmission is greater than or equal to a priority threshold, determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources. The method of claim 3.

7. determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources comprises: upon determining that a first ratio equal to the number of available resources divided by the number of resources in the frequency domain in the sidelink resource pool is greater than or equal to a first ratio threshold; determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources; upon determining that a second ratio equal to the number of available resources divided by the number of occupied resources in the frequency domain in the sidelink resource pool is greater than or equal to a second ratio threshold; determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources; or upon determining that a third ratio, equal to the number of occupied resources divided by the number of resources in the frequency domain in the sidelink resource pool, is less than or equal to a third ratio threshold; determining to perform the second sidelink transmission from the second starting point on the at least one of the available resources. The method of claim 3.

8. The second starting point is the second starting symbol in the slot. The method of claim 1.

9. performing the second sidelink transmission from the second starting point repeating the signal on the second starting symbol in a third symbol immediately preceding the second starting symbol; or repeating a signal on a fourth symbol immediately following the second start symbol with the second start symbol. performing symbol repetition on the second starting symbol. The method of claim 8.

10. performing the second sidelink transmission from the second starting point a second number of resource elements allocated for the second sidelink transmission within a physical resource block; the number of subcarriers in the physical resource block; the number of sidelink symbols in the slot; Physical sidelink feedback channel (PSFCH) resource overhead; a symbol offset between the first starting point and the second starting point; Channel state information reference signal and phase tracking reference signal overhead, or demodulation reference signal overhead; and determining a total number of resource elements allocated for the second sidelink transmission based on the second number of resource elements. The method of claim 1.

11. determining whether to perform the second sidelink transmission from the second starting point comprises: determining whether to perform the second sidelink transmission based on a configuration, the configuration including: a symbol index of the second starting point; a symbol offset between the first starting point and the second starting point; a first indication of whether the second starting point is enabled; a second indication of whether symbol repetition for the second starting point is enabled; a third indication indicating that the second starting point is not used in a slot containing Physical Sidelink Feedback Channel (PSFCH) resources; a priority threshold associated with the second starting point; a Channel Access Priority Class (CAPC) threshold associated with the second starting point; a first ratio threshold associated with the second starting point; a second ratio threshold associated with the second starting point; a third ratio threshold associated with the second starting point; the duration of the extension signal associated with the second starting point; or a first number of consecutive symbols in the slot for transmitting second sidelink control information (SCI) by the second terminal device. The method of claim 1.

12. A method of communication comprising: obtaining, at a first terminal device, a setting for a second starting point within the slot that follows a first starting point within the slot; performing a first sidelink transmission from a first sidelink start point based on the configuration; and A method comprising:

13. The setting is: a symbol index of the second starting point; a symbol offset between the first starting point and the second starting point; a first indication of whether the second starting point is enabled; a second indication of whether symbol repetition for the second starting point is enabled; a third indication indicating that the second starting point is not used in a slot containing Physical Sidelink Feedback Channel (PSFCH) resources; a priority threshold associated with the second starting point; a Channel Access Priority Class (CAPC) threshold associated with the second starting point; a first ratio threshold associated with the second starting point; a second ratio threshold associated with the second starting point; a third ratio threshold associated with the second starting point; the duration of the extension signal associated with the second starting point; or a first number of consecutive symbols in the slot for transmitting second sidelink control information (SCI) by the second terminal device. The method of claim 12.

14. The second starting point is the second starting symbol in the slot. The method of claim 12.

15. performing the first sidelink transmission repeating a signal on a third symbol immediately preceding the second start symbol with the second start symbol; repeating the signal on the second starting symbol in the third symbol; repeating the signal on the second starting symbol in a fourth symbol immediately following the second starting symbol; or repeating the signal on the fourth symbol with the second starting symbol. performing symbolic repetition, 15. The method of claim 14, comprising:

16. performing the first sidelink transmission from the first starting point transmitting a SCI on a Physical Sidelink Control Channel (PSCCH) resource associated with the first starting point, the SCI comprising: a first indication of whether the second starting point is enabled; or a second indication of whether symbol repetition for the second starting point is enabled or not. The method of claim 12.

17. performing the first sidelink transmission a third number of resource elements allocated for the first sidelink transmission within a physical resource block; the number of subcarriers in the physical resource block; the number of sidelink symbols in the slot; Physical sidelink feedback channel (PSFCH) resource overhead; overhead of the second starting point within the slot; Channel state information reference signal and phase tracking reference signal overhead, or demodulation reference signal overhead; and determining a total number of resource elements allocated for the first sidelink transmission based on the third number of resource elements. The method of claim 12.

18. a processor; a memory coupled to the processor and storing instructions, The instructions, when executed by the processor, perform the method of any one of claims 1 to 11. Terminal device.

19. a processor; a memory coupled to the processor and storing instructions, The instructions, when executed by the processor, perform the method of any one of claims 12 to 17. Terminal device.

20. storing instructions which, when executed on at least one processor of a device, cause said device to carry out the method of any one of claims 1 to 11 or any one of claims 12 to 17; Computer-readable medium.

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