Terminal device and method executed by the terminal device

Abstract

FIELD OF THE DISCLOSURE The present disclosure relates to communication. According to the present disclosure, a first terminal device receives a configuration for sidelink transmission from a network device. The configuration indicates a start symbol of sidelink transmission. The first terminal device performs a clear channel assessment for sidelink transmission. If CCA is successful, the first terminal device transmits a sidelink signal based on a length between CCA completion and the start symbol. In this way, resource efficiency is improved. Also, access capability can be improved.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and in particular, to methods, apparatuses, and computer-readable media for communication.

Background Art

[0002] With the development of communication technologies, various communication scenarios have been proposed. For example, sidelink communication has been proposed. Sidelink is a special communication mechanism between devices without going through a network device. The technology of "sidelink" can be applied to various scenarios such as, for example, V2V (vehicle-to-vehicle), V2X (Vehicle-to-Everything), etc.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Generally, exemplary embodiments of the present disclosure provide a solution for communication.

Means for Solving the Problems

[0004] In a first aspect, a communication method is provided. The communication method includes, at a first terminal device, receiving, from a network device, a sidelink transmission setting indicating a start symbol of sidelink transmission; performing a CCA (Clear Channel Assessment) for sidelink transmission; and transmitting, to a second terminal device, a sidelink signal including a cyclic prefix extension of a first symbol after the start symbol, according to a determination that the CCA is successful.

[0005]

[0006] In a second aspect, a communication method is provided. The communication method includes transmitting, at a second terminal device, a signal within a guard symbol in sidelink transmission in a shared spectrum.In a third aspect, a terminal device is provided. The terminal device includes a processor unit and a memory coupled to the processor unit and storing instructions. When the instructions are executed by the processor unit, the first terminal device is caused to perform operations. The operations include, at the first terminal device, receiving from a network device a configuration for side-link transmission indicating a start symbol of the side-link transmission, performing a CCA (Clear Channel Assessment) for the side-link transmission, and transmitting, according to a determination that the CCA is successful, a side-link signal including a cyclic prefix extension of a first symbol after the start symbol to a second terminal device.

[0007] In a fourth aspect, a terminal device is provided. The terminal device includes a processor unit and a memory coupled to the processor unit and storing instructions. When the instructions are executed by the processor unit, the second terminal device is caused to perform operations. The operations include transmitting a signal within a guard symbol in side-link transmission in a shared spectrum at the second terminal device.

[0008] In a fifth aspect, a computer-readable medium storing instructions is provided. When the instructions are executed in at least one processor, the at least one processor is caused to execute a method according to the first aspect or the second aspect.

[0009] Other features of the present disclosure should be readily understood through the following description.

Brief Description of the Drawings

[0010] Through a more detailed description of some exemplary embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure should become clearer.

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[0024] Throughout all the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and are useful for those skilled in the art to understand and implement the present disclosure, and do not imply any limitation to the scope of the present disclosure. The present disclosure described herein can be implemented in various ways other than those described below.

[0026] In the following description and claims, unless otherwise defined, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present disclosure belongs.

[0027] As used herein, the term "network device" refers to a device capable of providing or hosting a cell or coverage with which a terminal device can communicate. Examples of network devices include, but are not limited to, Node B (NodeB or NB), Evolved NodeB (eNodeB or eNB), NodeB for new radio access (gNB), Remote Radio Unit (RRU), Radio Head (RH), Remote Radio Head (RRH), femto node, low-power nodes such as pico nodes, satellite network devices, aircraft network devices, etc. Hereinafter, for the purpose of discussion, some exemplary embodiments will be described with reference to eNB as an example of a network device.

[0028] As used herein, the term "terminal device" refers to any device having a wireless or wired communication function. Examples of terminal devices include, but are not limited to, user equipment (UE), personal computer, desktop, mobile phone, cellular phone, smartphone, personal digital assistant (PDA), portable computer, tablet, wearable device, Internet of Things (IoT) device, Internet of Everything (IoE) device, machine type communication (MTC) device, vehicle-mounted device for V2X communication (where X means pedestrian, vehicle or infrastructure / network), imaging device such as digital camera, game device, music storage / playback device, Internet device enabling wireless / wired Internet access and browsing, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user terminal", "UE" may be used interchangeably.

[0029] The communications discussed in this specification may conform to any suitable standard, including but not limited to New Radio (NR), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for Mobile Communications (GSM). Further, the communications may be performed according to any generation of communication protocol known currently or developed in the future. Examples of communication protocols include, but are not limited to, the communication protocols of the first generation (1G), second generation (2G), 2.5G, 2.95G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), 5G-Advanced, and sixth generation (6G). The technologies described in this specification may be used not only for the above wireless networks and wireless technologies but also for other wireless networks and wireless technologies.

[0030] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "including" and its variations are to be construed as an open-ended term meaning "including but not limited to". The term "based on" is construed as "based at least in part on". The terms "one embodiment" and "an embodiment" are construed as "at least one embodiment". The term "another embodiment" is construed as "at least one other embodiment". The terms "first", "second", etc. may refer to different objects or the same object. There may be other explicit and implicit definitions included in the following content.

[0031] In some instances, a value, procedure, or device is referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It is understood that such descriptions are intended to indicate that a selection is possible from among a plurality of functional alternatives being used, and it will be understood that such a selection need not be better, smaller, higher, or more preferred than other selections.

[0032] As used herein, the term "circuit" may mean a hardware circuit and / or a combination of a hardware circuit and software. For example, a circuit may be an analog hardware circuit and / or a digital hardware circuit in combination with software / firmware. As a further example, a circuit may be any portion of a hardware processor with software, such as a digital signal processor, software, and memory that cooperate to cause a device such as a terminal device or a network device to perform various functions. In yet another example, a circuit may be a hardware circuit and / or a processor such as a microprocessor or a portion of a microprocessor that requires software / firmware for operation but may not have software present when not needed for operation. As used herein, the term circuit encompasses merely a hardware circuit or processor, or a portion of a hardware circuit or processor, and an implementation of software and / or firmware associated therewith (or therewith).

[0033] As described above, sidelink communication has been proposed. In the unlicensed band of sub-7 GHz, coexistence of NR with other systems is ensured through the Listen-Before-Talk (LBT) channel access mechanism. In this case, a UE attempting to perform sidelink transmission needs to first successfully complete an LBT check before it can start that same transmission. For the UE to pass the LBT check, it needs to observe that the channel is available during several consecutive Clear Channel Assessment (CCA) slots. In sub-7 GHz, the duration of these slots is 9 μs. The UE considers the channel to be available in a CCA slot if the measured power (i.e., the energy collected during the CCA slot) is below a threshold specified by the regulation (depending on the operating band and geographical area). As used herein, "Listen-Before-Talk (LBT)" refers to a technique used in wireless communication where a wireless transmitter first senses its wireless environment before starting transmission. A wireless device can use LBT to find a network in which it can operate or to find an available wireless channel for operation.

[0034] When a UE starts communication (i.e., when the UE acts as the initiating device), this UE must obtain the "right" to access the channel by applying the "extended" LBT procedure for a certain period of time represented as Channel Occupancy Time (COT) in the regulation (e.g., period 120 shown in FIG. 1). In this case, the channel must be considered idle during all periods of the contention window (CW) (e.g., shown as period 110 in FIG. 1). This "extended" LBT procedure is generally known as LBT Category 4 (LBT Cat.4). The term "sidelink" refers to the link between two terminal devices and enables device-to-device communication. As used herein, "TX UE" can refer to a UE that can transmit data to another UE when performing sidelink communication with the other UE. As used herein, "receiving (RX) UE" can refer to a UE that can receive data from another UE when performing sidelink communication with the other UE.

[0035] In the prior art, in the first orthogonal frequency division multiplexing (OFDM), the resource elements used for the physical sidelink shared channel (PSSCH) must be replicated to the OFDM symbol immediately preceding the first OFDM symbol. The first OFDM includes a demodulation reference signal (DMRS), a phase tracking reference signal (PTRS), or a channel state information reference signal (CSI-RS) generated in the first OFDM symbol. Further, the resource elements used for the physical sidelink control channel (PSCCH) in the first OFDM symbol must also be replicated to the immediately preceding OFDM symbol. The first OFDM symbol includes a DMRS, a PTRS, or a CSI-RS generated in the first OFDM symbol. Also, the UE shall not transmit the PSSCH in symbols not configured for sidelink. The symbols are configured for sidelink according to the upper layer parameters startSLsymbols and lengthSLsymbols. Here, startSLsymbols is the symbol index of the first symbol of the consecutive symbols of lengthSLsymbols configured for sidelink. Within a slot, the allocation of the PSSCH resources starts from symbol startSLsymbols + 1.

[0036] In the case of cyclic prefix (CP) extension (CPE) before transmission of at least a dynamically scheduled physical uplink shared channel (PUSCH), the CP extension is placed in the symbol immediately preceding the PUSCH allocation indicated by the start and length indicator value (SLIV). As used herein, "cyclic prefix (CP)" refers to the prefix of a symbol with a trailing repetition. The duration of the CP extension supported by the UE is 0 (i.e., no CP extension), C1 * symbol length (e.g., 25 us), C2 * symbol length (e.g., 16 us - timing advance (TA)), C3 * symbol length (e.g., 25 us - TA). For 15 kHz and 30 kHz subcarrier spacings (SCS), C1 can be set to 1. Also, for 60 kHz SCS, C1 can be set to 2. Several issues still need to be addressed. For example, are C2 / C3 fixed based on the TA of each subcarrier spacing or implicitly obtained, should the previous decision that restricts the resulting CP extension to less than one symbol of a given subcarrier spacing be relaxed, should this be applied to other UL transmissions, can the number of durations of CP extension that can be dynamically notified to the UE be set, etc.

[0037] Furthermore, the start position of sidelink transmission after LBT success is also not clear. If the symbol where LBT succeeds is not the indicated start symbol, the symbol length may not be satisfied. For example, LBT may succeed at a position after the physical slot, or LBT may succeed before the indicated start symbol. Additionally, it is necessary to study how to design the CPE before sidelink transmission considering the automatic gain control (AGC) symbol.

[0038] According to an embodiment of the present disclosure, a first terminal device receives a sidelink transmission setting from a network device. The setting indicates a start symbol of the sidelink transmission. The first terminal device performs a CCA (Clear Channel Assessment) for the sidelink transmission. When the CCA is successful, the first terminal device transmits a sidelink signal based on the length between the CCA completion and the start symbol. In this way, resource efficiency is improved. Also, the access capability can be improved.

[0039] FIG. 1 shows a schematic diagram of a communication system capable of implementing an embodiment of the present disclosure. A communication system 100, which is part of a communication network, includes terminal devices 110-1, 110-2, ···, 110-N, which can be collectively referred to as "terminal device 110". The number N can be any suitable integer. The terminal devices can communicate with each other via a sidelink.

[0040] The communication system 100 further includes a network device 120. The number of terminal devices and network devices shown in FIG. 1 is for illustrative purposes and does not imply any limitation.

[0041] Communication in the communication system 100 may be carried out in accordance with any suitable communication protocol. The communication protocol includes, but is not limited to, cellular communication protocols such as the first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), 5G-Advanced, and sixth generation (6G), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol known currently or developed in the future. Further, the communication may utilize any suitable wireless communication technology. The wireless communication technology includes, but is not limited to, Code Divided Multiple Address (CDMA), Frequency Divided Multiple Address (FDMA), Time Divided Multiple Address (TDMA), Frequency Divided Duplexer (FDD), Time Divided Duplexer (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple Access (OFDMA), and / or any other technology known currently or developed in the future.

[0042] Hereinafter, embodiments of the present disclosure will be described in detail. First, please refer to FIG. 2. FIG. 2 shows a signaling chart showing a process 200 between network devices according to some exemplary embodiments of the present disclosure. For the purpose of discussion only, the process 200 will be described with reference to FIG. 1. The process 200 may involve the terminal device 110-1, the terminal device 110-2, and the network device 120 (or the upper layer of the terminal device 110-1) shown in FIG. 1. For the purpose of explanation only, the terminal device 110-1 may be referred to as the first terminal device, and the terminal device 110-2 may be referred to as the second terminal device.

[0043] The network device 120 transmits the configuration of sidelink transmission to the terminal device 110-1 (2010). The configuration of sidelink transmission indicates one or more start symbols of sidelink transmission. Also, the configuration may indicate the length of the slot for sidelink transmission. Alternatively, or in addition, the configuration can indicate a resource set for sidelink transmission.

[0044] The terminal device 110-1 performs CCA for sidelink transmission (2020). For example, the terminal device 110-1 may measure the energy in the sidelink band / channel. If the measured energy is lower than the threshold energy, the CCA is successful. Note that the terminal device 110-1 can perform any suitable type of CCA. Alternatively, or in addition, the terminal device 110-1 may perform LBT in the sidelink band. Note that the terminal device 110-1 can perform any suitable operation to determine whether the sidelink band / channel is occupied. In some embodiments, the terminal device 110-1 can perform CCA if the CCA completion is within the symbol set within one slot.

[0045] When the CCA is successful, the terminal device 110-1 transmits a sidelink signal to the network device 120 based on the CCA completion and the start symbol (2030). The details of the transmission of the sidelink signal will be described with reference to FIGS. 3 to 8.

[0046] In some embodiments, if the CCA completion is within the start symbol and the remaining time within the start symbol is longer than a predetermined threshold, the terminal device 110-1 may transmit a sidelink signal after the CCA completion. The sidelink signal may include a part of the first symbol after the start symbol. For example, the sidelink signal may include a cyclic prefix extension of the first symbol. In some embodiments, the first symbol can be a symbol including the PSCCH. Note that the first symbol can be any suitable symbol. In this case, the sidelink signal does not include the AGC symbol. In other words, the conventional (legacy) AGC symbol is omitted in the sidelink signal. In this way, the resource efficiency and access capability are improved. As used herein, the "automatic gain control (AGC) symbol" can refer to a symbol including a replica of the first symbol after the start symbol. The AGC symbol can include any type of symbol that can be used for maintaining an appropriate signal amplitude.

[0047] Figure 3 shows a schematic block diagram of a sidelink slot according to some embodiments of the present disclosure. As shown in Figure 3, the sidelink slot 310 may include symbols 302-1, 302-2, 302-3, 302-4,..., 302-10, 302-11, 302-12, 302-13. For illustrative purposes only, the sidelink slot 310 may include 14 symbols. Note that the sidelink slot 310 can include any appropriate number of symbols. A setting (e.g., received in 2010) may indicate that the start symbol is symbol 302-1. Symbols 301-11, 301-12, 301-13 may be included in a preceding sidelink slot before the sidelink slot 310. Note that some symbols in the preceding sidelink slot are omitted.

[0048] As shown in FIG. 3, the CCA procedure 320 may start from symbol 301-13 and may complete within symbol 302-1. In other words, in this case, CCA succeeds at symbol #n, the start symbol (represented as "SL-StartSymbol") is symbol #n, and it can be represented by mod(SL-StartSymbol-#n,L_symbol)=0. If the remaining time 302-0-2 within symbol 302-0 is longer than a predetermined threshold, the terminal device can transmit a sidelink signal including a part of symbol 302-2, which is the first symbol after symbol 302-1. A part of symbol 302-2 can be the cyclic prefix extension of the first symbol. In some embodiments, the predetermined threshold can be the minimum AGC timing required for each SCS. Note that the predetermined threshold can be any appropriate value. If the remaining time 302-0-2 is less than the predetermined threshold, the terminal device 110-1 can determine that CCA has failed. In this case, symbol replication before the first symbol #(n + 1) (i.e., symbol 302-2) including PSCCH in the conventional (legacy) SL is not executed.

[0049] Symbol 302-2 can include PSCCH. For example, the signal of symbol 302-1 may be part of symbol 302-2 including PSCCH, and can be expressed as follows:

Equation

[0050] In other embodiments, when the length between the CCA completion and the start symbol is one symbol, the terminal device 110-1 can transmit a sidelink signal after the CCA completion. The sidelink signal can include the cyclic prefix extension of the AGC symbol.

[0051] Figure 4 shows a schematic block diagram of a sidelink slot according to some embodiments of the present disclosure. As shown in Figure 4, the sidelink slot 410 may include symbols 402-1, 402-2, 402-3, 402-4, ..., 402-10, 402-11, 402-12, 402-13. For illustrative purposes only, the sidelink slot 410 may include 14 symbols. Note that the sidelink slot 410 can include any suitable number of symbols. The configuration (e.g., received in 2010) may indicate that the start symbol is symbol 402-1. Symbols 401-11, 401-12, 401-13 may be included in a preceding sidelink slot before the sidelink slot 410. Note that some symbols in the preceding sidelink slot are omitted.

[0052] As shown in Figure 4, the CCA procedure 420 may start at symbol 401-12 and may complete within symbol 402-0. In other words, in this case, the CCA has succeeded at symbol #n, which means that the CCA has succeeded at a symbol one before the start symbol and can be represented by mod(SL-StartSymbol-#n,L_symbol)=1. The terminal device may transmit a sidelink signal including a cyclic prefix extension of symbol 402-1 during period 402-0-2. Symbol 402-1 can be an AGC symbol. In this way, the access capability is improved.

[0053] Alternatively, or additionally, if the length between the CCA completion and the start symbol exceeds a predetermined number of symbols, the terminal device 110-1 may transmit a sidelink signal after the CCA completion. The sidelink signal may include a cyclic prefix extension of an automatic gain control symbol and a replica of the automatic gain control symbol. The predetermined number can be any suitable number.

[0054] FIG. 5A shows a schematic block diagram of a sidelink slot according to some embodiments of the present disclosure. As shown in FIG. 5A, the sidelink slot 510 may include symbols 502-1, 502-2, 502-3, 502-4, ..., 502-10, 502-11, 502-12, 502-13. For illustrative purposes only, the sidelink slot 510 may include 14 symbols. Note that the sidelink slot 510 can include any suitable number of symbols. A configuration (e.g., received in 2010) may indicate that the start symbol is symbol 502-1. Symbols 501-11, 501-12, 501-13 may be included in a preceding sidelink slot before the sidelink slot 510. Note that some symbols in the preceding sidelink slot are omitted.

[0055] As shown in FIG. 5A, the CCA procedure 520 may be completed within symbol 501-11. The terminal device 110-1 can transmit a sidelink signal 530 including the cyclic prefix extension (501-11-2) of the AGC symbol 502-1, symbol 501-12, and symbol 501-13. For example, if CCA is successful at symbol #n, when mod(SL-StartSymbol-#n,L_symbol) is greater than 1, that is, if CCA is successful at a symbol further before the 1 symbol of SL-StartSymbol, the reservation signal may be as follows: (1) At symbols #n+1, n+2,... SL-StartSymbol - 1, a replication of the first symbol including PSCCH, that is, a replication of the conventional (legacy) AGC symbol, (2) At symbol #n, the CPE of the next AGC symbol.

[0056] If CCA is successful at symbol #n, but mod(SL-StartSymbol-#n,L_symbol) is not 1 but L_symbol = 14 (the symbol length of the slot), that is, the CCA success symbol is not the symbol immediately before SL-StartSymbol.

[0057] Alternatively, the TA offset may be considered after the success of CCA. In other words, if CCA succeeds at symbol #n, but mod(SL-StartSymbol - (#n+TA),L_symbol) is not equal to 1, that is, the symbol (CCA success time + TA) is not the symbol immediately preceding SL-StartSymbol. FIG. 5B shows a schematic block diagram of a sidelink slot according to some embodiments of the present disclosure. As shown in FIG. 5B, the sidelink slot 511 may include symbols 512-1, 512-2, 512-3, 512-4, 512-5, ..., 512-10, 512-11, 512-12, 512-13. For illustrative purposes only, the sidelink slot 511 may include 14 symbols. Note that the sidelink slot 511 can include any suitable number of symbols. A configuration (e.g., received in 2010) may indicate that the start symbol is symbol 512-5. Symbols 511-11, 511-12, 511-13 may be included in a preceding sidelink slot that precedes the sidelink slot 511. Note that some symbols in the preceding sidelink slot are omitted. As shown in FIG. 5b, the CCA procedure 521 may complete at symbol 512-0. The terminal device 110-1 can transmit a sidelink signal after the CCA procedure 521 and the timing advance 522.

[0058] As an exemplary embodiment, the terminal device 110-1 may transmit a sidelink signal when at least one condition is satisfied. In some embodiments, the conditions may include one or more of: the length being less than a threshold length, the priority of the sidelink transmission traffic being higher than a predetermined priority, the type of CCA being a predetermined type of CCA, or the cumulative symbol counter being higher than a threshold value. For example, the condition may be mod(SL-StartSymbol - #n,L_symbol)<=LengthReservation according to a (pre)setting of the upper layer. Alternatively, or in addition, the condition may be that the priority value of the traffic is lower than the PriorityReservation (pre)set by the upper layer. In other embodiments, the condition may include that the permitted CCA type set according to the priority value of the traffic is set. Further, the condition may be that the remaining SymbolCounter > (pre)set threshold, where SymbolCounter is the cumulative number of skipped symbols. The symbol counter can be set to 0 after accessing the sidelink band. If none of the above conditions are satisfied, the terminal device 110-1 can determine that the CCA has failed.

[0059] In some embodiments, the configuration may include a plurality of start symbol candidates for sidelink transmission. For example, as shown in FIG. 6, the start symbol candidates can include symbol 602-0-1, symbol 602-0-2, and symbol 602-0-3. Symbols 601-11, 601-12, 601-13 are included in the preceding slot. Note that some symbols in the preceding sidelink slot are omitted. The CCA procedure can be completed at symbol 601-11. By way of example only, SL-StartSymbol can indicate a plurality (e.g., 1 / 2 / 3) of values from {sym0...sym7} as valid start symbols for sidelink transmission. For example, in the case of three, they are sym0, sym1, sym2, or sym0, sym3 / 4, sym7, and in the case of two, they are 0, 7. SL-lengthSymbol should be respected by deferring the last symbol.

[0060] In some embodiments, in the case of a configured resource pool with scheduling of a plurality of slots, not all slots include an AGC symbol before the start of sidelink transmission. For example, only one AGC symbol may be defined within a configured time window. The AGC symbol may be placed at the first symbol of the start slot or the end slot within the time window. In some embodiments, the time window can be configured via radio resource control (RRC) signaling. Alternatively, the time window can include a plurality of scheduled slots.

[0061] In some embodiments, if the CCA completion is within the symbol set in one slot, the terminal device 110-1 can execute the CCA. In other words, if the CCA completion is within other symbols in the slot, the terminal device 110-1 may not execute the CCA. For example, the terminal device 110-1 shall not execute a CCA that is expected to end from symbol #7 to symbol #End CCA. Symbol #End CCA can be set at the upper layer, such as symbol #12, 11, 10...8. In other words, the terminal device 110-1 can execute a CCA that is expected to end with other symbols. By doing so, power can be saved and waste of resources can be suppressed. FIG. 7 shows an exemplary schematic diagram of a sidelink slot. Symbols 701-5, 701-6, 701-7, 701-8, 701-9, 701-10, 701-11, 701-12, 701-13 can be included in one slot, and symbols 702-0, 702-1, 702-2 can be included in another slot. As shown in FIG. 7, the CCA procedure 730 will end at symbol 701-7, and the terminal device 110-1 may not execute the CCA. In some embodiments, if the CCA ends with any of symbols 701-7, 701-8, 701-9, 701-10, 701-11, 701-12, 701-13, the terminal device 110-1 may not execute such a CCA.

[0062] In some embodiments, a sidelink slot can span a slot boundary. For example, as shown in FIG. 8A, the LTB procedure 830 is completed in symbol 801-8. Symbols 801-9, 801-10, 801-11, 801-12, 801-13, 802-0, 802-1 can be included in one sidelink slot. Note that a sidelink slot can include other symbols. Since symbols 802-0, 802-1 can be included in slot 810, the sidelink slot spans the slot boundary of slot 810. Alternatively, as shown in FIG. 8B, the LTB procedure 831 is completed in symbol 811-11. Symbols 801-12, 801-13, 802-0, 802-1 802-0, 802-1, 802-2, 802-3, 802-4, 802-5, 802-6 can be included in one sidelink slot. Note that a sidelink slot can include other symbols. Since symbols 802-0, 802-1 802-0, 802-1, 802-2, 802-3, 802-4, 802-5, 802-6 can be included in slot 811, the sidelink slot spans the slot boundary of slot 810.

[0063] Hereinafter, embodiments of the present disclosure will be described in detail. First, refer to FIG. 9. FIG. 9 shows a signaling chart showing a process 900 between network devices according to some exemplary embodiments of the present disclosure. For the purpose of discussion only, the process 900 will be described with reference to FIG. 1. The process 900 may involve the terminal devices 110-1 and 110-2 in FIG. 1. For the purpose of explanation only, the terminal device 110-1 may be referred to as the first terminal device, and the terminal device 110-2 may be referred to as the second terminal device. The process 900 will be described with reference to FIG. 10.

[0064] The terminal device 110-1 executes sidelink communication with the terminal device 110-2 (9010). As shown in FIG. 10, the sidelink slot 1000 can include a symbol 1001 including AGC, a symbol 1002 including DMRS, a symbol 1003 including PSSCH, a symbol 1004 including PSSCH, a symbol 1005 including DMRS, a symbol 1006 including PSSCH, a symbol 1007 including PSSCH, a symbol 1008 including DMRS, a symbol 1009 including PSSCH, a symbol 1010 including PSSCH, a guard symbol 1011, a symbol 1012 including AGC / physical sidelink feedback channel (PSFCH), a symbol 1013 including PSFCH, and a guard symbol 1014. The PSCCH 1015 can be transmitted in symbols 1002, 1003, and 1004. The "symbol including AGC" and the "AGC symbol" used in this specification are interchangeable. Similarly, the "symbol including DMRS" and the "DMRS symbol" used in this specification are also interchangeable, the "symbol including PSSCH" and the "PSSCH symbol" used in this specification are also interchangeable, and the "symbol including PSFCH" and the "PSFCH symbol" used in this specification are also interchangeable.

[0065] The terminal device 110-1 can determine whether a reception / transmission change time is required based on sidelink communication (9020). In some embodiments, the terminal device 110-1 can perform transmission with a PSSCH symbol before a guard symbol, while not performing reception with a PSFCH after the guard symbol. For example, the terminal device 110-1 may perform transmission with PSSCH symbol 1010 and not perform reception with PSFCH symbols 1012 and 1013 after guard symbol 1011. Alternatively, the terminal device 110-1 may perform transmission with PSSCH symbol 1010 and perform transmission with PSFCH symbols 1012 and 1013 after guard symbol 1011. In the above cases, the terminal device 110-1 can determine that a reception / transmission change time is not required. The terminal device 110-1 may further transmit something (e.g., DMRS, a replica of PSFCH, PSSCH) with guard symbol 1011 to occupy the channel. In other cases, the terminal device 110-1 may determine that a reception / transmission time is required.

[0066] In sidelink transmission in a shared spectrum, the terminal device 110-1 transmits a signal within a guard symbol (9030). In some embodiments, when a reception / transmission change time is required, the terminal device 110-1 may perform CCA (e.g., short-time CCA) after the reception / transmission change time from the end of the last PSSCH symbol (e.g., PSSCH symbol 1009). When the CCA is successful, the terminal device 110-1 may transmit a signal (e.g., a cyclic prefix extension of the next symbol (e.g., symbol 1011 of AGC / PSFCH)). For example, as shown in FIG. 10, within guard symbol 1011, the terminal device 110-1 may perform a reception / transmission change in period 1011-1 and perform CCA in period 1011-2. In this case, the terminal device 110-1 may transmit a signal in period 1011-3. In this way, the access capability is improved.

[0067] Alternatively, the terminal device 110-1 may perform CCA from the end of the last PSSCH symbol (e.g., PSSCH symbol 1009) and transmit a signal before the reception / transmission change time. As shown in FIG. 10, for example, within the guard symbol 1011, the terminal device 110-1 may perform CCA in period 1011-4 and transmit a signal in period 1011-5. The terminal device 110-1 may perform reception / transmission change in period 1011-6. In this way, the access capability is improved.

[0068] FIG. 11 shows a flowchart of an exemplary method 1100 according to an embodiment of the present disclosure. The method 1100 can be implemented on any suitable terminal device. For illustrative purposes only, the method 1100 can be implemented on the first terminal device 110-1 shown in FIG. 1.

[0069] In block 1110, the terminal device 110-1 receives a sidelink transmission setting from the network device 120. The setting indicates the start symbol of the sidelink transmission.

[0070] In block 1120, the terminal device 110-1 performs a Clear Channel Assessment (CCA) for sidelink transmission. In some embodiments, the terminal device 110-1 can perform CCA if the CCA completion is within a symbol set within one slot.

[0071] In block 1130, when the CCA is successful, the terminal device 110-1 transmits a sidelink signal including a cyclic prefix extension of the first symbol after the start symbol to the terminal device 110-2.

[0072] In some embodiments, if the CCA completion is within the start symbol and the remaining time within the start symbol is longer than a predetermined threshold, the terminal device 110-1 may transmit a sidelink signal after the CCA completion. The sidelink signal can include a part of the first symbol after the start symbol. The first symbol may include a Physical Sidelink Control Channel (PSCCH). In some embodiments, a part of the first symbol can include a cyclic prefix extension of the first symbol, and the sidelink signal lacks an automatic gain control symbol.

[0073] Alternatively, or in addition, if the CCA completion is within the start symbol and the remaining time within the start symbol is shorter than a predetermined threshold, the terminal device 110-1 can determine that the CCA has failed.

[0074] In some embodiments, if the length between the CCA completion and the start symbol is one symbol, the terminal device 110-1 may transmit a sidelink signal after the CCA completion. The sidelink signal may include a cyclic prefix extension of an automatic gain control symbol.

[0075] In another embodiment, if the length between the CCA completion and the start symbol exceeds a predetermined number of symbols, the terminal device 110-1 may transmit a sidelink signal after the CCA completion. In this case, the sidelink signal may include a cyclic prefix extension of an automatic gain control symbol and a replica of the automatic gain control symbol.

[0076] Alternatively, or in addition, the terminal device 110-1 may transmit a sidelink signal according to a determination that at least one of the following conditions is met: the length is smaller than a threshold length, the priority of the sidelink transmission traffic is higher than a predetermined priority, the type of CCA is a predetermined type of CCA, or the cumulative symbol counter is higher than a threshold value.

[0077] In some embodiments, the configuration may further indicate a plurality of start symbol candidates for sidelink transmission. In other embodiments, the sidelink transmission time window may include one automatic gain control symbol.

[0078] FIG. 12 shows a flowchart of an exemplary method 1200 according to an embodiment of the present disclosure. The method 1200 can be implemented on any suitable terminal device. For illustrative purposes only, the method 1200 can be implemented on the second terminal device 110-1 shown in FIG. 1.

[0079] In some embodiments, at block 1210, the terminal device 110-1 performs sidelink communication with the terminal device 110-2.

[0080] In some embodiments, based on the sidelink communication, the terminal device 110-1 determines whether a receive / transmit change time is required within the guard symbol in the sidelink slot. For example, the terminal device 110-1 may determine that the receive / transmit change time is not required according to a determination that one of the following is satisfied: sidelink transmission is performed in the physical sidelink shared channel (PSSCH) symbol before the guard symbol while sidelink reception is skipped in the physical sidelink feedback channel (PSFCH) symbol after the guard symbol, or sidelink transmission is performed in both the PSSCH symbol and the PSFCH.

[0081] At block 1230, in sidelink transmission in the shared spectrum, the terminal device 110-1 transmits a signal to the terminal device 110-2 within the guard symbol. In some embodiments, if a receive / transmit change time is required, the terminal device 110-1 may perform a first type of clear channel assessment (CCA) after the receive / transmit change time. In this case, if the CCA is successful, the terminal device 110-1 may transmit the signal.

[0082] In other embodiments, when a reception / transmission change time is required, the terminal device 110-1 may perform a first type of Clear Channel Assessment (CCA) from the end of a Physical SideLink Shared Channel (PSSCH) symbol preceding a guard symbol. If the CCA is successful, the terminal device 110-1 may transmit a signal before the reception / transmission change time.

[0083] Alternatively, when a reception / transmission change time is required, the terminal device 110-1 may perform a first type of Clear Channel Assessment (CCA) from the end of a Physical SideLink Shared Channel (PSSCH) symbol preceding a guard symbol. The signal may include at least one of a demodulation reference signal, a replica of a Physical SideLink Feedback Channel, or a Physical SideLink Shared Channel.

[0084] In some embodiments, the terminal device, at a first terminal device, receives a configuration of a side link transmission indicating a start symbol of the side link transmission from a network device, performs a Clear Channel Assessment (CCA) for the side link transmission, and in accordance with a determination that the CCA is successful, transmits a side link signal including a cyclic prefix extension of a first symbol after the start symbol to a second terminal device, and includes a circuit configured to do so.

[0085] In some embodiments, the terminal device includes a circuit configured to transmit a side link signal by transmitting the side link signal in accordance with a determination that the CCA completion is within a start symbol and the remaining time within the start symbol is longer than a predetermined threshold.

[0086] In some embodiments, the side link signal lacks a replica of a first symbol.

[0087] In some embodiments, the terminal device includes a circuit configured to determine that the CCA has failed according to a determination that the CCA completion is within the start symbol and the remaining time within the start symbol is shorter than a predetermined threshold.

[0088] In some embodiments, the terminal device includes a circuit configured to transmit a sidelink signal including a cyclic prefix extension of an automatic gain control symbol after CCA completion according to a determination that the length between the CCA completion and the start symbol is one symbol, thereby transmitting the sidelink signal.

[0089] In some embodiments, the terminal device includes a circuit configured to transmit a sidelink signal after CCA completion according to a determination that the gap between the CCA completion and the start symbol exceeds a predetermined number of symbols.

[0090] In some embodiments, the sidelink signal includes a cyclic prefix extension of a replication of a first symbol and a replication of the replication of the first symbol.

[0091] In some embodiments, the terminal device includes a circuit configured to transmit a sidelink signal according to a determination that at least one of the following is satisfied: the length is smaller than a threshold length, the priority of the sidelink transmission traffic is higher than a predetermined priority, the type of CCA is a predetermined type of CCA, or the cumulative symbol counter is higher than a threshold value, thereby transmitting the sidelink signal.

[0092] In some embodiments, the configuration further indicates a plurality of start symbol candidates for sidelink transmission.

[0093] In some embodiments, the terminal device includes a circuit configured to perform CCA according to a determination that the CCA completion is within a symbol set within one slot, thereby performing CCA.

[0094] In some embodiments, the sidelink transmission time window includes one replica of the first symbol.

[0095] In some embodiments, the terminal device includes circuitry configured to transmit a signal to a second terminal device within a guard symbol in sidelink transmission in a shared spectrum.

[0096] In some embodiments, the terminal device determines whether a receive / transmit change time is necessary by determining that one of the following is satisfied: sidelink transmission is performed in a physical sidelink shared channel (PSSCH) symbol before the guard symbol while sidelink reception is skipped in a physical sidelink feedback channel (PSFCH) symbol after the guard symbol, or sidelink transmission is performed in both the PSSCH symbol and the PSFCH. The terminal device includes circuitry configured to make such a determination.

[0097] In some embodiments, the terminal device includes circuitry configured to perform a first type of Clear Channel Assessment (CCA) from the end of a physical sidelink shared channel (PSSCH) symbol preceding the guard symbol according to a determination that a receive / transmit change time is necessary.

[0098] In some embodiments, the terminal device includes circuitry configured to perform a first type of Clear Channel Assessment (CCA) after a receive / transmit change time according to a determination that a receive / transmit change time is necessary. Here, transmitting a signal includes transmitting the signal according to a successful CCA.

[0099] In some embodiments, the terminal device includes a circuit configured to perform a first type of Clear Channel Assessment (CCA) from the end of a Physical SideLink Shared Channel (PSSCH) symbol preceding a guard symbol according to a determination that a receive / transmit change time is required. Here, transmitting a signal includes transmitting the signal before the receive / transmit change time according to a successful CCA.

[0100] In some embodiments, the signal includes at least one of a demodulation reference signal, a replica of a physical side link feedback channel, or a physical side link shared channel.

[0101] FIG. 13 is a schematic block diagram of an apparatus 1300 suitable for implementing embodiments of the present disclosure. The apparatus 1300 can be considered as a further exemplary implementation of the terminal device 110 and the network device 120 shown in FIG. 1. Therefore, the apparatus 1300 can be implemented in or at least as part of the terminal device 110 or the network device 120.

[0102] As shown in the figure, the apparatus 1300 includes a processor 1310, a memory 1320 coupled to the processor 1310, a suitable transmitter (TX) and receiver (RX) 1340 coupled to the processor 1310, and a communication interface coupled to the TX / RX 1340. The memory 1320 stores at least a part of the program 1330. The TX / RX 1340 is for two-way communication. The TX / RX 1340 has at least one antenna for facilitating communication. In practice, the access node described in the present application may have multiple antennas. The communication interface may represent any interface required for communicating with other network elements, for example, the X2 interface for two-way communication between eNBs, the S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, the Un interface for communication between an eNB and a Relay Node (RN), or the Uu interface for communication between an eNB and a terminal device.

[0103] The program 1330 is considered to include program instructions. When the program is executed by the associated processor 1310, it enables the apparatus 1300 to operate according to the embodiments of the present disclosure, as discussed with reference to FIGS. 2 to 12 herein. The embodiments herein may be implemented by computer software, hardware, or a combination of software and hardware executable by the processor 1310 of the apparatus 1300. The processor 1310 may be configured to implement various embodiments of the present disclosure. Also, the combination of the processor 1310 and the memory 1320 may constitute a processing means 1350 suitable for implementing various embodiments of the present disclosure.

[0104] Memory 1320 may be of any type suitable for a local technical network and may be implemented by any suitable data storage technology (examples include, but are not limited to, computer-readable non-transitory storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory, etc.). Although only one memory 1320 is shown in device 1300, a plurality of physically different memory modules may be installed in device 1300. Processor 1310 may be of any type suitable for a local technical network and may include, for example, but not be limited to, a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor configuration, one or more of which may be included. Device 1300 may have a plurality of processors, for example, an application-specific integrated circuit chip that is temporally dependent on a clock synchronized with a master processor.

[0105] Generally, various embodiments of the present disclosure may be implemented by hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented by hardware, and other aspects may be implemented by firmware or software that can be executed by a controller, a microprocessor, or other computing devices. Various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or shown by some other pictorial representation, and the blocks, devices, systems, techniques, or methods described herein may be implemented, for example, by hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or a combination thereof, but it will be understood that they are not limited thereto.

[0106] The present disclosure further provides at least one computer program product tangibly stored on a computer-readable non-transitory storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules. The instructions are executed on a device on a target physical processor or virtual processor, and execute the process or method described above with reference to any one of FIGS. 2 to 12, for example. Usually, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules may be combined or divided among program modules as needed. The machine-readable instructions of program modules may be executed within a local or distributed device. In a distributed device, program modules may be located on either local or remote storage media.

[0107] The program code for executing the method of the present disclosure may be described by any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device. When the program code is executed by the processor or controller, the functions / operations defined in the flowchart and / or block diagram are implemented. The program code may be executed entirely on a machine, partially on a machine, executed as an independent software package, partially executed on a machine and partially executed on a remote machine, or entirely executed on a remote machine or server.

[0108] The above program code may be embodied on a machine-readable medium, which may be any tangible medium that includes or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium may include one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0109] Note that although the operations have been described in a particular order, it should not be understood that such operations must be performed in the particular order shown or sequentially in order to obtain the desired result, and in some circumstances, multitasking and parallel processing may be advantageous. Similarly, although the above discussion includes some specific implementation details, these are not limitations on the scope of the present disclosure, but rather explanations of features that may be specific to a particular embodiment. Some features described in the context of individual embodiments may be implemented in combination in one embodiment. Conversely, various features described in the context of one embodiment may be implemented separately in a plurality of embodiments or in any suitable sub-combinations.

[0110] Although the present disclosure has been described in terms of words specific to structural features and / or methodological acts, it is to be understood that the disclosure defined by the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. Means for executing a channel access procedure to transmit sidelink (SL) transmission on a channel; After it is sensed that the channel is available by using the channel access procedure, for the start symbol of the SL transmission, within a first number of symbols before the start symbol, means for applying a cyclic prefix (CP) extension; Comprising: A terminal device.

2. The first number is 1; The terminal device according to Claim 1.

3. Further comprising means for receiving a setting indicating two start symbol candidates for sidelink transmission within one slot; The terminal device according to Claim 1.

4. The two start symbol candidates include a first start symbol candidate which is symbol 0 and a second start symbol candidate which is symbol 7; The terminal device according to Claim 3.

5. Further comprising means for applying a cyclic prefix (CP) extension in a symbol between a first SL transmission and a second SL transmission following the first SL transmission; The terminal device according to Claim 1.

6. Executing a channel access procedure to transmit sidelink (SL) transmission on a channel; After it is sensed that the channel is available by using the channel access procedure, for the start symbol of the SL transmission, within a first number of symbols before the start symbol, applying a cyclic prefix (CP) extension; Including: A method executed by a terminal device.

7. The first number is 1; The method according to Claim 6.

8. Further including receiving a setting indicating two start symbol candidates for sidelink transmission within one slot; The method according to Claim 6.

9. The two start symbol candidates include a first start symbol candidate which is symbol 0 and a second start symbol candidate which is symbol 7; The method according to Claim 8.

10. Further including applying a cyclic prefix (CP) extension in a symbol between a first SL transmission and a second SL transmission following the first SL transmission; The method according to Claim 6.

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