Time interval adjustment by user equipment for channel access procedure for sidelink communication in unlicensed spectrum

Abstract

A user equipment (UE) for a wireless communication network, such as a 3rd Generation Partnership Project (3GPP) network, is described. The UE will perform sidelink (SL) communications using a channel that includes resources from an unlicensed spectrum. The UE occupies a channel within a channel occupancy time (COT) and shares the COT with another UE, the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated for a protection duration. The UE will perform transmissions through the SL during a first portion of the COT. A second portion of the COT is used by another UE for transmission over the SL. The UE extends the transmission to a protection duration for transmission during a predefined duration starting from a start portion of the protection duration, the selected predefined duration making the remaining duration of the protection duration sufficient to allow another UE to perform a predefined channel access procedure CAP before accessing a shared COT.

Description

[0001] manual

[0002] The present invention relates to the field of wireless communication systems or networks, and more particularly to direct communication between user equipments via a side link using resources from an unlicensed spectrum, also referred to as SL-U. Embodiments relate to time interval adjustment by a user equipment for a channel access procedure CAP for side link communication in an unlicensed spectrum.

[0003] FIG. 1 is a schematic diagram of an example of a terrestrial wireless network 100. As shown in FIG. 1(a), the network includes a core network 102 and one or more radio access networks RAN1, RAN2, ...RAN N Figure 1(b) is a diagram of the radio access network RAN n 1061 to 1065. The base station provides services to users within the cell. One or more base stations can provide services to users within licensed and / or unlicensed frequency bands. The term base station BS refers to a gNB in ​​a 5G network, an eNB in ​​UMTS / LTE / LTE-A / LTE-APro, or a BS in other mobile communication standards. Users can be fixed devices or mobile devices. The wireless communication system can also be accessed by mobile or fixed IoT devices connected to the base station or the user. Mobile or fixed devices can include physical devices, ground vehicles (such as robots or cars), aerial vehicles (such as manned or unmanned aerial vehicles UAV, the latter also known as drones), buildings, and other items or devices with embedded electronics, software, sensors, actuators, etc. and network connections that enable these devices to collect and exchange data on existing network infrastructure. Figure 1(b) shows a schematic view of five cells, but the RAN n More or fewer cells may be included, and the RAN nOnly one base station may also be included. Figure 1(b) shows two users UE1 and UE2, also referred to as user equipment or user equipment, which are located in cell 1062 and served by base station gNB2. Another user UE3 is shown as being located in cell 1064 and served by base station gNB4. Arrows 1081, 1082 and 1083 graphically represent uplink / downlink connections for transmitting data from users UE1, UE2 and UE3 to base stations gNB2, gNB4, or for transmitting data from base stations gNB2, gNB4 to users UE1, UE2 and UE3. This can be achieved in a licensed band or an unlicensed band. In addition, Figure 1(b) shows two other devices 1101 and 1102 in cell 1064, such as IoT devices, which can be fixed devices or mobile devices. Device 1101 accesses the wireless communication system via base station gNB4 to receive and transmit data, as shown by arrow 1121. Device 1102 accesses the wireless communication system via user UE3, as shown by arrow 1122. The corresponding base stations gNB1 to gNB5 can be connected to the core network 102 via corresponding backhaul links 1141 to 1145, for example, via an S1 interface, which are schematically represented by arrows pointing to "core" in Figure 1(b). The core network 102 can be connected to one or more external networks. The external network can be the Internet, or it can be a private network, such as an intranet or any other type of campus network, such as a private WiFi communication system or a 4G or 5G mobile communication system. In addition, some or all of the corresponding base stations gNB1 to gNB5 can be interconnected via corresponding backhaul links 1161 to 1165 via an S1 or X2 interface or an XN interface in NR, which are schematically represented by arrows pointing to "gNB" in Figure 1(b). s ” These backhaul links are schematically represented. Sidelink channels allow direct communication between UEs, also known as device-to-device D2D communication. The sidelink interface in 3GPP is named PC5.

[0004] For data transmission, a physical resource grid can be used. The physical resource grid may include a set of resource elements to which various physical channels and physical signals are mapped. For example, the physical channels may include a physical downlink shared channel PDSCH, a physical uplink shared channel PUSCH and a physical sidelink shared channel PSSCH (carrying user-specific data, also referred to as downlink, uplink, sidelink payload data), a physical broadcast channel PBCH and a physical sidelink broadcast channel PSBCH (carrying, for example, a master information block MIB and one or more system information blocks SIB, one or more sidelink information blocks SLIB (if supported)), a physical downlink control channel PDCCH, a physical uplink control channel PUCCH and a physical sidelink control channel PSSCH (carrying, for example, downlink control information DCI, uplink control information UCI and sidelink control information SCI), and a physical sidelink feedback channel PSFCH (carrying feedback responses via PC5). The side link interface may support Level 2 SCI, which refers to a first control region (also referred to as a first level SCI) containing some portion of the SCI, and a second control region (also referred to as a second level SCI) optionally containing a second portion of control information.

[0005] For the uplink, the physical channels may also include a physical random access channel PRACH or RACH, which is used by the UE to access the network once the UE is synchronized and obtains the MIB and SIB. Physical signals may include reference signals or symbols RS, synchronization signals, etc. The resource grid may include a frame or radio frame with a specific duration in the time domain and a given bandwidth in the frequency domain. The frame may have a certain number of subframes of a predefined length (e.g., 1ms). Depending on the cyclic prefix CP length, each subframe may include one or more time slots of 12 or 14 OFDM symbols. The frame may also have a smaller number of OFDM symbols, for example, when utilizing a shortened transmission time interval sTTI or a mini-slot / non-slot based frame structure that includes only a few OFDM symbols.

[0006] The wireless communication system may be any single tone or multi-carrier system using frequency division multiplexing, such as an orthogonal frequency division multiplexing OFDM system, an orthogonal frequency division multiple access OFDMA system, or any other inverse fast Fourier transform IFFT-based signal with or without a cyclic prefix CP, such as discrete Fourier transform spread spectrum OFDM, i.e., DFT-s-OFDM. Other waveforms may be used, such as non-orthogonal waveforms for multiple access, such as filter bank multi-carrier FBMC, generalized frequency division multiplexing GFDM, or universal filtering multi-carrier UFMC. The wireless communication system may operate according to 3GPPs LTE, LTE-Advanced, LTE-Advanced Pro, or 5G or 3GPP NR (New Radio), or operate within NR-U (New Radio Unlicensed), which is specified in both LTE and NR specifications.

[0007] The wireless network or communication system shown in Figure 1 can be a heterogeneous network with different coverage networks, for example, a macrocellular network (where each macrocell includes a macro base station, such as base stations gNB1 to gNB5) and a small cell base station network (not shown in Figure 1, such as a femto base station or a pico base station). In addition to the above-mentioned terrestrial wireless networks, there are also non-terrestrial wireless communication networks NTN, including satellite-borne transceivers such as satellites and / or airborne transceivers such as drone systems. The non-terrestrial wireless communication network or system can operate in a similar manner to the terrestrial system described above with reference to Figure 1, for example, according to LTE-Advanced Pro or 5G or NR (New Radio).

[0008] In a mobile communication network, for example, in a network similar to that described above with reference to FIG. 1 (such as an LTE or 5G / NR network), there may be UEs that communicate directly with each other through one or more side link SL channels (for example, using a PC5 / PC3 interface or using WiFi direct connection). UEs that communicate directly with each other through side links may include vehicles that communicate directly with other vehicles (V2V communication), vehicles that communicate with other entities of the wireless communication network (such as roadside units RSU, roadside entities such as traffic lights, traffic signs, or pedestrians) (V2X communication). Depending on the specific network configuration, the RSU may have the functionality of a BS or a UE. Other UEs may not be vehicle-related UEs and may include any of the above-mentioned devices. These devices may also communicate directly with each other (D2D communication) using SL channels.

[0009] When considering two UEs communicating directly with each other via a side link, the two UEs may be served by the same base station, so that the base station can provide side link resource allocation configuration or assistance to the UEs. For example, both UEs may be within the coverage area of ​​a base station, such as one of the base stations shown in Figure 1. This is called the "in coverage" scenario. Another scenario is called the "out of coverage" scenario. It is worth noting that "out of coverage" does not mean that the two UEs are definitely not within one of the cells shown in Figure 1, but rather that these UEs

[0010] - may not be connected to the base station, e.g., they are not in a Radio Resource Control (RRC) Connected state, so the UE does not receive any sidelink resource allocation configuration or assistance from the base station, and / or

[0011] - may be connected to the base station, but due to one or more reasons, the base station may not provide sidelink resource allocation configuration or assistance to the UE, and / or

[0012] -Can connect to base stations that may not support NR V2X services, such as GSM, UMTS, LTE base stations.

[0013] FIG2(a) is a schematic diagram of a coverage scenario in which two UEs communicating directly with each other are both connected to one base station. The coverage area of ​​the base station gNB is schematically represented by a circle 200, which substantially corresponds to the cell schematically shown in FIG1 . The UEs communicating directly with each other include a first vehicle 202 and a second vehicle 204, both in the coverage area 200 of the base station gNB. Both vehicles 202, 204 are connected to the base station gNB, and furthermore, they are directly connected to each other via a PC5 interface. The gNB assists in the scheduling and / or interference management of V2V traffic via control signaling over the Uu interface, which is the wireless interface between the base station and the UE. In other words, the gNB provides SL resource allocation configuration or assistance to the UE, and the gNB allocates resources for V2V communication via a sidelink. This configuration is also referred to as a Mode 1 configuration in NR V2X, or a Mode 3 configuration in LTE V2X. Thus, in Mode 1, a SL UE (e.g., UE 202) is connected to the gNB via a Uu interface, and the gNB coordinates the resources of UE 202 for transmitting control and / or data to another UE (e.g., UE 204) via a SL interface (referred to as PC5 in NR).

[0014] FIG2( b) is a schematic diagram of an out-of-coverage scenario, in which UEs communicating directly with each other are either not connected to a base station, although they may be physically located within a cell of a wireless communication network, or some or all of the UEs communicating directly with each other are connected to a base station but the base station does not provide SL resource allocation configuration or assistance. The figure shows three vehicles 206, 208, and 210 communicating directly via a side link (e.g., using a PC5 interface). Scheduling and / or interference management of V2V traffic is based on an algorithm implemented between vehicles. This configuration is also referred to as a mode 2 configuration in NR V2X and a mode 4 configuration in LTE V2X. As described above, the scenario in FIG2( b) is an out-of-coverage scenario, which does not necessarily mean that the corresponding mode 2 UE in NR or the mode 4 UE in LTE is outside the coverage 200 of the base station, but rather, it means that the corresponding mode 2 UE in NR or the mode 4 UE in LTE is not served by the base station, is not connected to a base station in the coverage area, or is connected to a base station but does not receive SL resource allocation configuration or assistance from the base station. Therefore, within the coverage area 200 shown in FIG. 2( a ), in addition to UEs 202 and 204 in NR mode 1 or LTE mode 3, there may also be UEs 206, 208, and 210 in NR mode 2 or LTE mode 4. In addition, FIG. 2( b ) schematically shows an out-of-coverage UE communicating with the network using a relay. For example, UE 210 may communicate with UE 212 via a side link, and UE 212 may be connected to the gNB via a Uu interface. Therefore, UE 212 may relay information between the gNB and UE 210. Therefore, SL UEs (e.g., UEs 206-210) do not need to have a connection to the gNB, and, for example, when transmitting from UE 206 to UE 208, sensing and access resource allocation or random access-based resource allocation are performed. However, in order to successfully exchange data, basic configuration needs to be available to UEs 206-210. This information may be pre-configured or may be configured when the UE is within the coverage of the gNB. To this end, the gNB may provide basic configuration, such as basic information, which may be transmitted over a broadcast channel, for example, using a system information block (SIB). The BS may also assist Mode 2 UEs in providing basic information about which resource pool (RP) to use, or may act as a synchronization source.

[0015] Although Figures 2(a) and 2(b) show vehicle-mounted UEs, it should be noted that the in-coverage and out-of-coverage scenarios also apply to non-vehicle-mounted UEs. In other words, any UE (such as a handheld device) may be in-coverage and out-of-coverage when using the SL channel to communicate directly with another UE.

[0016] In the application scenario of the above-mentioned vehicle-mounted user equipment UE, multiple such user equipment can form a user equipment group, which can also be referred to as a group, and the communication between members within the group or among the members of the group can be carried out through the side link interface (such as the PC5 interface) between the user equipment. For example, the above-mentioned application scenario using vehicle user equipment can be applied to the field of transportation industry, in which multiple vehicles equipped with vehicle user equipment can be combined together through remote driving applications and other means. Other use cases in which multiple user equipment can be combined for side link communication include factory automation and power distribution. In factory automation, multiple mobile or fixed machines in a factory can be equipped with user equipment and combined together for side link communication, for example, to control the operation of the machine, such as the motion control of a robot. In power distribution, entities within the distribution network can be equipped with corresponding user equipment, which can be combined together in a certain area of ​​the system to communicate with each other through side link communication, thereby realizing the monitoring of the system and handling distribution network faults and interruptions.

[0017] It should be noted that the information in the above sections is only used to enhance the understanding of the background of the present invention, and therefore, it may contain information that does not constitute the prior art already known to a person of ordinary skill in the art.

[0018] Based on the above situation, it may be necessary to improve or enhance the side link in the wireless communication system or network.

[0019] The embodiments of the present invention are now described in further detail with reference to the accompanying drawings:

[0020] FIG1 is a schematic diagram of an example of a terrestrial wireless network;

[0021] Figure 2(a) is a schematic diagram of a scene within the coverage area;

[0022] Figure 2(b) is a schematic diagram of a scenario outside the coverage area;

[0023] FIG3 shows two examples of sidelink slot formats, wherein FIG3(a) illustrates a slot format with one guard symbol, and FIG3(b) illustrates a slot format with two guard symbols;

[0024] Figure 4 is a schematic diagram of a wireless communication system for implementing an embodiment of the present invention, wherein the wireless communication system includes a transmitter (such as a base station) and one or more receivers (such as user equipment UE);

[0025] Figure 5 The figure shows a wireless communication system according to an embodiment of the present invention, wherein the wireless communication system includes a user equipment and a base station;

[0026] Figure 6The figure shows a channel occupied by a first UE within a COT, the channel sharing the COT with a second UE, and according to an embodiment of the present invention, the first UE extends its transmission to the guard period between the two parts of the COT;

[0027] Figure 7 The figure shows a channel occupied by a first UE within a COT, which shares the COT with a second UE, which extends its transmission to the guard period between two parts of the COT according to an embodiment of the present invention;

[0028] Figure 8 The figure shows a channel occupied by a first UE within a COT, which shares the COT with a second UE. According to an embodiment of the present invention, the first UE and the second UE extend their transmissions to the guard period between the two parts of the COT;

[0029] FIG9( a ) illustrates a channel occupied by a COT initiating UE, the channel comprising two time slots, the structure of which is as shown in FIG3( a ), and the two time slots are separated by a guard symbol;

[0030] FIG9( b ) illustrates the channel of FIG9( a ) according to an embodiment of the present invention, wherein the transmission of the originating UE extends to the guard symbol;

[0031] FIG9( c ) illustrates the channel of FIG9( a ) according to an embodiment of the present invention, wherein the transmission of the responding UE extends to the guard symbol;

[0032] FIG10 illustrates an embodiment of the present invention, assuming that the duration of the COT is one time slot having a structure as in FIG3( b );

[0033] FIG11 illustrates an embodiment of the present invention, assuming that the duration of the COT is a first time slot having a structure as in FIG3( b ) and at least one subsequent time slot having a structure as in FIG3( a ) or FIG3( b );

[0034] FIG. 12 illustrates an embodiment of the present invention according to which the transmissions of the initiating UE and the responding UE are extended into a guard symbol between a first time slot having a structure as in FIG. 3( b ) and at least one subsequent time slot having a structure as in FIG. 3( a ) or FIG. 3( b ); and

[0035] Fig.13 The figure shows an example of a computer system on which the units or modules and the method steps described according to the method of the present invention can be executed.

[0036] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which the same or similar elements are given the same reference symbols.

[0037] In a mobile communication system or network, as described above with reference to FIG. 1 , for example, in an LTE or 5G / NR network, corresponding entities may use one or more frequency bands for communication. A frequency band includes a starting frequency, an ending frequency, and all intermediate frequencies between the starting frequency and the ending frequency. In other words, the starting frequency, the ending frequency, and the intermediate frequencies may define a certain bandwidth, such as 20 MHz. A frequency band may also be referred to as a carrier or subcarrier, a bandwidth portion, a BWP, a subband, a subchannel, etc.

[0038] When a single frequency band is used, communication may be referred to as single-band operation, for example, the UE transmits or receives radio signals to or from another network entity on a frequency within the frequency band (eg, a 20 MHz band).

[0039] When two or more frequency bands are used, the communication may be referred to as multi-band operation or broadband operation or carrier aggregation operation. These frequency bands may have different bandwidths or may have the same bandwidth, such as a 20 MHz frequency band. For example, in the case where the frequency bands have the same bandwidth, the UE may transmit or receive radio signals to or from another network entity at frequencies within two or more 20 MHz frequency bands, so that the frequency range of the radio communication may be a multiple of 20 MHz. The two or more frequency bands may be continuous / adjacent frequency bands or may be part or all of the frequency bands separated in the frequency domain.

[0040] Multi-band operation may include frequency bands in the licensed spectrum, frequency bands in the unlicensed spectrum, or frequency bands in both the licensed spectrum and the unlicensed spectrum.

[0041] Carrier aggregation CA is an example of using two or more frequency bands in licensed spectrum and / or unlicensed spectrum. It can also be a hybrid combination, such as one or more licensed bands and one or more unlicensed bands. In addition, CA can also be used to aggregate additional carriers in one direction only, for example as a supplementary carrier to improve transmission through UL, DL or SL.

[0042] 5G New Radio (NR) can support operation in unlicensed spectrum so that single-band operation or multi-band operation can include frequency bands or sub-bands in unlicensed spectrum. Unlicensed spectrum can include frequency bands with potential coexistence with IEEE 802.11, such as frequency bands within the 5 GHz and / or 6 GHz spectrum. For example, due to regulatory requirements, NR-U can support bandwidths of integer multiples of 20 MHz. The purpose of segmentation into sub-bands is to minimize interference to coexisting systems (such as IEE 802.11 systems), which can use the same nominal bandwidth channels (such as 20 MHz channels) in one or more of the same frequency bands. Other coexisting systems can use sub-bands with different sub-band sizes and nominal frequencies from the above-mentioned IEEE 802.11 systems. For example, the unlicensed spectrum can include the 5 GHz band, the 6 GHz band, the 24 GHz band, or the 60 GHz band. Examples of such unlicensed bands include industrial, scientific and medical (ISM) radio bands, which are reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than telecommunications.

[0043] During operation using unlicensed subbands, Listen Before Talk (LBT) may be performed on each subband separately. During operation using unlicensed subbands, Listen Before Talk (LBT) may be performed on each subband separately. This may result in one or more subbands being busy or occupied due to interference, for example, from other communication systems co-existing in the same band, such as other Public Land Mobile Networks (PLMNs) or systems operating in accordance with the IEEE 802.11 specification or systems operating in accordance with the ETSI Broadband Radio Access Network (BRAN) specification. In this case, the transmitter, whether it is a transmitting gNB or a transmitting UE, can only transmit on subbands that are detected to be not busy (also known as idle or unoccupied subbands). For example, when transmitting across more than 20MHz in the 5GHz unlicensed operating band, the transmitter (such as a gNB or a UE) performs Listen Before Talk (LBT) on each subband separately. Once the LBT results for each subband are obtained, the device (such as a gNB in ​​the downlink DL or a UE in the uplink UL) is allowed to transmit on the subbands determined to be idle or unoccupied, i.e., on the winning subbands. Transmissions are not allowed on occupied, busy, or unwon subbands.

[0044] In order to access resources or channels in the unlicensed spectrum, a so-called NR-U channel access is performed, which requires the use of a channel access procedure that is based on sensing to assess whether the channel is available for transmission. The basic unit of sensing may be a sensing slot with a certain duration, such as T sl=9μs. If the base station or UE senses the channel within the sensing time slot duration and determines that the power detected is less than the energy detection threshold for at least a certain period of time (such as 4μs) within the sensing time slot duration, then the sensing time slot duration T is considered to be sl is idle. Otherwise, the sensing time slot duration will be considered busy. When the channel is available or not busy, one or more transmissions can be performed on the channel. The so-called channel occupancy refers to one or more transmissions performed by the base station or UE on one or more channels after performing the corresponding channel access procedure. Channel occupation time (COT) refers to the total time that the base station or UE and any other base station or UE can share the channel occupation to perform one or more transmissions on the channel after the base station or UE performs the channel access procedure (CAP).

[0045] To determine the channel occupancy time, if the transmission interval is less than or equal to a certain period (eg, 25 μs), the interval duration is counted into the channel occupancy time. Transmissions between a base station and a corresponding UE may share the channel occupancy time.

[0046] There may be several types of channel access procedures (CAPs), for example:

[0047] Before the transmission of Type-1 CAP, the channel idle time sensed may be random. For example, the base station or UE may determine an initial counter N, which is between 0 and CW. p Randomly select between min,p ≤CW p ≤CW max,p , among which CW min,p and CW max,p Limited by the channel access procedure category CAPC. When the channel is sensed to be idle for a period of time, the N value will decrease, and transmission can only be performed when the N value reaches 0.

[0048] - Type 2A: Before transmission, the length of time that the channel is sensed to be idle may be determined, and the channel may need to be idle for two sensing slots (eg, at the beginning and at the end) within a sensing interval of a first length (eg, 25 μs).

[0049] - Type 2B: Before transmission, the sensed channel idle time duration may be determined, and the channel may need to be idle for one sensing slot within a sensing interval of a second time duration (eg, 16 μs) shorter than the first time duration.

[0050] - Type 2C: This type does not perform any channel sensing before transmission, and the corresponding transmission duration may have a predefined duration, for example, a maximum of 584 μs. This type may also be referred to as a non-LBT CAP.

[0051] Once the UE performs the channel access procedure CAP, the UE occupies a given frequency band or channel on which it performs LBT, and the COT begins. This UE is also referred to as the initiating UE. In the case of sidelink communication (SL-U), the initiating UE may also share the COT with another gNB or another UE (also referred to as the responding UE) using resources of unlicensed spectrum (such as unlicensed SL resource pool SL-U RP), including multiple resources of unlicensed spectrum for SL transmission. For sidelink communication (SL-U) using unlicensed spectrum, when the initiating UE shares the COT with another UE or responding UE (also referred to as UE-to-UE COT sharing), although the responding UE uses the shared COT on which the initiating UE has performed a CAP (such as LBT), the responding UE still needs to use the CAP to check the availability of the shared channel. The CAP used by the responding UE may be shorter than the CAP used by the initiating UE, such as a shorter LBT, such as the Type 2A or Type 2B CAP mentioned above. If the responding UE transmits feedback such as PSFCH, it can be classified as a short transmission because the feedback only spans two or three symbols, and the UE may also perform a Type 2C CAP without performing any LBT. For UE-to-UE COT sharing, the above 2A / 2B / 2C channel access procedures are applicable to the following situations:

[0052] -Type 2A channel access procedures may be applicable to one or more transmissions made by a UE following one or more transmissions made by another UE when the shared channel occupancy is ≥ 25 μs.

[0053] -Type 2B channel access procedures may be applicable to one or more transmissions made by a UE following one or more transmissions made by another UE when the shared channel occupancy is ≥ 16 μs.

[0054] -2C type channel access procedure may be applicable to one or more transmissions made by a UE following one or more transmissions made by another UE when the shared channel occupancy is ≤16 μs and the transmission duration is at most 584 μs.

[0055] For communications using a side link, the corresponding entity (such as a SL-UE) may adopt a side link frame structure as shown in FIG. 3 , which illustrates two time slot formats. FIG. 3( a) illustrates a time slot format with one guard symbol, and FIG. 3( b) illustrates a time slot format with two guard symbols. As can be seen from FIG. 3( a), a time slot includes 14 symbols. The first symbol is an automatic gain control (AGC) symbol, followed by a symbol carrying PSCCH and two PSSCH symbols. The fourth symbol is a demodulation reference signal (DMRS) symbol, followed by six PSSCH symbols and another DMRS symbol. The twelfth and thirteenth symbols are also PSSCH symbols, and the last symbol is a guard symbol. FIG. 3( b) illustrates a time slot format in which the first symbol is also an AGC symbol, followed by three symbols shared by DMRS, PSCCH, and PSSCH. The fifth symbol is a DMRS symbol, followed by two PSSCH symbols, and again a DMRS symbol, followed by two PSSCH symbols. The eleventh symbol is a guard symbol followed by another AGC symbol for the PSFCH, and in the thirteenth symbol the PSFCH is transmitted followed by another guard symbol.

[0056] The time slot format according to FIG. 3(a) can be used when the transmission / reception of payload data with feedback is disabled, for example for blind transmission. FIG. 3(b) illustrates a time slot format that can be used in the case where the PSFCH symbol is used to provide receiver transmission feedback. Therefore, the side link frame structure illustrated in FIG. 3 includes at least one guard symbol, which the UE uses to switch from a transmit mode (TX) to a receive mode (RX), and vice versa. For example, the time slot in FIG. 3(a) may be used by the first UE to send a transmission, and the last symbol, i.e., the guard symbol, is used by the first UE to switch from a transmit mode to a receive mode, for example for receiving a transmission from another UE in a subsequent time slot. In FIG. 3(b), the first UE may send payload data and switch from a transmit mode to a receive mode in the first guard symbol in order to receive feedback in the twelfth and thirteenth symbols. As shown in FIG. 3, although the duration of the guard symbol spans one OFDM symbol, the actual duration may vary depending on the subcarrier spacing SCS. In the case of a single component carrier CC using a CP-OFDM waveform and at least 10 resource blocks, the actual time required for the UE to switch between transmit and receive modes (i.e., AGC setup time) may be as follows:

[0057] -35μs for 15kHz SCS,

[0058] - 35μs for 30kHz SCS,

[0059] - 18 μs for 60 kHz SCS.

[0060] During the guard symbol, the UE neither sends nor receives any information, as shown in Figure 3, the guard symbol may appear at the end of the time slot or before the PSFCH symbol, because sending PSFCH in the same time slot requires the UE to switch between transmit / receive modes. Within the time slot that can be used for PSSCH transmission, 7 to 14 time slots can be reserved for sidelink operation, where PSSCH can be transmitted in 5 to 12 symbols. The remaining sidelink symbols can transmit some or all control information, such as PSCCH, PSFCH, reference symbols (such as DMRS), AGC, and guard symbols.

[0061] As described above, the duration of each symbol within a time slot depends on the numbers used to define the sidelink bandwidth portion, such as the configuration of the sidelink resource pool, which is used to determine the length of the guard symbol, as shown in the following table, which shows certain numbers and the corresponding duration of a symbol of the SCS within a time slot.

[0062] Parameter, value (μ) 0 1 2 Subcarrier spacing (kHz) 15 30 60 OFDM symbol duration (μs) 66.67 33.33 16.67 Cyclic prefix duration (μs) 4.69 2.34 1.17 OFDM symbol including CP (μs) 71.35 35.68 17.84

[0063] When considering the above-mentioned side link frame structure including at least one protection symbol, it has been found that, although the protection symbol is sufficient to allow the responding UE to perform the required CAP before starting transmission to ensure that the channel is available for the responding UE to perform transmission during the shared COT, at the same time, the duration of the protection symbol (i.e., the duration during which neither the initiating UE nor the responding UE transmits) is sufficient to allow another device to perform a channel access procedure, such as a device of another 3GPP wireless communication system or a device of a wireless communication system using a different RAT (such as a WiFi device or a Bluetooth device), so that the shared channel can be taken over and occupied by such a device, so that sharing the COT is no longer possible.

[0064] The present invention solves the above-mentioned problems and provides a method according to an embodiment, which can reduce or completely avoid the possibility of a channel being taken over by a different device that performs a successful CAP within the protection symbol duration during the COT. The embodiment of the present invention solves the above-mentioned problem by configuring the time interval between the initiating UE and the responding UE transmission, such that the time interval (i.e., the time when neither UE transmits is small enough) during the shared COT, no other device (such as other 3GPP devices or non-3GPP devices) can occupy the channel, and at the same time, the time interval is long enough for the responding UE to perform a channel access procedure (such as LBT or LBT-free CAP) before accessing the shared COT. Taking into account the time slot structure defined for side link communication as described above, according to an embodiment of the present invention, the time slot defined by the protection symbol or the protection is adjusted, thereby reducing the possibility of taking over the channel during the shared COT, or even making it completely impossible.

[0065] An advantage of the method of the present invention is that it allows the responding UE to at least perform a shortened CAP, such as the above-mentioned Type 2 channel access procedure, before using the shared COT, and at the same time, the protection symbol is no longer long enough so that other devices cannot occupy the channel. The basic structure of the time slot remains unchanged as the structure described above with reference to Figure 3, but, according to the method of the present invention, at least a portion of the protection symbols appear to be busy or occupied to another device (such as another 3GPP device or a non-3GPP device) that executes its CAP. Therefore, considering that in most cases, the CAP applied by other devices needs to span the duration of most of the protection symbols, the possibility that another device believes that the protection symbols are actually idle will be greatly reduced. According to certain embodiments, the time duration can actually span the entire or almost the entire duration of the protection symbol, which can fundamentally prevent another device from attempting to occupy the channel and thus interrupt COT sharing.

[0066] An embodiment of the present invention may be implemented in a wireless communication system as shown in FIG. 1 , FIG. 2( a ) or FIG. 2( b ), which system includes a base station and a user, such as a mobile terminal or an Internet of Things device. Figure 4 is a schematic diagram of a wireless communication system, including a transmitter 300 (such as a base station) and one or more receivers 302, 304 similar to user equipment UE. The transmitter 300 and the receivers 302, 304 can communicate via one or more wireless communication links or channels 306a, 306b, 308 (such as radio links). The transmitter 300 may include one or more antennas ANT coupled to each other. T Or an antenna array with multiple antenna elements, a signal processor 300a and a transceiver 300b. The receivers 302, 304 include one or more antennas ANTUE coupled to each other or an antenna array with multiple antennas, a signal processor 302a, 304a and transceivers 302b, 304b. The base station 300 and the UE 302, 304 can communicate through corresponding first wireless communication links 306a and 306b (such as radio links using Uu interfaces), and the UEs 302, 304 can communicate with each other through a second wireless communication link 308 (such as a radio link using PC5 or a side link SL interface). When the UEs are not served by the base station or are not connected to the base station, for example, they are not in an RRC connected state, or more generally, when the base station does not provide SL resource allocation configuration or assistance, the UEs can communicate with each other through the side link. Figure 4 systems or networks, Figure 4 One or more UEs 302, 304 and Figure 4 The base station 300 can operate according to the teachings of the invention described herein.

[0067] UE initiates COT

[0068] The present invention provides a user equipment UE for a wireless communication network (such as a third generation partnership project 3GPP network),

[0069] wherein the UE will perform sidelink SL communication using a channel including resources from an unlicensed spectrum,

[0070] The UE will occupy the channel within the channel occupation time COT and share the COT with another UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection time length,

[0071] wherein the UE will perform transmission via the SL during the first part of the COT,

[0072] wherein a second portion of the COT is used by the other UE to perform transmission via the SL, and

[0073] The UE extends the transmission into the protection duration so as to transmit during a predefined duration starting from the starting part of the protection duration, and the selected predefined duration should make the remaining duration of the protection duration sufficient to allow the other UE to perform a predefined channel access procedure CAP before accessing the shared COT.

[0074] According to an embodiment, the UE extends the transmission to the protection duration by obtaining or copying content from a first part of the COT or a predefined part of the first part of the transmission, for example, obtaining or copying content from the starting part of the last transmission symbol after the cyclic prefix CP or the extended cyclic prefix of the data in the last transmission symbol.

[0075] According to an embodiment, the last transmission symbol includes one or more of the following:

[0076] - Automatic gain control AGC symbol,

[0077] - Demodulation Reference Signal DMRS,

[0078] - data channels, such as the physical sidelink shared channel PSSCH,

[0079] - control channels, such as the Physical Sidelink Control Channel PSCCH,

[0080] - Feedback channel, such as Physical Sidelink Feedback Channel PSFCH.

[0081] UE Shared COT

[0082] The present invention provides a user equipment UE for a wireless communication network, such as a third generation partnership project 3GPP network,

[0083] wherein the UE will perform sidelink SL communication using a channel including resources from an unlicensed spectrum,

[0084] The UE will share the channel occupied by another UE within a channel occupation time COT initiated by another UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection time length,

[0085] wherein the first portion of the COT is used by the other UE to perform transmission via the SL,

[0086] wherein the UE is to perform transmission via the SL during the second part of the COT, the first part of the COT and the second part of the COT being separated by a protection duration, and

[0087] The UE extends the transmission into the protection duration so as to transmit during a predefined duration ending at the end of the protection duration, and the selected predefined duration makes the initial duration of the protection duration sufficient to allow the UE to perform a predefined channel access procedure CAP before accessing the shared COT.

[0088] According to an embodiment, the UE extends the transmission into the guard duration by obtaining or copying content from a predefined portion of the second part of the COT or the last part of the transmission, such as obtaining or copying content from the end of the next symbol.

[0089] According to an embodiment, the next symbol includes one or more of the following:

[0090] - Automatic gain control AGC symbol,

[0091] - Demodulation Reference Signal DMRS,

[0092] - data channels, such as the physical sidelink shared channel PSSCH,

[0093] - control channels, such as the Physical Sidelink Control Channel PSCCH,

[0094] - feedback channels, such as the physical sidelink feedback channel PSFCH,

[0095] - The automatic gain control AGC symbol before the PSFCH.

[0096] According to an embodiment, the next symbol used to copy the content belongs to the same time slot or to the next time slot.

[0097] The present invention provides a user equipment UE for a wireless communication network (such as a third generation partnership project 3GPP network),

[0098] wherein the UE will perform sidelink SL communication using a channel including resources from an unlicensed spectrum,

[0099] The UE will share the channel occupied by another UE within a channel occupation time COT initiated by another UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection time length,

[0100] wherein the first portion of the COT is used by the other UE to perform transmission via the SL, the other UE extending the transmission into a guard duration so as to transmit during a first predefined duration starting from a start portion of the guard duration, and

[0101] The UE will perform transmission via the SL during the second part of the COT, and the UE will extend the transmission into the protection duration so as to transmit during a second predefined duration ending at the end of the protection duration.

[0102] According to an embodiment, before accessing the shared COT, the UE accesses the shared COT without performing a listen-before-talk (LBT) procedure.

[0103] According to an embodiment, one of the first predefined duration or the second predefined duration is zero so that one of the UE or the other UE occupies the entire guard duration.

[0104] According to an embodiment,

[0105] - the other UE will extend the transmission into the guard duration by obtaining or copying content from the first part of the COT or a predefined part of the first part of the transmission, for example, obtaining or copying content from the beginning of the last transmission symbol immediately following the cyclic prefix CP or the extended cyclic prefix of the data in the last transmission symbol, and / or

[0106] - The UE will extend the transmission into the guard duration by obtaining or copying content from a predefined part of the second part of the COT or the last part of the transmission, for example, obtaining or copying content from the end of the next symbol, such as an automatic gain control AGC symbol.

[0107] According to an embodiment, the last transmitted symbol or the next symbol includes one or more of the following:

[0108] - Automatic gain control AGC symbol,

[0109] - Demodulation Reference Signal DMRS,

[0110] - data channels, such as the physical sidelink shared channel PSSCH,

[0111] - control channels, such as the Physical Sidelink Control Channel PSCCH,

[0112] - feedback channels, such as the physical sidelink feedback channel PSFCH,

[0113] - The automatic gain control AGC symbol before the PSFCH.

[0114] According to an embodiment, the UE extends the transmission into the guard duration by obtaining or copying content from a predefined portion of the second portion of the COT, for example, obtaining or copying content from the end of an automatic gain control AGC symbol.

[0115] According to an embodiment, the other UE that performs transmission through SL during the first part of the COT is a first another UE, and the UE will perform transmission to the first another UE or to a second another UE through SL during the second part of the COT, and the second another UE is different from the first another UE.

[0116] UE rise / Shared channel occupation time COT

[0117] According to an embodiment, the protection duration has one or more of the following lengths:

[0118] -CP length,

[0119] - Extend the length of the cyclic prefix ECP,

[0120] -OFDM symbol length,

[0121] - a multiple of the OFDM symbol length, such as one-half or twice the OFDM symbol length,

[0122] - multiple OFDM symbols,

[0123] - frame interval, such as the short frame interval SIFS used in WiFi systems,

[0124] - A configured or preconfigured duration, such as a time defined in microseconds.

[0125] According to an embodiment, the CAP is one of the following:

[0126] -Type 1 CAP, which senses the channel for random durations,

[0127] - Type 2A CAP, sensing two sensing time slots at an interval of at least 25 μs, e.g. at the start and end of a time slot,

[0128] -2B CAP, sensing a 9μs sensing time slot within an interval of at least 16μs,

[0129] -2C type CAP, does not sense channels.

[0130] According to an embodiment, the CAP type used by the UE for its transmissions depends on certain conditions.

[0131] According to an embodiment, the specific conditions are one or more of the following:

[0132] - a transmission length, such as the size of data to be transmitted by the UE, wherein if the transmission length is equal to or above a predefined threshold, the UE shall perform LBT, and wherein if the transmission length is less than the predefined threshold, the UE shall not perform LBT,

[0133] - the type of data to be transmitted, for example, feedback data such as PSFCH, or an IUC request,

[0134] - Control and / or data transmission has a certain priority.

[0135] According to an embodiment, the COT spans at least a first time slot including a plurality of symbols, the first part of the COT includes a first number of symbols, the second part of the COT includes a second number of symbols, and the guard duration includes a time interval between a last symbol of the first number of symbols and a first symbol of the second number of symbols.

[0136] According to an embodiment,

[0137] - the COT spans at least the first time slot and a second time slot, the second time slot comprising a plurality of symbols, and the first time slot comprising another guard duration, the other guard duration comprising a time interval being the last symbol in the first time slot, and / or

[0138] - the UE extends the transmission to a subsequent guard duration and / or another guard duration, or

[0139] - The other UE extends the transmission to the previous guard duration.

[0140] According to an embodiment, the COT spans at least two time slots, each time slot includes multiple symbols, the first part of the COT includes a first time slot, the second part of the COT includes a second time slot, and the protection time length includes a time interval, which is the last symbol in the first time slot.

[0141] According to an embodiment,

[0142] - the first time slot and / or the second time slot comprises a plurality of symbols, a first part of the first time slot and / or the second time slot comprises a first number of symbols, a second part of the first time slot and / or the second time slot comprises a second number of symbols, and the first part of the first time slot and / or the second time slot comprises a further guard duration, the further guard duration comprising a time interval between a last symbol of the first number of symbols and a first symbol of the second number of symbols, and

[0143] - the UE extends the transmission to a subsequent guard duration and / or another guard duration, or

[0144] - The other UE extends the transmission to the previous guard duration.

[0145] According to an embodiment, the predefined duration is determined in μs as follows:

[0146]

[0147] in

[0148] μ is a numerical parameter, for example, for 15kHz subcarrier spacing SCS, μ=0, for 30kHz SCS, μ=1, for 60kHz SCS, μ=2,

[0149] TG min The minimum time for executing a predefined CAP before accessing the shared COT, for example, 25 μs for Type 2A LBT and 16 μs for Type 2B LBT.

[0150] According to an embodiment, the duration of the guard symbols decreases as the subcarrier spacing and / or bandwidth increases.

[0151] According to an embodiment, the guard period has a duration such as a switching time, allowing the UE to switch between a transmission mode and a reception mode.

[0152] system

[0153] The present invention provides a wireless communication system (such as a 3rd Generation Partnership Project 3GPP system). According to an embodiment of the present invention, the system includes one or more user equipments UE.

[0154] According to an embodiment, the UE includes one or more of the following: a power-limited UE; or a handheld UE, such as a user equipment used by pedestrians, and is called a vulnerable road user VRU; or a pedestrian user equipment P-UE; or a wearable or handheld UE used by public safety personnel and emergency personnel, also known as a public safety user equipment PS-UE; or an IoTUE, for example, a sensor, actuator or UE provided in a campus network that performs repetitive tasks and requires regular input from a gateway node; or a mobile terminal; or a fixed terminal; or a cellular IoT user equipment; or a SL UE or a vehicle UE; or a vehicle-mounted master user equipment GL-UE or a dispatch user equipment S-UE; or an IoT or narrowband IoT NB-IoT device; or a ground vehicle; or an aircraft; or a drone; or a mobile base station; or a roadside unit RSU; or a building; or any other item or device with a network connection that enables the item / device to communicate using a wireless communication network, such as a sensor or actuator; or any other item or device with a network connection that enables the item / device to communicate using a wireless communication network, such as a sensor or actuator; or any network entity that can implement a side link.

[0155] According to an embodiment, the base station includes one or more of the following: a macrocell base station; or a small cell base station; or a central unit of a base station; or a distributed unit of a base station; or an integrated access and backhaul IAB node; or a roadside unit RSU; or a UE; or a SL UE; or a master user equipment GL-UE; or a relay or remote radio head; or an access and mobility management function AMF; or a session management function SMF; or a core network entity; or a mobile edge computing MEC entity; or a network slice in a new radio NR or 5G core environment; or any transmission / reception point TRP that enables an item or device to communicate using a wireless communication network, and the item or device is provided with a network connection to communicate using the wireless communication network.

[0156] method

[0157] A method for operating a user equipment (UE) for a wireless communication network such as a 3rd Generation Partnership Project (3GPP) network, wherein the UE is to perform a sidelink (SL) communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises:

[0158] Occupy the channel within the channel occupation time COT,

[0159] Sharing a COT with another UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT are separated by a guard duration,

[0160] During a first portion of the COT, transmission is performed over the SL, wherein a second portion of the COT is transmitted by another UE over the SL, and

[0161] The transmission is extended into the guard duration so as to transmit during a predefined duration starting from the start of the guard duration, the predefined duration being selected such that the remaining duration of the guard duration is sufficient to allow the other UE to perform a predefined channel access procedure CAP before accessing the shared COT.

[0162] The present invention provides a method for operating a user equipment UE for a wireless communication network such as a 3rd Generation Partnership Project 3GPP network, wherein the UE is to perform a sidelink SL communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises:

[0163] sharing a channel occupied by another UE within a channel occupation time COT initiated by another UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT are separated by a guard duration, and wherein the first part of the COT is used by the other UE to perform transmission through the SL,

[0164] performing transmission over the SL during a second portion of the COT, the first portion and the second portion of the COT being separated by a guard duration, and

[0165] The transmission is extended into the guard duration so as to be transmitted during a predefined duration ending at the end of the guard duration, the predefined duration being selected such that an initial duration of the guard duration is sufficient to allow the UE to perform a predefined channel access procedure CAP before accessing the shared COT.

[0166] The present invention provides a method for operating a user equipment UE for a wireless communication network such as a 3rd Generation Partnership Project 3GPP network, wherein the UE is to perform a sidelink SL communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises:

[0167] sharing a channel occupied by another UE within a channel occupation time COT initiated by another UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT are separated by a guard duration, wherein the first part of the COT is transmitted by the other UE through the SL, and the other UE extends the transmission into the guard duration so as to transmit within a first predefined duration starting from the guard duration,

[0168] The transmission is performed via the SL during the second part of the COT,

[0169] The transmission is extended into the guard period to transmit during a second predefined period ending at the end of the guard period.

[0170] According to an embodiment, before accessing the shared COT, the shared COT is accessed without performing a listen-before-talk (LBT) procedure.

[0171] Computer program product

[0172] An embodiment of a first aspect of the present invention provides a computer program product, which includes instructions. When a computer executes the program, the instructions can cause the computer to perform one or more methods consistent with the present invention.

[0173] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. It should be noted that the aspects or embodiments summarized and described below may be combined to implement some or all aspects / embodiments in one embodiment. In addition, it should be noted that when "resources" are mentioned in this specification, resources should be understood to include one or more of the following resources:

[0174] - one or more symbols,

[0175] - one or more time slots or subframes or frames,

[0176] - one or more frequencies or carriers or subchannels or groups of subchannels,

[0177] - one or more frequency bands, such as unlicensed sub-bands,

[0178] - one or more bandwidth portions,

[0179] - one or more resource pools,

[0180] - one or more LBT sub-bands,

[0181] - One or more spatial resources, for example using spatial multiplexing.

[0182] In addition, it should be noted that when "a set of resources" is mentioned in this specification, a set of resources may include one or more resources, and the definition of resources is as described above. In addition, it should be noted that when "channel" is mentioned in this specification, it may refer to a collection of the above resources. Therefore, "channel" may also refer to a subchannel, a subband, a resource pool or an SL BWP.

[0183] It should be noted that in the description of this article, when referring to the above-mentioned "shared channel occupation", it is also referred to as UE sharing COT or using shared COT. This means that the UE can use the channel originally occupied by another UE within the COT started in response to other UEs performing LBT or during at least a part of the COT to ensure that the channel is available, initiate COT and occupy the channel.

[0184] Figure 5 The figure shows a wireless communication system, such as the system described above with reference to FIG. 1 , FIG. 2 or FIG. 3 , for example, a system or network of the Third Generation Partnership Project 3GPP.

[0185] The wireless communication system includes user equipment 400, 402 and one or more base stations 404 operating according to an embodiment of the present invention. UE 400 (also referred to as sidelink UE, SL-UE) includes one or more antennas 400a and a signal processor 400b for performing one or more operations, such as operations involving antenna 400a, such as sending / receiving data (such as payload data or control data), or inter-UE coordination (IUC) messages. UE 400 can communicate with other UEs (such as UE 402) using a sidelink or PC5 interface, as shown at 408. UE 402 (also referred to as sidelink UE, SL-UE) includes one or more antennas 402a and a signal processor 402b for performing one or more operations, such as operations involving antenna 400a, such as sending / receiving data (such as payload data or control data) or inter-UE coordination (IUC) messages. In addition, UE 400 and / or UE 402 can be connected to a base station or gNB 404. The gNB 404 includes one or more antennas 404a for wireless communication with other network entities such as UE 400 and / or UE 402, and a signal processor 404b. When operating in Mode 1, UE 400 and UE 402 receive resources allocated by gNB 404 via Uu interface 412, which will be used by the UE to communicate via side link 408. As described above, when operating in Mode 2, UE 400 and / or UE 402 may not have a connection with gNB 404, and sensing-based resource allocation or random access-based resource allocation is performed before performing transmission.

[0186] Figure 5A spectrum 414 is further schematically illustrated, such as a radio spectrum including resources for communication within a wireless communication system or network. Resources that can be used for SL communication may include one or more of the following: one or more symbols, one or more time slots or subframes or frames, one or more resource blocks (RBs) or frequencies or carriers or subchannels or subchannel groups, one or more frequency bands. As shown, the spectrum 414 includes a licensed spectrum 416 and an unlicensed spectrum 418. The licensed spectrum 416 is a portion of the spectrum reserved for a wireless communication system including UEs 400 and 402 and base stations 404. In other words, the resources in the licensed spectrum are only used by the wireless system according to regulations of regulatory agencies and entities. The unlicensed spectrum 418 includes resources that can be used by multiple wireless communication systems, such as another wireless communication system that complies with the 3GPP standard but is operated by a different operator, or a system that uses a different wireless access technology (such as WiFi or Bluetooth).

[0187] According to an embodiment, a resource pool 420 (also referred to as a side link resource pool, SL-RP) may be provided for side link communications, and the UE 400 may be configured or pre-configured with the resource pool 420. Although only one resource pool is depicted in the figure, multiple such resource pools may be configured or pre-configured. The resource pool may include only resources from the unlicensed spectrum 418, or only resources from the licensed spectrum 416, or as described above. Figure 5 As shown, resources from the licensed spectrum 416 and the unlicensed spectrum 420 may be included. According to further embodiments, resources in the unlicensed spectrum may be aggregated using carrier aggregation.

[0188] According to an embodiment of the present invention, UE 400 is a SL-UE that communicates on the SL using resources from an unlicensed spectrum, and in the following description of the embodiment of the present invention, it is assumed that UE 400 is the above-mentioned COT initiating UE or initiating UE, and UE 402 is assumed to be a COT sharing UE or responding UE. The method of the present invention is not limited to this case, but UE 400 can share COT with one or more other network entities of the wireless communication network. In order to perform transmission through the side link 408, such as transmission to one or more other UEs (such as UE 402), UE 400 (as shown in 422) occupies a channel, that is, a resource spanning a certain time in the time domain and a certain frequency in the frequency domain. Occupying the channel further starts or initiates a channel occupation time COT. According to an embodiment, UE 400 occupies the channel in response to a successful channel access procedure CAP performed by UE 400 on the channel. According to other embodiments, UE 400 can obtain assistance from, for example, gNB 404 or any other network entity, so that there is no need to perform CAP on the channel. UE 400 may receive information regarding resources or channels to be used for transmission, for example, gNB 404 may provide a grant that indicates a channel (e.g., a resource in an unlicensed spectrum) for UE 400 to use for transmission on the sidelink. UE 400 may also perform sensing and resource selection when operating in Mode 2 to determine resources to be used for transmission. In either case, UE 400 performs a CAP, as shown in 422, UE 400 occupies a channel for transmission, and initiates a COT. After a successful CAP causes UE 400 to occupy a channel and initiate a COT, UE 400 may share the COT with another network entity (e.g., UE 402, also referred to as a responding or another UE), as shown in FIG. Figure 5 As shown in 422.

[0189] The channel occupied by UE 400 in the COT is Figure 6 It is schematically illustrated in and extends to the COT in the time domain and to a certain number of frequencies or subcarriers in the frequency domain. Figure 6The figure shows a shared channel 426, the duration of which corresponds to the COT. The COT has a first part 428 and a second part 430, which are separated by a guard duration 432. The first and second parts of the COT may have the structure as described above with reference to FIG. 3, and the guard duration 432 may include one or more guard symbols. As described above, during the guard duration 432, neither the UE 400 nor the UE 402 transmits. Therefore, for another device (such as a non-3GPP device), when the CAP is performed during the guard duration 432, the channel or frequency band 426 appears to be idle, and it may occupy the channel 426, thereby interrupting the COT sharing. To solve this problem, according to an embodiment of the present invention, the UE 400 that occupies the channel 426 to start the COT performs a transmission during the first part 428 of the COT, and extends the transmission to the guard duration 432 as shown in 434, thereby effectively shortening the duration that the channel 426 appears to be idle to other devices. This reduces or even eliminates the possibility that another device takes over the channel 426 and occupies the channel for transmission. In other words, according to the method of the present invention, the protection duration 432, like the protection symbol described above with reference to FIG. 3 , can be used as a time interval required for the response UE to perform the necessary channel access procedure when using the shared COT. However, by extending the transmission in the first part 428 to the protection duration 432 within a configured or preconfigured duration by UE 400, it is possible to avoid the actual time interval for performing CAP during the protection duration or protection symbol 342 from becoming too long (depending on the SCS and parameter configuration used), thereby causing the CAP of another device to also be busy for the protection duration, thereby avoiding or at least greatly reducing the possibility of other devices occupying the channel 426.

[0190] Therefore, according to Figure 5 In the embodiment, during the first part of the COT, the channel 426 occupied by UE 400 in the COT is used for UE 400 to transmit via the side link, and UE 402 can also use the second part 430 to transmit via the side link. As shown in Figure 436, as described above with reference to Figure 6 As described, UE 400 extends its transmission into guard duration 432 so as to transmit during its predefined duration. Figure 6 As can be seen in FIG. 4 , the duration starts from the beginning of the guard duration, and the selected duration makes the remaining duration 438 of the guard duration 432 sufficient for the UE 402 to perform the predefined channel access procedure before actually accessing the shared COT or channel 426.

[0191] It is noteworthy that UE 400 can perform a sidelink transmission during the first portion 428 of the COT, which is directed to UE 402 or any other UE around UE 400 and capable of communicating with UE 400 via the sidelink. Similarly, UE 402 can use the second portion 430 of the COT to perform a transmission to the initiating UE 400 or any other UE around that can communicate with UE 402 via the sidelink.

[0192] According to an embodiment, in order to extend the transmission to the guard duration 432, the UE 400 may obtain or copy certain content from a predefined portion of the COT first portion 428 or the first portion of the transmission in the previous symbol before the guard symbol. In other words, certain information transmitted in the COT first portion 428 may simply be copied to the guard duration 432. When considering the above-mentioned sidelink frame structure with reference to FIG. 3, according to an embodiment, the UE 400 may obtain information from the beginning of the last transmission symbol, such as from the PSSCH symbol located before the guard symbol and immediately after the cyclic prefix of the data in the last PSSCH symbol. According to other embodiments, the last transmission symbol may include an AGC symbol, a DMRS, a data channel (such as PSSCH), a control channel (such as PSCCH), or a feedback channel (such as PSFCH). In addition, any other type of information may be used, even information that is not related to the transmission to be performed by the initiating UE, which is not important because the information transmitted during the duration 434 will not be considered or actually decoded.

[0193] According to other embodiments, the method of the present invention may be implemented by a responding UE 402 instead of an initiating UE 400, and the responding UE 402, like the initiating UE 400, performs sidelink communication using a channel containing unlicensed spectrum 418 resources. The UE 402 as the responding UE receives an indication from the initiating UE 400 that the UE 400 occupies the channel and shares the COT with the UE 402, as described above with reference to Figure 6 The channel 426. Figure 7The figure shows how the responding UE 402 operates according to an embodiment of the present invention to overcome the problems of the conventional method of using a completely idle guard period 432. As described above, the responding UE 402 shares a channel 426 within the COT with an initiating UE 400, the initiating UE 400 performs transmissions on the side link during a first portion 428 of the channel 426, and provides COT information to the UE 402 during the first portion 428 so that the responding UE 402 can perform transmissions on the side link during a second portion 430 of the COT. In addition to the above embodiment with respect to the initiating UE, in this embodiment, the responding UE 402 extends its transmission into the guard period 432 so as to transmit for a predefined duration 434 that starts at the start time of the guard period 432 and ends or terminates at the end of the guard period 432 so that the initial duration 440 at the beginning of the guard period 432 is sufficient for the responding UE 402 to perform a predefined channel access procedure before accessing the channel 426. In other words, UE 402 starts transmitting at the beginning of 434 and continues to the second part 430. The responding UE 402 can extend its transmission to the guard duration 432 by obtaining or copying content from the last part of the transmission in the predefined part of the second part 430 of the COT or the next symbol. For example, the content can be obtained from the end of the automatic gain control (AGC) symbol and copied into the duration 434. When considering the above-mentioned side link frame structure with reference to Figure 3, according to an embodiment, UE 400 can obtain information from the end of the next transmission symbol, just like the AGC symbol after the guard symbol. According to other embodiments, the next transmission symbol may include an AGC symbol, a DMRS, a data channel (such as PSSCH), a control channel (such as PSCCH), a feedback channel (such as PSFCH), or an AGC symbol before PSFCH. In addition, any other type of information can be used, even information that is irrelevant to the transmission to be performed by the responding UE, which is not important because such information transmitted during the duration 434 will not be considered or actually received.

[0194] According to a further embodiment, reference may be combined Figure 6 and Figure 7 The described embodiment is such that both the initiating UE 400 and the responding UE 402 extend the corresponding transmission into the guard period 432 . Figure 8The figure shows a channel 426 shared by UE 400 and UE 402 within the COT. The initiating UE 400 performs transmission via the side link during a first portion 428 of the COT, and the responding UE performs transmission via the side link during a second portion 430 of the COT. The initiating UE 400 and the responding UE 402 extend their transmissions into the guard duration 432 by a first duration 4341 and a second duration 4342, respectively, making the middle duration 442 of the guard duration 432 invalid. It is worth noting that according to other embodiments, the transmissions of the two UEs may be extended in such a way that there is no blank area 442, i.e., the extended transmission of the responding UE 402 may start when the extended transmission of the initiating UE ends. In other words, according to Figure 8 In an embodiment, the invalid duration of the guard duration or the guard period 432 can be completely eliminated or reduced to a short time interval 442 in the middle of the guard duration 432. In this case, the responding UE is allowed to access the shared channel or the shared COT 426 without performing a channel access procedure before accessing the shared COT 426, also known as LBT-free access. Figure 8 In the embodiment of the present invention, the above reference Figure 6 and Figure 7 The described approach extends the transmission to the protection period 432 .

[0195] It is worth noting that according to other embodiments, according to Figure 8 The method described can also be extended by Figure 6 The transmission of the initiating UE 400 is implemented so as to occupy the entire or substantially the entire protection period. In this case, the intermediate duration 442 (if any) is at the end of the protection period. According to other embodiments, Figure 8 The method can also be extended by Figure 7 The transmission of the responding UE 402 is implemented by occupying the entire or substantially the entire protection period. In this case, the intermediate duration 442 (if any) is at the beginning of the protection period.

[0196] about Figures 6 to 8 In the above embodiment described in, the corresponding transmission may be such that the initiating UE 400 transmits to the responding UE or any other UE, and the responding UE 402 transmits to the initiating UE 400 or any other UE.

[0197] In a scenario where the first portion of the transmission performed by the initiating UE is directed to the responding UE 402, the responding UE 402 may be aware of the transmission directed to it, for example, through a received SCI message (which also includes the COT sharing information), and during the first portion of the COT, the responding UE is in a receiving mode. At the end of the first portion 428 and during the interval duration 432, the responding UE may switch to a transmitting mode to transmit over the sidelink during the second portion. Figure 6 In the embodiment, the responding UE does not need the information transmitted by the initiating UE 400 during the guard period 432, so at the interface between the first part 428 and the guard period 432, the responding UE can start to switch from the receive mode to the transmit mode because there is no need to receive the extended transmission during the guard period 432, as this may be a copy of the transmitted information (as described above) or any other type of signal, but these signals are not part of the actual transmission to be received by the responding UE 402.

[0198] Likewise, in Figure 7 In an embodiment, if the transmissions performed by the responding UE are directed to the initiating UE 400, the initiating UE 400 may begin switching from the transmit mode to the receive mode during the guard duration 432, because the transmissions of the responding UE have been extended into the guard duration so as to preserve the COT during the duration 434 at the end of the guard duration, and the initiating UE 400 does not need to receive these transmissions because these transmissions are either redundant information also included in the actual transmissions transmitted during the second portion 430, or are arbitrary information that is not intended to be part of the transmission to the initiating UE.

[0199] about Figure 8 In the embodiment, when the transmission of the initiating UE 400 during the first part 428 is directed to the responding UE 402, and the transmission performed by the responding UE during the second part 430 is also directed to the initiating UE 400, the middle duration 442 of the guard duration and the durations 4311 and 4342 are respectively selected such that the combined duration of 4342 and 442 is sufficient for the initiating UE to switch from the transmitting mode to the receiving mode, and the combined duration of 4341 and 442 is sufficient for the responding UE to switch from the receiving mode to the transmitting mode. Therefore, in Figure 8 In the scenario of , the responding UE 402 can switch during the first part of the guard duration 432 (combining durations 4341 and 442), while the initiating UE 400 continues to transmit. After switching, the responding UE 402 can start transmitting, for example, by extending the AGC symbol, while the initiating UE 400 has enough time (duration 4342 plus 442) to switch from the transmit mode to the receive mode to allow the UE 400 to receive the AGC and the transmission performed by the responding UE during the second part 430 of the COT.

[0200] Referenced above Figures 5 to 8 An embodiment of the present invention is described, and it is assumed that the channel 426 has a certain duration within the COT. According to an embodiment of the present invention, the channel 426 may include one or more time slots, such as the one or more time slots shown above with reference to FIG. 3. According to an embodiment, the channel 426 may include one or more time slots having a frame structure as shown in FIG. 3(a), or one or more time slots having a frame structure as shown in FIG. 3(b). In addition, the channel may also include two or more time slots, one of which has a frame structure as shown in FIG. 3(a), and another time slot has a frame structure as described above with reference to FIG. 3(b).

[0201] Therefore, according to an embodiment, when a time slot having a frame structure as described above with reference to FIG. 3 is used, there are more than one guard duration 432 so that there may be another guard duration between the second part 430 of the COT and the third part or other part of the frequency band. If the other part of the frequency band is not part of the shared channel 426, there is no need to apply the method of the present invention to another guard duration (e.g., after the second part 430 of the COT) because the COT sharing is terminated at this time and another device can actually occupy the frequency band or channel for transmission. However, if the duration of the COT extends to the first and second parts and another part, the corresponding parts can be separated by multiple guard durations, and the method of the present invention can be used to minimize the probability of the channel being occupied by other devices (such as non-3GPP devices).

[0202] In the following, further embodiments of the method of the present invention are described with reference to a channel using a frame structure according to FIG. 3( a). FIG. 9( a) illustrates an embodiment according to which: Figure 5 The channel 426 initially occupied by the UE 400 initiating the COT includes two time slots, and its structure is shown in FIG. 3( a ), assuming that the COT starts from the first symbol in the first time slot 428 forming the first part of the COT, and is end-to-end with the PSCCH symbol in the second time slot 430 forming the second part of the COT. In order to prevent the channel 426 from being taken over and occupied by another device, the method of the present invention is applied to the protection symbol 432 which is the last symbol of the first time slot 428. As described above with reference to Figure 6 and Figure 7As described, a portion of the transmission of the initiating UE 400 in the first time slot 428 may be extended into the guard symbol 432, or another portion of the transmission performed by the responding UE in the second time slot 430 may be extended into the guard symbol 430. FIG9(b) illustrates a case where the transmission of the initiating UE 400 is extended into the guard period or guard symbol 432 by copying the first portion of the PSSCH to the first portion of the guard symbol 432, as schematically indicated by arrow 444, thereby extending the transmission by a duration 4341. FIG9(c) illustrates an embodiment according to which the transmission of the responding UE is extended into the guard symbol 432, as described above with reference to FIG9(d). Figure 7 According to the depicted embodiment, a portion of the AGC symbol, such as its end, may be duplicated, as indicated by arrow 446 at the end of the guard symbol, thereby defining a duration 4342 for the transmission of the responding UE to extend to the guard symbol 432. In addition, the methods of FIG. 9( b) and FIG. 9( c) may be implemented as described above with reference to FIG. Figure 8 The described approaches are combined so that the transmissions of both the initiating UE 400 and the responding UE 402 extend into the guard symbols 432 .

[0203] As shown in FIG. 9 , the COT ends at the last PSSCH symbol of the second time slot 430 and no action needs to be taken for another guard symbol at the end of the second time slot because the COT ends at this point, leaving the frequency band or channel 426 free for other devices to occupy.

[0204] Another embodiment of the present invention for shortening the blank time of the guard symbol is now described with reference to the sidelink frame structure according to FIG. 3( b). As described above, according to the method of the present invention, guard symbols are employed so as to provide the responding UE with the time interval required to perform the necessary CAP, such as LBT, when a shared COT is used. FIG. 10 illustrates an embodiment, assuming that the COT has a duration of one time slot, during a first portion 428 of the COT (over 10 symbols), the COT initiating UE 400 performs a transmission. During a second portion 430 of the COT covering the 12th and 13th symbols of the COT, the responding 402 performs a transmission. The 11th and 14th symbols are guard symbols, where, conventionally, the initiating UE 400 and the responding UE 402 do not send anything. According to FIG. 10( a ), a guard symbol 432 between the PSSCH and the PSFCH is considered, and the initiating UE extends the transmission of the PSSCH into the guard symbol 432, as shown in 4341 in FIG. 10( a ), so that the configured or preconfigured duration starting from the guard symbol 432 within the guard symbol 432 undergoes the PSSCH transmission. Therefore, due to the additional transmission during the duration 4341, the duration that the guard symbol 432 is idle is shortened, so that other devices performing CAP may consider the guard symbol busy, thereby greatly reducing or even eliminating the possibility that the channel 426 is taken over and occupied by another device performing CAP in the guard symbol 432.

[0205] FIG. 10( b ) illustrates a situation similar to FIG. 10( a ), as described above with reference to FIG. Figure 7 As described in more detail, except that the transmission from the responding UE is extended into the guard symbol 432. In the embodiment of FIG10( b), the responding UE begins transmission before the end of the guard symbol, thereby covering the duration 4342 at the end of the guard symbol 432. According to FIG10( b), the responding UE extends the AGC transmission of the PSFCH into the previous guard symbol within the configured or preconfigured duration 4342.

[0206] FIG. 11 illustrates another embodiment of the method of the present invention, according to which it is assumed that the COT covers a first time slot and at least one subsequent time slot. It is assumed that the first time slot has a frame structure as shown in FIG. 3( b), and the second time slot or any other time slot may have a structure as shown in FIG. 3( a) or FIG. 3( b) or any other frame structure. As shown in FIG. 11( a), it is assumed that the COT starts from the 11th symbol of the time slot, and according to such embodiments, the COT initiating UE may be UE 402, for example, in order to send PSFCH, UE 402 occupies a channel 426 within the COT, therefore, in the illustrated embodiment, the first part 428 of the COT includes the 12th and 13th symbols of the first time slot, and the second part 430 of the COT includes symbols from the subsequent time slot, the two time slots being separated by a guard symbol 432. UE 402 may also start COT from the first symbol of the time slot for transmission of control and data, and occupy channel 426 within the COT, so that the first part 428 of the COT includes the first to the 10th symbols of the first time slot, for sending PSFCH related to the previous transmission, occupying the 12th and 13th symbols of the first time slot, and avoiding another device from using COT by extending the PSSCH transmission in the 10th symbol into the 11th symbol. In order to avoid channel 426 being occupied by another device performing CAP during the guard symbol 432, according to an embodiment of the method of the present invention, UE 402 occupies the channel for PSFCH transmission and shares COT (see Figure 5 448 in FIG. 448), and extends its PSFCH transmission to the protection symbol 432 (see FIG. Figure 5 450), as referenced above Figure 7 As described above, the difference is that the transmission in the first part 428 is now performed by the UE 402. Therefore, the UE 402 extends the transmission of the PSFCH into the guard symbol 432 within the duration 4341.

[0207] 11( b) illustrates another embodiment, according to which the transmission of the second part 430 of the next time slot or COT will be extended into the guard symbol 432. For example, a UE transmitting during the second part 430 of the COT (i.e., a COT sharing UE of UE 400 in this embodiment) extends the transmission of the AGC symbol into the guard symbol 432 at the end of the previous time slot for a duration of 4342.

[0208] Also as mentioned above Figure 7As described, in the embodiments of Figures 10(b) and 11(b), the UE receiving the transmission in the second portion 430 of the COT performs AGC measurements on the AGC symbols separately, according to the symbol boundary, after the transmission of the transmitting UE has extended to the guard symbol 432. In other words, any excess overflow of the guard symbol will not affect the AGC measurement before the PSFCH, PSSCH or PSCCH transmission, because the measurement is performed separately in the AGC symbol, and the UE does not consider the transmission of the AGC in the guard symbol in the AGC measurement.

[0209] FIG. 12 illustrates an embodiment according to which the transmissions from the initiating UE and the responding UE are extended into the guard symbol 432, FIG. 12(a) illustrates a combination of the embodiments of FIG. 10(a) and FIG. 10(b), while FIG. 12(b) illustrates a combination of the embodiments of FIG. 11(a) and FIG. 11(b). Thus, as described above with reference to Figure 8 Described in more detail, whether at the beginning of the guard symbol or at the end of the guard symbol 432, the transmission from the initiating UE and the responding UE are extended for a certain duration 4311 and 4342 respectively, entering the guard symbol 432, and the middle blank area 442 is significantly reduced or completely eliminated. In other words, combining the above embodiments in the manner described with reference to FIG. 12 can eliminate or reduce the duration of idleness of the guard symbol or guard period, because in this case, the time interval when the guard symbol 432 is idle is very short, or there is no idle duration of the guard symbol 432 at all.

[0210] As mentioned above Figure 8 As described above, this can be achieved by switching the responding UE in the first part of the guard symbol while the initiating UE continues to transmit, thereby achieving an LBT transmission without gaps, such as feedback transmission. After switching, the responding UE can start transmitting, for example, by extending the AGC symbol into the guard symbol 432, while the initiating UE has enough time to switch from the transmit mode to the receive mode to receive the actual AGC symbol in the two symbols after the guard symbol 432. As shown in Figure 12(b), the same is true for the guard symbol 432 at the end of the time slot.

[0211] According to another embodiment, when the initiating UE 400 transmits a portion of the previous symbol 4341 into the guard symbol 432, when gapless LBT is enabled, the switching time between the reception mode and the transmission mode is maintained, and the responding UE 402 performs a switch from the reception mode to the transmission mode from the beginning of the guard symbol, after which the initiating UE 400 performs a switch from the transmission mode to the reception mode from the end of its transmission 4341 until the end of the guard band, and the responding UE 402 that has completed the switch starts transmitting a portion of the next symbol 4342 within the guard band 432.

[0212] The actual duration of the extended transmission in the guard symbol may depend on values ​​such as the subcarrier spacing SCS. For example, as shown in the table above, an SCS of 15kHz results in a symbol length or duration of 71.36μs, which is long enough for a responding UE to perform, for example, a Type 2A LBT. However, this duration is also long enough to allow another device to take over the channel. When considering an SCS of 60kHz, the symbol length is 17.84μs, so Type 2B or Type 2C CAP can still be used. Therefore, in order to maintain the minimum time interval TG for the UE to perform a Type 2CAP min , while ensuring that other devices do not occupy or take over the frequency band or channel, according to an embodiment, the following relationship is used to determine the duration within the protection symbol of the initiating UE sending, for example, PSSCH or the responding UE sending, for example, PSVCH AGC. The predefined durations 4341 and 4342 can be defined in μs as follows: spacing, SCS. For example, as shown in the table above, an SCS of 15kHz results in a symbol length or duration of 71.36μs, which is sufficient for the responding UE to perform, for example, Type 2A LBT. However, this duration is also long enough for another device to take over the channel. When considering an SCS of 60kHz, the symbol length is 17.84μs, so Type 2B or Type 2C CAP can still be used. Therefore, in order to maintain the minimum time interval TG for the UE to perform Type 2CAP min , while ensuring that other devices do not occupy or take over the frequency band or channel, according to an embodiment, the following relationship is used to determine the duration within the protection symbol of the initiating UE transmission (e.g., PSSCH) or the responding UE transmission (e.g., PSFCH AGC). The predefined durations 4341 and 4342 can be defined in μs as follows:

[0213]

[0214] in

[0215] μ is a numerical parameter, for example, μ=0 is used for 15kHz subcarrier spacing SCS, μ=1 is used for 30kHz SCS, and μ=2 is used for 60kHz SCS.

[0216] TG min The minimum time for executing a predefined CAP before accessing the shared COT, for example, 25 μs for Type 2A LBT and 16 μs for Type 2B LBT.

[0217] It is worth noting that if the result of the above equation is negative, the UE has nothing to transmit in the guard symbol. This is because if the result of this equation is negative, it means that the minimum time interval required to perform CAP is greater than the symbol length of the guard symbol. Therefore, the UE does not have to transmit anything in the guard symbol because it needs the entire guard symbol to perform CAP, and more guard symbols may need to be introduced to allow the UE to perform CAP.

[0218] It is noteworthy that, according to an embodiment, the selection of the type of CAP or LBT to be performed by the responding UE depends on the transmission that the responding UE intends to transmit. In the case where the responding UE is transmitting PSFCH or another short transmission, the responding UE can perform a Type 2B or Type 2C CAP, while in the case of transmitting a longer transmission (such as PSCCH and / or PSSCH), a Type 1 or Type 2A CAP can be performed.

[0219] According to another embodiment, when considering a high subcarrier spacing that results in a reduction in OFDM symbol length, the spacing required to perform CAP may no longer fit into the existing time slot structure. According to an embodiment, in this case, one or more guard symbols may be introduced at the end or beginning of the time slot, or, in the example of Figure 3(b), one or more guard symbols are introduced between PSSCH and PSFCH. For example, when considering a 60kHz SCS, the symbol length is only 17.84μs, but the minimum spacing of a type 2A CAP is 25μs, so two guard symbols are required in this case. According to another example, when considering a 30kHz SCS, the length of a single symbol is 35.68μs, while the switching time between transmit mode and receive mode (also known as AGC stabilization time) is 35μs. Also in this case, another guard symbol may be introduced, thereby extending the protection period and achieving gapless LBT, as described above with reference to Figure 8 In this case, the initiating UE continues to transmit in the first guard symbol of length 35.68 μs, while the responding UE has enough time (i.e., at least 35 μs) to switch from receive mode to transmit mode, and the second guard symbol allows the initiating UE to switch from transmit mode to receive mode while the responding UE is already transmitting.

[0220] According to further embodiments, certain restrictions may be applied. For example, one of the purposes of the guard symbol is to ensure that the initiating UE has enough time to switch from transmit mode to receive mode or from receive mode to transmit mode. If the guard symbol is shortened by using a higher SCS, and another guard symbol cannot be introduced by design or configuration, and the initiating UE sends PSSCH, the responding UE may not use PSFCH to send feedback back to the initiating UE in the same time slot, but to a different UE because the initiating UE does not have enough time to switch to receive mode. For example, when considering a 30kHz SCS, the length of a single symbol is 35.68μs, while the switching time between transmit mode and receive mode (also known as AGC stabilization time) is 35μs. In the absence of other guard symbols, the initiating UE does not have enough time to switch from transmit mode to receive mode and perform extended transmission within the guard symbol in order to receive any PSFCH transmission from the responding UE in the same time slot. In this case, the responding UE can use COT and PSFCH in the same time slot, but only for transmission to another UE. Therefore, in the case where the initiating UE transmits data in the PSSCH, all other UEs in the vicinity of the initiating UE, except the responding UE, can use the gapless LBT or CAP transmission to extend the cyclic prefix (CPE) and then transmit the PSFCH. This is because the responding UE needs the time provided by the guard symbol to switch from the receiving mode to the transmitting mode. In other words, if the guard between PSSCH and PSFCH is shortened, and if the transmitter UE (UE1) of the PSSCH is also the receiver of the feedback, the switching time may not be enough for UE1 to receive the beginning of the feedback symbol from the receiving UE (UE2). Another UE (UE3) can switch earlier and receive the feedback. However, if UE1 is aware of the smaller gap, it may only receive the second half of the symbol, which is still fine for decoding the feedback message.

[0221] Furthermore, due to the additional half-duplex issues caused by this situation, the affected resources may be included in the non-preferred resource set of the Assistance Information Message (AIM) reported by the UE. As described above, in the case where UE1 may not be able to receive PSFCH in the same time slot due to insufficient switching time, the time slot or PSFCH resource may be included in the non-preferred resource set of Inter-UE Coordination (IUC) or AIM, so that when UE1 provides AIM or IUC to UE2, it includes the time slot in the list because it cannot receive any PSFCH transmission in the said time slot due to the half-duplex issue.

[0222] When a UE intends to transmit PSFCH in a time slot and no other UE in the same time slot has previously used PSCCH or PSSCH, the responding UE can perform a Type 1 CAP to check the availability of the band or channel and send AGC and PSFCH as usual. As described in European Patent Application 22170639.3 "SLUNLICENSED FRAME STRUCUTRE" filed on April 28, 2022 and incorporated herein by reference, the UE may also have multiple start symbols within a time slot to start its PSCCH / PSSCH transmission, where the UE uses a mini-slot for transmission. Assuming that the start symbol of the transmission starts from the 8th symbol and no UE transmits PSCCH or PSSCH within the mini-slot, the UE can perform LBT at the secondary starting point within the time slot and then transmit an extended CPE of dynamic length until the start of the AGC-PSFCH symbol.

[0223] As described above, embodiments of the present invention provide:

[0224] - User equipment UE used in a wireless communication network (such as a 3rd Generation Partnership Project 3GPP network).

[0225] ○ With respect to the 5G NR standard, in an embodiment, the user equipment UE may correspond to a user equipment (UE) in the standard.

[0226] -The UE shall perform sidelink (SL) communication using a channel comprising resources of unlicensed spectrum.

[0227] ○ In the 5G NR standard, NR version 18 specifies the NR side link on unlicensed spectrum (SL-U).

[0228] -The UE will occupy the channel within the channel occupation time COT and share the COT with another UE.

[0229] ○ According to RAN1#109-e (May 9-20, 2022), UE-to-UE COT sharing is supported in NR sidelink (SL-U) operation on shared channels.

[0230] The COT has a first part and a second part, the first part of the COT and the second part of the COT being separated by a protection time.

[0231] ○ According to RAN1#113 (May 22-26, 2023), for the case where a COT initiating UE initiates SL transmission using a Type 1 channel access procedure, a UE supporting COT initiation may send a transmission within the same channel occupancy following the SL transmission of the COT responding UE according to the channel access procedure. According to RAN1#113 (May 22-26, 2023), for the time domain information that is part of the COT shared information, at least the following is included: Remaining COT duration.

[0232] Therefore, the UE sharing the COT can perform transmission within the COT, and the second part of the COT is shared with another UE. The COT sharing information includes the duration of the second part of the COT corresponding to the remaining COT time. Therefore, as described in the embodiment, the COT is divided into the first and second parts.

[0233] ○ In addition, according to RAN1#113 (May 22-26, 2023), if the responding UE uses a Type 1 SL channel access procedure on a channel sharing the channel occupancy initiated by the COT initiating UE, the responding UE may send a SL transmission after an interval that follows the SL transmission of the COT initiating UE as follows:

[0234] ■ If the interval is at least 25 μs, the responding UE may send a SL transmission on the shared channel after performing a Type 2A SL channel access procedure.

[0235] ■ If the interval is equal to 16 μs, the responding UE may send a SL transmission on the shared channel after performing a Type 2B SL channel access procedure.

[0236] ■ If the interval is up to 16 μs and the transmission is limited to 584 μs, the responding UE can transmit SL transmission on the channel after performing Type 2C SL channel access.

[0237] Therefore, the protection period in an embodiment may correspond to the SL transmission after the interval.

[0238] - The UE shall perform transmissions over the SL during the first part of the COT.

[0239] ○ According to RAN1#113 (May 22-26, 2023), for the case where the COT initiating UE uses the Type 1 channel access procedure to initiate SL transmission, the COT initiating UE can send transmission within the same channel occupancy after the SL transmission of the COT responding UE according to the channel access procedure.

[0240] Therefore, the UE in the embodiment may correspond to the COT initiating UE in the protocol.

[0241] - the second part of the COT is used by another UE to perform transmissions over the SL,

[0242] ○ According to RAN1#113 (May 22-26, 2023), when the UE performs a Type 2 channel access to start transmission within the shared COT (to be further studied and selected in RAN1#114)

[0243] ■Alternative 1: Method using CPE in case the UE performs Type 1 channel access to initiate COT for PSCCH / PSSCH transmission;

[0244] ■Alternative 2: Use only the (pre-)configured default CPE start position;

[0245] ■Alternative 3: Use CPE to make the interval less than or equal to 16us;

[0246] ■Option 4: Other.

[0247] ○ According to RAN1#114 (August 21-25, 2023), when the UE performs Type 2 channel access to transmit PSCCH / PSSCH within the COT:

[0248] ■By default, only one value is (pre)configured for the CPE start position set inside the COT:

[0249] ●This value is the default CPE starting position.

[0250] ●The UE only uses the (pre-)configured default CPE starting position.

[0251] ■When multiple values ​​are (pre)configured for the CPE start position set inside the COT:

[0252] ●One of the values ​​is the default CPE starting position.

[0253] • When the UE performs Type 1 channel access to initiate COT for PSCCH / PSSCH transmission, the UE uses the same method to use CPE.

[0254] ■FFS: Whether to support the transmission of a CPE between any two consecutive SL transmissions between the COT initiator and responder to reduce the interval between two transmissions to no more than 16μs. The CPE is selected from the CPEs (pre-)configured for PSCCH / PSSCH within the COT.

[0255] Therefore, the other UE of the embodiment may correspond to the UE starting transmission within the shared COT. In addition, the transmission extension of the embodiment may correspond to a CP (Cyclic Prefix) Extension (CPE).

[0256] - the UE extends the transmission into the guard period so that the transmission occurs within a predefined duration starting from the guard period,

[0257] ○CP extension (CPE) is supported for NR sidelink operation in shared channels as per RAN1#109-e (May 9-20, 2022). Based on a predefined set of all candidate CPE starting positions, each resource pool is (pre)configured with a set of one or more candidate CPE starting positions that can be used for PSCCH / PSSCH transmissions inside the COT (in case of shared COT) and outside the COT (in case of initiating COT) as per RAN1#113 (May 22-26, 2023). For the shared COT case, CPE occurs after the LBT interval for types 2A / 2B / 2C.

[0258] Therefore, the transmission extension in the embodiment may correspond to a CP (Cyclic Prefix) Extension (CPE).

[0259] - The predefined duration is selected such that the remaining duration of the guard duration is sufficient to allow another UE to perform a predefined channel access procedure CAP before accessing the shared COT.

[0260] ○ According to RAN1#113 (May 22-26, 2023), if the responding UE uses Type 1 SL channel access procedure on a channel sharing the channel occupancy initiated by the COT initiating UE, the responding UE may send a SL transmission after an interval that follows the SL transmission of the COT initiating UE as follows:

[0261] ■ If the interval is at least 25 μs, the responding UE may transmit SL transmissions on the shared channel after performing a Type 2A SL channel access procedure.

[0262] ■ If the interval is equal to 16 μs, the responding UE may transmit a SL transmission on the shared channel after performing a Type 2B SL channel access procedure.

[0263] ■ If the interval is up to 16μs and the transmission is limited to 584μs, the responding UE can transmit SL transmission on the channel after performing Type 2C SL channel access.

[0264] ○ According to RAN1#113 (May 22-26, 2023), when the UE performs a Type 2 channel access to start transmission within the shared COT (to be further studied and selected in RAN1#114):

[0265] ■Alternative 1: Method using CPE in case the UE performs Type 1 channel access to initiate COT for PSCCH / PSSCH transmission;

[0266] ■Alternative 2: Use only the (pre-)configured default CPE start position;

[0267] ■Alternative 3: Use CPE to make the interval less than or equal to 16us;

[0268] ■Option 4: Other.

[0269] Therefore, the remaining duration of the protection in the embodiment may correspond to the interval in the protocol.The other UE in the embodiment may correspond to a responding UE that performs a predefined CAP corresponding to a 2A, 2B or 2C type channel access procedure in the protocol.

[0270] - If the UE performs Type 1 channel access to initiate a COT for transmission, and if there are multiple CPE candidate locations, the procedure for how to select a specific CPE starting location must be defined.

[0271] ○ According to RAN1#114 (August 21-25, 2023), when the UE performs a Type 1 channel access to initiate a COT for PSCCH / PSSCH transmission, in Scheme 2 agreed upon in RAN1#113, the CPE start position is randomly selected from one or more CPE start candidate positions (pre-)configured according to the PSCCH / PSSCH transmission priority. The priority is based on the L1 priority.

[0272] Thus, in an embodiment, the condition for selecting a certain CAP type as a priority may correspond to the priority used in selecting one or more CPE starting locations belonging to a certain channel access procedure CAP.

[0273] Overview

[0274] The embodiments of the present invention have been described in detail above, and each embodiment and aspect may be implemented alone, or two or more embodiments or aspects may be implemented in combination.

[0275] It is worth noting that the method of the present invention is not limited to CG or DG. According to other embodiments, the grant may be smaller than the CG or DG, or it may be just a broad resource coordination, such as which subband or subchannel to use or avoid.

[0276] Depending on the embodiment, the wireless communication system may include a terrestrial network or a non-terrestrial network, or a network or network segment using an airborne vehicle or a spaceborne vehicle as a receiver, or a combination thereof.

[0277] According to an embodiment of the present invention, the user equipment includes one or more of the following: a power-limited UE; or a handheld UE, such as a UE used by pedestrians, called a vulnerable road user (VRU); or a pedestrian user equipment (P-UE); or a wearable or handheld UE used by public safety personnel and emergency personnel, also known as a public safety user equipment (PS-UE); or an Internet of Things user equipment (IoTUE), for example, a sensor, actuator or UE provided in a campus network that performs repetitive tasks and requires regular input from a gateway node, or a mobile terminal; or a fixed terminal; or a cellular Internet of Things user equipment; or a vehicle UE; or an on-board master control User Equipment GL-UE or Sidelink Relay; or Internet of Things (IoT) or Narrowband Internet of Things (NB-IoT); or wearable devices such as smart watches, fitness trackers, smart glasses, ground vehicles, aircraft, drones, mobile base stations, roadside units (RSUs) or buildings; or any other item or device equipped with a network connection that enables the item / device to communicate using a wireless communication network, such as a sensor or actuator; or any other item or device with a network connection that enables the item / device to communicate using a wireless communication network (such as a sensor or actuator) or any network entity with sidelink functionality.

[0278] According to an embodiment of the present invention, the network entity includes one or more of the following: a macrocell base station; a small cell base station; or a central unit of a base station, an integrated access and backhaul IAB node of a base station or a distributed unit of a base station, a road side unit (RSU), a remote radio head; or an AMF; or an MME; or an SMF; or a core network entity; or a mobile edge computing (MEC) entity; or a network slice in an NR or 5G core environment; or any transmission / reception point TRP, enabling an item or device to communicate using a wireless communication network, and the item or device is provided with a network connection to communicate using the wireless communication network.

[0279] Although some aspects of the described concepts are described in the context of an apparatus, it is apparent that these aspects also represent a description of a corresponding method, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus.

[0280] The various elements and features of the present invention can be implemented in hardware, software using analog and / or digital circuits, by executing instructions through one or more general or special processors, or as a combination of hardware and software. For example, embodiments of the present invention can be implemented in the environment of a computer system or another processing system. Fig.13An example of a computer system 600 is shown. These units or modules and the method steps performed by these units can be executed on one or more computer systems 600. The computer system 600 includes one or more processors 602, such as a dedicated or general-purpose digital signal processor. The processor 602 is connected to a communication infrastructure 604, such as a bus or a network. The computer system 600 includes a main memory 606, such as a random access memory RAM, and an auxiliary memory 608, such as a hard drive and / or a removable storage drive. The auxiliary memory 608 can allow computer programs or other instructions to be loaded into the computer system 600. The computer system 600 can also include a communication interface 610 to allow software and data to be transmitted between the computer system 600 and external devices. Communication can use electronic, electromagnetic, optical or other signals that can be processed by the communication interface. Communication can use wires or cables, optical fibers, telephone lines, cellular phone links, RF links and other communication channels 612.

[0281] The terms "computer program medium" and "computer readable medium" generally refer to tangible storage media, such as a removable storage unit or a hard disk installed in a hard drive. These computer program products are means for providing software to the computer system 600. The computer program, also referred to as computer control logic, is stored in the main memory 606 and / or the secondary memory 608. The computer program may also be received via the communication interface 610. When the computer program is executed, the computer system 600 is able to implement the present invention. In particular, when executed, the computer program enables the processor 602 to implement the present invention, such as any of the methods described herein. Therefore, such a computer program may represent a controller of the computer system 600. When the present disclosure is implemented using software, the software may be stored in a computer program product and loaded into the computer system 600 using a removable storage drive, an interface (such as the communication interface 610).

[0282] The implementation in hardware or software may be performed using a digital storage medium, such as cloud storage, floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM or flash memory, on which electronically readable control signals are stored, which cooperate or can cooperate with a programmable computer system to perform the corresponding method. Therefore, the digital storage medium can be computer readable.

[0283] Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.

[0284] Generally, the embodiments of the present invention can be implemented as a computer program product with a program code, wherein when the computer program product is run on a computer, the program code is used to perform one of the methods. The program code can be stored on a machine-readable carrier, for example.

[0285] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. In other words, therefore, one embodiment of the inventive method is a computer program having a program code for performing one of the methods described herein when it runs on a computer.

[0286] Therefore, another embodiment of the method of the present invention is a data carrier or a digital storage medium, or a computer-readable medium, on which is recorded a computer program for performing one of the methods described herein. Therefore, another embodiment of the method of the present invention is a data stream or a signal sequence representing a computer program for performing one of the methods described herein. The data stream or signal sequence can, for example, be configured to be transmitted via a data communication connection (e.g., via the Internet). Another embodiment includes a processing device, such as a computer or a programmable logic device, which is configured to or adapted to perform one of the methods described herein. Another embodiment includes a computer having installed thereon a computer program for performing one of the methods described herein.

[0287] In some embodiments, a programmable logic device, such as a field programmable gate array, can be used to perform some or all of the functions of the methods described herein. In some embodiments, a field programmable gate array can be used in conjunction with a microprocessor to perform one of the methods described herein. Generally, these methods are preferably performed by any hardware device.

[0288] The above embodiments are only used to illustrate the principles of the present invention. It should be understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. Therefore, the present invention is intended to be limited only by the scope of the patent claims to be proposed, and not by the specific details proposed herein by describing and explaining the embodiments.

Claims

1. A user equipment UE for a wireless communication network such as a 3rd Generation Partnership Project 3GPP network, in, The UE will perform sidelink SL communication using a channel including resources from the unlicensed spectrum, The UE will occupy the channel within a channel occupation time COT and share the COT with another UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection time length, wherein the UE is to perform transmission via the SL during a first part of the COT, wherein a second portion of the COT is used by the other UE to perform transmission via the SL, and The UE extends the transmission into the protection duration so as to transmit during a predefined duration starting from the starting part of the protection duration, and the selected predefined duration makes the remaining duration of the protection duration sufficient to allow the other UE to perform a predefined channel access procedure CAP before accessing the shared COT.

2. The user equipment UE according to claim 1, wherein: The UE extends the transmission to the protection duration by obtaining or copying content from a first part of the COT or a predefined part of the first part of the transmission, for example, obtaining or copying content from the starting part of the last transmission symbol after the cyclic prefix CP or the extension cyclic prefix of the data in the last transmission symbol.

3. The user equipment UE according to claim 2, wherein: The last transmission symbol includes one or more of the following: - Automatic gain control AGC symbol, - Demodulation Reference Signal DMRS, - data channels, such as the physical sidelink shared channel PSSCH, - control channels, such as the Physical Sidelink Control Channel PSCCH, - Feedback channel, such as Physical Sidelink Feedback Channel PSFCH.

4. A user equipment UE for a wireless communication network such as a 3rd Generation Partnership Project 3GPP network, in, The UE will perform sidelink SL communication using a channel including resources from the unlicensed spectrum, The UE will share a channel occupied by another UE during a channel occupation time COT initiated by the other UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection duration, wherein a first portion of the COT is used by the other UE to perform transmission via the SL, wherein the UE is to perform transmission via the SL during the second part of the COT, the first part of the COT and the second part of the COT being separated by a guard duration, and wherein the UE extends the transmission into the protection duration so as to transmit during a predefined duration ending at the end of the protection duration, and the selected predefined duration makes the initial duration of the protection duration sufficient to allow the UE to perform a predefined channel access procedure CAP before accessing the shared COT.

5. The user equipment UE according to claim 4, wherein: The UE extends the transmission into the guard duration by obtaining or copying content from a second part of the COT or a predefined part of the last part of the transmission, such as obtaining or copying content from the end of the next symbol.

6. The user equipment UE according to claim 5, wherein: The next symbol includes one or more of the following: - Automatic gain control AGC symbol, - Demodulation Reference Signal DMRS, - data channels, such as the physical sidelink shared channel PSSCH, - control channels, such as the Physical Sidelink Control Channel PSCCH, - feedback channels, such as the physical sidelink feedback channel PSFCH, - The automatic gain control AGC symbol before the PSFCH.

7. The user equipment UE according to claim 5 or 6, wherein: The next symbol from which the content is copied belongs to the same time slot or the next time slot.

8. A user equipment UE for a wireless communication network such as a 3rd Generation Partnership Project 3GPP network, in, The UE will perform sidelink SL communication using a channel including resources from the unlicensed spectrum, The UE will share a channel occupied by another UE during a channel occupation time COT initiated by the other UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection time length, wherein a first portion of the COT is used by the other UE to perform transmission over the SL, the other UE extending the transmission into the guard duration so as to transmit during a first predefined duration starting from a start portion of the guard duration, and The UE will perform transmission via the SL during the second part of the COT, and the UE will extend the transmission into the protection duration so as to transmit during a second predefined duration ending at the end of the protection duration.

9. The user equipment according to claim 8, wherein: Before accessing the shared COT, the UE will access the shared COT without performing a listen-before-talk (LBT) procedure.

10. The user equipment UE according to claim 8 or 9, wherein: One of the first predefined duration or the second predefined duration is zero so that one of the UE or the other UE occupies the entire guard period.

11. The user equipment UE according to any one of claims 8 to 10, wherein - said other UE extends said transmission into said guard duration by obtaining or copying content from said first part of said COT or a predefined part of said first part of said transmission, for example from the beginning of a last transmission symbol after a cyclic prefix or an extension of a cyclic prefix of data in a last transmission symbol, and / or - The UE will extend the transmission into the guard duration by obtaining or copying content from a predefined part of the second part of the COT or the last part of the transmission, for example, obtaining or copying content from the end of the next symbol, such as an automatic gain control AGC symbol.

12. The user equipment UE according to any one of claims 8 to 11, wherein: The last transmitted symbol or the next symbol includes one or more of the following: - Automatic gain control AGC symbol, - Demodulation Reference Signal DMRS, - data channels, such as the physical sidelink shared channel PSSCH, - control channels, such as the Physical Sidelink Control Channel PSCCH, - feedback channels, such as the physical sidelink feedback channel PSFCH, - The automatic gain control AGC symbol before the PSFCH.

13. The user equipment UE according to any one of claims 4 to 12, wherein: The UE extends the transmission into the guard duration by obtaining or copying content from a predefined portion of the second portion of the COT, such as obtaining or copying content from the end of an automatic gain control AGC symbol.

14. The user equipment UE according to any one of claims 4 to 13, wherein: The other UE that performs transmission through the SL during the first part of the COT is a first another UE, and the UE will perform transmission to the first another UE or a second another UE through the SL during the second part of the COT, and the second another UE is different from the first another UE.

15. A user equipment (UE) according to any one of the preceding claims, wherein: The protection duration has one or more of the following lengths: -CP length, - Extended Cyclic Prefix (ECP) length, -OFDM symbol length, - a multiple of the OFDM symbol length, such as one-half or twice the length of an OFDM symbol, - multiple OFDM symbols, - frame interval, for example a short frame interval SIFS as used in WiFi systems, - For example, using a configuration or preconfigured duration defined in microseconds.

16. A user equipment (UE) according to any one of the preceding claims, wherein: The CAP is one of the following: -Type 1 CAP, which senses the channel for random durations, - 2A type CAP, sensing two sensing time slots within an interval of at least 25 μs, for example, the beginning and the end thereof, -2B type CAP, sensing one sensing time slot of 9μs within an interval of at least 16μs, -2C type CAP, does not sense channels.

17. A user equipment (UE) according to any one of the preceding claims, wherein: The type of CAP used by the UE for its transmissions depends on certain conditions.

18. The user equipment UE according to claim 17, wherein: The specific conditions are one or more of the following: - transmission length, such as the size of data to be transmitted by the UE, wherein if the length of the transmission is equal to or above a predefined threshold, the UE shall perform LBT, and wherein if the length of the transmission is less than the predefined threshold, the UE shall not perform LBT, - the type of data to be transmitted, for example, the data to be transmitted is feedback data such as PSFCH, or the data to be transmitted is an IUC request, - The priority of control and / or data transmission has a certain priority.

19. A user equipment (UE) according to any one of the preceding claims, wherein: The COT spans at least a first time slot including a plurality of symbols, a first portion of the COT includes a first number of symbols, a second portion of the COT includes a second number of symbols, and the guard duration includes a time interval between a last symbol of the first number of symbols and a first symbol of the second number of symbols.

20. The user equipment UE according to claim 19, wherein - the COT spans at least the first time slot and a second time slot, the second time slot includes a plurality of symbols, and the first time slot includes another guard time length, the other guard time length includes a time interval that is the last symbol in the first time slot, and / or - the UE extends the transmission to a subsequent guard duration and / or the further guard duration, or - the other UE extends the transmission to the previous guard duration.

21. The user equipment (UE) according to any one of claims 1 to 18, wherein: The COT spans at least two time slots, each time slot includes multiple symbols, the first part of the COT includes a first time slot, the second part of the COT includes a second time slot, and the guard duration includes a time interval that is the last symbol in the first time slot.

22. The user equipment UE according to claim 21, wherein - the first time slot and / or the second time slot comprises a plurality of symbols, a first part of the first time slot and / or the second time slot comprises a first number of symbols, a second part of the first time slot and / or the second time slot comprises a second number of symbols, and the first part of the first time slot and / or the second time slot comprises a further guard duration, the further guard duration comprising a time interval between a last symbol of the first number of symbols and a first symbol of the second number of symbols, and - the UE extends the transmission to a subsequent guard duration and / or the further guard duration, or - the other UE extends the transmission to the previous guard duration.

23. A user equipment (UE) according to any one of the preceding claims, wherein: The predefined duration is determined in μs as follows: in μ is a numerical parameter, for example, for 15kHz subcarrier spacing SCS, μ=0, for 30kHz SCS, μ=1, for 60kHz SCS, μ=2, TG min The shortest time for executing a predefined CAP before accessing the shared COT is, for example, 25 μs for a type 2A LBT and 16 μs for a type 2B LBT.

24. A user equipment (UE) according to any one of the preceding claims, wherein: The duration of the guard symbol decreases as the subcarrier spacing and / or bandwidth increases.

25. A user equipment (UE) according to any one of the preceding claims, wherein: The guard time has a duration, such as a switching time, so as to allow the UE to switch between a transmission mode and a reception mode.

26. A wireless communication system, such as a 3rd Generation Partnership Project 3GPP system, comprising one or more user equipments UE and one or more base stations according to any one of the preceding claims.

27. The user equipment UE according to claim 26, wherein: The UE includes one or more of the following: a power-limited UE; or a handheld UE, such as a UE used by pedestrians and referred to as a vulnerable road user, VRU; or a pedestrian user equipment, P-UE; or wearable or handheld UE used by public safety personnel and first responders, also known as public safety user equipment PS-UE; or Internet of Things user equipment IoT UE, such as sensors, actuators or UEs provided in a campus network to perform repetitive tasks and require regular input from a gateway node; or mobile terminal; or fixed terminal; or cellular IoT-UE; or SL UE; or vehicle-mounted UE; or vehicle-mounted master user equipment GL-UE; or dispatch user equipment S-UE; or Internet of Things or Narrowband Internet of Things NB-IoT device; or ground vehicle; or aircraft; or drone; or mobile base station; or roadside unit RSU; or building; or any other item or device, such as a sensor or actuator, that is provided with a network connection to enable the item / equipment to communicate using a wireless communication network; or any other item or device, such as a sensor or actuator, that is provided with a network connection to enable the item / equipment to communicate using a sidelink wireless communication network; or any network entity capable of implementing a sidelink.

28. The wireless communication system according to claim 26 or 27, wherein: The base station includes one or more of the following: a macrocell base station; or a small cell base station; or a central unit of a base station; or a distributed unit of a base station; or an integrated access backhaul with IAB node; or a roadside unit RSU; or a UE; or a SL UE; or a master user equipment GL-UE; or a relay or remote radio head; or an access and mobility management function AMF; or a session management function SMF; or a core network entity; or a mobile edge computing MEC entity; or a network slice in a new radio NR or 5G core environment; or any transmission / reception point TRP that enables an item or device to communicate using a wireless communication network, and the item or device is provided with a network connection to communicate using the wireless communication network.

29. A method for operating a user equipment (UE) for a wireless communication network such as a 3rd Generation Partnership Project (3GPP) network, wherein: The UE is to perform sidelink SL communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises: occupying the channel for a channel occupation time COT, sharing the COT with another UE, wherein the COT has a first part and a second part, and the first part of the COT and the second part of the COT are separated by a protection duration, performing transmissions via the SL during a first portion of the COT, wherein a second portion of the COT is performed by the other UE transmitting via the SL, and The transmission is extended into the protection duration so as to be transmitted during a predefined duration starting from the start part of the protection duration, the predefined duration being selected such that a remaining duration of the protection duration is sufficient to allow the other UE to perform a predefined channel access procedure CAP before accessing the shared COT.

30. A method for operating a user equipment (UE) for a wireless communication network such as a 3rd Generation Partnership Project (3GPP) network, wherein: The UE is to perform sidelink SL communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises: sharing a channel occupied by another UE during a channel occupation time COT initiated by the other UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT are separated by a guard duration, and wherein the first part of the COT is used by the other UE to perform transmission over the SL, performing transmission over the SL during a second portion of the COT, the first portion and the second portion of the COT being separated by a guard duration, and The transmission is extended into the protection period so as to be transmitted during a predefined period ending at the end of the protection period, the predefined period being selected such that an initial period of the protection period is sufficient to allow the UE to perform a predefined channel access procedure CAP before accessing the shared COT.

31. A method for operating a user equipment (UE) for a wireless communication network such as a 3rd Generation Partnership Project (3GPP) network, wherein: The UE is to perform sidelink SL communication using a channel comprising resources from an unlicensed spectrum, and wherein the method comprises: sharing a channel occupied by another UE during a channel occupation time COT initiated by the other UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT are separated by a guard duration, wherein the first part of the COT is transmitted by the other UE through the SL, and the other UE extends the transmission into the guard duration so as to transmit during a first predefined duration starting from the start part of the guard duration, performing transmission through the SL during a second portion of the COT, The transmission is extended into the guard period to transmit during a second predefined period ending at the end of the guard period.

32. The method according to claim 31, wherein: Before accessing the shared COT, access the shared COT without performing a listen-before-talk (LBT) procedure.

33. A non-transitory computer program product comprising a computer readable medium storing instructions which, when executed on a computer, perform the method of any one of claims 29 to 32.

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