Method and apparatus for multiple sidelink transmission opportunities in one slot - Patents.com

Abstract

[0003] Embodiments of the present disclosure relate to methods and apparatus for sidelink transmission in unlicensed spectrum. According to some embodiments of the present disclosure, a method may include determining a set of candidate starting positions for sidelink transmission and performing a first channel access procedure on a first candidate starting position of the set of candidate starting positions in a first slot.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE

[0002] Embodiments of the present disclosure relate generally to wireless communications technologies, and more specifically, to sidelink transmissions in unlicensed spectrum. [Background technology]

[0002] In a wireless communication system, a user equipment (UE), e.g., a mobile device, may communicate with another UE via a data path supported by an operator's network, e.g., a cellular or Wi-Fi network infrastructure. The data path supported by an operator's network may include a base station (BS) and multiple gateways.

[0003] When the UEs are relatively close to each other, a wireless link or sidelink may be established between both UEs to provide device-to-device (D2D) communication without going through a direct link to a BS. The term "sidelink" or "SL" may refer to a direct wireless link established to communicate between devices, e.g., UEs, as opposed to communicating via a cellular infrastructure (uplink and downlink) as discussed above. In this case, the "sidelink" may also be referred to as a D2D or sidelink communication link. The sidelink communication link may be used in any suitable telecommunications network according to various standards, and the telecommunications network may configure a resource pool to be used by the UEs during such sidelink communication.

[0004] D2D communication has evolved into Vehicle-to-Everything (V2X) communication in the Long Term Evolution (LTE) sidelink standard. V2X communication technology encompasses communication involving vehicles as a message source or destination. In a New Radio (NR) communication system, a transmitting (Tx) UE may send a sidelink transmission to a specific receiving (Rx) UE in unicast mode, to a group of Rx UEs in broadcast mode, or to Rx UEs within a certain range in broadcast mode.

[0005] A UE may operate in both licensed and unlicensed spectrum. For transmission in the unlicensed spectrum, in order to achieve fair coexistence between wireless systems, a channel access procedure (e.g., a Listen-Before-Talk (LBT) procedure) may be required before transmission in the unlicensed spectrum. In the LBT procedure, the UE may perform energy detection in a specific channel. If the detected energy is lower than a predefined threshold, the channel is determined to be empty and available for transmission, and the LBT procedure is successful. Only if the LBT procedure is successful, the UE may start transmission in the channel and occupy the channel for a certain channel occupation time (COT), which is less than a maximum channel occupation time (MCOT). If not, the UE may not start transmission and may continue to perform another LBT procedure until the LBT procedure is successful. Sidelink transmissions may also be performed in the unlicensed spectrum.

[0006] There is a need to address sidelink transmissions in unlicensed spectrum, e.g., to enhance sidelink transmissions in unlicensed spectrum, a solution that can improve radio resource utilization with a relatively simple implementation is desired. Summary of the Invention [Means for solving the problem]

[0007] Some embodiments of the present disclosure provide a method, which may include determining a set of candidate starting locations for sidelink transmissions and performing a first channel access procedure on a first candidate starting location of the set of candidate starting locations in a first slot.

[0008] Some embodiments of the present disclosure provide an apparatus. According to some embodiments of the present disclosure, the apparatus may include at least one non-transitory computer-readable medium having computer-executable instructions stored thereon, at least one receiving circuit, at least one transmitting circuit, and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit, and the at least one transmitting circuit, and the at least one non-transitory computer-readable medium and the computer-executable instructions may be configured by the at least one processor to cause the apparatus to perform a method according to some embodiments of the present disclosure.

[0009] To explain how the advantages and features of the present disclosure can be obtained, a description of the disclosure will be given by reference to specific embodiments thereof that are illustrated in the accompanying drawings, which depict only exemplary embodiments of the disclosure and therefore should not be considered as limiting its scope. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a wireless communication system according to some embodiments of the present disclosure. [Diagram 2] FIG. 2 illustrates an example symbol group configuration according to some embodiments of the present disclosure. [Diagram 3] FIG. 2 illustrates an example symbol group configuration according to some embodiments of the present disclosure. [Figure 4] FIG. 2 illustrates an example symbol group configuration according to some embodiments of the present disclosure. [Diagram 5] FIG. 2 illustrates an example symbol group configuration according to some embodiments of the present disclosure. [Figure 6] FIG. 1 illustrates an example sidelink transmission according to some embodiments of the present disclosure. [Figure 7] FIG. 1 illustrates an example sidelink transmission according to some embodiments of the present disclosure. [Figure 8] FIG. 1 illustrates an example sidelink transmission according to some embodiments of the present disclosure. [Figure 9] FIG. 1 illustrates an example sidelink transmission according to some embodiments of the present disclosure. [Figure 10] FIG. 2 illustrates an example UE-initiated COT in accordance with some embodiments of the present disclosure. [Figure 11] 4 is a flowchart of an example procedure for wireless communication according to some embodiments of the present disclosure. [Figure 12] FIG. 1 is a block diagram of an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The detailed description of the accompanying drawings is intended as an illustration of preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present disclosure.

[0012] Reference will now be made in detail to several embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios, such as Third Generation Partnership Project (3GPP) 5G (NR), 3GPP Long Term Evolution (LTE) Release 8, etc. With the development of network architectures and new service scenarios, it is contemplated that all the embodiments in the present disclosure are also applicable to similar technical problems, and further, the terms described in the present disclosure may be changed, which should not affect the principle of the present disclosure.

[0013] FIG. 1 illustrates a schematic diagram of a wireless communication system 100 in accordance with some embodiments of the present disclosure.

[0014] 1, the wireless communication system 100 may include a base station (e.g., a BS 120) and a number of UEs 110 (e.g., a UE 110a, a UE 110b, and a UE 110c). Although a particular number of UEs 110 and one BS 120 are shown in FIG. 1, it is contemplated that the wireless communication system 100 may include more BSs and more or fewer UEs within or outside the coverage of the BSs.

[0015] The UE and BS may support communication based on, for example, 3G, Long Term Evolution (LTE), LTE-advanced (LTE-A), New Radio (NR), or other suitable protocols. In some embodiments of the present disclosure, the BS 102 may be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node B, an evolved Node B (eNB), a gNB, a home Node B, a relay node, or a device, or may be described using other terms used in the art. The UE 110a, UE 110b, or UE 110c may include, for example, but not limited to, a computing device, a wearable device, a mobile device, an IoT device, a vehicle, etc. Those skilled in the art should understand that with the development and progress of technology, the terms described in the present disclosure may change, but should not affect or limit the principles and gist of the present disclosure.

[0016] The BS 120 may define one or more cells, and each cell may have a coverage area 130. In the exemplary wireless communications system 100, some UEs (e.g., UE 110a and UE 110b) are within the coverage of a BS 120, which may not be the particular base station 120 shown in FIG. 1 and may be any one of the base stations 120 in the wireless communications system, and some UEs (e.g., UE 110c) are outside the coverage of the BS 120. For example, if the wireless communications system includes two base stations 120, UE 110a being within the coverage of any one of the two base stations 120 means that UE 110a is within the coverage of the base station 120 in the wireless communications system (i.e., in-coverage), and UE 110a being outside the coverage of both base stations 120 means that UE 110a is outside the coverage of the base stations 120 in the wireless communications system (i.e., out-of-coverage).

[0017] Still referring to FIG. 1, UE 110a and UE 110b may communicate with BS 120, for example, via a Uu link (indicated by the dotted arrow in FIG. 1). UE 110a, UE 110b, and UE 110c may communicate with each other via a sidelink (indicated by the solid arrow in FIG. 1) and form a UE group. There may be two resource allocation modes for sidelink transmission. One of the two resource allocation modes is based on base station scheduling and may be referred to as mode 1, and the other is based on UE autonomous selection and may be referred to as mode 2.

[0018] In both Mode 1 and Mode 2, sidelink transmissions may include a physical sidelink control channel (PSCCH) and an associated physical sidelink shared channel (PSSCH) that is scheduled by sidelink control information (SCI) carried on the PSCCH. The SCI and associated PSSCH may be transmitted from a transmitting UE (hereinafter referred to as a “Tx UE”) to a receiving UE (hereinafter referred to as an “Rx UE”) in a unicast manner, to a group of Rx UEs in a groupcast manner, or to Rx UEs within a certain range in a broadcast manner. For example, referring to FIG. 1, UE 110a (acting as a Tx UE) may transmit data to UE 110b or UE 110c (acting as an Rx UE).

[0019] In Mode 1, resources may be assigned by the base station via dynamic scheduling or configured grants. In Mode 2, the UE may need to perform resource sensing by monitoring and decoding all SCIs transmitted in the SCI resource pool to obtain resource reservation information. By doing so, the UE may identify available candidate resources for communication. The UE may then, for example, randomly select the required resource from the identified candidate resources.

[0020] A BS (e.g., BS 120 in FIG. 1) and UEs (e.g., UE 110a, UE 110b, and UE 110c in FIG. 1) may operate in both licensed and unlicensed spectrum. For example, the unlicensed spectrum may be at a carrier frequency of about 6 GHz or 60 GHz. For transmissions in the unlicensed spectrum, to achieve fair coexistence between wireless systems (e.g., NR system access in unlicensed spectrum system (NR-U) and other wireless systems such as Wi-Fi systems), a channel access procedure, also known as a listen-before-talk (LBT) test or LBT procedure, may be performed before communicating in the unlicensed spectrum.

[0021] The channel access procedure may be performed based on sensing (or energy detection) to evaluate the availability of a channel for performing a transmission. The basic unit of sensing is a sensing slot. In some examples, a sensing slot is a period of T sl = 9 microseconds. The BS or UE may have a sensing slot duration T sl During the sensing slot, the channel is sensed to determine whether the detected energy for at least a certain period (e.g., 4 microseconds) within the sensing slot duration is greater than or equal to the energy detection threshold (X Thresh ), the sensing slot duration T sl Since the channel may be considered as idle, the channel may be considered as empty or clear or available in the sensing slot. Otherwise, the sensing slot duration T sl may be considered as busy, so that the channel may be considered as occupied or unavailable in the sensing slot.

[0022] In an NR-U system, when a BS or UE attempts to start a channel occupation time (COT) for DL ​​or UL transmission, a type 1 DL or UL channel access procedure, also known as an "LBT Category 4 procedure" or "LBT Cat.4 procedure", may be performed. In response to a successful type 1 DL or UL channel access procedure, the BS or UE may start transmission in the channel and occupy the channel up to a maximum channel occupation time (MCOT). If not, the BS or UE may not start transmission and may continue to perform another LBT procedure until the success of the LBT procedure. The duration of the MCOT may depend on the value of the corresponding channel access priority class (CAPC) and the presence of other technologies (e.g., WiFi) that share the same unlicensed spectrum as the NR-U system. A more detailed type 1 channel access procedure is specified in the 3GPP standard specification TS 37.213.

[0023] Channel Occupancy (CO) refers to the transmission on a channel by a BS or UE after performing the corresponding channel access procedure. Channel Occupancy Time (COT) may refer to the total time that a particular BS or UE and any other BSs or UEs that share the channel occupancy perform transmission on a channel after the particular BS or UE performs the corresponding channel access procedure. Channel occupancy time may be shared for transmission between BS and UE or between UEs.

[0024] If an unlicensed spectrum is used for sidelink transmission, a channel access procedure is still required before any sidelink transmission for fair coexistence. Due to the unpredictability of the channel access procedure, the UE cannot determine when the channel is available for sidelink transmission, which may be problematic. For example, assuming that the UE prepares a PSCCH and associated PSSCH (hereinafter referred to as "PSCCH / PSSCH") from symbol 0, once the UE successfully performs the channel access procedure and acquires the channel from symbol 7 of a particular slot (e.g., slot n), the UE may have to wait or transmit some reservation signal and start transmitting the prepared PSCCH / PSSCH from symbol 0 of the next slot (e.g., slot n+1). In this scenario, half of the slot (e.g., symbols 7 to 13 of slot n) is wasted.

[0025] In another scenario, if a UE may be assigned a slot in a COT initiated by the BS or another UE, for example, if the assigned resource starts at symbol 0 of a particular slot (e.g., slot n), the UE may prepare a PSCCH and associated PSSCH from symbol 0. However, if the UE does not successfully perform a channel access procedure before symbol 0 of slot n, the UE cannot transmit the prepared PSCCH / PSSCH in that slot. Thus, the UE misses a transmission opportunity and must wait for the next resource allocation.

[0026] In order to improve radio resource utilization and increase transmission opportunities, in some embodiments of the present disclosure, before performing a channel access procedure, the UE may prepare multiple PSCCHs / PSSCHs corresponding to multiple candidate starting positions in a slot. For example, the UE may prepare a first PSCCH / PSSCH starting at symbol 0, a second PSCCH / PSSCH starting at symbol 4, and a third PSCCH / PSSCH starting at symbol 8. According to the result of the channel access procedure, the UE may select one of the multiple prepared PSCCHs / PSSCHs. For example, from the multiple prepared PSCCHs / PSSCHs, the UE may select a specific PSCCH / PSSCH prepared with a starting position aligned with the current candidate starting position where the channel access procedure was successful, or the UE may select a specific PSCCH / PSSCH prepared with a starting position closest to the next candidate starting position. The UE may then transmit the selected PSCCH / PSSCH starting from the current candidate starting position or the next closest candidate starting position.

[0027] In the following text, an enhanced solution is provided that can reduce implementation complexity while providing multiple transmission opportunities for sidelink transmissions in unlicensed spectrum. Further details of the embodiments of the present disclosure are described in the following text in combination with the accompanying drawings.

[0028] In some embodiments of the present disclosure, for sidelink transmission over unlicensed spectrum, all symbols in a slot available for transmitting the PSSCH may be divided into one or more symbol groups for PSSCH transmission. The number of symbol groups may depend on the total number of symbols available for transmitting the PSSCH in the slot. Each symbol group of the one or more symbol groups may include the same or different number of symbols.

[0029] In some embodiments, the first symbol of a slot (e.g., symbol 0) may be used for automatic gain control (AGC) tuning. A PSCCH that schedules a PSSCH may be placed at the beginning of a sidelink transmission following the first symbol for AGC tuning. If a PSCCH and an associated PSSCH are multiplexed based on pure time division multiplexing (TDM), the PSCCH is not included in any of the symbol groups because a symbol for transmitting the PSCCH is not available for transmitting the PSSCH. If a PSCCH and an associated PSSCH are multiplexed based on TDM and frequency division multiplexing (FDM), the symbol for transmitting the PSCCH is included in a symbol group (e.g., a first symbol group of one or more symbol groups).

[0030] In some embodiments of the present disclosure, the structure of the symbol groups in a slot may be configured by Radio Resource Control (RRC) signaling. For example, the number of symbol groups in a slot, the number of symbols in each symbol group, or both may be configured by RRC signaling. In some embodiments of the present disclosure, the structure of the symbol groups in a slot may be predefined, for example, in a standard. In some embodiments of the present disclosure, a set of candidate starting positions for sidelink transmissions in a slot may be determined based on the structure of the symbol groups. In some examples, the number of candidate starting positions in a slot may be equal to the number of symbol groups in the slot. Details regarding the method of determining the set of candidate starting positions based on the symbol groups are described in the following text.

[0031] In some embodiments of the present disclosure, the structure of the symbol groups in a slot may be determined based on a set of candidate starting positions. The set of candidate starting positions may be configured by RRC signaling or may be predefined, for example, in a standard. In some examples, the number of candidate starting positions in a slot may be equal to the number of symbol groups in the slot. Details regarding the method of determining the symbol groups based on the set of candidate starting positions are described in the following text.

[0032] The following are some principles for determining the symbols available for transmitting the PSSCH. As mentioned above, the first symbol in a slot (e.g., symbol 0) may be used for AGC tuning, so the first symbol may not be counted into the symbols available for transmitting the PSSCH. If the last symbol in a slot (e.g., symbol 13) is left blank due to a gap, the last symbol is not counted into the symbols available for transmitting the PSSCH. If the PSCCH and PSSCH are pure time division multiplexed in a slot, i.e., there is no overlap between the PSCCH and the PSSCH in the frequency domain, when dividing into symbol groups, the symbols for PSCCH transmission are not counted into the symbols available for transmitting the PSSCH.

[0033] A demodulation reference signal (DMRS) may be required to decode the PSSCH. In some embodiments of the present disclosure, each symbol group in a slot may include at least one DMRS symbol. In some embodiments of the present disclosure, at least one of the symbol groups in a slot may not include any DMRS symbols. For example, a first symbol group of the one or more symbol groups in a slot includes a DMRS symbol, and the remaining symbol groups of the one or more symbol groups do not include any DMRS symbols. In some other examples, both the first symbol group and the third symbol group include a DMRS symbol, and the remaining symbol groups do not include any DMRS symbols.

[0034] 2 illustrates an example symbol group configuration 200 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0035] In Figure 2, the PSCCH and associated PSSCH are multiplexed in a slot (e.g., slot n) based on TDM and FDM. Slot n may include 14 symbols (e.g., symbols 0 through 13 marked as 0 through 13 along the time (t) axis in Figure 2). It is contemplated that a slot may include more or fewer symbols according to the communication standard employed.

[0036] Referring to FIG. 2, the first symbol (e.g., symbol 0) in slot n may be used for AGC tuning, and the last symbol (e.g., symbol 13) in slot n is available for transmitting PSSCH. Thus, there are 13 symbols available for PSSCH transmission, and the 13 symbols may be divided into one or more symbol groups for PSSCH transmission. In the exemplary symbol group configuration 200, all symbols available for PSSCH transmission are divided into four symbol groups (SG), including SG0, SG1, SG2, and SG3. It should be understood by those skilled in the art that the symbols available for PSSCH transmission may be divided into more or fewer symbol groups. For example, the symbols available for PSSCH transmission in a slot may be divided into two or three symbol groups.

[0037] In some examples, SG0 may include symbols 1-4, SG1 may include symbols 5-7, SG2 may include symbols 8-10, and SG3 may include symbols 11-13. It should be understood by those skilled in the art that the symbol groups for PSSCH transmission may include more or fewer symbols. For example, the number of symbols in each group may be 1, 2, 3, 4, 5, 6, or 7.

[0038] 3 illustrates an example symbol group configuration 300 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0039] In Figure 3, the PSCCH and associated PSSCH are multiplexed in a slot (e.g., slot n) based on TDM and FDM. Slot n may include 14 symbols (e.g., symbols 0 through 13 marked as 0 through 13 along the time (t) axis in Figure 3). It is contemplated that a slot may include more or fewer symbols according to the communication standard employed.

[0040] Referring to FIG. 3, the first symbol (e.g., symbol 0) in slot n may be used for AGC tuning. The last symbol (e.g., symbol 13) in slot n is left blank as a gap and therefore is not available for transmitting PSSCH. As a result, there are 12 symbols available for PSSCH transmission, and the 12 symbols may be divided into one or more symbol groups for PSSCH transmission. In the exemplary symbol group configuration 300, all symbols available for PSSCH transmission are divided into four symbol groups (SGs), including SG0, SG1, SG2, and SG3. It should be understood by those skilled in the art that the symbols available for PSSCH transmission may be divided into more or fewer symbol groups. For example, the symbols available for PSSCH transmission in a slot may be divided into two or three symbol groups.

[0041] In some examples, each of the four symbol groups may have the same number of symbols. That is, SG0 may include symbols 1-3, SG1 may include symbols 4-6, SG2 may include symbols 7-9, and SG3 may include symbols 10-12. It should be understood by those skilled in the art that each symbol group in a slot may be a different number of symbols, and that the symbol groups for PSSCH transmission may include more or fewer symbols. For example, the number of symbols in each group may be 1, 2, 3, 4, 5, 6, or 7.

[0042] 4 illustrates an example symbol group configuration 400 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0043] In Figure 4, the PSCCH and associated PSSCH are multiplexed in a slot (e.g., slot n) based on pure TDM. Slot n may include 14 symbols (e.g., symbols 0 through 13 marked as 0 through 13 along the time (t) axis in Figure 4). It is contemplated that a slot may include more or fewer symbols according to the communication standard employed.

[0044] Referring to FIG. 4, the first symbol in slot n (e.g., symbol 0) may be used for AGC tuning, the PSCCH occupies two symbols in slot n (e.g., symbols 1 and 2), and the last symbol in slot n (e.g., symbol 13) is available for transmitting the PSSCH. Thus, there are 11 symbols available for PSSCH transmission, and the 11 symbols may be divided into one or more symbol groups for PSSCH transmission. In the exemplary symbol group configuration 400, all symbols available for PSSCH transmission are divided into three symbol groups (SG), including SG0, SG1, and SG2. It should be understood by those skilled in the art that the symbols available for PSSCH transmission may be divided into more or fewer symbol groups. For example, the symbols available for PSSCH transmission in a slot may be divided into two or four symbol groups.

[0045] In some examples, SG0 may include symbols 3 through 6, SG1 may include symbols 7 through 10, and SG2 may include symbols 11 through 13. It should be understood by those skilled in the art that the symbol groups for PSSCH transmission may include more or fewer symbols. For example, the number of symbols in each group may be 1, 2, 3, 4, 5, 6, or 7.

[0046] 5 illustrates an example symbol group configuration 500 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0047] In Figure 5, the PSCCH and associated PSSCH are multiplexed in a slot (e.g., slot n) based on TDM. Slot n may include 14 symbols (e.g., symbols 0 through 13 marked as 0 through 13 along the time (t) axis in Figure 5). It is contemplated that a slot may include more or fewer symbols according to the communication standard employed.

[0048] Referring to FIG. 5, the first symbol (e.g., symbol 0) in slot n may be used for AGC tuning, and the PSCCH occupies two symbols (e.g., symbols 1 and 2) in slot n. The last symbol (e.g., symbol 13) in slot n is left blank as a gap and is therefore unavailable for transmitting PSSCH. Thus, there are 10 symbols available for PSSCH transmission, and the 10 symbols may be divided into one or more symbol groups for PSSCH transmission. In the exemplary symbol group configuration 500, all symbols available for PSSCH transmission are divided into three symbol groups (SG), including SG0, SG1, and SG2. It should be understood by those skilled in the art that the symbols available for PSSCH transmission may be divided into more or fewer symbol groups. For example, the symbols available for PSSCH transmission in a slot may be divided into two or four symbol groups.

[0049] In some examples, SG0 may include symbols 3 through 6, SG1 may include symbols 7 through 9, and SG2 may include symbols 10 through 12. It should be understood by those skilled in the art that the symbol groups for PSSCH transmission may include more or fewer symbols. For example, the number of symbols in each group may be 1, 2, 3, 4, 5, 6, or 7.

[0050] It should be understood that the symbol group configurations shown above are for illustrative purposes only and should not be construed as limiting the embodiments of the present disclosure. For example, in Figures 2-5, the DMRS is transmitted in a particular symbol in a slot, but it is contemplated that the DMRS may be transmitted in more or fewer symbols in a slot. Although the PSCCH is transmitted in symbols 1-3 in Figures 2 and 3 and occupies two symbols (e.g., symbols 1 and 2) in Figures 4 and 5, the PSCCH may be transmitted in more or fewer symbols in a slot or occupy more or fewer symbols in a slot.

[0051] In order to provide multiple transmission opportunities for sidelink transmissions in a slot, a set of candidate starting positions for sidelink transmissions in a slot may be configured by RRC signaling, may be predefined, or may be implicitly determined based on the structure of the symbol groups. In a slot, a channel access procedure (e.g., an LBT procedure) may be performed before a first candidate starting position of the set of candidate starting positions. If the channel access procedure is successful, the sidelink transmission may start from the first candidate starting position in the slot. If the channel access procedure fails, another channel access procedure may be performed before a next (e.g., a second) candidate starting position of the set of candidate starting positions until the channel access procedure is successful in one of the set of candidate starting positions. After the channel access procedure for all candidate starting positions in a slot fails, the channel access procedure may be performed in a similar manner in the next slot. For example, the channel access procedure may be performed before the first candidate starting position of the next slot.

[0052] In some embodiments of the present disclosure, the set of candidate starting positions may be {0,3,6,9}, which includes candidate starting positions at symbols 0, 3, 6, and 9. In some embodiments of the present disclosure, the set of candidate starting positions may be {0,4,7} or {0,3,7} or {0,7}. It is contemplated that the set of candidate starting positions may include other possible symbol indices. In principle, both the Tx UE and the Rx UE should maintain the same set of candidate starting positions so that the Rx UE knows the possible starting positions for receiving sidelink transmissions. For example, the same set of candidate starting positions may be configured by RRC signaling or may be predefined. In another example, the Tx UE and the Rx UE may follow the same rule of determining the set of candidate starting positions based on the same structure of symbol groups configured for both the Tx UE and the Rx UE by RRC signaling or predefined.

[0053] From the perspective of the Tx UE, a single PSCCH / PSSCH may be prepared for a slot before performing the channel access procedure. The PSCCH / PSSCH may be transmitted at a location based on the result of the channel access procedure. For example, the UE may transmit the prepared PSCCH / PSSCH at the last available symbol in the slot (e.g., symbol 12 if symbol 13 is left blank as shown in Figures 3 and 5, or symbol 13 if symbol 13 is available for sidelink transmission) from the candidate starting position where the channel access procedure was successful. Based on the result of the channel access procedure, the symbols prepared for the PSCCH / PSSCH are transmitted from left to right (i.e., from lowest symbol index to higher symbol index) at the available symbols in the slot. The prepared symbols after the last available symbol, if any, are punctured.

[0054] For example, assuming that N symbols are prepared for PSCCH / PSSCH in a slot, including the first symbol for AGC tuning, if the channel access procedure for a candidate starting position (e.g., symbol x) is successful, it may be determined that there are (14-xy) symbols available for PSCCH / PSSCH transmission, where 14 is the number of symbols in the slot, and y=1 if the last symbol in the slot (symbol 13) is left as a gap, and y=0 if the last symbol in the slot is available for transmission. In this case, the first (14-xy) symbols of the N prepared symbols may be transmitted in the actual symbols from symbol x to symbol 13-y, and the last (N-14+x+y) symbols of the N prepared symbols are punctured.

[0055] In other words, if the number of symbols prepared for the PSCCH / PSSCH is greater than the number of symbols actually available for transmission in a slot, e.g., if the PSCCH / PSSCH is prepared with 14 symbols and the actual transmission does not start at symbol 0, the prepared PSCCH / PSSCH is punctured from right to left (i.e., from highest symbol index to lower symbol index). In this way, the PSCCH placed at the beginning of each sidelink transmission can be transmitted instead of being punctured.

[0056] 6 illustrates an example sidelink transmission 600 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0057] In some embodiments of the present disclosure, the structure of the symbol groups within a slot may be configured or predefined as described with reference to Figure 2. Specifically, with reference to Figure 6, the first symbol group SG0 may include symbols 1-4, the second symbol group SG1 may include symbols 5-7, the third symbol group SG2 may include symbols 8-10, and the fourth symbol group SG3 may include symbols 11-13.

[0058] The candidate starting positions may be determined based on the structure of the symbol groups. For example, the number of candidate starting positions may be equal to the number of symbol groups in a slot. Based on the above symbol group structure, the UE may determine that the set of candidate starting positions is {0, 3, 6, 9}. That is, the first candidate starting position (symbol 0) is determined based on the assumption that all symbol groups may be transmitted, the second candidate starting position (symbol 3) is determined based on the assumption that symbol groups SG0 to SG2 may be transmitted, the third candidate starting position (symbol 6) is determined based on the assumption that symbol groups SG0 and SG1 may be transmitted, and the fourth candidate starting position (symbol 9) is determined based on the assumption that symbol group SG0 may be transmitted.

[0059] Referring to Figure 6, including the first symbol for AGC tuning, the UE may prepare a single PSCCH / PSSCH with 14 symbols without the last gap symbol. If the channel access procedure for the first candidate starting position (symbol 0) of slot n is successful, all the prepared 14 symbols from symbol 0 to symbol 13 are transmitted in the actual symbols of the slot, as shown at 610 in Figure 6. Otherwise, if the channel access procedure for symbol 0 fails, the UE may perform the channel access procedure for the second candidate starting position (symbol 3) of slot n.

[0060] If the channel access procedure for symbol 3 is successful, then since there are a total of 11 symbols available in the slot (symbol 3 to symbol 13), the first 11 of the 14 prepared symbols, from symbol 3 to symbol 13, are transmitted in the actual symbols of the slot, as shown at 620 in Figure 6. Otherwise, if the channel access procedure for symbol 3 fails, the UE may perform the channel access procedure for the third candidate starting position (symbol 6) of slot n.

[0061] If the channel access procedure for symbol 6 is successful, then since there are a total of 8 symbols available in the slot (symbol 6 to symbol 13), the first 8 of the 14 prepared symbols, from symbol 6 to symbol 13, are transmitted in the actual symbols of the slot, as shown at 630 in Figure 6. If the channel access procedure for symbol 6 fails, the UE may perform the channel access procedure for the fourth candidate starting position of slot n (symbol 9).

[0062] If the channel access procedure for symbol 9 is successful, then since there are a total of 5 symbols available in the slot (symbol 9 to symbol 13), the first 5 symbols of the 14 prepared symbols, from symbol 9 to symbol 13, are transmitted in the actual slot of the slot, as shown at 640 in Figure 6. If the channel access procedure for symbol 9 fails, the UE may perform the channel access procedure for the first candidate starting position (symbol 0) in the next slot (slot n+1).

[0063] 7 illustrates an example sidelink transmission 700 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0064] In some embodiments of the present disclosure, the structure of the symbol groups within a slot may be configured or predefined as described with reference to Figure 3. Specifically, with reference to Figure 7, the first symbol group SG0 may include symbols 1-3, the second symbol group SG1 may include symbols 4-6, the third symbol group SG2 may include symbols 7-9, and the fourth symbol group SG3 may include symbols 10-12.

[0065] The candidate start positions may be determined based on the structure of the symbol groups. For example, the number of candidate start positions may be equal to the number of symbol groups in a slot. Based on the above symbol group structure, the UE may determine what the set of candidate start positions are, for example, the set of candidate start positions may be {0, 3, 6, 9}. That is, the first candidate start position (symbol 0) is determined based on the assumption that all symbol groups may be transmitted, the second candidate start position (symbol 3) is determined based on the assumption that symbol groups SG0 to SG2 may be transmitted, the third candidate start position (symbol 6) is determined based on the assumption that symbol groups SG0 and SG1 may be transmitted, and the fourth candidate start position (symbol 9) is determined based on the assumption that symbol group SG0 may be transmitted.

[0066] Referring to Figure 7, including the first symbol for AGC tuning, the UE may prepare a single PSCCH / PSSCH with 13 symbols with the last gap symbol (symbol 13). If the channel access procedure for the first candidate starting position (symbol 0) of slot n is successful, all the prepared 13 symbols from symbol 0 to symbol 12 are transmitted in the actual symbols of the slot, as shown at 710 in Figure 7. Otherwise, if the channel access procedure for symbol 0 fails, the UE may perform the channel access procedure for the second candidate starting position (symbol 3) of slot n.

[0067] If the channel access procedure for symbol 3 is successful, then since there are a total of 10 symbols available in the slot (symbol 3 to symbol 12), the first 10 symbols of the 13 prepared symbols, from symbol 3 to symbol 12, are transmitted in the actual symbols of the slot, as shown at 720 in Figure 7. Otherwise, if the channel access procedure for symbol 3 fails, the UE may perform the channel access procedure for the third candidate starting position (symbol 6) of slot n.

[0068] If the channel access procedure for symbol 6 is successful, then since there are a total of 7 symbols available in the slot (symbol 6 through symbol 12), the first 7 of the 13 prepared symbols, from symbol 6 through symbol 12, are transmitted in the actual symbols of the slot, as shown at 730 in Figure 7. If the channel access procedure for symbol 6 fails, the UE may perform the channel access procedure for the fourth candidate starting position (symbol 9) of slot n.

[0069] If the channel access procedure for symbol 9 is successful, then since there are a total of four symbols available in the slot (symbol 9 to symbol 12), the first four of the 13 prepared symbols, from symbol 9 to symbol 12, are transmitted in the actual slot of the slot, as shown at 740 in Figure 7. If the channel access procedure for symbol 9 fails, the UE may perform the channel access procedure for the first candidate starting position (symbol 0) in the next slot (slot n+1).

[0070] 8 illustrates an example sidelink transmission 800 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0071] In some embodiments of the present disclosure, the structure of the symbol groups within a slot may be configured or predefined as described with reference to Figure 4. Specifically, with reference to Figure 8, the first symbol group SG0 may include symbols 3-6, the second symbol group SG1 may include symbols 7-10, and the third symbol group SG2 may include symbols 11-13.

[0072] The candidate starting positions may be determined based on the structure of the symbol groups. For example, the number of candidate starting positions may be equal to the number of symbol groups in a slot. Based on the above symbol group structure, the UE may determine that the set of candidate starting positions is {0, 3, 7}. That is, the first candidate starting position (symbol 0) is determined based on the assumption that all symbol groups may be transmitted, the second candidate starting position (symbol 3) is determined based on the assumption that symbol groups SG0 and SG1 may be transmitted, and the third candidate starting position (symbol 7) is determined based on the assumption that symbol group SG0 may be transmitted.

[0073] Referring to Figure 8, including the first symbol for AGC tuning, the UE may prepare a single PSCCH / PSSCH with 14 symbols without the last gap symbol. If the channel access procedure for the first candidate starting position (symbol 0) of slot n is successful, all the prepared 14 symbols from symbol 0 to symbol 13 are transmitted in the actual symbols of the slot, as shown at 810 in Figure 8. Otherwise, if the channel access procedure for symbol 0 fails, the UE may perform the channel access procedure for the second candidate starting position (symbol 3) of slot n.

[0074] If the channel access procedure for symbol 3 is successful, then since there are a total of 11 symbols available in the slot (symbol 3 to symbol 13), the first 11 of the 14 prepared symbols, from symbol 3 to symbol 13, are transmitted in the actual symbols of the slot, as shown at 820 in Figure 8. Otherwise, if the channel access procedure for symbol 3 fails, the UE may perform the channel access procedure for the third candidate starting position (symbol 7) of slot n.

[0075] If the channel access procedure for symbol 7 is successful, since there are a total of 7 symbols available in the slot (symbol 7 to symbol 13), the first 7 symbols of the 14 prepared symbols, from symbol 7 to symbol 13, are transmitted in the actual slot of the slot, as shown at 830 in Figure 8. If the channel access procedure for symbol 7 fails, the UE may perform the channel access procedure for the first candidate starting position (symbol 0) in the next slot (slot n+1).

[0076] 9 illustrates an example sidelink transmission 900 in accordance with some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0077] In some embodiments of the present disclosure, the structure of the symbol groups within a slot may be configured or predefined as described with reference to Figure 5. Specifically, with reference to Figure 9, the first symbol group SG0 may include symbols 3-6, the second symbol group SG1 may include symbols 7-9, and the third symbol group SG2 may include symbols 10-12.

[0078] The candidate starting positions may be determined based on the structure of the symbol groups. For example, the number of candidate starting positions may be equal to the number of symbol groups in a slot. Based on the above symbol group structure, the UE may determine that the set of candidate starting positions is {0, 3, 6}. That is, the first candidate starting position (symbol 0) is determined based on the assumption that all symbol groups may be transmitted, the second candidate starting position (symbol 3) is determined based on the assumption that symbol groups SG0 and SG1 may be transmitted, and the third candidate starting position (symbol 6) is determined based on the assumption that symbol group SG0 may be transmitted.

[0079] Referring to Figure 9, including the first symbol for AGC tuning, the UE may prepare a single PSCCH / PSSCH with 13 symbols with the last gap symbol (symbol 13). If the channel access procedure for the first candidate starting position (symbol 0) of slot n is successful, all the prepared 13 symbols from symbol 0 to symbol 12 are transmitted in the actual symbols of the slot, as shown at 910 in Figure 9. Otherwise, if the channel access procedure for symbol 0 fails, the UE may perform the channel access procedure for the second candidate starting position (symbol 3) of slot n.

[0080] If the channel access procedure for symbol 3 is successful, then since there are a total of 10 symbols available in the slot (symbol 3 to symbol 12), the first 10 symbols of the 13 prepared symbols, from symbol 3 to symbol 12, are transmitted in the actual symbols of the slot, as shown at 920 in Figure 9. Otherwise, if the channel access procedure for symbol 3 fails, the UE may perform the channel access procedure for the third candidate starting position (symbol 6) of slot n.

[0081] If the channel access procedure for symbol 6 is successful, since there are a total of 7 symbols available in the slot (symbol 6 to symbol 12), the first 7 symbols of the 13 prepared symbols, from symbol 6 to symbol 12, are transmitted in the actual slot of the slot, as shown at 930 in Figure 9. If the channel access procedure for symbol 6 fails, the UE may perform the channel access procedure for the first candidate starting position (symbol 0) in the next slot (slot n+1).

[0082] Although the above embodiments described that the set of candidate starting positions may be determined based on a configured or predefined symbol group structure, it is contemplated that the set of candidate starting positions may also be configured by RRC signaling or may be predefined, for example, in a standard. In other words, either the set of candidate starting positions or the symbol group structure may be configured by RRC signaling or may be predefined.

[0083] In some embodiments of the present disclosure, the structure of the symbol groups may be determined by a configuration or a predefined set of candidate starting positions (e.g., C0, C1, ..., C m For example, the UE may determine that the number of symbol groups in the slot is equal to the number of candidate starting positions. The UE may then determine the number of symbols in these symbol groups (e.g., N0, N1, ..., N m ) may further be determined.

[0084] For example, considering that the first symbol in a slot (e.g., symbol 0) may be used for AGC tuning, the UE may determine that the first symbol group (SG0) includes N0 symbols, where N0=(14-ykp)-C m, 14 is the number of symbols in a slot, y=1 if the last symbol in the slot (symbol 13) is left as a gap, and y=0 if the last symbol in the slot is available for transmission, k is the number of symbols for AGC tuning, which may be equal to 1, p is the number of symbols for PSCCH transmission only (e.g., symbols 1 and 2 in Figures 4 and 5), and C m is the last candidate starting position.

[0085] The UE may determine that the second symbol group (SG1) includes N1 symbols, where N1=(14-ykp)-C m-1 -N0, 14 is the number of symbols in a slot, y=1 if the last symbol in the slot (symbol 13) is left as a gap, y=0 if the last symbol in the slot is available for transmission, k is the number of symbols for AGC tuning, which may be equal to 1, p is the number of symbols for PSCCH transmission only, C m-1 is the penultimate candidate starting position.

[0086] Similarly, the UE determines whether the last symbol group (SGm) is N m symbols, where N m =(14-ykp)-C0-(N0+N1+...N m-1 ), 14 is the number of symbols in the slot, y=1 if the last symbol in the slot (symbol 13) is left as a gap, and y=0 if the last symbol in the slot is available for transmission, k is the number of symbols for AGC tuning and may be equal to 1, p is the number of symbols for PSCCH transmission only, and C0 is the first candidate starting position.

[0087] For example, assuming that the set of candidate starting positions may be configured or predefined as {0,3,6,9}, the UE may determine that the number of symbol groups in a slot is 4. Assuming that there is no gap symbol and that the PSCCH and associated PSSCH are multiplexed based on both TDM and FDM (e.g., p=0), the UE may further determine that the first symbol group (SG0) includes 4 symbols. Since the first symbol (e.g., symbol 0) is used for AGC tuning, the UE may further determine that the first symbol group includes symbols 1-4. The UE may determine that the second symbol group includes 3 symbols, i.e., symbols 5-7. The UE may determine that the third symbol group includes 3 symbols, i.e., symbols 8-10. The UE may determine that the fourth symbol group includes 3 symbols, i.e., symbols 11-13.

[0088] In another example, assuming that a set of candidate starting positions may be configured or predefined as {0,3,7}, the UE may determine that the number of symbol groups in a slot is 3. Assuming that there is no gap symbol and that the PSCCH and associated PSSCH are multiplexed based on TDM (e.g., p=2), the UE may further determine that the first symbol group (SG0) includes 4 symbols. Since the first symbol (e.g., symbol 0) is used for AGC tuning and the second and third symbols (e.g., symbols 1 and 2) are used only for PSCCH transmission, the UE may further determine that the first symbol group includes symbols 3-6. The UE may determine that the second symbol group includes 4 symbols, i.e., symbols 7-10. The UE may determine that the third symbol group includes 3 symbols, i.e., symbols 11-13.

[0089] Within each symbol group in a slot, for a transport block (TB) to be carried in the slot, several methods may be adopted for PSSCH rate matching within the slot.

[0090] For example, in some embodiments of the present disclosure, an integer number of code blocks (CBs) of TB may be included in each symbol group with rate matching performed independently. In this case, each and every CB does not cross symbol groups. Thus, symbol group-based retransmission may be necessary. If the physical sidelink feedback channel (PSFCH) is disabled, the UE (e.g., Tx UE) may retransmit the CB included in the punctured symbol group. If the PSFCH is enabled, the number of HARQ-ACK feedback bits of a slot is equal to the number of symbol groups, and each of the HARQ-ACK feedback bits corresponds to a respective one of the symbol groups. In response to receiving the symbol group-based HARQ-ACK feedback, the UE may retransmit the CB included in the symbol group associated with a negative acknowledgement (NACK) as indicated by another UE (e.g., Rx UE).

[0091] In some embodiments of the present disclosure, an integer number of code block groups (CBGs) of a TB may be included with rate matching performed independently in each symbol group. In this case, each and every CBG does not cross symbol groups. Therefore, CBG-based retransmission may be necessary. If the PSFCH is disabled, the UE (e.g., Tx UE) may retransmit the CBGs included in the punctured symbol group. If the PSFCH is enabled, the number of HARQ-ACK feedback bits of a slot is equal to the number of CBGs per TB, and each of the HARQ-ACK feedback bits corresponds to a respective one of the CBGs. In response to receiving the CBG-based HARQ-ACK feedback, the UE may retransmit the CBG associated with the NACK as indicated by another UE (e.g., Rx UE).

[0092] In yet another embodiment of the present disclosure, multiple redundancy versions (RVs) of a TB may be carried on one or more symbol groups. That is, each symbol group may be used to transmit a respective RV of a TB. For example, if there are four symbol groups (e.g., SG0, SG1, SG2, and SG3) in a slot, the four symbol groups may be used to transmit RV0, RV2, RV3, and RV1 of a TB, respectively. RV0 is a repetition of a TB with the most systematic bits. If there are three symbol groups (e.g., SG0, SG1, and SG2) in a slot, the three symbol groups may be used to transmit RV0, RV2, and RV3 of a TB, respectively. In these embodiments, since multiple RVs of a TB are transmitted, the reliability is relatively high. Even if the PSFCH is disabled, the possibility of retransmission of the entire TB is very low. If the PSFCH is enabled, a single HARQ-ACK feedback bit corresponding to the TB is required.

[0093] In some embodiments of the present disclosure, to further reduce the UE implementation complexity and the overhead of CBG-based or symbol group-based HARQ-ACK feedback, only the sidelink transmission in the initial slot is split into one or more symbol groups as described above and fed back with the CBG-based or symbol group-based HARQ-ACK feedback bits. This is because the channel access procedure for the initial slot (e.g., slot j) is unpredictable and is not necessary for the remaining slots in the COT (e.g., slot j+1). That is, after the channel access procedure in the initial slot is successful, the UE (e.g., Tx UE) may occupy the channel for a certain COT. The sidelink transmission in the remaining slots (e.g., slot j+1) of the COT initiated by the Tx UE is always transmitted from the first symbol (e.g., symbol 0) of the slot. In this scenario, it may not be necessary to apply the symbol group mechanism to the remaining slots. Meanwhile, only the TB-based HARQ-ACK feedback may be applied to the remaining slots. In this way, the UE implementation complexity and the feedback overhead may be significantly improved.

[0094] 10 illustrates an example UE-initiated COT 1000 according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG.

[0095] A UE (e.g., a Tx UE) may initiate a COT 1000 for transmitting data after successfully performing a channel access procedure. The COT 1000 may start at slot n and end at slot n+3. As shown in FIG. 10, the initial slot (slot n) is not completely contained within the COT 1000. The last slot (slot n+3) is also not completely contained within the COT 1000. In some other embodiments of the present disclosure, the initial slot and the last slot may be completely contained within the COT 1000.

[0096] The UE may transmit a sidelink transmission 1010 and a sidelink transmission 1020 within the COT 1000. Each of the sidelink transmissions 1010 and 1020 may include a corresponding PSCCH and an associated PSSCH. The sidelink transmission 1010 in an initial slot (slot n) is divided into one or more symbol groups as described above, and the sidelink transmission 1020 is transmitted slot-by-slot (e.g., starting from symbol 0 of the corresponding slot). Furthermore, if CBG-based or symbol group-based HARQ-ACK feedback is employed, the sidelink transmission 1010 is fed back with one or more HARQ-ACK feedback bits corresponding to the CBG or symbol group. The sidelink transmission 1020 is fed back every TB (i.e., TB-based HARQ-ACK feedback).

[0097] 11 illustrates a flowchart of an example procedure 1100 of wireless communication according to some embodiments of the present disclosure. The details described in all of the previous embodiments of the present disclosure are applicable to the embodiment illustrated in FIG 11. The procedure may be performed by a UE, for example, UE 110a, UE 110b, or UE 110c in FIG 1.

[0098] Referring to FIG. 11, at operation 1111, the UE may determine a set of candidate starting locations (e.g., {0, 3, 6, 9}) for sidelink transmission. In some examples, the set of candidate starting locations may be configured by radio resource control (RRC) signaling or may be predefined. In some other examples, the set of candidate starting locations may be determined based on one or more symbol groups. In some embodiments, the number of candidate starting locations in the set of candidate starting locations may be equal to the number of symbol groups of the one or more symbol groups.

[0099] In operation 1113, the UE may perform a channel access procedure based on the set of candidate starting positions. For example, the UE may perform a channel access procedure (hereinafter, "first channel access procedure") for one candidate starting position (hereinafter, "first candidate starting position") of the set of candidate starting positions in a slot (hereinafter, "first slot"). The first candidate starting position may be one having a lowest symbol index, such as symbol 0. In response to the channel access procedure failing for all candidate starting positions (e.g., symbols 0, 3, 6, and 9) of the set of candidate starting positions in the first slot, another channel access procedure is performed for the first candidate starting position in another slot following the first slot.

[0100] In some embodiments of the present disclosure, a UE may generate a PSCCH (hereinafter, a "first PSCCH") and a PSSCH (hereinafter, a "first PSSCH"), where the first PSSCH is scheduled by the first PSCCH for transmitting a transport block (TB). In response to the first channel access procedure being successful, the UE may transmit the first PSCCH and the first PSSCH from a first candidate starting position in the first slot.

[0101] In some embodiments of the present disclosure, the first slot may be divided into one or more symbol groups, for example, as described above with reference to Figures 2-10. In some examples, the one or more symbol groups may be configured by RRC signaling or may be predefined. In some other examples, the one or more symbol groups may be determined based on a set of candidate starting positions. In some embodiments, the number of candidate starting positions in the set of candidate starting positions may be equal to the number of symbol groups of the one or more symbol groups.

[0102] In some embodiments of the present disclosure, each symbol group of the one or more symbol groups may include an integer number of CBs of TB. In other words, each and every CB does not cross the symbol group. In this scenario, the UE may receive a respective HARQ-ACK feedback corresponding to each of the one or more symbol groups. In response to the HARQ-ACK feedback for the first PSSCH symbol group being a NACK, the UE may transmit (or retransmit) the first PSSCH symbol group.

[0103] In some embodiments of the present disclosure, each symbol group may include an integer number of CBGs of TB. In other words, each and every CBG does not cross symbol groups. In this scenario, the UE may receive a respective HARQ-ACK feedback corresponding to each of the CBGs. In response to the HARQ-ACK feedback for a CBG being a NACK, the UE may transmit (or retransmit) the CBG.

[0104] In some embodiments of the present disclosure, each symbol group may include an RV for a TB. In this scenario, the UE may transmit one or more RVs for a TB in one or more symbol groups. In response to the HARQ-ACK feedback for a TB being a NACK, the UE may transmit (or retransmit) the TB.

[0105] In some embodiments of the present disclosure, the first PSSCH may be transmitted in available symbols in the first slot. If the number of symbols of the first PSSCH is greater than the number of available symbols in the first slot, the first PSSCH may be punctured to align with the number of available symbols in the first slot. In some examples, the last one or more symbols of the first PSSCH may be punctured. In some examples, the last one or more symbol groups of the first PSSCH may be punctured.

[0106] In some embodiments of the present disclosure, in response to the first PSSCH being transmitted in the first slot, the UE may further transmit another PSSCH (hereinafter, a "second PSSCH") in another slot following the first slot. The UE may receive symbol group-based HARQ-ACK feedback or CBG-based HARQ-ACK feedback for the first PSSCH and may receive TB-based HARQ-ACK feedback for the second PSSCH.

[0107] It should be understood by one of ordinary skill in the art that the order of operations in the exemplary procedure 1100 may be changed and that some of the operations in the exemplary procedure 1100 may be deleted or modified without departing from the spirit and scope of the present disclosure.

[0108] FIG. 12 illustrates a block diagram of an example apparatus 1200 according to some embodiments of the present disclosure.

[0109] 12, the apparatus 1200 may include at least one non-transitory computer-readable medium 1201, at least one receiving circuit 1202, at least one transmitting circuit 1204, and at least one processor 1206 coupled to the non-transitory computer-readable medium 1201, the receiving circuit 1202, and the transmitting circuit 1204. The apparatus 1200 may be a base station side apparatus (e.g., BS) or a communication device (e.g., UE).

[0110] In this figure, elements such as at least one processor 1206, transmitting circuit 1204, and receiving circuit 1202 are described in the singular, but the plural is contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, the receiving circuit 1202 and the transmitting circuit 1204 are combined into a single device, such as a transceiver. In certain embodiments of the present application, the apparatus 1200 may further include an input device, a memory, and / or other components.

[0111] In some embodiments of the present disclosure, the non-transitory computer-readable medium 1201 may store computer-executable instructions that, when executed, cause the processor 1206 to interact with the receiving circuitry 1202 and the transmitting circuitry 1204 to perform the operations related to the UE as described above with respect to the UE.

[0112] In some embodiments of the present disclosure, the non-transitory computer-readable medium 1201 may store computer-executable instructions that cause a processor to implement a method for the BS as described above. For example, the computer-executable instructions, when executed, cause the processor 1206 to interact with the receiving circuitry 1202 and the transmitting circuitry 1204 to perform operations for the BS described in Figures 1-9. In some examples, the BS may send an RRC message to the UE to configure at least one of a structure of symbol groups and a set of candidate starting positions.

[0113] Those skilled in the art will understand that the operations or steps of the methods described in connection with the embodiments disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of the two. The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. In addition, in some embodiments, the operations or steps of the methods may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium that may be incorporated into a computer program product.

[0114] Although the present disclosure has been described using specific embodiments thereof, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be exchanged, added, or substituted in other embodiments. Also, not all elements in each figure are necessary for the operation of the disclosed embodiments. For example, a person skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply using the elements of the independent claims. Therefore, the embodiments of the present disclosure described herein are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0115] In this document, the terms "comprise", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements may include not only those elements, but also other elements not expressly listed or other elements inherent to such process, method, article, or apparatus. An element preceded by "a", "an", etc. does not, without more constraints, preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term "another" is defined as at least a second or more. As used herein, terms such as "having" are defined as "including". The terms "first" and "second" are used only to clarify the embodiments of this application and are not used to limit the substance of this application. [Explanation of symbols]

[0116] 100 Wireless communication system 110UE 110a UE 110b UE 110c UE 120 BS, base station 130 Coverage Area 200 Symbol Group Configuration 300 Symbol Group Configuration 400 Symbol Group Configuration 500 Symbol Group Configuration 600 Sidelink transmission 700 Sidelink transmission 800 Sidelink transmission 900 Sidelink transmission 1000 UE start COT, COT 1010 Sidelink transmission 1020 Sidelink transmission 1200 equipment 1201 Non-transitory computer-readable medium 1202 Receiver circuit 1204 Transmitting circuit 1206 Processor

Claims

1. determining a set of candidate starting positions for sidelink transmissions; performing a first channel access procedure on a first candidate starting location of the set of candidate starting locations in a first slot; Including, The set of candidate starting locations is configured by radio resource control (RRC) signaling. A method for wireless communication. determining a set of candidate start positions for sidelink transmissions; performing a first channel access procedure on a first candidate starting location of the set of candidate starting locations in a first slot; Including, The set of candidate starting locations is predefined. A method for wireless communication.

3. generating a first physical sidelink control channel (PSCCH) and a first physical sidelink shared channel (PSSCH), the first PSSCH being scheduled by the first PSCCH for transmitting a transport block (TB); transmitting the first PSCCH and the first PSSCH from the first candidate starting position within the first slot in response to the first channel access procedure being successful; 3. The method of claim 1 or 2, further comprising:

4. The method of claim 3 , wherein the first PSSCH is divided into one or more symbol groups.

5. 5. The method of claim 4, wherein the one or more symbol groups are configured by radio resource control (RRC) signaling, predefined, or determined based on the set of candidate starting positions.

6. The method of claim 4 , wherein each symbol group includes an integer number of code blocks (CBs) of the TB.

7. 7. The method of claim 6, further comprising receiving a respective Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) feedback corresponding to each of the one or more symbol groups.

8. 8. The method of claim 7, further comprising: retransmitting the first PSSCH symbol group in response to the HARQ-ACK feedback for the symbol group being a negative acknowledgement (NACK).

9. The method of claim 4 , wherein each symbol group includes an integer number of Code Block Groups (CBGs) of the TB.

10. 10. The method of claim 9, further comprising receiving a respective Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) feedback corresponding to each of the CBGs.

11. The method of claim 10, further comprising the step of retransmitting the CBG in response to the HARQ-ACK feedback for the CBG being a negative acknowledgement (NACK).

12. The method of claim 4 , wherein each symbol group includes a redundancy version (RV) of the TB.

13. The method of claim 12, further comprising transmitting a plurality of RVs of the TB in the one or more symbol groups.

14. 2. The method of claim 1, wherein the set of candidate starting locations is determined based on one or more symbol groups, the one or more symbol groups being configured by radio resource control (RRC) signaling.

15. The method of claim 2, wherein the set of candidate starting positions is determined based on one or more symbol groups, the one or more symbol groups being predefined.

16. 16. The method of claim 1, 2, 14 or 15, wherein the number of candidate starting locations in the set of candidate starting locations is equal to the number of symbol groups of the one or more symbol groups.

17. The method of claim 3 , wherein the first PSSCH is transmitted in an available symbol in the first slot.

18. 18. The method of claim 17, wherein if a number of symbols of the first PSSCH is greater than a number of the available symbols in the first slot, the first PSSCH is punctured.

19. 20. The method of claim 18, wherein a last symbol or symbols of the first PSSCH are punctured.

20. 20. The method of claim 18, wherein a last one or more symbol groups of the first PSSCH are punctured.

21. 4. The method of claim 3, further comprising the step of transmitting, in response to the first PSSCH being transmitted in the first slot, a second PSSCH in a second slot following the first slot.

22. receiving symbol group-based Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) feedback or code block group (CBG)-based HARQ-ACK feedback for the first PSSCH; receiving TB-based HARQ-ACK feedback for the second PSSCH; 22. The method of claim 21, further comprising:

23. 3. The method of claim 1, further comprising the step of performing a second channel access procedure to the first candidate starting location in a second slot following the first slot in response to a failure of a channel access procedure to all candidate starting locations of the set of candidate starting locations in the first slot.

24. At least one non-transitory computer-readable medium having computer-executable instructions stored thereon; at least one receiving circuit; at least one transmit circuit; at least one processor coupled to the at least one non-transitory computer readable medium, the at least one receiving circuit, and the at least one transmitting circuit; An apparatus comprising: The computer executable instructions cause the at least one processor to perform a method according to any one of claims 1 to 23. Device.

Images