Method and apparatus for burst-based sidelink transmission

Abstract

The embodiment of the invention relates to a method and equipment for burst-based sidelink transmission. In accordance with an embodiment of the present disclosure, a method for wireless communication includes performing a first type 1 channel access procedure for sidelink transmission on a carrier starting from a first candidate start symbol within a first time slot, where the first candidate start symbol is in a set of candidate start symbols for the sidelink transmission; determining a channel occupancy time (COT) in response to the first type 1 channel access procedure being successful; and within the COT, performing the sidelink transmission on the carrier starting from the first candidate start symbol within the first time slot, where the sidelink transmission is continuous in time domain without any gap.

Description

[0001] Divisional application information

[0002] This application is a divisional application of the invention patent application filed on March 31, 2020, with application number "202080099271.0" and invention title "Method and apparatus for burst-based secondary link transmission". Technical Field

[0003] Embodiments of this disclosure relate to wireless communication technologies, and more specifically, to methods and apparatus for secondary link transmission over unlicensed spectrum. Background Technology

[0004] In a wireless communication system, a user equipment (UE), such as a mobile device, can communicate with another UE via a data path supported by an operator network (such as a cellular or Wi-Fi network infrastructure). The data path supported by the operator network may include a base station (BS) and multiple gateways.

[0005] When two UEs are relatively close to each other, a radio link or secondary link can be established between the two UEs to provide device-to-device (D2D) communication without a direct link to the BS. The term "secondary link" can refer to communication between devices (e.g., UEs) rather than a direct radio link established via communication through the cellular infrastructure (uplink and downlink) discussed above. In this context, the "secondary link" is also referred to as a D2D communication link. D2D communication links can be used in any suitable telecommunications network according to various standards, where a resource pool can be configured for use by the UEs during this D2D communication.

[0006] D2D communication has evolved into Vehicle-to-Everything (V2X) communication in the Long Term Evolution (LTE) secondary link standard. V2X communication technology covers communication involving vehicles as either the source or destination of messages. In the New Radio (NR) communication system, a transport (Tx) UE can send secondary link transmissions to a specific receive (Rx) UE in unicast mode, to a group of Rx UEs in multicast mode, or to a range of Rx UEs in broadcast mode.

[0007] The UE can operate on both licensed and unlicensed spectrum. For transmissions on unlicensed spectrum, to achieve fair coexistence with other radio systems, the UE is required to perform a channel access procedure, also known as the "Listen-Before-Tell" (LBT) procedure, before transmitting on the unlicensed spectrum. In the LBT procedure, the UE performs an energy detection on a given channel. If the detected energy is below a predefined threshold, the channel is considered empty and available for transmission, and the LBT procedure succeeds. Only when the LBT procedure succeeds can the UE begin transmitting on that channel and occupy it for up to the maximum channel occupancy time (MCOT); otherwise, the UE cannot begin transmitting and continues executing another LBT procedure until the LBT procedure succeeds. Secondary link transmissions can also be performed on unlicensed spectrum. Summary of the Invention

[0008] According to embodiments of this disclosure, a method for wireless communication may include: executing a first type 1 channel access procedure for a secondary link transmission on a carrier, starting from a first candidate start symbol within a first time slot, wherein the first candidate start symbol is in a set of candidate start symbols for the secondary link transmission; determining a channel occupancy time (COT) in response to the success of the first type 1 channel access procedure; and executing the secondary link transmission on the carrier, starting from the first candidate start symbol within the first time slot, within the COT, wherein the secondary link transmission is continuous in the time domain without any gaps.

[0009] According to another embodiment of this disclosure, a method for wireless communication may include: detecting a secondary link transmission on a carrier starting from a first candidate start symbol in a first time slot, wherein the first candidate start symbol is in a set of candidate start symbols for the secondary link transmission; and receiving the secondary link transmission from the first candidate start symbol within the first time slot in response to the detection of the secondary link transmission on the carrier starting from the first candidate start symbol, wherein the secondary link transmission is continuous in the time domain without any gaps.

[0010] According to another embodiment of this disclosure, an apparatus may include: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuitry; a transmitting circuitry; and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry, and the transmitting circuitry. The computer-executable instructions may cause the processor to perform the method described according to any embodiment of this disclosure.

[0011] Details of one or more examples are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the description and drawings and from the claims. Attached Figure Description

[0012] In order to describe the advantages and features of this disclosure, the description of the disclosure is presented with reference to specific embodiments of the disclosure illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the disclosure and are therefore not intended to limit the scope of the disclosure.

[0013] Figure 1 This application illustrates a schematic diagram of a wireless communication system according to some embodiments of the present application.

[0014] Figure 2 (a) to 2(d) illustrate a set of instanced candidate start positions within a time slot for sub-link transmission according to some embodiments of the present disclosure;

[0015] Figure 3 A flowchart illustrating a method for secondary link transmission according to an embodiment of the present disclosure;

[0016] Figure 4 (a) through 4(f) illustrate a set of instanced candidate end positions within a time slot for sub-link transmission according to some embodiments of the present disclosure;

[0017] Figure 5 A flowchart illustrating a method for secondary link transmission according to an embodiment of the present disclosure;

[0018] Figure 6 Explaining exemplary block diagrams of a device according to embodiments of the present disclosure; and

[0019] Figure 7 An exemplary block diagram illustrating a device according to another embodiment of the present disclosure. Detailed Implementation

[0020] The detailed description of the accompanying drawings is intended to describe the currently preferred embodiments of this disclosure and is not intended to represent the only form in which this disclosure may be implemented. It should be understood that the same or equivalent functionality may be achieved through different embodiments intended to be covered within the spirit and scope of this disclosure.

[0021] Reference will now be made in detail to some embodiments of this disclosure, with examples of the disclosure illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided for specific network architectures and new service scenarios, such as 3GPP (3rd Generation Partnership Project) 5G, 3GPP LTE Release 8, etc. Those skilled in the art will readily recognize that the embodiments in this disclosure are also applicable to similar technical problems as network architectures and new service scenarios evolve.

[0022] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of this application.

[0023] like Figure 1As shown, the wireless communication system 100 may include a base station (e.g., BS 120) and several UEs 110 (e.g., UE 110a, UE 110b, and UE 110c). Although in Figure 1 The diagram depicts a specific number of UEs 110 and one BS 120, but it is considered that the wireless communication system 100 may also include more BSs and more or fewer UEs within and outside the coverage area of ​​the BSs.

[0024] The UE and base station may support communication based on, for example, 3G, Long Term Evolution (LTE), LTE-Advanced (LTE-A), New Radio (NR), or (some) other suitable protocols. For example, BS 120 may include an eNB or gNB. UE 110a, UE 110b, or UE 110c may include, for example, but not limited to, computing devices, wearable devices, mobile devices, IoT (Internet of Things) devices, vehicles, etc. Those skilled in the art will understand that the terminology described in this disclosure may change as technology develops and advances, but this should not affect or limit the principles and spirit of this disclosure.

[0025] BS 120 may define one or more cells, and each cell may have a coverage area 130. In the exemplary wireless communication system 100, some UEs (e.g., UE 110a and UE 110b) are within the coverage area of ​​BS 120, which may not be... Figure 1 The specific base station 120 shown may be any of the base stations 120 in a wireless communication system, and some UEs (e.g., UE 110c) may be outside the coverage area of ​​the base station 120. For example, in the case where the wireless communication system includes two base stations, UE 110a being within the coverage area of ​​either of the two base stations 120 means that UE 110a is within the coverage area of ​​the base station 120 in the wireless communication system (i.e., within the coverage area); and UE 110a being outside the coverage area of ​​either base station 120 means that UE 110a is outside the coverage area of ​​the base station 120 in the wireless communication system (i.e., outside the coverage area).

[0026] Still referencing Figure 1 UE 110a and UE 110b can be connected via, for example, a Uu link (from... Figure 1 (Indicated by the dashed arrow in the diagram) communicates with BS120. UE 110a, UE 110b, and UE 110c can communicate via a secondary link (from...). Figure 1 The solid arrows in the diagram indicate that UEs communicate with each other and can form UE groups. During secondary link communication, the transmitting UE (hereinafter referred to as "Tx UE") can transmit signaling, data, or both to the receiving UE (hereinafter referred to as "Rx UE"). For example, see Reference Figure 1A Tx UE (e.g., UE 110a) can transmit data to an Rx UE (e.g., UE 110b or UE 110c).

[0027] BS (for example, Figure 1 BS 120) and UE (e.g., Figure 1 UEs 110a, 110b, and 110c can operate in both licensed and unlicensed spectrum. For example, unlicensed spectrum may be located near carrier frequencies of 6 GHz or 60 GHz. NR-U (NR System Access on Unlicensed Spectrum) operating bandwidth can be an integer multiple of 20 MHz. To achieve fair coexistence between NR systems (e.g., NR-U systems) and other radio systems, a channel access procedure, also known as a Listen-Before-Speak (LBT) test, can be performed in 20 MHz increments before communication can occur on unlicensed spectrum. For bandwidths greater than 20 MHz, such as 40 MHz, 60 MHz, 80 MHz, or 100 MHz, the carrier bandwidth can be divided into subbands, each with a 20 MHz bandwidth and indexable.

[0028] When unlicensed spectrum is used for secondary link transmissions between UEs (e.g., between a Tx UE and an Rx UE), the Tx UE is required to perform an LBT procedure before performing any secondary link transmissions. The LBT procedure is performed based on energy detection in each sensing slot. Specifically, if the energy detected on a channel in a sensing slot is below an energy detection threshold, the channel is considered empty, idle, or available in that sensing slot; otherwise, the channel is considered occupied or unavailable in that sensing slot. For Type 1 channel access procedures (also known as "LBT Category 4 or LBT Cat.4 procedures"), energy detection typically needs to be performed over a range of several to hundreds of sensing slots. At the start of the LBT Cat.4 procedure, a random backoff counter is selected from the contention window. Whenever the Tx UE detects an empty channel in a sensing slot, the random backoff counter is decremented by 1. When the random backoff counter decrements to zero, the channel is considered available and the LBT Cat.4 procedure is successful. Next, the Tx UE can determine a COT no greater than the MCOT and begin secondary link transmission on the channel within the COT. In the LBT Cat.4 procedure, the contention window is continuously updated based on Hybrid Automatic Repeat Request (HARQ)-Acknowledgement (ACK) feedback from the Rx UE. A more detailed Type 1 channel access procedure is specified in 3GPP standard document TS37.213. Therefore, the timing of the successful LBT Cat.4 procedure is unpredictable, and consequently, the timing of the commencement of secondary link transmission is also unpredictable.

[0029] For simplicity, secondary link transmissions can be limited to always starting from the first symbol of a timeslot, which typically contains 14 symbols, such as symbols 0 through 13. However, this limitation will inevitably lead to wasted resources unless the Tx UE happens to capture the channel from symbol 0 of the timeslot. For example, if the Tx UE captures the channel from symbol 1 of the timeslot (i.e., COT starts from symbol 1 of the timeslot) and waits for transmission to begin from symbol 0 of the next timeslot, then a total of 13 symbols (i.e., symbols 1 through 13 of the timeslot) will be wasted. Therefore, it is beneficial to allow multiple starting positions or symbols for secondary link transmissions.

[0030] On the other hand, MCOT can have different durations (e.g., 4 ms in Japan, and 6 ms, 8 ms, or 10 ms in European countries). Therefore, if the Tx UE does not capture the channel from symbol 0, it may not end its transmission at symbol 13 in the last time slot of the COT. If only the last symbol of the time slot, such as symbol 13, could be the last symbol for secondary link transmission, it would also result in wasted resources in the last time slot, provided that the entire last time slot cannot be occupied due to MCOT limitations. Therefore, allowing multiple end positions or symbols for secondary link transmission can reduce or avoid resource waste.

[0031] Figure 2 (a) to (d) illustrate a set of exemplary candidate start positions within a time slot for secondary link transmission according to some embodiments of this disclosure. Figure 2 In (a) to 2(d), the dark positions in the time slots represent candidate start positions for secondary link transmission. Figure 2 In the first embodiment shown in (a), the candidate starting position set includes symbols 0, 2, 4, 6, 8, 10, and 12. In the following... Figure 2 In the second embodiment shown in (b), the candidate starting position set includes symbols 0, 3, 6, and 9. In such... Figure 2 In the third embodiment shown in (c), the candidate starting position set includes symbols 0, 4, and 8. In such... Figure 2 In the fourth embodiment shown in (d), the candidate start position set includes symbols 0 and 7. It should be understood that other sets containing other combinations of candidate start positions are also applicable. The minimum candidate start position set may contain only one symbol of the time slot, such as symbol 0. The maximum candidate start position set may contain all symbols of a time slot, such as symbols 0, 1, 2, 3, ..., and 13.

[0032] The candidate start location set for secondary link transmission can be configured by the base station (e.g., gNB) or Tx UE via higher-layer signaling (e.g., Radio Resource Control (RRC) signaling). The Tx UE can also signal the candidate start location set to the Rx UE via RRC signaling. Alternatively, the candidate start location set can be pre-configured during implementation or predefined in the standard. Several principles should be considered when selecting candidate start locations for the candidate start location set, including but not limited to: (1) efficient resource utilization; (2) blind detection operation of the Rx UE; and (3) channel variation and LBT success probability between two consecutive candidate start locations. These principles can be considered individually or in any combination. The more candidate start locations the set contains, the more efficient the resource utilization can be, and the more blind detection operation the Rx UE needs to perform.

[0033] Figure 3 A flowchart illustrating a method 300 for secondary link transmission according to an embodiment of the present disclosure is provided. This method can be performed at a Tx UE or other device with similar functionality. Figure 3 As shown in the diagram, in step 302, the candidate start symbol set of the TxUE in the time slot (e.g., Figure 2 Before the first candidate start symbol (e.g., symbol 0) in any of the sets described in (a) to 2(d), a first type 1 channel access procedure (e.g., the first LBT Cat.4 procedure) for sublink transmission on a carrier is executed.

[0034] When the first channel access procedure fails (i.e., the "No" branch of step 304), method 300 may return to step 302, and may, for example, have the Tx UE execute a second type 1 channel access procedure (e.g., a second LBT Cat.4 procedure) for sublink transmission on the carrier before the second candidate start symbol in the candidate start symbol set of the time slot. The second candidate start symbol in the candidate start symbol set may be after the first candidate start symbol, i.e., the second candidate start symbol is later in the time domain than the first candidate start symbol. For example, the second candidate start symbol may be... Figure 2 In the embodiment of (a), symbol 2, Figure 2 In the embodiment of (b), symbol 3, Figure 2 (c) In the embodiment, symbol 4 or Figure 2Symbol 7 in embodiment (d). In embodiments of this disclosure, if the random backoff counter of the first LBT Cat.4 procedure does not decrement to zero at the first candidate start symbol, then the first LBT Cat.4 procedure is considered to have failed and is immediately terminated by the Tx UE. If the second type 1 channel access procedure also fails, then a third type 1 channel access procedure (e.g., a third LBT Cat.4 procedure) for sublink transmission on the carrier may be executed by the Tx UE, for example, before the third candidate start symbol in the candidate start symbol set of the time slot, and so on, until the type 1 channel access procedure for the candidate start symbol of the time slot succeeds. If the type 1 channel access procedure fails for all candidate start symbols of the time slot, then the Tx UE may execute the type 1 channel access procedure for each candidate start symbol of the next time slot in the same manner.

[0035] If the channel access procedure for any candidate start symbol of the time slot is successful (i.e., the "Yes" branch of step 304), then method 300 may proceed to step 306, and the COT may be determined, for example, by the Tx UE in response to the successful channel access procedure. Next, in step 308, within the COT, a secondary link transmission may be performed by the Tx UE on the carrier, starting from the candidate start symbol corresponding to the successful channel access procedure, to the Rx UE. For example, if the first type 1 channel access procedure is successful, then the Tx UE may perform a secondary link transmission on the carrier starting from the first candidate start symbol; and if the second type 1 channel access procedure is successful, then the Tx UE may perform a secondary link transmission on the carrier starting from the second candidate start symbol. In step 310, the Tx UE may receive HARQ-ACK feedback corresponding to the secondary link transmission from the Rx UE, for example.

[0036] According to embodiments of this disclosure, to avoid the risk of losing occupied channels, the Tx UE can perform secondary link transmissions within secondary link transmission bursts without any gaps in the time domain. That is, secondary link transmissions within the COT are continuous in the time domain without any gaps.

[0037] Secondary link transmission may span one or more time slots within the COT. Within each of the one or more time slots, secondary link transmission may include a Physical Secondary Link Control Channel (PSCCH) and an associated Physical Secondary Link Shared Channel (PSSCH), the PSSCH being scheduled by a Secondary Link Control Information (SCI) format carried on the PSCCH. The associated PSSCH may have various multiplexing methods with the PSCCH. The SCI format can be used to indicate the start position of the associated PSSCH to the Rx UE. In embodiments of this disclosure, the SCI format carried on the PSCCH may indicate the index of the start symbol of the associated PSSCH. In another embodiment of this disclosure, the SCI format carried on the PSCCH may indicate the offset between the start symbol of the associated PSSCH and the start symbol of the PSCCH. In yet another embodiment of this disclosure, the SCI format carried on the PSCCH may indicate the offset between the start symbol of the associated PSSCH and the end symbol of the PSCCH. In some other embodiments of this disclosure, the start position of the associated PSSCH within a time slot is default and not explicitly indicated by the SCI format. According to embodiments of this disclosure, the start position of the associated PSSCH is always the same as the start position of the PSCCH; that is, the PSCCH and associated PSSCH begin from the same symbol in the time slot. For example, if a first type 1 channel access procedure is successful for the first candidate start symbol of the time slot, the Tx UE may transmit the PSCCH and its associated PSSCH starting from the first candidate start symbol in the time slot. According to another embodiment of this disclosure, the associated PSSCH may always be transmitted immediately after the end symbol of the PSCCH. According to some other embodiments of this disclosure, the offset between the start symbol of the associated PSSCH and the start or end symbol of the PSCCH may be configured via RRC signaling, for example by the base station (e.g., gNB) or the Tx UE. The Tx UE may also signal the offset to the Rx UE via RRC signaling. Alternatively or additionally, the offset may be preconfigured or predefined in the standard.

[0038] In some embodiments of this disclosure, the SCI format carried on the PSCCH in each time slot can indicate the end position of the associated PSSCH. As discussed above, it is beneficial to allow multiple end positions for secondary link transmission in order to save resources. Therefore, the end position of the associated PSSCH can be selected from a set of candidate end positions for secondary link transmission.

[0039] The candidate end location set for secondary link transmissions can be configured via RRC signaling, for example by a base station (e.g., gNB) or a TxUE. The Tx UE can also signal the candidate end location set to the Rx UE via RRC signaling. Alternatively, the candidate end location set can be pre-configured during implementation or predefined in the standard. Several principles should be considered when selecting candidate end locations for the candidate end location set, including but not limited to: (1) efficient resource utilization; (2) Rx UE decoding complexity; (3) channel changes between two consecutive candidate end locations; (4) reserving a gap in the last time slot of the COT for other UEs to perform LBT procedures; (5) reserving a gap within the COT for the Physical Secondary Link Feedback Channel (PSFCH) corresponding to the secondary link transmission; and (6) reserving a gap before the PSFCH for the Rx UE to decode the secondary link transmission and / or perform LBT procedures for transmitting the PSFCH. These principles can be considered individually or in any combination. The minimum candidate end location set may contain only one symbol of the time slot, such as symbol 13. The maximum candidate end position set can contain all symbols of a time slot, such as symbols 0, 1, 2, 3, ..., and 13. The more candidate end positions the set contains, the more efficient the resource utilization can be, and the more decoding work the Rx UE needs to perform.

[0040] Figure 4 Sections (a) to (f) illustrate a set of exemplary candidate end positions within a time slot for secondary link transmission according to some embodiments of this disclosure. Figure 4 In (a) to 4(f), the dark positions in the time slots represent candidate end positions for secondary link transmission.

[0041] In such Figure 4 In the first embodiment shown in (a), the candidate end position set includes symbols 1, 3, 5, 7, 9, 11, and 13. In the following... Figure 4 In the second embodiment shown in (b), the candidate end position set includes symbols 3, 7, 11, and 13. In such... Figure 4 In the third embodiment shown in (c), the candidate end position set includes symbols 4, 8, and 13. Figure 4 In the fourth embodiment shown in (d), the candidate end position set includes symbols 6 and 13. Figure 4 The embodiments described in (a) to 4(d) consider providing multiple candidate end positions when selecting a group of candidate end positions to achieve more efficient channel utilization.

[0042] Figure 4(e) This describes an embodiment of the present disclosure for providing multiple candidate end positions to allow for gaps to be suitable for other UEs to execute a Type 2 channel access procedure, also known as an "LBT Cat.2 procedure," which is an LBT procedure different from the Type 1 channel access procedure. The Type 2 channel access procedure requires one energy detection within a sensing interval of at least 16 μs or 25 μs. Therefore, the random backoff counter generation and decrementing procedure is absent in the Type 2 channel access procedure, which is a major difference compared to the Type 1 channel access procedure. A more detailed procedure for the Type 2 channel access procedure is specified in 3GPP standard document TS37.213. Figure 4 As shown in (e), the candidate end position set in a time slot may include symbols 12 and 13. If a Tx UE needs to reserve a symbol for other UEs to compete for the channel starting from the next time slot, then the SCI format carried on the PSCCH in the time slot may indicate that symbol 12 is the end symbol of the associated PSSCH in the time slot, so that other UEs can execute the LBT procedure in symbol 13; otherwise, the SCI format carried on the PSCCH in the time slot may indicate that symbol 13 is the end symbol of the associated PSSCH in the time slot.

[0043] exist Figure 4 In the embodiment shown in (e), a gap containing only one symbol (e.g., symbol 13) may be reserved for other UEs to perform LBT procedures. It should be understood that different candidate end positions may be included in the candidate end position set to accommodate different gap durations required for performing LBT procedures. The required gap duration depends on the subcarrier spacing value. Therefore, the candidate end position set also depends on the subcarrier spacing value. For example, in the case of a 15 kHz subcarrier spacing and a 30 kHz subcarrier spacing, a gap of at least one symbol is required, so the candidate end position set may include symbols 12 and 13. In the case of a 60 kHz subcarrier spacing, a gap of at least two symbols is required, so the candidate end position set may include symbols 11 and 13. In the case of a 120 kHz subcarrier spacing, a gap of at least three or four symbols is required, so the candidate end position set may include symbols 9, 10, and 13; or include symbols 9 and 13.

[0044] Figure 4 (f) An embodiment of the present disclosure is provided for providing multiple candidate end positions such that a first gap is suitable for other UEs to perform a type 2 channel access procedure (e.g., LBT Cat.2 procedure), a second gap is suitable for Rx UEs to transmit PSFCH, and a third gap is suitable for Rx UEs to perform a type 2 channel access procedure for transmitting PSFCH.

[0045] After receiving a secondary link transmission from the Tx UE, the Rx UE can transmit a HARQ-ACK feedback corresponding to the secondary link transmission to the Tx UE on the PSFCH. To transmit the PSFCH on unlicensed spectrum, the Rx UE also needs to perform an LBT procedure before transmitting the PSFCH. As discussed above, the LBT Cat.4 procedure can lead to unpredictable sensing times. If the LBT Cat.4 procedure for transmitting the PSFCH fails or succeeds under prolonged sensing, the PSFCH can be discarded. According to embodiments of this disclosure, the Tx UE reserves resources for the PSFCH within a COT initiated by the Tx UE, allowing the Rx UE to perform a shorter LBT Cat.2 procedure than the LBT Cat.4 procedure before transmitting the PSFCH on the reserved resources, and resulting in a higher probability of successful channel access. To perform the LBT Cat.2 procedure, the Tx UE can reserve an LBT gap before the resources reserved for the PSFCH.

[0046] like Figure 4 As shown in (f), the candidate end position set in a time slot may include symbols 9, 12, and 13. If the Tx UE needs to reserve both the PSFCH resource and one symbol in the time slot for other UEs to compete for the channel starting from the next time slot, then the SCI format carried on the PSCCH in the time slot may indicate that symbol 9 is the end symbol of the associated PSSCH in the time slot, so that four symbols are reserved and not used to transmit the associated PSSCH. These four symbols may be reserved as the first gap of a symbol at the end of the time slot (e.g., symbol 13) for other UEs to perform LBT procedures, such as... Figure 4 As shown in (e), a second gap of two symbols (e.g., symbols 11 and 12) is reserved for the Rx UE to transmit the PSFCH, and a third gap of one symbol (e.g., symbol 10) is reserved between the end symbol of the PSSCH (e.g., symbol 9) and the start symbol of the PSFCH (e.g., symbol 11) for the Rx UE to perform LBT procedures. If a Tx UE needs to reserve only one symbol for other UEs to compete for the channel from the next time slot, the SCI format carried on the PSCCH in the time slot can indicate that symbol 12 indicates the end symbol of the associated PSSCH in the time slot, so that other UEs can perform LBT procedures in symbol 13. If a Tx UE does not need to reserve PSFCH resources or LBT gaps in the time slot, the SCI format carried on the PSCCH in the time slot can indicate that symbol 13 is the end symbol of the associated PSSCH in the time slot.

[0047] exist Figure 4In the embodiment shown in (f), a gap containing only one symbol (e.g., symbol 10 or symbol 13) may be reserved for the Rx UE or other UE to perform LBT procedures (e.g., LBT Cat.2 procedures). It should be understood that different candidate end positions may be included in the candidate end position set to accommodate different gap durations required for performing the LBT procedure. The required gap duration depends on the subcarrier spacing value. Therefore, the candidate end position set also depends on the subcarrier spacing value. For example, in the case of a 15 kHz subcarrier spacing and a 30 kHz subcarrier spacing, a gap of at least one symbol is required, so the candidate end position set may include symbols 9, 12, and 13. In the case of a 60 kHz subcarrier spacing, a gap of at least two symbols is required, so the candidate end position set may include symbols 7, 11, and 13. In the case of a 120 kHz subcarrier spacing, a gap of at least four symbols is required, so the candidate end position set may include symbols 3, 9, and 13.

[0048] exist Figure 4 In the embodiment shown in (f), a gap containing two symbols (e.g., symbols 11 and 12) may be reserved for the Rx UE to transmit the PSFCH. It should be understood that different candidate end positions may be included in the candidate end position set to accommodate PSFCHs with different numbers of symbols.

[0049] Any of the first, second, and third gaps described above can be made by culling (i.e., data mapped onto each symbol in the gap when not being transmitted) or rate matching (i.e., data not mapped onto each symbol in the gap during the resource mapping procedure).

[0050] Provided for illustrative purposes Figure 4 The embodiments shown in (a) through 4(f). Those skilled in the art will understand that other sets including other combinations of candidate end positions are also applicable.

[0051] According to some embodiments of this disclosure, the first N consecutive symbols in the first time slot of the sublink transmission can be used as automatic gain control (AGC) symbols, and the other time slots of the sublink transmission do not contain any AGC symbols. For example, in the first time slot, the first N consecutive symbols are a one-to-one repetition of the next N consecutive symbols. Alternatively, in the first time slot, each of the first N consecutive symbols is a repetition of the (N+1)th symbol. The number N of AGC symbols depends on the subcarrier spacing value. For example, in the case of a 15 kHz subcarrier spacing and a 30 kHz subcarrier spacing, at least one symbol is required to achieve the AGC purpose. In the case of a 60 kHz subcarrier spacing, at least two symbols are required to achieve the AGC purpose. In the case of a 120 kHz subcarrier spacing, at least four symbols are required to achieve the AGC purpose.

[0052] Figure 5 A flowchart illustrating a method 500 for secondary link transmission according to an embodiment of this disclosure is provided. For simplicity, method 500 is described below with respect to an Rx UE. It should be understood that method 500 may be performed by other devices having similar functionality.

[0053] like Figure 5 As shown, in step 502, the Rx UE may perform a blind detection procedure to detect secondary link transmissions on a carrier, starting from the first candidate start symbol (e.g., symbol 0) of the time slot, wherein the first candidate start symbol is in the set of candidate start symbols used for secondary link transmissions (e.g., ...). Figure 2 The candidate start location set (as described in any of (a) to (d)) is used. For example, the Rx UE can detect the presence of an SCI format from a first candidate start symbol. The candidate start location set for secondary link transmission can be configured via RRC signaling, for example by the base station (e.g., gNB) or the Tx UE. The Tx UE can also signal the candidate start location set to the Rx UE via RRC signaling. Alternatively or concurrently, the candidate start location set can be preconfigured during implementation or predefined in the standard.

[0054] If a secondary link transmission starting from the first candidate start symbol of the time slot is not detected (i.e., the "No" branch of step 504), for example, if the SCI format is not detected from the first candidate start symbol, then method 500 may return to step 502, and the RxUE may detect secondary link transmissions on the carrier starting from the second candidate start symbol in the candidate start symbol set of the time slot. The second candidate start symbol in the candidate start symbol set may follow the first candidate start symbol. For example, the second candidate start symbol may be... Figure 2 In the embodiment of (a), symbol 2, Figure 2 In the embodiment of (b), symbol 3, Figure 2 (c) In the embodiment, symbol 4 or Figure 2 Symbol 7 in embodiment (d). If a secondary link transmission starting from the second candidate start symbol is still not detected, then the Rx UE may start detecting the secondary link transmission from the third candidate start symbol in the candidate start symbol set of the time slot, and so on, until a secondary link transmission is detected from the candidate start symbol of the time slot. If the Rx UE fails to detect the secondary link transmission from any candidate start symbol of the time slot, then the Rx UE may start detecting the secondary link transmission from each candidate start symbol of the next time slot in the same manner.

[0055] If a secondary link transmission starting from a candidate start symbol of a time slot is detected (i.e., the "Yes" branch of step 504), for example, if an SCI format is detected from a candidate start symbol, then method 500 may proceed to step 506, and the Rx UE may receive the secondary link transmission from the candidate start symbol. For example, if a secondary link transmission starting from a first candidate start symbol is detected, then the Rx UE may receive the secondary link transmission on the carrier from the first candidate start symbol; if a secondary link transmission starting from a second candidate start symbol is detected, then the Rx UE may receive the secondary link transmission on the carrier from the second candidate start symbol. According to embodiments of this disclosure, the secondary link transmission is continuous in the time domain without any gaps.

[0056] Secondary link transmissions may span one or more time slots. Within each of these time slots, the secondary link transmission may include a PSCCH and an associated PSSCH, the PSSCH being scheduled by an SCI format carried on the PSCCH. The associated PSSCH may have various multiplexing methods with the PSCCH. The SCI format may indicate the start position of the associated PSSCH to the Rx UE, and the Rx UE can determine the start position of the associated PSSCH by decoding the SCI format. In embodiments of this disclosure, the SCI format carried on the PSCCH may indicate the index of the start symbol of the associated PSSCH. In another embodiment of this disclosure, the SCI format carried on the PSCCH may indicate the offset between the start symbol of the associated PSSCH and the start symbol of the PSCCH. In yet another embodiment of this disclosure, the SCI format carried on the PSCCH may indicate the offset between the start symbol of the associated PSSCH and the end symbol of the PSCCH. In some other embodiments of this disclosure, the start position of the associated PSSCH in a time slot is default and not explicitly indicated by the SCI format. According to embodiments of this disclosure, the start position of the associated PSSCH is always the same as the start position of the PSCCH; that is, the PSCCH and associated PSSCH start from the same symbol in the time slot. For example, in the case where a secondary link transmission starting from the first candidate start symbol is detected, the Rx UE can receive the PSCCH and its associated PSSCH from the first candidate start symbol in the time slot. According to another embodiment of this disclosure, the associated PSSCH can always be transmitted immediately after the end symbol of the PSCCH. According to some other embodiments of this disclosure, the offset between the start symbol of the associated PSSCH and the start or end symbol of the PSCCH can be configured via RRC signaling, for example by the base station (e.g., gNB) or the Tx UE. The Tx UE can also signal the offset to the Rx UE via RRC signaling. Alternatively or additionally, the offset can be preconfigured or predefined in the standard.

[0057] In some embodiments of this disclosure, the SCI format carried on the PSCCH in each time slot can indicate the end position of the associated PSSCH, and the Rx UE can determine the end position of the associated PSSCH by decoding the SCI format. The end position of the associated PSSCH is in a set of candidate end positions used for secondary link transmission (e.g., Figure 4 The candidate end location set for secondary link transmission can be configured via RRC signaling, for example by the base station (e.g., gNB) or the Tx UE. The Tx UE can also signal the candidate end location set to the Rx UE via RRC signaling. Alternatively, the candidate end location set can be preconfigured during implementation or predefined in the standard.

[0058] Return to reference Figure 5 After receiving the secondary link transmission, the Rx UE can determine, in step 508, the resources for the HARQ-ACK feedback corresponding to the secondary link transmission. The HARQ-ACK feedback is to be transmitted to the Tx UE on the PSFCH. According to embodiments of this disclosure, resources for HARQ-ACK feedback are reserved within the COT initiated by the Tx UE. For example, symbols 11 and 12 in the last slot of the COT can be reserved for the Rx UE to transmit the PSFCH, as referenced above. Figure 4 (f) As discussed. It should be understood that within a COT initiated by a TxUE, PSFCH resources may be reserved in other symbols or other time slots.

[0059] In step 510, the Rx UE may perform a channel access procedure within the gap between the end symbol of the secondary link transmission and the start symbol of the resource determined in step 508 for the HARQ-ACK feedback corresponding to the secondary link transmission. Where resources are reserved within the COT initiated by the Tx UE, the Rx UE may perform an LBT Cat.2 procedure within the gap, which requires a shorter sensing time and a higher probability of successful channel access compared to the LBT Cat.4 procedure. The number of symbols within the gap depends on the subcarrier spacing value of the carrier. For example, with a 15 kHz subcarrier spacing and a 30 kHz subcarrier spacing, a gap of at least one symbol is required. With a 60 kHz subcarrier spacing, a gap of at least two symbols is required. With a 120 kHz subcarrier spacing, a gap of at least three or four symbols is required. A gap may be reserved within the COT initiated by the Tx UE for the Rx UE to perform the LBT Cat.2 procedure, for example, as referenced above. Figure 4 (f) discusses this.

[0060] In response to a successful channel access procedure, in step 512, the Rx UE may transmit a HARQ-ACK feedback corresponding to the secondary link transmission on the resource determined in step 508.

[0061] Figure 6 This illustration shows an exemplary block diagram of a device 600 according to embodiments of the present disclosure. In some embodiments of the present disclosure, the device 600 may be a Tx UE or other device with similar functionality, which may at least perform... Figure 3 The method described in the document.

[0062] like Figure 6 As shown, device 600 may include at least one receiving circuitry system 602, at least one transmitting circuitry system 604, at least one non-transitory computer-readable medium 606, and at least one processor 608 coupled to at least one receiving circuitry system 602, at least one transmitting circuitry system 604, and at least one non-transitory computer-readable medium 606.

[0063] Despite Figure 6 In this disclosure, elements such as receiving circuitry system 602, transmitting circuitry system 604, non-transitory computer-readable medium 606, and processor 608 are described in the singular, but plural forms are contemplated unless explicitly stated otherwise. In some embodiments of this disclosure, at least one receiving circuitry system 602 and at least one transmitting circuitry system 604 are combined into a single device, such as a transceiver. In some embodiments of this disclosure, device 600 may further include input devices, memory, and / or other components.

[0064] In some embodiments of this disclosure, at least one non-transitory computer-readable medium 606 may store computer-executable instructions thereon, said instructions being programmed to cause at least one processor 608 to perform, for example, actions using at least one receiving circuitry system 602 and at least one transmitting circuitry system 604. Figure 3 The steps of the method described in the view. For example, when executed, the instructions may cause at least one processor 608 to execute a Type 1 channel access procedure for sublink transmission on a carrier, starting from a first candidate start symbol within a time slot, and to determine the COT in response to a successful Type 1 channel access procedure. The instructions may further cause at least one processor 608 to utilize at least one transmission circuitry system 604 to execute sublink transmission on a carrier, starting from the first candidate start symbol. The instructions may further cause at least one processor 608 to utilize at least one receiver circuitry system 602 to receive HARQ-ACK feedback corresponding to the sublink transmission.

[0065] Figure 7This illustration shows an exemplary block diagram of a device 700 according to another embodiment of the present disclosure. In some embodiments of the present disclosure, the device 700 may be an Rx UE or other device with similar functionality, which may at least perform Figure 5 The method described in the document.

[0066] like Figure 7 As shown, the device 700 may include at least one receiving circuit system 702, at least one transmitting circuit system 704, at least one non-transitory computer-readable medium 706, and at least one processor 708 coupled to at least one receiving circuit system 702, at least one transmitting circuit system 704, and at least one non-transitory computer-readable medium 706.

[0067] Despite Figure 7 In this disclosure, elements such as receiving circuitry system 702, transmitting circuitry system 704, non-transitory computer-readable medium 706, and processor 708 are described in the singular, but plural forms are contemplated unless explicitly stated otherwise. In some embodiments of this disclosure, at least one receiving circuitry system 702 and at least one transmitting circuitry system 704 are combined into a single device, such as a transceiver. In some embodiments of this disclosure, device 700 may further include input devices, memory, and / or other components.

[0068] In some embodiments of this disclosure, at least one non-transitory computer-readable medium 706 may store computer-executable instructions thereon, said instructions being programmed to cause at least one processor 708 to perform, for example, actions using at least one receiving circuitry system 702 and at least one transmitting circuitry system 704. Figure 5 The steps of the method described in the view are as follows. For example, when executed, the instructions may cause at least one processor 708 to detect a sublink transmission on a carrier starting from a first candidate start symbol of a time slot. In response to the detection of a sublink transmission on the carrier starting from the first candidate start symbol, the instructions may cause at least one processor 708 to receive the sublink transmission from the first candidate start symbol using at least one receiver circuitry system 702. The instructions may further cause at least one processor 708 to determine a resource reserved for HARQ-ACK feedback for the sublink transmission, and to execute a Type 2 channel access procedure during the gap between the end symbol of the sublink transmission and the start symbol of the resource. The instructions may further cause at least one processor 708 to transmit HARQ-ACK feedback using at least one transmitter circuitry system 704 in response to a successful Type 2 channel access procedure.

[0069] Those skilled in the art will understand that the steps of the methods described in conjunction with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module 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. Additionally, in some aspects, the steps of the method may reside as one or any combination or set of code and / or instructions on a non-transitory computer-readable medium that may be incorporated into a computer program product.

[0070] Although this disclosure has been described using specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations will be readily apparent. For example, various components of the described embodiments may be interchanged, added, or substituted in other embodiments. Moreover, not all elements of each figure are essential to the operation of the disclosed embodiments. For example, those of ordinary skill in the art will be able to make and use the teachings of this disclosure by simply employing the elements of the independent claims. Therefore, the embodiments of this disclosure as set forth herein are intended to be illustrative and not restrictive. Various changes may be made without departing from the spirit and scope of this disclosure.

[0071] In this document, the term "includes" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to the process, method, article, or apparatus. Unless otherwise specified, an element beginning with "a," "an," etc., does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the term "another" is defined as at least a second or more. As used herein, the terms "having," etc., are defined as "includes."

Claims

1. A method for wireless communication, comprising: A first type 1 channel access procedure is executed for sublink transmission on a carrier starting from a first candidate start symbol in a first time slot, wherein the first candidate start symbol is in a set of candidate start symbols for the sublink transmission; The Channel Occupancy Time (COT) is determined in response to the successful completion of the first type 1 channel access procedure. Within the COT, the sublink transmission on the carrier is executed starting from the first candidate start symbol within the first time slot, wherein the sublink transmission is continuous in the time domain without gaps. Within the COT, resources are reserved for Hybrid Automatic Repeat Request (HARQ) - Acknowledgement (ACK) feedback corresponding to the secondary link transmission; The gap between the end symbol of the secondary link transmission and the start symbol of the resource is preserved; and The HARQ-ACK feedback is received within the reserved gap.

2. The method according to claim 1, wherein the secondary link transmission in the first time slot includes a first physical secondary link control channel (PSCCH) and a first physical secondary link shared channel (PSSCH) transmitted from the first candidate start symbol, and the first PSSCH is scheduled by the first secondary link control information (SCI) format carried on the first PSCCH.

3. The method according to claim 1, further comprising: In response to a failure of the first type 1 channel access procedure for the secondary link transmission starting from the first candidate start symbol, a second type 1 channel access procedure for the secondary link transmission starting from the second candidate start symbol within the candidate start symbol set is executed; and In response to the successful completion of the second type 1 channel access procedure, the sublink transmission on the carrier is executed starting from the second candidate start symbol.

4. The method of claim 3, wherein the second candidate start symbol follows the first candidate start symbol.

5. An apparatus comprising: Receiver circuit: Transmitter circuit; as well as A processor, coupled to the receiver circuitry and the transmitter circuitry, is configured to cause the device to perform the following operations: A first type 1 channel access procedure is executed for sublink transmission on a carrier starting from a first candidate start symbol in a first time slot, wherein the first candidate start symbol is in a set of candidate start symbols for the sublink transmission; The Channel Occupancy Time (COT) is determined in response to the successful completion of the first type 1 channel access procedure. Within the COT, the sublink transmission on the carrier is executed starting from the first candidate start symbol within the first time slot, wherein the sublink transmission is continuous in the time domain without gaps. Within the COT, resources are reserved for Hybrid Automatic Repeat Request (HARQ) - Acknowledgement (ACK) feedback corresponding to the secondary link transmission; The gap between the end symbol of the secondary link transmission and the start symbol of the resource is preserved; and The HARQ-ACK feedback is received within the reserved gap.

6. The device according to claim 5, wherein the secondary link transmission in the first time slot includes a first physical secondary link control channel PSCCH and a first physical secondary link shared channel PSSCH transmitted from the first candidate start symbol, and the first PSSCH is scheduled by the first secondary link control information SCI format carried on the first PSCCH.

7. The device of claim 6, wherein the first SCI format indicates one or more of the following: The index of the start symbol of the first PSSCH; The offset between the start symbol of the first PSSCH and the start symbol of the first PSCCH; or The offset between the start symbol of the first PSSCH and the end symbol of the first PSCCH.

8. The device of claim 6, comprising one or more of the following: The first PSSCH is transmitted from the first candidate start symbol; or The first PSSCH is transmitted after the end symbol of the first PSCCH.

9. The device of claim 6, comprising one or more of the following: The offset between the start symbol of the first PSSCH and the start symbol of the first PSCCH is obtained through one or more of the following methods: configured, pre-configured, or pre-defined via Radio Resource Control (RRC) signaling; or The offset between the start symbol of the first PSSCH and the end symbol of the first PSCCH is obtained by one or more of the following methods: via Radio Resource Control (RRC) signaling configuration, preconfiguration, or predefinition.

10. The device of claim 5, wherein the processor is further configured to cause the device to perform the following operations: In response to a failure of the first type 1 channel access procedure for the secondary link transmission starting from the first candidate start symbol, a second type 1 channel access procedure for the secondary link transmission starting from the second candidate start symbol within the candidate start symbol set is executed; and In response to the successful completion of the second type 1 channel access procedure, the sublink transmission on the carrier is executed starting from the second candidate start symbol.

11. The device of claim 5, wherein the processor is further configured such that the device uses the gap to execute a Type 2 channel access procedure for the transmission of the HARQ-ACK feedback.

12. The device of claim 11, wherein the number of symbols within the gap is at least partially based on the subcarrier spacing value of the carrier.

13. The device of claim 10, wherein the second candidate start symbol follows the first candidate start symbol.

14. An apparatus comprising: Receiver circuit: Transmitter circuit; as well as A processor, coupled to the receiver circuitry and the transmitter circuitry, is configured to cause the device to perform the following operations: The detection of sublink transmission on a carrier begins from the first candidate start symbol in the first time slot, wherein the first candidate start symbol is in the set of candidate start symbols for the sublink transmission; In response to the detection of a secondary link transmission on the carrier starting from the first candidate start symbol, the secondary link transmission is received starting from the first candidate start symbol within the first time slot, wherein the secondary link transmission is continuous in the time domain without gaps. In response to the fact that the secondary link transmission on the carrier starting from the first candidate start symbol is not detected, the secondary link transmission on the carrier is detected starting from the second candidate start symbol in the first time slot; and In response to the detection of a secondary link transmission on the carrier starting from the second candidate start symbol, the secondary link transmission is received starting from the second candidate start symbol within the first time slot, wherein the secondary link transmission is continuous in the time domain without gaps.

15. The apparatus of claim 14, wherein the secondary link transmission within the first time slot includes a first physical secondary link control channel (PSCCH) and a first physical secondary link shared channel (PSSCH) transmitted from the first candidate start symbol, and the first PSSCH is scheduled by a first secondary link control information (SCI) format carried on the first PSCCH.

16. The device of claim 15, wherein the first SCI format indicates one or more of the following: The index of the start symbol of the first PSSCH; The offset between the start symbol of the first PSSCH and the start symbol of the first PSCCH; or The offset between the start symbol of the first PSSCH and the end symbol of the first PSCCH.

17. The device of claim 15, comprising one or more of the following: The offset between the start symbol of the first PSSCH and the start symbol of the first PSCCH is obtained through one or more of the following methods: configured, pre-configured, or pre-defined via Radio Resource Control (RRC) signaling; or The offset between the start symbol of the first PSSCH and the end symbol of the first PSCCH is obtained by one or more of the following methods: via Radio Resource Control (RRC) signaling configuration, preconfiguration, or predefinition.

18. The device of claim 14, wherein in the set of candidate start symbols, the second candidate start symbol follows the first candidate start symbol.

19. The device of claim 14, wherein the processor is further configured to cause the device to perform the following operations: The resources are determined to be reserved for the Hybrid Automatic Repeat Request (HARQ) - Acknowledgement (ACK) feedback corresponding to the transmission on the secondary link. Execute a type 2 channel access procedure during the gap between the end symbol of the secondary link transmission and the start symbol of the resource; and The HARQ-ACK feedback is transmitted in response to the successful completion of the Type 2 channel access procedure.

20. The device of claim 19, wherein the number of symbols within the gap is at least partially based on the subcarrier spacing value of the carrier.

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