Method and node for transmission over unlicensed bands

Abstract

The embodiments relate to sharing of channel occupation time for sidelink transmissions on unlicensed bands. A method is proposed, performed by a first node, comprising: starting a first transmission within an occupied channel occupation time (COT) over the unlicensed band; and transmitting information about the COT to at least one second node to enable the at least one second node to start a second transmission within the COT over the unlicensed band, where at least one of the first transmission or the second transmission is a sidelink transmission. In the embodiments, the frequency of LBT operations may be reduced, and latency may be reduced due to the reduced LBT operations. As multiple UEs are allowed to share the channel, channel utilization may be improved and QoS (Quality of Service) service satisfaction may also be improved.

Description

[Technical Field]

[0001] FIELD Embodiments herein relate generally to the field of wireless communications, and more particularly, embodiments herein relate to methods and nodes for transmitting over unlicensed bands. [Background technology]

[0002] Next-generation communication systems are expected to support a wide range of use cases with different requirements, ranging from fully mobile devices to fixed Internet of Things (IoT) or fixed wireless broadband devices. In many use cases, traffic patterns are expected to include short and long bursts of data traffic with varying lengths of waiting time (also known as inactivity). According to an upcoming 3rd Generation Partnership Project (3GPP®) release, sidelink transmission over unlicensed spectrum is an emerging technology that is attracting strong interest from enterprises.

[0003] To support sidelink transmissions over unlicensed spectrum, a sidelink-capable user equipment (UE) may need to perform clear channel assessment (CCA). This procedure typically involves detecting that a medium, such as an air interface, is idle for several time intervals. If the channel is determined to be occupied, the transmitter performs a random backoff within a contention window before the next CCA attempt. As a CCA technique, listen-before-talk (LBT) is designed for unlicensed spectrum coexistence with other radio access technologies (RATs). However, LBT operation introduces transmission latency for sidelink transmissions over unlicensed spectrum. Summary of the Invention

[0004] Considering the above problems, embodiments herein provide a method for sharing channel occupancy time for sidelink transmissions on unlicensed bands. Ta The present invention proposes a method, a node, a computer-readable medium, and a computer program product for the above-described method.

[0005] According to some embodiments, a method is proposed that is performed by a first node (e.g., a sidelink-capable UE or a gNB). According to one embodiment, the method may comprise initiating a first transmission over an unlicensed band within an occupied channel occupation time (COT). Furthermore, the method further comprises transmitting information regarding the COT to at least one second node to enable the at least one second node to initiate a second transmission over the unlicensed band within the COT. Here, at least one of the first transmission or the second transmission may be a sidelink transmission.

[0006] According to one embodiment, the first node may be a first UE or a NodeB (such as a gNB), the first transmission may be a sidelink transmission, the at least one second node may include a second UE or may be a NodeB, and the second transmission may be a Uu transmission.

[0007] According to one embodiment, the first node may be a first UE, the first transmission may be a Uu transmission, the at least one second node may include a second UE, and the second transmission may be a sidelink transmission.

[0008] According to one embodiment, the first node may be a Node B, the first transmission may be a Uu transmission, the at least one second node may include a second UE, and the second transmission may be a sidelink transmission.

[0009] According to one embodiment, the first node may be a first UE or a NodeB, and the first transmission may be a sidelink transmission for a first-cast type, and the at least one second node may include a second UE, and the second transmission may be a sidelink transmission for a second-cast type. According to one embodiment, the first or second-cast type may be one of unicast, groupcast, or broadcast.

[0010] According to one embodiment, the COT may be occupied by one or more sidelink transmissions using a Scheduling Request (SR) procedure, a two-step Random Access (RA), or a sidelink grant. According to one embodiment, the COT may be occupied after a successful LBT operation. According to one embodiment, the sidelink grant may be one of a dynamic sidelink grant obtained from a resource pool by the first node itself, a configured sidelink grant, or a sidelink grant.

[0011] According to one embodiment, information regarding the COT may be transmitted via a sidelink and / or a Uu link. According to one embodiment, information regarding the COT may be transmitted via Downlink Control Information (DCI)-based signaling, Medium Access Control (MAC) Control Element (CE)-based signaling, Radio Resource Control (RRC) signaling, protocol layer of The information about the COT may be transmitted from the NodeB to the second UE via at least one of control packet data unit (PDU) based signaling. According to another embodiment, the information about the COT may be transmitted from the first UE to the second UE via at least one of RRC signaling over the sidelink, MAC CE over the sidelink, protocol layer PDUs over the sidelink, and Layer 1 (L1) signaling over the sidelink.

[0012] According to one embodiment, the gap between the first and second transmission may be less than 16 μs or between 16 μs and 25 μs.

[0013] According to one embodiment, information for COT sharing between a first node and at least one second node may be obtained directly or indirectly from information related to the COT.

[0014] According to one embodiment, the information regarding the COT may include at least one of the time the COT starts, the time the COT ends, the time at which a channel switch may occur, or the maximum number of channel switch events.

[0015] In one embodiment, the information about the COT may further include at least one of the following: COT occupying UE ID or destination L2 ID gNB ID or cell ID that is allowed to use / share COT UE IDs that are allowed to share / use COT Group ID that is allowed to share / use COT in case of groupcast; Destination L2 IDs that are allowed to share / use the COT SL transmission cast types allowed within COT Indicator of whether COT can be shared with Uu transmissions Index of the service / logical channel / logical channel group / channel access priority class that is allowed to transmit within the COT What types of control signaling / data are allowed to be transmitted within the COT, or A category of LBT operation in which at least a second node is permitted to occupy the COT applied prior to its transmission during the COT.

[0016] According to one embodiment, the information regarding the COT further comprises at least one of the types of sidelink grants that are allowed to be used during the COT or time positions reserved for potential discovery reference signal (DRS) transmissions.

[0017] According to some embodiments, a method is proposed that is performed by a second node (e.g., a sidelink-capable UE or a gNB). According to one embodiment, the method includes receiving information from a first node regarding a COT occupied by the first node for initiating a first transmission over an unlicensed band. Furthermore, the method can further include initiating a second transmission over the unlicensed band within the COT, wherein at least one of the first transmission or the second transmission may be a sidelink transmission.

[0018] According to one embodiment, the method may further include performing an LBT operation according to the COT information before starting the second transmission. According to another embodiment, the method may further include performing an LBT operation according to a gap between the end of the first transmission and the start of the second transmission before starting the second transmission. Here, the second transmission may be started after the LBT operation is successful.

[0019] According to an embodiment, the method may further comprise transmitting information regarding the COT to at least one third node to enable the at least one third node to initiate a third transmission or reception within the COT via the unlicensed band, wherein at least one of the second transmission or the third transmission or reception may be a sidelink transmission or reception.

[0020] According to one embodiment, the method may further comprise increasing the frequency for physical downlink control channel (PDCCH) and / or sidelink control information (SCI) monitoring if a COT is assigned to the second node with COT information. In another embodiment, the method may further comprise reducing the frequency of PDCCH and / or SCI monitoring if a COT is not assigned to the second node with COT information.

[0021] According to one embodiment, the method may further comprise the step of sending an acknowledgement message to the first node to indicate acceptance or denial of participation in the COT sharing.

[0022] According to some embodiments, a node is proposed that may be configured as the first or second node described above. According to one embodiment, the node may further comprise at least one processor and a non-transitory computer-readable medium coupled to the at least one processor. Here, the non-transitory computer-readable medium may include instructions executable by the at least one processor, whereby the at least one processor may be configured to perform any of the above methods associated with the first or second node.

[0023] According to some embodiments, a computer readable medium is proposed comprising computer readable code that, when executed on an apparatus, causes the apparatus to perform any of the above methods relating to a first or second node.

[0024] According to some embodiments, a computer program product is proposed comprising computer readable code that, when executed on an apparatus, causes the apparatus to perform any of the above methods relating to a first or second node.

[0025] According to embodiments herein, the frequency of LBT operations may be minimized, and latency may be reduced due to fewer LBT operations. Thus, by allowing multiple UEs to share a channel, channel utilization may be improved, and QoS (Quality of Service) service satisfaction may also be improved. [Brief explanation of the drawings]

[0026] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate various embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and enable those skilled in the art to make and use the embodiments disclosed herein. In the drawings, like reference numbers indicate identical or functionally similar elements: [Figure 1] FIG. 1 is a schematic diagram illustrating an example of gNB-initiated COT sharing. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of UE-initiated COT sharing. [Figure 3] 1 is a schematic block diagram illustrating a communication system in which embodiments of the present specification can be implemented. [Figure 4] FIG. 1 is a schematic signaling diagram illustrating messages in an exemplary COT sharing for sidelink over unlicensed bands according to embodiments herein. [Figure 5] 1 is a schematic signaling chart illustrating messages in another exemplary COT sharing for sidelink over unlicensed bands, in accordance with embodiments herein. [Figure 6] 1 is a schematic flowchart illustrating an exemplary method in a first node according to embodiments herein. [Figure 7] 1 is a schematic flowchart illustrating an exemplary method in a second node, according to embodiments herein. [Figure 8] 1 is a schematic block diagram illustrating an exemplary first node according to embodiments herein. [Figure 9]1 is a schematic diagram illustrating an exemplary second node according to an embodiment of the present specification. [Figure 10] 1 is a schematic block diagram illustrating an exemplary computer-implemented apparatus, according to embodiments herein. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will now be described in detail with reference to the accompanying drawings illustrating embodiments thereof. However, these embodiments herein may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Elements of the drawings are not necessarily to scale relative to each other.

[0028] A reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment.

[0029] As used herein, the term "node" refers to both a wireless communication node and a base node. For example, a node may be a user equipment or a mobile station in any of the communication standards, such as 2G, 3G, 4G, 5G, or beyond. For example, a node may be a base station, Node B, eNB, or gNB in ​​any of the communication standards, such as 2G, 3G, 4G, 5G, or beyond.

[0030] As used herein, the term "A, B, or C" means "A" or "B" or "C," and as used herein, the term "A, B, and C" means "A" and "B" and "C," and as used herein, the term "A, B, and / or C" means "A," "B," "C," "A and B," "A and C," "B and C," or "A and B and C."

[0031] NR-based access to unlicensed spectrum In New Radio (NR), Licensed Assisted Access Both LBT-based unlicensed and standalone unlicensed operation will be supported by 3GPP. Therefore, procedures for Physical Random Access Channel (PRACH) transmission and / or SR transmission in unlicensed spectrum are being investigated in 3GPP. In the following, unlicensed channel based on LBT will be discussed. Ne NR-U and Cha for Ne A rule access procedure will be introduced.

[0032] Introduction of NR-U To address the ever-increasing demand for data, NR will be supported in both licensed and unlicensed spectrum (i.e., referred to as NR-U). Licensed Assisted Access Compared to (LAA), NR-U supports DC (dual connectivity) and standalone scenarios, and MAC procedures including the random access channel (RACH) and scheduling procedures on unlicensed spectrum are affected by LBT failures, whereas in LTE LAA, there was no such restriction because licensed spectrum exists in LAA scenarios, and therefore RACH and scheduling-related signaling may be transmitted on licensed spectrum instead of unlicensed spectrum.

[0033] DRS transmissions such as Primary Synchronization Signal (PSS) / Secondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH), and channel state information References Signaling (CSI-RS), control channel transmissions such as the Physical Uplink Control Channel (PUCCH) / PDCCH, physical data channels such as the Physical Uplink Shared Channel (PUSCH) / Physical Downlink Shared Channel (PDSCH), and sounding References Uplink sounding, such as signal (SRS) transmission References Signals should undergo channel sensing to determine channel availability before a physical signal is transmitted using the channel.

[0034] Since NR-U aims to reuse LAA / eLAA / feLAA technologies as much as possible to handle coexistence between NR-U and other legacy RATs, radio resource management (RRM) procedures in NR-U are generally quite similar to those in LAA. RRM measurements and reports include special configuration procedures for channel sensing and channel availability.

[0035] Therefore, the cha for LAA Ne Route access / selection has been one of the key aspects for coexistence with other RATs such as Wi-Fi. For example, LAA aims to use carriers that are congested with Wi-Fi.

[0036] In licensed spectrum, the UE receives downlink radio channels (e.g., synchronization signals and PBCH blocks (SSB), CSI-RS) References Signal Received Power (RSRP) and References The eNB / gNB measures the signal reception quality (RSRQ) and provides measurement reports to its serving eNB / gNB. However, they do not reflect the interference strength on the carrier. Another indicator, the received signal strength indicator (RSSI), can serve for such purpose. On the eNB / gNB side, it is possible to derive the RSSI based on the received RSRP and RSRQ reports, but this requires that they must be available. Due to LBT failures, the RSRP or some reports on the RSRP may be blocked ( References Signal transmission (DRS) is blocked in the downlink or measurement report(This may be due to either the UE being blocked in the uplink or the UE being blocked in the uplink). Therefore, measurements from an RSSI perspective are very useful. RSSI measurements, together with time information about when and for how long the UE made the measurement, can help the gNB / eNB to detect hidden nodes. Furthermore, the gNB / eNB can measure the carrier load situation, which can be useful for load balancing and channel selection. Ne It is useful for the network to prioritize some channels for the purposes of network access bottleneck avoidance.

[0037] The LTE LAA is defined to support measurements of average RSSI and channel occupancy for measurement reporting. Channel occupancy is defined as the percentage of time that the RSSI is measured above a configured threshold. For this purpose, the RSSI measurement timing configuration (RMTC) includes the measurement duration (e.g., 1-5 ms) and the period between measurements (e.g., {40, 80, 160, 320, 640} ms).

[0038] COT sharing in NR-U A node (e.g., an NR-U gNB / UE, an LTE-LAA eNB / UE, or a Wi-Fi access point (AP) / station (STA)) typically needs to perform CCA to be allowed to transmit in unlicensed spectrum (e.g., the 5 GHz band). This procedure typically involves sensing that the medium is idle for some time interval. Sensing the medium to be idle can be done in various ways, for example, using energy detection, preamble detection, or virtual carrier sensing, where the latter implies that the node reads control information from other transmitting nodes that indicates when transmission will end. After sensing that the medium is idle, the node is typically allowed to transmit for a certain period of time, sometimes called a transmit opportunity (TXOP). The length of the TXOP depends on the regulation and type of CCA performed, but typically ranges from 1 ms to 10 ms. This duration is often referred to as the COT.

[0039] In Wi-Fi, data acknowledgement (ACK) feedback is sent without performing a clear channel assessment. Prior to the feedback transmission, a short duration (called short interframe space (SIFS)) is introduced between the data transmission and the corresponding feedback that does not involve actual sensing of the channel. According to IEEE 802.11, the SIFS period (16 μs for an Orthogonal Frequency Division Multiplexing (OFDM) physical layer (PHY) in the 5 GHz band) is defined as follows: aSIFSTime = aRxPHYDelay + aMACProcessingDelay + aRxTxTurnaroundTime where: ● aRxPHYDelay defines the duration required by the PHY layer to deliver a packet to the MAC layer. ● aMACProcessingDelay defines the duration that the MAC layer must trigger the PHY layer to send a response. ● aRxTxTurnaroundTime defines the time required to switch the radio from receive mode to transmit mode.

[0040] Therefore, the SIFS duration is used to absorb the hardware delay for switching direction from receive to transmit.

[0041] For NR in unlicensed bands (NR-U), it is expected that a similar gap will be allowed to accommodate radio turnaround time. For example, this allows the UE to transmit not only a PUSCH carrying data and possible UCI, but also a PUCCH carrying uplink control information (UCI) feedback within the same TXOP obtained by the originating gNB without performing CCA before the PUSCH / PUCCH transmission, as long as the gap between downlink and uplink transmissions is 16 μs or less. Such operation is typically referred to as "COT sharing." Figure 1 is a schematic diagram illustrating an example of gNB-initiated COT sharing, where CCA is performed by the originating node (gNB) and shows TXOPs both with and without COT sharing. With COT sharing, the gap between downlink and uplink transmissions is less than 16 μs.

[0042] When a UE accesses the medium via Category 4 (Cat-4) LBT with a pre-configured grant outside the gNB COT, the UE and gNB may also share the UE-acquired COT to schedule downlink data to the same UE. The UE COT information may be indicated in the UCI, such as the Configured Grant-Uplink Control Information (CG-UCI) for the PUSCH resource of the configured grant. Figure 2 is a schematic diagram illustrating an example of UE-initiated COT sharing. With COT sharing, the gap between uplink and downlink transmissions is less than 16 μs.

[0043] NR-U Channel Access Procedure LBT is designed for unlicensed spectrum coexistence with other RATs. In this mechanism, wireless devices apply a CCA check (i.e., channel sensing) before any transmission. The transmitter performs energy detection (ED) for a predetermined period, which is compared with an energy detection threshold (ED threshold) to determine whether the channel is idle. If the channel is determined to be occupied, the transmitter performs a random backoff within the contention window before the next CCA attempt. To protect ACK transmissions, the transmitter must postpone a period after each busy CCA slot before resuming backoff. As soon as the transmitter gains access to the channel, it is only allowed to perform transmissions up to a maximum duration (i.e., maximum channel occupancy time (MCOT)). For QoS differentiation, channels based on service type are used. Ne For example, channel access priority between services using Contention Window Size (CWS) and MCOT duration. Ne For differentiation of access priority, four LBT priority classes are defined.

[0044] As described in 3GPP® TR38.889, channel access schemes for NR-based access for unlicensed spectrum can be classified into the following categories: Category 1: Immediate transmission after a short switching gap, i.e., no LBT * This is used by the transmitter to transmit immediately after an uplink / downlink switching gap in the COT. * The receive-to-transmit switching gap is less than 16 μs to accommodate transceiver turnaround time. Category 2: LBT without random backoff * The duration for which the channel is sensed idle before the transmitting entity transmits is deterministic. Category 3: LBT with a fixed-size contention window and random backoff * The LBT procedure has the following steps as one of its components: The transmitting entity rolls a random number N within a contention window. The size of the contention window is specified by the minimum and maximum values ​​of N. The size of the contention window is fixed. The random number N is used in the LBT procedure to determine the length of time (duration) that the channel is sensed as idle before the transmitting entity transmits on the channel. Category 4: LBT with variable-sized contention windows and random backoff * The LBT procedure has as one of its components: The transmitting entity rolls a random number N within a contention window. The size of the contention window is specified by the minimum and maximum values ​​of N. The transmitting entity can change the size of the contention window when rolling the random number N. The random number N is used in the LBT procedure to determine the length of time (duration) that the channel is sensed as idle before the transmitting entity transmits on the channel.

[0045] Different categories of channel access schemes may be used for different transmissions within the COT and for different channels / signals to be transmitted.

[0046] Sidelink transmission in NR Sidelink transmissions over NR are specified for 3GPP Release 16. They are an extension of ProSe (Proximity-Based Services) specified for LTE. Four new extensions are introduced to NR sidelink transmissions, among others: ● Support for unicast and groupcast transmissions is added in the NR sidelink. For the unicast and groupcast cases, a physical sidelink feedback channel (PSFCH) is introduced for the receiver UE to respond to the transmitter UE with the decoding status. ● Grant-free transmission, which is employed in NR uplink transmission, is also provided in NR sidelink transmission to improve latency performance. ● To mitigate resource collisions between different sidelink transmissions initiated by different UEs, the channel sensing and resource selection procedures are enhanced, which also leads to a new design of the PSCCH. ● To achieve high connection density, congestion control and therefore QoS management is supported in NR sidelink transmissions.

[0047] To enable the above expansion, new physical channels and References Signaling is introduced in NR (previously available in LTE). ● PSSCH (Physical Sidelink Shared Channel, sidelink version of PDSCH): PSSCH is transmitted by the UE on the sidelink transmitter side and carries sidelink transmission information, system information blocks (SIBs) for RRC configuration, and part of the sidelink control information (SCI). ● PSFCH (Physical Sidelink Feedback Channel): The PSFCH is transmitted by the UE on the receiver side of the sidelink for unicast and groupcast cases, and carries 1-bit information across one resource block for Hybrid Automatic Repeat Request (HARQ) acknowledgements (ACKs) and negative ACKs (NACKs). Additionally, channel state information (CSI) is carried in the MAC CE via the PSSCH instead of the PSFCH. ● PSCCH (Physical Sidelink Common Control Channel, sidelink version of PDCCH): When traffic to be transmitted to the receiver UE arrives at the transmitter UE, the transmitter UE first transmits the PSCCH, which is the time-frequency resource reserved for transmission, demodulation, etc. References It carries part of the SCI (Sidelink Control Information, the sidelink equivalent of DCI) to be decoded by any UE for channel sensing purposes, including signal (DMRS) pattern and antenna port. ● Sidelink Primary / Secondary Synchronization Signal (S-PSS / S-SSS): Similar to downlink transmission in NR, primary and secondary synchronization signals (S-PSS and S-SSS, respectively) are supported in sidelink transmission. By detecting S-PSS and S-SSS, a UE can identify the sidelink synchronization identifier (SSID) from the UE transmitting the S-PSS / S-SSS. Therefore, by detecting S-PSS / S-SSS, a UE can learn the characteristics of the UE transmitter transmitting the S-PSS / S-SSS. The process of acquiring timing and frequency synchronization along with the UE's SSID is called initial cell search. Note that the UE transmitting the S-PSS / S-SSS does not necessarily have to be involved in the sidelink transmission; the node (UE / eNB / gNB) transmitting the S-PSS / S-SSS is called the synchronization source. Within a cell, there are two S-PSS sequences and 336 S-SSS sequences, forming a total of 672 SSIDs. ● Physical Sidelink Broadcast Channel (PSBCH): The PSBCH is transmitted as a synchronization signal / PSBCH block (SSB) along with the S-PSS / S-SSS. The SSB has the same numerology as the PSCCH / PSSCH on that carrier, and the SSB should be transmitted within the bandwidth of the configured BWP. The PSBCH carries synchronization information such as the Direct Frame Number (DFN), an indication of slot and symbol-level time resources for sidelink transmissions, and an in-coverage indicator. The SSB is transmitted periodically every 160 ms. ● DMRS, phase tracking References Signal (PT-RS), channel state information References Signaling (CSIRS): These physical signals supported by NR downlink / uplink transmissions References The signal is also employed by sidelink transmissions. Similarly, PT-RS is only applicable to FR2 transmissions.

[0048] Another new feature is the two-stage sidelink control information (SCI). This is a sidelink version of DCI. Unlike DCI, only a part of the SCI (the first stage) is transmitted on the PSCCH. This part is used for channel sensing purposes (including reserved time-frequency resources for transmission, DMRS pattern, and antenna ports) and can be read by all UEs. Meanwhile, the remaining scheduling and control information (the second stage), such as an 8-bit source identification (ID) and a 16-bit destination ID, NDI, RV, and HARQ process ID, is transmitted on the PSSCH to be decoded by the receiver UE.

[0049] Similar to PRoSE in LTE, NR sidelink transmission has two resource allocation modes: ● Mode 1: Sidelink resources are scheduled by the gNB. ● Mode 2: The UE autonomously selects sidelink resources from a (pre-)configured sidelink resource pool based on a channel sensing mechanism.

[0050] For UEs that are in coverage, the gNB may be configured to employ Mode 1 or Mode 2. For UEs that are out of coverage, only Mode 2 may be employed.

[0051] Similar to LTE, scheduling on the sidelink in NR is done differently for Mode 1 and Mode 2.

[0052] Mode 1 supports two types of grants: Dynamic grant: When traffic to be transmitted over the sidelink arrives at the transmitter UE, the UE requests sidelink resources from the gNB through a four-message exchange procedure (SR on the uplink, grant, BSR (Buffer Status Report) on the uplink, and a Buffer Status Report (BSR) on the sidelink). DeDuring the resource request procedure, the gNB may assign a Sidelink Radio Network Temporary Identifier (SL-RNTI) to the transmitter UE. If this sidelink resource request is granted by the gNB, the gNB indicates resource allocation for the PSCCH and PSSCH in the DCI carried by the PDCCH using a cyclic redundancy check (CRC) scrambled on the SL-RNTI. When the transmitter UE receives such DCI, it can obtain the grant only if the scrambled CRC of the DCI is successfully resolved by the assigned SL-RNTI. The transmitter UE then indicates the time-frequency resources and transmission scheme of the assigned PSSCH in the PSCCH and launches the PSCCH and PSSCH on the resources allocated for sidelink transmission. Once a grant is obtained from the gNB, the transmitter UE can transmit only a single transport block (TB). As a result, this type of grant is suitable for traffic with moderate latency requirements.

[0053] Configured grant: For traffic with strict delay requirements, performing a four-message exchange procedure to request sidelink resources may induce unacceptable delays. In this case, the transmitter UE may perform a four-message exchange procedure to request a set of resources before the traffic arrives. If a grant is available from the gNB, the requested resources are reserved periodically. Once the traffic arrives at the transmitter UE, the UE can launch the PSCCH and PSSCH at the next resource opportunity. In fact, this type of grant is also known as grant-free transmission.

[0054] In both dynamic and configured grants, the sidelink receiver UE cannot receive the DCI (because it is looking at the transmitter UE), and therefore the receiver UE should perform blind decoding to identify the presence of PSCCH and find the resources for PSSCH through SCI.

[0055] When the transmitter UE activates the PSCCH, the CRC is also inserted into the SCI without any scrambling.

[0056] In Mode 2 resource allocation, when traffic arrives at the transmitter UE, the transmitter UE should autonomously select resources for the PSCCH and PSSCH. To further minimize the delay time of feedback HARQ ACK / NACK transmission and subsequent retransmissions, the transmitter UE may also reserve resources for the PSCCH / PSSCH for retransmissions. To further increase the probability of successful one-shot TB (Transport Block) decoding and thus reduce the probability of performing retransmissions, the transmitter UE can repeat TB transmissions along with the initial TB transmission. This mechanism is also known as blind retransmission. As a result, when traffic arrives at the transmitter UE, the transmitter UE should select resources for the following transmissions. 1) A PSSCH associated with the PSCCH for initial transmission and blind retransmission. 2) A PSSCH associated with the PSCCH for retransmission.

[0057] Since each transmitter UE in a sidelink transmission should autonomously select resources for its transmission, it can be seen that a key issue in Mode 2 is how to prevent different transmitter UEs from selecting the same resource. Therefore, a specific resource selection procedure is imposed for Mode 2 based on channel sensing. The channel sensing algorithm involves measuring RSRP on different subchannels and requires knowledge of different UE power levels for DMRS on PSSCH or DMRS on PSCCH, depending on the configuration. This information is only known after the receiver-side SCI is activated by all other UEs. The sensing and selection algorithm is quite complex.

[0058] To support sidelink transmissions over unlicensed spectrum (SL-U), a channel similar to NR-U is used. Ne A secure access mechanism needs to be implemented in SL-U. Ne In the sidelink access mechanism, a sidelink (SL)-capable UE may need to perform an LBT operation before SL transmission. However, the LBT operation introduces transmission latency for SL transmission. In this case, it is beneficial to support a COT sharing mechanism similar to that for NR-U.

[0059] However, the COT sharing mechanism in NR-U is not directly reusable for SL-U. In NR-U, COT sharing allows a UE to share uplink COT with a gNB (i.e., so-called uplink COT sharing) or allows a gNB to share downlink COT with one or more UEs (i.e., so-called downlink COT sharing). In SL-U, the COT sharing mechanism can allow COT to be shared between SL UEs. Therefore, the COT sharing mechanism needs to be enhanced.

[0060] In the embodiments, a mechanism is proposed to enable a COT initiated by an SL UE or a gNB for SL transmission to be shared with other UEs for SL transmission. A similar mechanism can also be applied to enable a COT initiated by a UE or a gNB for Uu transmission to be shared with other UEs for SL transmission.

[0061] Therefore, the COT information associated with the shared COT needs to be signaled to other UEs. It is proposed that the COT information includes different contents.

[0062] Additionally, various signaling options for COT information have been proposed.

[0063] The embodiments are described in the context of NR, i.e., two or more SL UEs are located in the same or different NR cells. However, the same principles may be applied to LTE or any other technology that allows direct connection of two (or more) nearby devices. The embodiments are also applicable to relay scenarios, including UE network relay or UE relay, where the remote UE and relay UE may be based on LTE sidelink or NR sidelink, and the Uu connection between the relay UE and the base station may be LTE Uu or NR Uu.

[0064] The proposed mechanism is applicable to unlicensed operation in SL (i.e., SL transmission on unlicensed bands). The term LBT may also be interchangeably referred to as clear channel assessment (CCA), shared spectrum access procedure, etc. Carriers to which LBT is applied may belong to shared spectrum, unlicensed bands, or bands with contention-based access, etc. The following embodiments are not limited by terminology. Any similar terminology is equally applicable herein.

[0065] The configurable LBT schemes may include at least one of the following LBT categories, but are not limited to the following examples: * Category 1: Immediate transmission after a short switching gap, i.e., no LBT * * This is used by the transmitter to transmit immediately after the UL / DL switching gap in the COT. * * The receive to transmit switching gap is less than 16 μs to accommodate transceiver turnaround time. * Category 2: LBT without random backoff * * The length (duration) for which the channel is sensed idle before the transmitting entity transmits is deterministic. * Category 3: LBT with a fixed-size contention window and random backoff * * The LBT procedure has the following steps as one of its components: The transmitting entity rolls a random number N within a contention window. The size of the contention window is specified by the minimum and maximum values ​​of N. The size of the contention window is fixed. The random number N is used in the LBT procedure to determine the length of time (duration) that the channel is sensed as idle before the transmitting entity transmits on the channel. * Category 4: LBT with variable-sized contention windows and random backoff * * The LBT procedure has as one of its components the following: The transmitting entity rolls a random number N within a contention window. The size of the contention window is specified by the minimum and maximum values ​​of N. The transmitting entity can change the size of the contention window when rolling the random number N. The random number N is used in the LBT procedure to determine the length of time (duration) that the channel is sensed to be idle before the transmitting entity transmits on the channel.

[0066] Other LBT methods such as directional LBT, omnidirectional LBT, receiver-assisted LBT, etc. are also applicable. The above-mentioned similar LBT methods may be referred to by different terminology (e.g., Type 1 or Type 2 channels in 3GPP TS37.213 V16.6.0). Ne It may also be called the "router access procedure."

[0067] Note: In some unlicensed operation technologies (e.g., unlicensed operation for LTE or unlicensed operation for NR), when the gap from the end of a first transmission in one direction (e.g., from UE1 to UE2) to the start of a second subsequent transmission in the other direction (e.g., from UE2 to UE1) is less than or equal to a fixed period (e.g., 16 μs or 25 μs), either Category 1 or Category 2 LBT may be selected before the second transmission to avoid the latency incurred by using Category 4 LBT operation. For SL transmissions, a similar gap period may also be introduced. However, the value of the gap period may differ from that used in these unlicensed operation technologies.

[0068] FIG. 3 is a schematic block diagram illustrating a communication system 300 in which embodiments herein may be implemented.

[0069] According to an embodiment, the communication system 300 may include a plurality of UEs (e.g., UEs 101, 102, and 103) and a basic node (e.g., gNB 111). Links via Uu interfaces (e.g., Uu links 121, 122) are established between the UEs 101, 102 and the gNB 111, and sidelinks (also called direct connections) (e.g., sidelinks 131, 132) are established between the UEs 101, 102, and 103.

[0070] According to one embodiment, a method is proposed for enabling a shared COT among multiple SL-capable UEs. The COT is requested and occupied by a first UE 101 intended for SL transmission purposes. The COT may be acquired or occupied by the first UE 101 after a successful LBT operation. The COT information is signaled by the first UE 101 to neighboring SL UEs (e.g., UEs 102, 103). Within this shared COT, after an SL transmission by the first UE 101 to one or more neighboring UEs 102, 103, another SL transmission initiated by the second UE 102 to one or more neighboring UEs (e.g., UE 103) of the second UE 102 is allowed to occupy the channel without performing an LBT operation.

[0071] In this way, the COT is shared between the first UE 101 and the second UE 102. In other words, a channel occupancy switch occurs between the first UE 101 and the second UE 102. After one or more SL transmissions performed by the second UE 102 within the shared COT, the COT may be further shared with the third UE 103, a fourth UE, etc. for SL transmission or reception.

[0072] FIG. 4 is a schematic signaling diagram illustrating messages in an exemplary COT sharing for sidelink over an unlicensed band according to embodiments herein.

[0073] In this schematic signaling chart, the COT is shared between a first UE 101 and a second UE 102. According to an embodiment, the COT sharing procedure may include the following messages or steps: 1. The first UE 101 may obtain a sidelink grant from the gNB 111.

[0074] 2. The first UE 101 may perform an LBT procedure and occupy the channel after the LBT is successful. Then, the first UE 101 may start transmission (such as sidelink transmission) by using the occupied COT.

[0075] 3. The first UE 101 may send COT information to the second UE 102 for COT sharing.

[0076] 4. The second UE 102 may start sidelink transmission during the COT by skipping the LBT before transmission.

[0077] FIG. 5 is a schematic signaling diagram illustrating messages in another example COT sharing for sidelink over an unlicensed band, according to embodiments herein.

[0078] In this schematic signaling chart, the COT is shared between a first UE 101 and second and third UEs 102, 103. According to an embodiment, the COT sharing procedure may include the following messages or steps: 1. The first UE 101 may obtain a sidelink grant from the gNB 111. 2. The first UE 101 may perform an LBT procedure and occupy the channel after the LBT is successful. Then, the first UE 101 may start transmission (such as sidelink transmission) by using the occupied COT. 3. The first UE 101 may send COT information to the second UE 102 for COT sharing. 4. The second UE 102 may start sidelink transmission during the COT by skipping the LBT before transmission. 5. The second UE 102 may send the COT information to an additional third UE 103 for COT sharing. 6. The third UE 102 may start sidelink transmission during the COT by skipping the LBT before transmission.

[0079] According to one embodiment, the COT may be further shared with other UEs for Uu transmission or reception. For example, the UE 103 may use this COT for Uu transmission or reception with the gNB 111.

[0080] According to one embodiment, the COT may be shared with the gNBs for Uu transmission or reception. For example, the gNB 111 may use this COT for Uu transmission or reception with any of the UEs.

[0081] According to one embodiment, the signaling regarding the COT structure may include / indicate, as a baseline, in the first information set, at least one of the following pieces of information: ● Time when COT starts ● Time when COT ends ● Cha Ne When rule switching may occur time ● Cha Ne The maximum number of rule switch events.

[0082] Additionally, other information may also be included in the second set of information, for example: ● UE ID that initiated COT or destination L2 ID ● gNB ID or cell ID that is allowed to use / share COT ● UE IDs that are allowed to share / use COT ● Group ID for sharing / using COT for groupcast ● Destination L2 IDs that are allowed to share / use the COT ● SL transmission cast types allowed within the COT (i.e., unicast, groupcast or broadcast) ● Indicator of whether COT can be shared with Uu transmissions ● Index of the service / logical channel / logical channel group / channel access priority class that is allowed to transmit within the COT ● What type of control signaling / data can be transmitted within the COT? ● The category of LBT operations where other nodes are allowed to occupy the COT before their transmission, e.g. As an example, a node (UE or gNB) may skip the LBT (i.e., Category 1 LBT) before its transmission. As an example, a node (UE or gNB) must perform a Category 2 LBT before its transmission. As an example, a node (UE or gNB) must perform a Category 3 or Category 4 LBT before its transmission. ● In the case where the COT is shared with other nodes (UE or gNB), whether CP (cyclic prefix) extension is enabled and how CP extension is performed by other nodes before their transmission when occupying the COT. ● The type of SL grant that is allowed to be used during the COT, i.e., dynamic grant, configured grant, or grant obtained using Mode 2 resource allocation. ● Time positions reserved for potential DRS transmissions.

[0083] In this way, UEs 101, 102, 103 that share the same COT may avoid LBT operations or at least reduce the frequency of LBT operations. Both delay and spectrum efficiency may be improved.

[0084] According to one embodiment, the COT information may not include the UE ID, or any destination L2 ID, or group ID, in which case the COT is open to any nearby UE. Any UE that can receive the COT information is allowed to access the channel without performing an LBT operation.

[0085] According to one embodiment, and referring to step 1 above in Figures 4 and 5, the COT is requested and obtained by an SL-capable UE (such as UE 101) via at least one of the following alternatives:

[0086] Alternative 1: Sending a PUCCH-SR and / or SL BSR to the gNB to request SL resources for the UE. In this option, the UE has a Uu connection to the gNB. The gNB can allocate COTs to one or more UEs. In this alternative, the gNB can allocate a shared COT to the associated UEs as soon as it receives an SR. In existing specifications, the triggering of a PUCCH-SR only indicates the availability of new data for the LCH. This means that some necessary extensions to the PUCCH-SR are required to indicate the buffer status. In one example, a UE may be assigned multiple PUCCH-SR resources (in the frequency or time domain) for the LCH, and each SR resource is associated with a specific buffer level. The UE triggers the corresponding SR based on the buffer level of the new data. In another example, the single-bit PUCCH SR is extended to a multi-bit SR, and then more information can be conveyed using the multi-bit SR.

[0087] Alternative 2: Transmission of a two-step RA to the gNB to request SL resources for the UE. In MsgA, a buffer status report and / or a PHR may be carried in the payload. In this alternative, a two-step RA is triggered instead of a PUCCH-SR for the arrival of new data or data of higher priority, since the two-step RA can carry a BSR or a PHR in the payload. Alternatively, transmission of a four-step RA to the gNB to request SL resources for the UE may be applied.

[0088] Alternative 3: Send an SR and a subsequent BSR to the gNB to request SL resources for the UE. This is one common alternative. The UE first sends an SR indicating that there is SL data for transmission. The gNB responds with a grant so that the UE can provide a more detailed buffer status report by including a BSR in subsequent data transmissions.

[0089] Alternative 4: The uplink control information (UCI) provided by the UE to the gNB is extended to carry a priority indicator and / or a buffer status report for the UE. The UCI includes at least one of the following content or signaling: ● HARQ ACK / NAK ● Scheduling Request (SR) ● CSI.

[0090] The UCI may be carried on the PUCCH or the PUSCH.

[0091] In Alternatives 1 and 2, the UE may not need to transmit a BSR in subsequent data transmissions after the initial transmission of an SR or RA, in order for the gNB to assign the UE a COT that may be shared with other UEs. In Alternative 3, the gNB may need to rely on both the SR and subsequent BSRs to learn the current full buffer status for the UE. For all alternatives, the gNB can estimate the length of the period during which the COT may be shared between UEs. Within this shared COT, these UEs can manage to empty their buffers, taking into account sidelink radio link quality and power headroom. UEs assigned to the COT are scheduled based on an improved scheduling strategy, so that scheduling decisions for UEs during the COT may be valid for the entire COT period. In other words, other UEs that are not allowed to share this COT are not scheduled during this COT period. In a normal scheduling procedure, a UE's scheduling decision is usually valid for only one scheduling period / TTI / slot.

[0092] Alternative 5: COT is initiated by the UE by initiating one or more SL transmissions using a configured grant for SL.

[0093] For any one of the above alternatives, the COT is used by the UE to perform SL transmissions using the SL grant obtained via the Mode 1 resource allocation.

[0094] Alternative 6: The COT is initiated by the UE by initiating one or more SL transmissions using a Mode 2 resource allocation SL grant obtained by the UE itself from the resource pool, i.e., using a Mode 2 resource allocation SL grant.

[0095] According to one embodiment, referring to steps 4 and 6 above in Figures 4 and 5, if one or several UEs receive signaling indicating that a COT is allocated to them, the UEs then switch from an infrequent PDCCH and / or SCI monitoring pattern to a more frequent PDCCH and / or SCI monitoring pattern. Whenever each of these UEs obtains a grant (via Mode 1 or Mode 2 resource allocation) within the indicated shared COT period, the UE constructs a MAC PDU and triggers transmission accordingly. Within the shared COT period, the UEs participating in the shared COT period schedule / organize their transmissions taking into account the following aspects:

[0096] 1) This allows multiple UEs to use the medium / channel during the same period (e.g., they may use different frequency resources), improving resource utilization and preventing a single UE from completely occupying the channel and blocking other UEs trying to access it. Alternatively, a single UE may be allowed to exclusively occupy a channel for higher rate transmission or reception. b. Whether to allow a single UE to occupy a channel exclusively or to allow multiple UEs to share a channel may be configured by the gNB or may be pre-configured in the standard specification.

[0097] 2) The gap between any two consecutive transmissions is less than a configured period (e.g., 16 μs or 25 μs. The gap may be a value different from 16 μs or 25 μs for SL transmissions, e.g., a value less than 16 μs or a value between 16 μs and 25 μs). In this way, either Category 1 or Category 2 LBT can be selected to avoid the latency introduced by using Category 4 LBT operation.

[0098] According to one embodiment, referring to steps 3 and 5 above in Figures 4 and 5, for UEs that have not been assigned a COT, they can wait to access the channel after their current COT (shared by other UEs) expires, and these UEs can switch to an infrequent PDCCH and / or SCI monitoring pattern until the current COT period expires for power saving purposes. After the current COT expires, these UEs can switch to a more frequent PDCCH and / or SCI monitoring pattern to prepare for receiving DL signaling or SCI signaling. After a while, if the UE has a COT assigned but not intended to be used again, the UE can switch back to the infrequent PDCCH and / or SCI monitoring pattern, but if the UE has a COT assigned, the UE switches to the frequent PDCCH and / or SCI monitoring pattern.

[0099] It should be noted that the above embodiments are not limited to sharing a COT between UEs, but may also be applicable to enable sharing a COT between SL-capable UEs (i.e., the UEs are authorized to use the COT to perform SL transmission or reception) and / or sharing a COT between an SL-capable UE and a gNB (i.e., the COT is authorized to be used by the UE and the gNB for transmission or reception in the Uu interface). To enable COT sharing between SL UEs and between an SL UE and a gNB, COT information needs to be distributed or signaled in the SL link and the Uu link. Therefore, when the COT is shared with a gNB, the COT information may include the corresponding gNB ID or cell ID that is authorized to use the COT.

[0100] In one example, the COT may be initially initiated by an SL UE or gNB for SL transmissions, and the COT may be shared with other UEs and gNBs for Uu transmissions.

[0101] In one example, the COT may be initially initiated by the UE for Uu transmission, and the COT may be shared with other UEs for SL transmission.

[0102] In one example, the COT may be initiated by the gNB for Uu transmissions, and the COT may be shared with other UEs for SL transmissions.

[0103] In one example, the COT may be initially initiated by an SL UE or gNB for SL transmissions of a particular cast type (e.g., unicast), and the COT may be shared with other UEs for SL transmissions of a different cast type (e.g., groupcast or broadcast).

[0104] The COT information may be signaled or distributed in the SL link and / or the Uu link. A UE or gNB that receives COT information for a UE or gNB can forward the COT information to other UEs or gNBs using the SL signaling alternative or the Uu signaling alternative.

[0105] According to an embodiment, and with reference to above step 3 and step 5 of Figures 4 and 5, the COT information is signaled by the gNB to the UE via at least one of the following signaling options: 1) DCI-based signaling option: The DCI may be a group-common PDCCH format. In one option, the UEs that are allowed to share the COT are explicitly signaled in the DCI. In another option, the UEs that are allowed to share the COT are implicitly signaled in the DCI. For example, the DCI is addressed to or scrambled with a specific ID that indicates the UEs that are allowed to share the COT. 2) MAC CE based signaling option: A new MAC CE may be defined accordingly. 3) RRC signaling messages: New RRC signaling messages may be introduced accordingly. 4) Protocol Layer Control PDU (e.g., SDAP, PDCP, or RLC) based signaling options.

[0106] The COT information is signaled in the cell / carrier / BWP / channel / subband so that all UEs can read the signaling regarding whether COT is scheduled in the cell / carrier / BWP / channel / subband. For each UE, there may be two options for the gNB to signal to the UE whether the UE is assigned to COT or not: Option 1: The UE ID assigned to the COT is carried by the COT information signaling Option 2: The UE can determine whether it is assigned a COT via second signaling. The second signaling may be a dedicated DCI. In this option, the UE first detects whether there is a COT assigned by the gNB via the COT information. The UE can then further determine whether a COT is assigned to it via reception of the second signaling. During the COT period, there may be multiple second signaling messages for the UE. Each signaling message may indicate a new grant. Option 3: The UE can determine whether it is implicitly assigned a COT. In one example, signaling is addressed to a specific sequence or a specific ID associated with the UE. When a specific ID associated with the UE detects signaling addressed to a specific sequence, the UE can determine that the COT is assigned to it.

[0107] According to an embodiment, referring to above step 3 and step 5 of Figures 4 and 5, the COT information is signaled by the UE to other UEs via at least one of the following signaling options: 1) RRC signaling over SL 2) MAC CE on SL 3) Control PDUs of the protocol layer above the SL (e.g., SDAP, PDCP, RLC, or the adaptation layer in the case of SL relay). 4) L1 signaling on SL (eg, signaling may be carried on PSSCH, PSCCH, PSFCH, etc.).

[0108] When the COT information of the COT is signaled in the SL link, the COT information may be transmitted in any cast type (i.e., unicast, groupcast, or broadcast) that may differ from the cast type of the SL transmission that is allowed to use / occupy the channel during the COT.

[0109] When the UE receives the COT information of the COT, the UE may provide an acknowledgement message to the UE or gNB that initiated the COT. In the acknowledgement message, the UE may indicate whether the UE agreed or disagreed to participate in COT sharing. After receiving one or more acknowledgement messages, the UE or gNB may update the COT information and signal the updated COT information to the UE.

[0110] Similarly, when the gNB receives the COT information of the COT, the gNB may provide an acknowledgement message to the UE or gNB that initiated the COT.

[0111] Furthermore, a signaling message may convey COT information for one or more COTs, where the same COT information is applicable or valid for multiple COTs. In this way, the signaling overhead introduced by the COT information can be minimized.

[0112] According to one embodiment, referring to Figures 4 and 5 above, upon receiving the COT information signaling sent by the UE or gNB, another UE may send an acknowledgement message to the UE or gNB indicating acceptance or refusal to participate in COT sharing.

[0113] 6 is a schematic flowchart illustrating an exemplary method 600 in a first node according to an embodiment herein. According to one embodiment, the flowchart of FIG. 6 may be implemented in the first node (e.g., UE 101) of FIGS. 3-5.

[0114] The method 600 may begin at step S601 where a first node may initiate a first transmission within an occupied COT on an unlicensed band.

[0115] According to an embodiment, the COT may be occupied by one or more sidelink transmissions using an SR procedure, a two-step RA, or a sidelink grant. According to an embodiment, the COT may be occupied after a successful LBT operation. According to an embodiment, the sidelink grant may be one of a dynamic sidelink grant, a configured sidelink grant, or a sidelink grant obtained by the first node itself from a resource pool.

[0116] The method 600 may then proceed to step S602, where the first node transmits information regarding the COT to at least one second node to enable the at least one second node to initiate second transmissions within the COT over the unlicensed band, where at least one of the first transmissions or the second transmissions may be a sidelink transmission.

[0117] According to one embodiment, information for COT sharing between a first node and at least one second node may be obtained directly or indirectly from information related to the COT.

[0118] According to one embodiment, the information about the COT may be transmitted via the sidelink and / or the Uu link. According to one embodiment, the information about the COT may be transmitted via DCI-based signaling, MAC CE-based signaling, RRC signaling, protocol layer of The information about the COT may be transmitted from the Node B to the second UE via at least one of RRC signaling over the sidelink, MAC CE over the sidelink, protocol layer PDUs over the sidelink, and L1 signaling over the sidelink.

[0119] According to one embodiment, the information regarding the COT may include at least one of the following: the time when the COT starts, the time when the COT ends, the time when a channel switch may occur, or the maximum number of channel switch events.

[0120] In one embodiment, the information about the COT may further include at least one of the following: COT occupying UE ID or destination L2 ID gNB ID or cell ID that is allowed to use / share COT UE IDs that are allowed to share / use COT Group ID that is allowed to share / use COT in case of groupcast; Destination L2 IDs that are allowed to share / use the COT SL transmission cast types allowed within COT Indicator of whether COT can be shared with Uu transmissions Index of the service / logical channel / logical channel group / channel access priority class that is allowed to transmit within the COT What types of control signaling / data are allowed to be transmitted within the COT, or A category of LBT operation in which at least a second node is permitted to occupy the COT applied prior to its transmission during the COT.

[0121] According to an embodiment, the information regarding the COT further comprises at least one of the types of sidelink grants that are allowed to be used during the COT or the time positions reserved for potential DRS transmissions.

[0122] According to one embodiment, the first node may be a first UE or a NodeB (such as a gNB), the first transmission may be a sidelink transmission, the at least one second node may include a second UE or may be a NodeB, and the second transmission may be a Uu transmission.

[0123] According to one embodiment, the first node may be a first UE, the first transmission may be a Uu transmission, the at least one second node may include a second UE, and the second transmission may be a sidelink transmission.

[0124] According to one embodiment, the first node may be a Node B, the first transmission may be a Uu transmission, the at least one second node may include a second UE, and the second transmission may be a sidelink transmission.

[0125] According to one embodiment, the first node may be a first UE or a NodeB, and the first transmission may be a sidelink transmission for a first-cast type, and the at least one second node may include a second UE, and the second transmission may be a sidelink transmission for a second-cast type. According to one embodiment, the first or second-cast type may be one of unicast, groupcast, or broadcast.

[0126] According to one embodiment, the gap between the first and second transmission may be less than 16 μs or between 16 μs and 25 μs.

[0127] The method 600 may then proceed to step S602, where the first node may receive a notification message from the second network function, the notification message including information indicating the PDN connection status.

[0128] The above steps are merely exemplary, and the first node may perform any of the operations described with respect to Figures 3 to 5 to monitor the PDN connectivity status of the UE via the PDN Connectivity Status Subscription procedure.

[0129] 7 is a schematic flowchart illustrating an exemplary method 700 in a second node, according to an embodiment herein. According to one embodiment, the flowchart of FIG. 7 may be implemented in the second node (e.g., UE 102) of FIGS. 3-5.

[0130] The method 700 may begin at step S701, where the second node may receive information regarding the COT from the first node, and the COT is occupied by the first node to initiate a first transmission over an unlicensed band.

[0131] According to one embodiment, the method may further comprise increasing the frequency of PDCCH and / or SCI monitoring if a COT is assigned to the second node having the COT information. In another embodiment, the method may further comprise decreasing the frequency of PDCCH and / or SCI monitoring if a COT is not assigned to the second node using the COT information.

[0132] The method 700 then proceeds to step S702, where the second node may send an optional acknowledgement message to the first node to indicate acceptance or denial of participation in COT sharing.

[0133] Method 700 then proceeds to step S703, where the second node may perform any LBT operations depending on the gap or COT information between the end of the first transmission and the start of the second node's transmission. For example, the second node may optionally perform an LBT before its transmission: 1) If the COT information so indicates, or 2) If the gap between the first transmission and the second node's transmission is greater than the gap period;

[0134] The method 700 may then proceed to step S704, where the second node may initiate a second transmission within the COT via the unlicensed band. Note that the second node's transmission may be initiated after the optional LBT operation is successful. Here, at least one of the first transmission or the second transmission may be a sidelink transmission.

[0135] The method 700 then proceeds to step S704, where the second node may optionally transmit information regarding the COT to at least one third node to enable the at least one third node to initiate a third transmission or reception within the COT via the unlicensed band, where at least one of the second transmission or the third transmission or reception may be a sidelink transmission or reception.

[0136] The above steps are merely exemplary, and the second node may perform any of the operations described with respect to Figures 3 to 5 to monitor the PDN connectivity status of the UE via the PDN connectivity status subscription procedure.

[0137] FIG. 8 is a schematic block diagram illustrating an exemplary first node (such as UE 101) according to embodiments herein.

[0138] According to an embodiment, the first node 800 may include at least one processor 801 and a non-transitory computer-readable medium 802 connected to the at least one processor 801. The non-transitory computer-readable medium 802 includes instructions executable by the at least one processor 801, and the at least one processor 801 is configured to perform steps in the exemplary method 600 as shown in the schematic flowchart of Figure 6, the details of which will be omitted here.

[0139] The first node 800 is a hardware Eh A, Software Eh The first node 800 may be implemented in software, firmware, or any combination thereof. For example, the first node 800 may include multiple units, circuits, modules, etc., each of which may be used to perform one or more steps of the example method 600 associated with the first node (e.g., the UE 101) or one or more steps illustrated in FIGS. 3-5.

[0140] It will be appreciated that the first node may be implemented as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on a suitable platform, for example a cloud infrastructure.

[0141] FIG. 9 is a schematic diagram illustrating an example second node (eg, UE 102) according to embodiments herein.

[0142] According to an embodiment, the second node 900 may include at least one processor 901 and a non-transitory computer-readable medium 902 connected to the at least one processor 901. The non-transitory computer-readable medium 902 includes instructions executable by the at least one processor 901, and the at least one processor 901 is configured to perform steps in the exemplary method 700 as shown in the schematic flowchart of Figure 7, details of which will be omitted here.

[0143] The second node 900 is a hardware Eh A, Software Eh The second node 900 may be implemented in software, firmware, or any combination thereof. For example, the second node 900 may include multiple units, circuits, modules, etc., each of which may be used to perform one or more steps of the example method 700 or one or more steps illustrated in Figures 3-5 related to the second node (e.g., the UE 102).

[0144] It will be appreciated that the second node may be implemented as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on a suitable platform, for example a cloud infrastructure.

[0145] 10 is a schematic block diagram illustrating an exemplary computer-implemented apparatus 1000 according to embodiments herein. According to an embodiment, the apparatus 1000 may be configured as an apparatus described above, such as a first node (e.g., UE 101) or a second node (e.g., UE 102).

[0146] According to one embodiment, the device 1000 may include at least one processor, such as, but not limited to, a central processing unit (CPU) 1001, a computer-readable medium 1002, and a memory 1003. The memory 1003 may comprise volatile (e.g., random access memory, RAM) and / or non-volatile memory (e.g., a hard disk or flash memory). According to one embodiment, the computer-readable medium 1002 may be configured to store computer programs and / or instructions that, when executed by the processor 1001, cause the processor 1001 to perform any of the methods described above.

[0147] According to one embodiment, computer readable medium 1002 (e.g., a non-transitory computer readable medium) may be stored in memory 1003. According to another embodiment, the computer program may be stored in a remote location, such as in computer program product 1004 (which may be embodied as a computer readable medium), and may be accessible by processor 1001, for example, via carrier 1005.

[0148] The computer readable medium 1002 and / or the computer program product 1004 may be distributed and / or stored on a removable computer readable medium, such as a diskette, a CD (compact disc), a DVD (digital video disc), flash or similar removable memory medium (e.g., CompactFlash, SD (Secure SD), Digital Memory Stick, Mini SD card, MMC Multimedia Card, SmartMedia), HD-DVD (High Definition DVD) or Blu-ray DVD, USB (Universal Serial Bus) based removable memory medium, magnetic tape medium, optical storage medium, magneto-optical medium, bubble memory, or may be distributed as a propagated signal over a network (e.g., Ethernet, ATM, ISDN, PSTN, X.25, the Internet, a local area network (LAN), or similar network capable of transporting data packets to infrastructure nodes).

[0149] Exemplary embodiments are described herein with reference to block diagrams and / or flowcharts of computer-implemented methods, devices (systems and / or apparatus) and / or non-transitory computer program products. of Blocks, and block diagrams and / or flowcharts ofIt will be understood that combinations of blocks may be implemented by computer program instructions executed by one or more computer circuits. These computer program instructions can be provided to general-purpose computer circuits, special-purpose computer circuits, and / or processor circuits of other programmable data processing circuits to generate a machine such that the instructions, transformation and control transistors, values ​​stored in memory locations, and other hardware components within such circuits execute via the processor of the computer and / or other programmable data processing apparatus, implement the functions / operations specified in the block diagram and / or flowchart blocks or blocks, thereby creating means (functions) and / or structure for implementing the functions / operations specified in the block diagram and / or flowchart blocks.

[0150] These computer program instructions may also be stored on a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored on the computer-readable medium produce an article of manufacture that includes instructions that implement the functions / acts specified in the block diagram and / or flowchart block or blocks. Thus, embodiments of the inventive concepts may be embodied in hardware and / or software (including firmware, resident software, microcode, etc.) running on a processor, such as a digital signal processor, which may be referred to collectively as a "circuit," "module," or variations thereof.

[0151] It should also be noted that, according to some alternative embodiments, the functions / acts noted in the blocks may occur in an order different from that noted in the flowcharts. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functions / acts involved. Furthermore, the functionality of a given block in the flowcharts and / or block diagrams may be separated into multiple blocks, and / or the functionality of two or more blocks in the flowcharts and / or block diagrams may be at least partially integrated. Finally, other blocks may be added / inserted between the illustrated blocks, and / or blocks / acts may be omitted, without departing from the scope of the inventive concept. Furthermore, while some of the figures include arrows on communication paths to indicate a primary direction of communication, it should be understood that communication may occur in a direction opposite to that of the depicted arrows.

[0152] Many variations and modifications can be made to the embodiments without substantially departing from the principles of the inventive concept. All such variations and modifications are intended to be included within the scope of the inventive concept. Accordingly, the subject matter disclosed above should be considered illustrative and not limiting, and the accompanying examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments that fall within the spirit and scope of the inventive concept. Thus, to the maximum extent permitted by law, the scope of the inventive concept should be determined by the broadest permissible interpretation of this disclosure, including the following example embodiments and their equivalents, and is not intended to be limited or constrained by the foregoing detailed description.

[0153] Abbreviation 3GPP(R): Third Generation Partnership Project 2G: Second generation mobile communication technology 3G: Third generation mobile communication technology 4G: Fourth generation mobile communication technology 5G: Fifth generation mobile communication technology CCA: Clear Channel Assessment CE: Control element COT: Channel Occupancy Time DCI: Downlink Control Information DRS: Discovery Reference Signal IoT: Internet of Things LAA: Licensed Assisted Access LBT: Listen Before Talk LTE: Long Term Evolution MAC: Medium Access Control NR: New Radio PDU: Packet Data Unit PDCCH: Physical Downlink Control Channel QoS: Quality of Service RA: Random Access RACH: Random Access Channel RAT: Radio Access Technology RRC: Radio Resource Control SCI: Sidelink Control Information SL: Side Link SR: Scheduling Request TXOP: Transmission Opportunity UE: User Equipment

Claims

1. A method (600) performed by a first node (101), comprising: Initiating a first transmission (S601) over an unlicensed band within an occupied Channel Occupancy Time (COT); transmitting (S602) information regarding the COT to at least one second node (102) to enable the at least one second node (102) to initiate a second transmission within the COT via the unlicensed band; at least one of the first transmission or the second transmission is a sidelink transmission; A method wherein the gap between the first transmission and the second transmission is less than 16 μs or between 16 μs and 25 μs.

2. 2. The method (600) of claim 1, wherein the first node (101) is a first user equipment (UE), the first transmission is a sidelink transmission; the at least one second node (102) comprises a second UE or is a NodeB; The method, wherein the second transmission is a Uu transmission.

3. 2. The method (600) of claim 1, wherein the first node (101) is a first user equipment (UE), the first transmission is a Uu transmission; the at least one second node (102) includes a second UE; The method, wherein the second transmission is a sidelink transmission.

4. 2. The method (600) of claim 1, wherein the first node (101) is a NodeB; the first transmission is a Uu transmission; the at least one second node (102) includes a second UE; The method, wherein the second transmission is a sidelink transmission.

5. 2. The method (600) of claim 1, wherein the first node (101) is a first user equipment (UE), the first transmission is a sidelink transmission for a first cast type; the at least one second node (102) includes a second UE; the second transmission is a sidelink transmission for a second cast type; and The method, wherein the first cast type or the second cast type is one of a unicast, a groupcast, or a broadcast.

6. 2. The method (600) of claim 1, wherein the COT is occupied by one or more sidelink transmissions using a scheduling request (SR) procedure, a two-step random access (RA), or a sidelink grant.

7. 7. The method (600) of claim 6, wherein the COT is occupied after a successful listen-before-talk (LBT) operation.

8. 7. The method (600) of claim 6, wherein the sidelink grant is one of a dynamic sidelink grant, a configured sidelink grant, or a sidelink grant obtained by the first node itself from a resource pool.

9. 2. The method (600) of claim 1, wherein the information regarding the COT is transmitted via a sidelink and / or a Uu link.

10. 10. The method (600) of claim 9, wherein the information regarding the COT is transmitted from a NodeB (111) to the second node (102) via at least one of Downlink Control Information (DCI)-based signaling, Medium Access Control (MAC) Control Element (CE)-based signaling, Radio Resource Control (RRC) signaling, and Protocol Layer Control Packet Data Unit (PDU)-based signaling.

11. 10. The method (600) of claim 9, wherein the information regarding the COT is transmitted from the first node (101) to the second node (102) via at least one of: Radio Resource Control (RRC) signaling on the sidelink; Medium Access Control (MAC) Control Element (CE) on the sidelink; Protocol Layer Control Packet Data Unit (PDU) on the sidelink; Layer 1 (L1) signaling on the sidelink.

12. 2. The method (600) of claim 1, wherein information for COT sharing between the first node (101) and the at least one second node (102) is obtained directly or indirectly from the information regarding the COT.

13. A method (600) performed by a first node (101), comprising: Initiating a first transmission (S601) over an unlicensed band within an occupied Channel Occupancy Time (COT); transmitting (S602) information regarding the COT to at least one second node (102) to enable the at least one second node (102) to initiate a second transmission within the COT via the unlicensed band; at least one of the first transmission or the second transmission is a sidelink transmission; the information regarding the COT includes at least one of a time when the COT starts, a time when the COT ends, a time when a channel switch may occur, or a maximum number of channel switch events; The information regarding the COT may further include: The types of sidelink grants allowed for use during the COT; and / or and time locations reserved for potential discovery reference signal (DRS) transmission.

14. 14. The method (600) of claim 13, wherein the information regarding the COT further comprises: a UE ID occupying the COT or a destination L2 ID; A gNB ID or cell ID that is authorized to use / share the COT; UE IDs that are allowed to share / use the COT; A group ID that is allowed to share / use the COT for groupcast purposes; and Destination L2 IDs that are allowed to share / use the COT; SL transmission cast types allowed within the COT; an indicator of whether the COT can be shared with Uu transmissions; indexes of services / logical channels / logical channel groups / channel access priority classes that are allowed to transmit within the COT; the types of control signaling / data that are permitted to be transmitted within the COT; and / or a category of LBT operation that the at least second node is allowed to occupy during the COT applied before its transmission; The method includes at least one of the following:

15. A method (700) performed by a second node (102), comprising: receiving (S701) information from a first node (101) regarding a channel occupation time (COT), wherein said COT is occupied by said first node (101) to initiate a first transmission over an unlicensed band; commencing a second transmission within the COT via the unlicensed band (S704); at least one of the first transmission or the second transmission is a sidelink transmission; The method further comprises: performing a listen-before-talk (LBT) operation according to a gap between an end of the first transmission and a start of the second transmission before starting the second transmission (S703); A method wherein the second transmission is initiated after the LBT operation is successful.

16. A method (700) performed by a second node (102), comprising: receiving (S701) information from a first node (101) regarding a channel occupation time (COT), wherein said COT is occupied by said first node (101) to initiate a first transmission over an unlicensed band; commencing a second transmission within the COT via the unlicensed band (S704); at least one of the first transmission or the second transmission is a sidelink transmission; The method further comprises: transmitting (S705) information about the COT to at least one third node (103) to enable the at least one third node (103) to initiate a third transmission or reception within the COT via the unlicensed band; 10. The method of claim 1, wherein at least one of the second transmission or the third transmission or reception is a sidelink transmission or reception.

17. A first node (800), At least one processor (801); a non-transitory computer-readable medium (802) connected to the at least one processor (801), the non-transitory computer-readable medium (802) including instructions executable by the at least one processor (801), whereby the at least one processor (801) is configured to perform the method (600) of any one of claims 1 to 14.

18. A second node (900), At least one processor (901); a non-transitory computer-readable medium (902) connected to the at least one processor (901), the non-transitory computer-readable medium (902) comprising instructions executable by the at least one processor (901), whereby the at least one processor (901) is configured to perform the method (700) of claim 15 or 16.

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