Resource selection for sidelink communication (SL-u) on unlicensed band

Abstract

Some aspects of the present description relate to techniques for mode 2 resource selection for sidelink communication (SL-U) on an unlicensed frequency band based on CCA operation. The transmitting UE performs CCA operations and then selects resources using mode 2 sensing and a resource selection procedure. The sensory algorithm begins by identifying potential candidate resources within a selection window. In some aspects, the selection window is defined by an expected CCA time for the type 1 CCA operation such that the potential candidate resources are limited to time slots after the expected completion time for the type 1 CCA operation. Therefore, since less transmission failures of incomplete CCA operations will occur, the transmission success rate of SL-U transmission may be improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to wireless communication networks, including techniques for sidelink communications over unlicensed bands. BACKGROUND

[0002] More use of mobile applications has led to increased interest in developing wireless systems that are capable of transmitting large amounts of data at high speeds. Sidelink (SL) communications can be used to facilitate direct device-to-device communications and offload and bypass base stations, and are capable of quickly exchanging data in a short period of time. Solutions for efficiency and reliability continue to evolve to include enhancements and new features. BRIEF DESCRIPTION OF DRAWINGS

[0003] The present disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings. Like reference numerals can designate like structural and functional elements. The drawings and corresponding description are provided as non-limiting examples of aspects, implementations, etc. of the present disclosure, and the mention of “an” or “one” aspect, implementation, etc. can not necessarily be a reference to the same aspect, implementation, etc., and can mean at least one, one, or more than one, etc.

[0004] Figure 1 is a block diagram illustrating a plurality of user equipments (UEs) configured to perform sidelink communications over unlicensed bands (SL-U) in accordance with some aspects of the present description.

[0005] Figure 2 is a schematic diagram illustrating timing of resource selection for SL-U in accordance with some aspects of the present description.

[0006] Figure 3 is a schematic diagram illustrating timing of resource selection based on clear channel assessment (CCA) for SL-U operation in accordance with some aspects of the present description.

[0007] Figure 4 is a logic flow diagram illustrating a process for selecting and excluding resources based on CCA operation for SL-U in accordance with some aspects of the present description.

[0008] Figure 5 is a schematic diagram illustrating selecting and excluding resources based on CCA operation for SL-U in accordance with some aspects of the present description.

[0009] Figure 6 is a process flow diagram illustrating a process for a transmitting UE to perform sidelink communications over unlicensed bands (SL-U) in accordance with some aspects of the present description.

[0010] Figure 7is a logic flow diagram illustrating a process for a transmitting UE to receive shared channel occupancy time (COT) information and select resources for SL-U according to some aspects of the present description.

[0011] Figure 8 is a timing diagram illustrating resource selection for SL-U according to some aspects of the present description.

[0012] Figure 9 is a process flow diagram illustrating a process for a transmitting UE to perform sidelink communication on unlicensed band (SL-U) using shared COT according to some aspects of the present description.

[0013] Figure 10 is a block diagram of a device that can be used to perform resource selection for SL-U through CCA operation according to some aspects of the present description.

[0014] Figure 11 is a block diagram of a baseband circuit that can be used to perform resource selection for SL-U through CCA operation according to some aspects of the present description. DETAILED DESCRIPTION

[0015] The following detailed description references the drawings. Like reference numerals can refer to like or similar features throughout the drawings. Additionally, the disclosure is not limited to the described embodiments in that other embodiments can be utilized and structural and logical changes can be made without departing from the scope of the present disclosure.

[0016] A wireless communication network can include user equipment (UE) that are capable of wirelessly communicating with base stations and other network nodes and also capable of UE-to-UE direct communication using sidelink signaling. For sidelink communication between UEs, resource allocation can be performed using mode 1 or mode 2. In mode 1, the network (e.g., a base station) allocates resources and communicates the resource allocation to the UEs via Uu operation, and the UEs transmit / receive sidelink signals using the allocated resources. In mode 2, a transmitting UE participating in sidelink communication can autonomously allocate resources and use the allocated resources to communicate data to one or more other UEs. Sidelink resources can be determined based on a sensing and selection procedure, aided by resource reservation announcements by other UEs. The resources can be selected and / or reserved from a pool of sidelink resources that can be shared by multiple sidelink UEs.

[0017] In addition, sidelink transmissions can use unlicensed bands for standalone operation or license-assisted access as a complementary spectrum to provide higher system capacity and transmission flexibility. To operate in unlicensed bands, a UE can perform one or more clear channel assessment (CCA) operations in order to determine whether one or more channels in the unlicensed spectrum are unavailable or otherwise occupied before transmitting in the unlicensed spectrum. The CCA operations can be performed in accordance with a listen-before-talk (LBT) protocol or other channel occupancy detection procedure. For example, a transmitting UE can listen for other potential transmission activity on a channel for a deferral duration before declaring the channel available, and then wait for a backoff period before transmitting. The CCA operations help to coordinate spectrum usage across multiple devices and even different radio access technologies. However, the time required for CCA operations (e.g., the deferral duration and backoff period as mentioned) negatively impacts successful selection of sidelink resources and thus can delay transmission of sidelink data. For example, a time slot of a resource selected by a transmitting UE can arrive before completion of the CCA operations, which would result in a failure to transmit sidelink data using the selected resource.

[0018] Accordingly, some aspects of the present description relate to techniques for mode-2 resource selection for sidelink communications (SL-U) on unlicensed bands based on CCA operations. A transmitting UE performs CCA operations and then selects resources using a mode-2 sensing and resource selection procedure. The sensing algorithm starts by identifying potential candidate resources within a selection window. In some aspects, the selection window is bounded by an expected CCA time of a type-1 CCA operation, such that the potential candidate resources are limited to time slots after an expected completion time of the type-1 CCA operation. Accordingly, the transmission success rate of SL-U transmissions can be improved since fewer transmission failures of incomplete CCA operations would occur. Additionally or alternatively, the selection window is bounded by a COT duration of a shared COT initiated by an initiating UE when selecting or reselecting resources for transmitting to the initiating UE using the shared COT. In some further aspects, the transmitting UE receives a consistent LBT failure indication from a higher layer and excludes corresponding resources accordingly to form a set of adjusted (e.g., remaining) candidate resources. Thereby, the efficiency of resource selection and subsequent SL-U transmissions can be improved since busy channels are excluded without involving multiple individual CCA operations. Other aspects and details of the present disclosure are further described below with respect to the figures.

[0019] Figure 1is a block diagram of a system and device illustrating an example network 100 of multiple UEs such as UE 110-1, UE 110-2, UE 110-3, UE 110-4, and the like (hereinafter also referred to as UEs 110) configured to perform sidelink communications over an unlicensed band, and related methods and operations in accordance with some aspects of the present description. The UEs 110 can also communicate with and establish connections with (e.g., be communicatively coupled with) radio access network (RAN) nodes such as base stations 111. UE 110-1 is shown as a transmitting UE with sidelink data to transmit to a receiving UE such as UE 110-2. In the case of resource allocation mode 2, the transmitting UE 110-1 decides autonomously resources to use for the sidelink transmission based on a sensing and resource selection procedure 106, as will be described in more detail below and also associated with Figure 2 The sensing and resource selection procedure 106 can be aided by resource reservations 102 received from other UEs 110-2, 110-3, 110-4, and the like. The resource reservations 102 can be broadcast by the other UEs 110-2, 110-3, 110-4 as part of first-stage SCI transmitted on a physical sidelink control channel (PSCCH). Resources can be reserved and / or selected from a pool of sidelink resources that can be shared by multiple UEs 110.

[0020] The UEs 110 communicate with each other over licensed medium (also referred to as “licensed spectrum” and / or “licensed band”), unlicensed medium (also referred to as “unlicensed spectrum” and / or “unlicensed band”), or a combination thereof. The licensed spectrum can correspond to a channel or band of frequencies selected, reserved, regulated, etc. for certain types of wireless activity (e.g., wireless telecommunication network activity), whereas the unlicensed spectrum can correspond to one or more bands of frequencies that are unrestricted for certain types of wireless activity. Whether a particular band of frequencies corresponds to licensed or unlicensed medium can depend on one or more factors such as frequency allocation determined by a public sector organization (e.g., a government agency, a regulatory body, etc.), frequency allocation determined by a private sector organization involved in developing wireless communication standards and protocols, etc.

[0021] To operate in the unlicensed spectrum, the UEs 110 and the base stations 111 can operate independently or using License Assisted Access (LAA), eLAA, and / or feLAA mechanisms. In these implementations, the transmitting UE 110-1 can perform CCA operations 104 such as various types of medium sensing operations or carrier sensing operations in order to determine whether one or more channels in the unlicensed spectrum are unavailable or otherwise occupied before transmitting in the unlicensed spectrum. The medium / carrier sensing operations can be performed in accordance with a listen before talk (LBT) protocol and other procedures.

[0022] As shown in action 112, the sending UE 110-1 then transmits sidelink data to the receiving UE 110-2 on the selected resources. The sidelink data is transmitted as a transport block (TB) carried on the Physical Sidelink Shared Channel (PSSCH). The TB is associated with an SCI. The SCI indicates the resources used by the PSSCH carrying the associated TB, as well as additional information used for decoding the TB. The SCI can be transmitted in the same time slot as the sidelink data and in two phases. The first phase SCI is carried on the Physical Sidelink Control Channel (PSCCH), while the second phase SCI is carried on the corresponding PSSCH carrying the TB. The second phase SCI enables a flexible SCI design to support unicast, multicast, and broadcast transmission. Dividing the SCI into two phases allows other UEs (e.g., UEs 110-3, 110-4) to decode only the first phase SCI for channel sensing purposes, thereby determining the resources reserved by the sending UE 110-1. On the other hand, the second-stage SCI provides additional control information that is needed to be sent to the receiving UE 110-2.

[0023] As shown in action 114, in some aspects, transmitting UE 110-1 may receive shared COT information initiated by another UE, such as UE 110-2, which is the initiating UE of a shared COT potentially shared by UE 110-1 and / or other COT sharing candidate UEs (such as UE 110-3, 110-4). The shared COT information is transmitted from UE 110-2 to UE 110-1 along with a data payload. The shared COT information indicates parameters of the shared COT, such as the duration of the COT, the UE identifier of the initiating UE, and the Channel Access Priority Class (CAPC) value (CAPC-COT) used to grant the COT. The shared COT information may be transmitted on the Phase 1 SCI carried on the PSCCH and broadcast or multicast to multiple UEs (such as UE 110-1, 110-3, 110-4). The data payload is carried on the PSSCH and may be transmitted to UE 110-1 in the same time slot as the PSCCH carrying the shared COT information.

[0024] As indicated by the first indicator 1.1 and related to Figure 2 Further discussed in connection with the other figures herein, in some aspects, the expected time period for performing CCA operation 104 is used to define the resource selection window of sensing and resource selection procedure 106. Specifically, the start time of the resource selection window is adapted to the minimum expected time period (“T”) of CCA operation 104. CCA_min The resource selection window's end time adapts to the maximum expected time period of CCA operation 104 ("T"). CCA_max”). T is computed based on the channel access priority class (CAPC) value of the sidelink data to be transmitted and the current contention window size (“CW_p”) of the CCA operation 104 CCA_min and T CCA_max . In some additional aspects, the CCA operation 104 includes determining a channel occupancy ratio, R0c, and T is further computed based on the channel occupancy ratio CCA_min and T CCA_max .

[0025] As indicated by the second indicator 1.2 and further discussed in association with Figure 3 and other figures herein, in some aspects, the channel occupancy condition determined by the CCA operation 104 is used to exclude resources during the sensing and resource selection procedure 106. Specifically, information of the set of resource blocks with consistent LBT failure is obtained from the MAC layer and indicated to the physical layer of the transmitting UE 110-1, and the set of resource blocks is excluded from the initial set of candidate resources “S A ”.

[0026] As shown by the third indicator 1.3 and further discussed in association with Figure 2 and other figures herein, in some aspects, if the transmitting UE 110-1 shares a COT with the receiving UE 110-2, the resource selection is performed based on parameters of the COT. For example, the selection window (e.g., selection window 202 in Figure 2 ) is bounded by the COT duration of the COT, such that the SL transmission can be transmitted and completed in time during the COT.

[0027] Additionally, the base station 111 can be configured to wirelessly communicate with the UEs 110 and can provide the UEs 110 with mode 2 sidelink resource allocation configurations, as shown by the action 116. These configurations are designed to optimize the use of available resources and ensure that the UEs 110 can reliably and efficiently communicate with each other. For example, the base station 111 can configure the size and number of resource blocks that are available for use by the UEs 110. This can include setting aside specific resource blocks for specific use cases, such as emergency services or specific kinds of communication.

[0028] The base station 111 can also configure the sidelink channel, such as the frequency band, bandwidth, and modulation scheme used for sidelink communication. The base station 111 can also configure the maximum transmit power that the UEs 110 can use for sidelink communication. This helps prevent interference with other devices and ensures that the network operates efficiently.

[0029] The UEs 110 can include various types of mobile computing devices or non-mobile computing devices, such as consumer electronics devices, cellular telephones, smartphones, feature phones, tablet computers, wearable computer devices, personal digital assistants (PDAs), pagers, wireless handsets, desktop computers, laptop computers, in-vehicle infotainment (IVI), in-car entertainment (ICE) devices, instrument cluster (IC) devices, heads-up display (HUD) devices, onboard diagnostic (OBD) devices, DME, MDT, EEMS, ECU, ECM, embedded systems, microcontrollers, control modules, EMS, networked or "smart" appliances, MTC devices, M2M, IoT devices, and the like.

[0030] The systems and devices of the example network 100 can operate in accordance with one or more communication standards, such as 4th Generation (4G) (e.g., Long-Term Evolution (LTE)) of the 3rd Generation Partnership Project (3GPP), 5th Generation (5G) (e.g., New Radio (NR)) of the 3GPP, and / or other communication standards. Additionally or alternatively, one or more of the systems and devices of the example network 100 can operate in accordance with other communication standards and protocols discussed herein, including future releases or generations of 3GPP standards (e.g., 6th Generation (6G) standards, etc.), Institute of Electrical and Electronics Engineers (IEEE) standards (e.g., Wireless Metropolitan Area Network (WMAN), Worldwide Interoperability for Microwave Access (WiMAX), etc.), and more communication standards and protocols.

[0031] In some aspects, a RAN node (such as a base station 111) can be a Next Generation (NG) RAN or 5G RAN, an Evolved-UMTS Terrestrial RAN (E-UTRAN), or a legacy RAN (such as a UTRAN or GERAN). As used herein, the term “NG RAN” or like terms can refer to a RAN node that operates in an NR or 5G system, and the term “E-UTRAN” or like terms can refer to a RAN node that operates in an LTE or 4G system. The RAN node can be further connected to a core network (CN) via an NG interface. The CN can include a number of network elements configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UEs 110) connected to the CN via the RAN.

[0032] Figure 2is a diagram 200 illustrating resource selection for sidelink data transmission on unlicensed bands according to some aspects of the present description. As described above in association with the sensing and resource selection procedure 106, in mode 2 resource allocation, a transmitting UE (e.g., transmitting UE 110-1 in FIG. 1) involved in sidelink communication can autonomously allocate resources for transmission and retransmission if the resources are not used by other UEs with higher priority traffic (determined by the sensing procedure performed within the sensing window 201). The transmitting UE can then select and occupy resources within a selection window 202 for an appropriate amount of time until a reselection event is triggered. Figure 1

[0033] The sensing procedure starts with the transmitting UE determining a selection window and all potential candidate resources within the selection window 202. The selection of resources by the transmitting UE for its (re)transmission is based on the sensing results for the potential candidate resources within the selection window 202 during the sensing window 201. The selection window 202 is determined to be bounded to a time frame (n+T1, n+T2), where n is the triggering time for resource allocation, and n+T1 is the lower bound of the selection window 202, and n+T2 is the upper bound of the selection window 202. As an example, the triggering time n can be the arrival time of the transport block. There are two processing times (Tproc0 and Tproc1) before and after the triggering time n, which can refer to the required time in the physical layer and MAC layer for processing inter-layer information exchange and preparing the sidelink physical channel, respectively. In resource allocation mode 2, the transmitting UE can perform continuous sensing. When the resource selection event is triggered at the triggering time n in the transmitting UE, the UE considers its most recent sensing results within the sensing window 201 (e.g., between 1100 ms and 100 ms) before the triggering time n for resource selection. The sensing results at the further boundary n-T0 (e.g., 1100 ms) of the sensing window 201 are beneficial to identify resources reserved by other UEs for periodic traffic, and the sensing results at the closer boundary n-T1 (e.g., 100 ms) of the sensing window 201 are particularly useful for aperiodic traffic. proc,0

[0034] In some aspects, the lower bound n+T1 of the selection window 202 is determined considering a minimum expected CCA time T CCA_min such that the resource candidates can be limited to the resource candidates after the CCA operation is completed, and thus increase the success rate of SL-U transmission. As an example, the lower bound n+T1 can be determined as T CCA_min ≤T1≤Tproc,1+T CCA_min ​​Tproc,1 is the processing time required for resource selection for sidelink transmission and can be in slots or in time. For example, for subcarrier spacing (SCS) of 15 kHz, 30 kHz, 60 kHz, or 120 kHz, Tproc,1 can equal 3, 5, 9, or 17 slots, respectively. Tproc,1 can be calculated based on the channel access priority class (CAPC) value of the sidelink data to be transmitted and the current contention window size (“CW_p”) of the CCA operation. CCA_min In some additional aspects, T CCA_min also includes a channel occupancy ratio R0c when calculating T

[0035] In some aspects, the upper bound n + T2 of the selection window 202 is determined considering a maximum expected CCA time T CCA_max , so that the time taken by the CCA operation can be considered to expand the resource candidates, and thus increase the availability and efficiency of the resource selection. As an example, the upper bound n + T2 can be determined as T 2,min + T CCA_max ≤ T2 ≤ T PDB , where T 2,min is a predefined or preconfigured time parameter of the minimum selection period, and T PDB is the remaining packet delay budget (PDB) for meeting the latency requirement. For example, T 2,min may equal 1, 5, 10, or 20 slots. T 2,min may also be defined in time, instead of slots. T CCA_max may be calculated based on the CAPC value of the sidelink data to be transmitted and the current contention window size (“CW_p”) of the CCA operation. In some additional aspects, a channel occupancy ratio R0c is also included in calculating T CCA_max . More details of the expected CCA time T CCA_min and T CCA_max are described below in connection with the figures of Figure 3 .

[0036] Figure 3A timing diagram illustrating resource selection based on clear channel assessment (CCA) for SL-U operation is shown. CCA operation helps to coordinate spectrum usage across multiple devices and even different radio access technologies. There are different types of CCA operation for various communication schemes. Type 1 CCA is used to initiate one or more transmissions within the same channel occupancy time (COT), while Type 2 CCA is used for COT sharing and transmission of discovery bursts. Type 2 CCA includes Type 2A, 2B, or 2C performed depending on the length of the COT gap between transmissions. Type 2A CCA is performed when the COT gap is equal to or greater than 25 μβ and is used for transmission of discovery bursts. Type 2B CCA is performed when the COT gap is equal to or greater than 16 μβ but less than 25 μβ. Type 2C CCA is performed when the COT gap is less than 16 μβ.

[0037] When the CCA operation is Type 1 CCA, the transmitting UE can listen for other potential transmission activity on the channel for a deferral duration T d and then wait for a backoff period before transmitting. An example Type 1 CCA operation can include the steps shown in the logic diagram 300: 1) Initialize a backoff counter N by a random value uniformly distributed between 0 and the current contention window size (“CW_p”), as shown in action 310; 2) Wait until the channel is idle for a deferral duration Td(e.g., 16 μβ + m 9 μβ), as shown in action 320; 3) Determine whether N is equal to 0, as shown in action 330; 4) If N = 0, the transmitting UE is ready to transmit sidelink data as scheduled, as shown in action 360; 5) If N > 0, set N = N - 1, as shown in action 340; and 6) After the decrement of the backoff counter N, sense the channel for an additional sensing slot duration (e.g., 9 μβ), as shown in action 350. If the additional sensing slot duration is idle, go to action 330 to determine whether N is reduced to 0; otherwise, go to action 320 to wait for the channel to become idle for another deferral duration Td.

[0038] The deferral duration T d depends on the priority of the data. As an example, the deferral duration T d is composed of a fixed time period Tf(e.g., 16 μβ) and an integer multiple m of the sensing slot duration (e.g., m 9μs) consists. The quantity m can be related to the CAPC value of the data to be transmitted. Table 301 shows an example of m values and allowed CW sizes for the corresponding CAPC categories. Thus, high priority traffic (of smaller CAPC values) senses the channel for a shorter time period Td and thus can grab the channel faster than low priority traffic. The backoff counter N is randomly selected by the CCA operation between 0 and the current contention window size ("CW p") to avoid collisions between multiple transmitters. Without random backoff, two UEs waiting for the channel to become available would start at the same time, causing a collision. With random backoff, the likelihood of multiple UEs trying to access the channel at the same time is greatly reduced. Furthermore, high priority traffic (of smaller CAPC values) uses a smaller CW to access the channel faster, while low priority traffic uses a larger CW, increasing the likelihood of high priority traffic being transmitted before low priority traffic. The size of the current contention window CW p is adjusted based on acknowledgement / negative acknowledgement (ACK / NACK) feedback. For example, CW p can be set to its minimum value after receiving a positive ACK / NACK feedback, and can be doubled to a maximum limit if a negative ACK / NACK is received. Thus, if the transmission is successful, the channel is used more aggressively for efficiency, while if the transmission fails, the channel is used less aggressively to reduce collisions with other transmissions.

[0039] Thus, in some aspects, the above minimum expected CCA time T CCA_min consists of the deferral duration Td and the backoff duration Tb. For example, T CCA_min is set to Td + Tb, where Td is 16μs + m 9μs. However, the estimated backoff duration Tb depends on the individual transmission conditions. Assuming that all sensing slots are sensed as idle during action 350 of the type 1 CCA operation shown in logic diagram 300, the estimated backoff duration Tb is N 9μs. Thus, T CCA_min may be set to 16μs + m 9μs + N 9μs. However, in various user conditions, a more busy channel will result in a longer backoff duration Tb, as the channel can be sensed as occupied by action 350 and thus a longer CCA operation is taken. Thus, in some further aspects, the estimation of the expected backoff duration Tb can be enhanced by involving a channel occupancy ratio Roc, which indicates the ratio of sensing slots that are considered busy / occupied. As an example, T CCA_min may be set to 16μs + m 9μs + N 9μs / (1 - Roc).

[0040] In one aspect, a received signal strength indicator (RSSI) measurement is performed for a sidelink transmission. The RSSI measurement can be configured or preconfigured by a base station through a channel occupancy threshold (e.g., channelOccupancyThreshold ) and a measurement window (e.g., reportInterval ). The configuration can be included as part of a reporting configuration (e.g., RRC IE reportConfig ). The RSSI measurement result is used to define a channel occupancy ratio, Roc. Specifically, the channel occupancy ratio, Roc, is defined as a percentage of samples with RSSI higher than the channel occupancy threshold measured in the measurement window. For example, the channel occupancy ratio, Roc, can be a percentage of samples with power level of received signal greater than a configurable threshold (e.g., configured in a range of 0 dBm to -76 dBm) or preconfigured to a predefined value (e.g., -72 dBm) in a configurable measurement window (e.g., 160 ms).

[0041] In some alternative aspects, the measurement result of CCA operation is used to define the channel occupancy ratio, Roc. Specifically, the channel occupancy ratio, Roc, is defined as a percentage of sensing slots that are identified as busy / occupied slots among total sensing slots in a predefined time window. For example, if 9 sensing slots are identified as busy slots in a time window of 20 sensing slots, the channel occupancy ratio, Roc, is 45%. A sensing slot can be identified as busy / occupied if the received energy during at least 4us of the 9us sensing slot satisfies a threshold.

[0042] Similarly, the maximum CCA time T CCA_max max described above can also be set to Td+Tb, where Td is 16us+m 9us, and Tb is estimated as N 9us in some aspects and N 9us / (1-Roc) in some alternative aspects. The expected backoff duration Tb can be further extended to the current contention window, CW_p, or additionally take into account the channel occupancy ratio, Roc, as CW_p / (1-Roc), such that more potentially available candidate resources can be included in the resource selection. Thus, the maximum CCA time T CCA_max max can be set to 16us+m 9us+CW_p or 16us+m 9us+CW_p / (1-Roc).

[0043] Figure 4 A logic flow diagram 400 illustrating a procedure for selecting and excluding resources based on CCA operation for SL-U in accordance with some aspects of the present description is shown. As shown in act 410, a selection window is determined, and potential candidate resources within the selection window are identified. The above has been described in connection withFigures 1 to 3 The determination of the selection window is described in relation to this. The selection window, represented by (n+T1, n+T2), is defined by the expected CCA time of the Type 1 CCA operation, thus limiting potential candidate resources to time slots after the expected completion of the Type 1 CCA operation. This improves the transmission success rate of SL-U transmissions.

[0044] As shown in action 420, the sensing window before the selection window is determined. (n-T0, nT) proc,0 The sensing window, denoted by ), is used to receive channel occupancy information, such as resource reservations made by other UEs. Sensing results at the farther boundary n-T0 (e.g., 1100 ms) of the sensing window are helpful in identifying resources reserved by other UEs for periodic services, and at the closer boundary nT of the sensing window... proc,0 Sensing results at (e.g., 100ms) are particularly useful for non-periodic operations.

[0045] As shown in actions 430 to 470, if certain criteria are met, resource reservations received from other UEs during the sensing window are decoded to exclude them from the candidate resources. As shown in action 430, the UE obtains an initial RSRP threshold. In some aspects, the initial RSRP threshold is configured or pre-configured on a per-resource-pool basis. In some additional or alternative aspects, the initial RSRP threshold is based on the priority of transmitted data. prio_TX For example, if the data being sent has a high priority, a higher initial RSRP threshold can be used. A higher RSRP threshold results in fewer candidate resources being excluded from selection, thus making more adjusted candidate resources available. Conversely, if the data being sent has a low priority, a lower initial RSRP threshold can be used.

[0046] As shown in action 440, the UE obtains the initial candidate resource set "S" for SL-U transmission. A In some respects, the UE selects initial candidate resources S A Resources overlapping with the set of RBs that have consistent LBT failures are excluded to form an adjusted (e.g., remaining) candidate resource set. The set of RBs with consistent LBT failures is indicated from a higher layer (e.g., the MAC layer) to the physical layer. Consistent LBT failures are detected and indicated for each RB set by counting the LBT failure indications sent from the physical layer to the MAC layer via the SL-U. Then, when the LBT failure indications reach a (pre)configured threshold, the MAC layer determines a consistent LBT failure. The MAC entity may be configured with a consistent LBT failure recovery procedure by the RRC. The RRC configures parameters for detecting consistent side-link LBT failures for operation utilizing shared spectrum channel access. For example, the maximum LBT failure count ( lbt-FailureInstanceMaxCount ) and failure detection timers (e.g.,lbt-FailureDetectionTimer ) can be configured and used to determine consistent LBT failures. lbt- FailureRecoveryConfig ) can be configured and used to determine consistent LBT failures.

[0047] As shown in act 450, if the UE receives an SCI reserving a resource during the sensing window, and if the RSRP associated with the SCI is greater than the RSRP threshold, the set of adjusted (e.g., remaining) candidate resources is further filtered to exclude resources. In some additional or alternative aspects, the initial RSRP threshold is based on the priority of the SCI received from another UE prio_RX . For example, if the UE receives an SCI from another UE reserving a resource for a high priority (e.g., during the sensing window), the UE can initially use a lower RSRP threshold. As a result, the high priority resource is more likely to be excluded from resource selection, thereby reducing interference to the high priority transmission of the other UE. Alternatively, if the UE only receives an SCI from other UEs reserving a resource for a SL-PRS with a low priority, the UE can choose to use a higher initial RSRP threshold, such that resources are more likely to be available candidate resources.

[0048] As shown in act 460, if the set of adjusted candidate resources is less than a threshold percentage “X” of the initial candidate resources S A As shown in act 470, the resource pool is re-arranged, and the MAC layer then selects a resource with the updated resource pool. As an example of re-arranging the resource pool, the RSRP threshold is increased by the RSRP adjustment value, and the process is repeated. Otherwise, the adjusted candidate resources are reported to a higher layer (e.g., MAC layer) for subsequent resource selection and SL-U data transmission, as shown in act 480. The threshold percentage value X can be configured or pre-configured. For example, after excluding reserved resources from the selection window (as shown and described in association with acts 440 and 450), the MAC layer can select a resource from the set of adjusted candidate resources. The selection can be random, or based on timing, traffic priority, and / or measurement conditions. For example, a resource can be randomly selected from the best 20% of resources with a measured RSRP less than a (pre)configured threshold, and based on traffic priority. If the remaining resources after the exclusion procedure of acts 440 and 450 are less than 20% of all resources in the selection window, the UE relaxes the RSRP threshold (by 3 dB) until at least 20% (or 35%, 50% based on traffic priority) of all resources in the selection window are used for resource allocation by the UE. The final selection of a resource is done in the MAC layer of the UE receiving the set of unoccupied resources from the physical layer.

[0049] Figure 5A diagram 500 illustrating selection of a resource pool within a selection window based on CCA operation for SL-U and exclusion of resources is shown. In some aspects, if the UE receives information about a set of RBs with consistent LBT failure, as described above in association with action 440, the set of RBs is excluded from the resource pool. In some aspects, the set of RBs is identified as covering one or more subchannel frequencies and being unrestricted in time. Thus, multiple time slots can be excluded from potential candidate resources without requiring multiple CCA operations. Figure 4

[0050] Figure 6 is a process flow diagram 600 illustrating a process for a transmitting UE (e.g., a transmitting UE 110-1 as described throughout this description) to perform communication on SL-U based on CCA operation in accordance with some aspects of the present description.

[0051] As shown in action 610, the transmitting UE senses reservations from other UEs and selects resources for SL-U transmission. The selection of resources can take into account parameters and conditions of the CCA operation to be performed. In one aspect, as shown in action 611, the determination of the selection window takes into account an expected CCA operation time that the CCA operation can take. As described above, for Type 1 CCA, the expected CCA operation time includes a defer duration Td and a backoff period Tb. The defer duration Td depends on the priority of the data. As an example, the defer duration Td can consist of a fixed time period Tf (e.g., 16 μβ) and an integer m times of the sensing slot duration (e.g., m d d may consist of a fixed time period Tf (e.g., 16 μβ) and an integer m times of the sensing slot duration (e.g., m 9 μβ). The number m can be related to the CAPC value of the data to be transmitted. The estimated backoff duration Tb depends on the individual transmission conditions. Assuming all sensing slots are idle during the Type 1 CCA operation, the estimated backoff duration Tb is N 9 μβ, where N is an integer randomly picked between 0 and the current contention window. Thus, the minimum expected CCA operation time T CCA_min may be set to 16 μβ + m 9 μβ + N 9 μβ. However, in various user cases, a more busy channel will result in a longer backoff duration Tb because the channel can be sensed as occupied and thus result in a longer CCA operation. Thus, in some further aspects, the estimation of the expected backoff duration Tb can be enhanced by involving a channel occupancy ratio Roc, which indicates the ratio of sensing slots that are considered busy / occupied. As an example, T CCA_min may be set to 16 μβ + m 9 μβ + N ​​9μs / (1-Roc). T CCA_min The lower bound of the selection window can be used to limit the selection window such that the transmission failures due to incompleteness of CCA operation are reduced. In another aspect, as shown in act 612, the candidate resource set can be adjusted by excluding candidates based on consistent LBT failure. One or more RB sets with consistent LBT failure are indicated from a higher layer (e.g., MAC layer) to the physical layer. A consistent LBT failure is detected and indicated for each RB set by counting the LBT failure indications from the physical layer to the MAC layer. Then, a consistent LBT failure is determined by the MAC layer when the LBT failure indications reach a (pre)configured threshold.

[0052] As shown in act 620, a CCA operation for SL-U is performed. The CCA operation can be a Type 1 CCA for initiating one or more transmissions within the same channel occupancy time (COT). Alternatively or additionally, the CCA operation can include a Type 2 CCA for transmission of COT sharing and discovery burst. Type 2 CCA includes Type 2A, 2B, or 2C performed depending on the length of the COT gap between transmissions. Type 2A CCA is performed when the COT gap is equal to or greater than 25μs and for transmission of discovery burst. Type 2B CCA is performed when the COT gap is equal to or greater than 16μs but less than 25μs. Type 2C CCA is performed when the COT gap is less than 16μs. When the CCA operation is Type 1 CCA, the transmitting UE can listen for other potential transmission activities on the channel for a deferral duration Td before declaring the channel available and then wait for a backoff period Tb before transmission.

[0053] As shown in act 630, after selecting the resources, the transmitting UE transmits data to another UE using the selected resources for SL-U.

[0054] Figure 7 is a logic flow diagram 700 illustrating a process for a transmitting UE (e.g., transmitting UE 110-1 as described throughout the description) to receive shared channel occupancy time (COT) information and select resources for SL-U in accordance with some aspects of the present description.

[0055] At act 710, shared channel occupancy time (COT) information is transmitted from the UE 110-2, which is the initiating UE, to the transmitting UE 110-1. The shared COT information includes information of a shared COT initiated by the initiating UE. In some aspects, the shared COT information includes one or more of a duration of the COT, a UE identity of the initiating UE 110-2. In some aspects, the shared COT information can also include a priority threshold for using the COT. In some aspects, the shared COT information is transmitted in a Sidelink Control Information (SCI) format. The shared COT information can be transmitted on a Physical Sidelink Control Channel (PSCCH). In some aspects, the shared COT information can be communicated specifically between the initiating UE 110-2 and the transmitting UE 110-1 (unicast). In other aspects, the initiating UE 110-2 can transmit the shared COT information to be received by all candidate UEs within a radio transmission range of the initiating UE 110-2 (broadcast), or by a group of receivers that satisfy certain conditions (groupcast).

[0056] At act 720, the SCI including the shared COT information can be decoded and passed from the physical layer to the MAC layer of the UE 110-1. Based on the shared COT information, and for example by evaluating the availability and priority of MAC-CEs and / or logical channels for the UE 110-1 and / or other candidate UEs based on the shared COT information, it is determined whether the UE 110-1 can share the COT.

[0057] At act 730, resources are selected or reselected for transmitting within the shared COT from the transmitting UE 110-1 to the initiating UE 110-2. The resource selection window for SL-U has a start time and an end time. The end time is not later than the remaining COT duration or the remaining PDB duration of the COT.

[0058] At act 740, data is transmitted from the UE 110-1 to the UE 110-2 using the selected or reselected resources within the shared COT.

[0059] Figure 8A diagram 800 illustrating a resource pool within a selection window 202 that a transmitting UE (e.g., a transmitting UE 110-1 as described throughout the specification) uses to select resources for SL-U transmissions according to some aspects of the present description is shown. In addition or alternatively to the various limitations of the sensing window as already described, in some aspects, the selection window 202 is also bounded to a remaining COT duration 804. Thus, in some aspects, the selection window 202 is determined as the minimum of the PDB 803 and the remaining COT duration 804. As such, the selection window 202 is limited by the remaining COT duration 804 such that a sidelink transmission for the initiating UE can be completed during the remaining COT duration 804. The resource selection can be random, or based on timing, traffic priority, and / or measurement conditions. For example, a resource can be randomly selected from the available candidate resources (e.g., R1, R2, R3, and R4 in the figure). Alternatively, an earlier resource (e.g., R1, R2) can be selected in preference to a later resource (e.g., R3, R4) to better use the shared COT. If the remaining resources after the exclusion procedure are less than a threshold, a resource pool rearrangement can be performed as described above.

[0060] Figure 9 A process flow diagram 900 illustrating a process for a transmitting UE (e.g., a transmitting UE 110-1 as described throughout the present description) to transmit data on SL-U using a shared COT according to some aspects of the present description is shown.

[0061] As shown in act 910, shared channel occupancy time (COT) information is received from the initiating UE to the transmitting UE. The shared COT information includes information of a shared COT initiated by the initiating UE. In some aspects, the shared COT information includes one or more of a duration of the COT, a UE identity of the initiating UE. In some aspects, the shared COT information is transmitted in a sidelink control information (SCI) format. The shared COT information can be transmitted on a physical sidelink control channel (PSCCH). The shared COT information can be decoded and passed from the physical layer to the MAC layer. Based on the shared COT information, and for example by evaluating the availability and priority of MAC-CEs and / or logical channels for the transmitting UE based on the shared COT information, it is determined whether the transmitting UE can use the shared COT.

[0062] As shown in act 920, if it is determined that the transmitting UE can use the shared COT, resources for the shared COT transmission from the transmitting UE to the initiating UE are selected or reselected. A resource selection window is determined in which the end time is no later than the remaining COT duration or the remaining PDB duration of the COT.

[0063] As represented by action 930, data is transmitted from the transmitting UE to the initiating UE using the selected or reselected resources within the shared COT.

[0064] Figure 10 is a diagram illustrating an example of a component of the device 1000 of one or more implementations described herein. The device 1000, or its components, can also be a UE, such as the transmitting UE 110-1, described throughout this disclosure, or be included in a UE.

[0065] As described, the device 1000 can be configured to perform sensing and resource selection reselection procedures based on CCA operations, including setting a selection window considering expected CCA operation time and / or excluding RBs experiencing consistent LBT failures as indicated by a MAC layer. In some alternative or additional aspects, the device 1000 receives shared COT information from a COT sharing initiating device and performs a resource selection / reselection procedure through a selection window bounded by a remaining duration of the shared COT. The device 1000 can then transmit to the initiating device on SL-U using the shared COT after a Type 2A / 2B / 2C CCA.

[0066] In some implementations, the device 1000 can include application circuitry 1002, baseband circuitry 1004, RF circuitry 1006, front-end module (FEM) circuitry 1008, one or more antennas 1010, and power management circuitry (PMC) 1012 coupled together as shown in the example of FIG. 10. In some implementations, the device 1000 can include less circuitry (e.g., a RAN node can not utilize application circuitry 1002, but rather include a processor / controller to process IP data received from a CN such as a 5GC or Evolved Packet Core (EPC)). In some implementations, the device 1000 can include additional elements such as, for example, memory / storage, display, cameras, sensors (including one or more temperature sensors, such as a single temperature sensor, multiple temperature sensors located at different locations in the device 1000, etc.), or input / output (I / O) interface. In other implementations, the components described below can be included in more than one device (e.g., such circuitry can be separately included in more than one device in a cloud-RAN (C-RAN) implementation).

[0067] The application circuitry 1002 can include one or more application processors. For example, the application circuitry 1002 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors can include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors can be coupled with memory / storage and can be configured to execute instructions stored in the memory / storage to enable various applications or operating systems to run on the device 1000. In some implementations, the processors of the application circuitry 1002 can process IP data packets received from the CN.

[0068] The baseband circuitry 1004 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1004 can include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 1006 and to generate baseband signals for a transmit signal path of the RF circuitry 1006. The baseband circuitry 1004 can interface with the application circuitry 1002 for generation and processing of the baseband signals and for control of the RF circuitry 1006. For example, in some implementations, the baseband circuitry 1004 can include a 3G baseband processor 1004A, a 4G baseband processor 1004B, a 5G baseband processor 1004C, or other baseband processor(s) 1004D for other existing generations, generations in development or to be developed in the future (e.g., 2G, 6G, etc.). The baseband circuitry 1004 (e.g., one or more of the baseband processors 1004A-D) can handle various radio control functions, implementing the radio control functions via the storage 1004G and central processing unit(s) (CPU) 1004E. The radio control functions can include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some implementations, modulation / demodulation circuitry of the baseband circuitry 1004 can include fast-Fourier transform (FFT), precoding, or constellation mapping / demapping functionality. In some implementations, encoding / decoding circuitry of the baseband circuitry 1004 can include convolution, tail-biting convolution, turbo, Viterbi, or low-density parity check (LDPC) encoder / decoder functionality. The implementations of the modulation / demodulation and encoder / decoder functionality are not limited to these examples and can include other suitable functionality in other implementations.

[0069] In some implementations, the baseband circuitry 1004 can include one or more audio digital signal processors (DSP) 1004F. The audio DSP(s) 1004F can include elements for compression / decompression and echo cancellation, and can include other suitable processing elements in other implementations. In some implementations, components of baseband circuitry can be combined with components of application circuitry 1002 in a single chip or

[0070] In some implementations, the baseband circuitry 1004 can provide communication compatible with one or more radio technologies. For example, in some implementations, the baseband circuitry 1004 can support communication with a NG-RAN, an evolved universal terrestrial radio access network (EUTRAN), or other wireless metropolitan area networks (WMAN), wireless local area networks (WLANs), wireless personal area networks (WPANs), and so on. Implementations in which the baseband circuitry 1004 is configured to support wireless communication compatible with more than one wireless protocol can be referred to as multi-mode baseband circuitry.

[0071] The RF circuitry 1006 can enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various implementations, the RF circuitry 1006 can include switches, filters, amplifiers, etc. to facilitate the communication with wireless networks. RF circuitry 1006 can include a receive signal path, which can include circuitry to down-convert and amplify the received signal, and a transmit signal path, which can include circuitry to up-convert and amplify the transmit signal. The receive signal path of the RF circuitry 1006 can include circuitry to down-convert RF signals received from the FEM circuitry 1008 and provide baseband signals to the baseband circuitry 1004. The transmit signal path of the RF circuitry 1006 can include circuitry to up-convert baseband signals provided by the baseband circuitry 1004 and provide RF output signals to the FEM circuitry 1008 for transmission.

[0072] In some implementations, the receive signal path of the RF circuitry 1006 can include mixer circuitry 1006A, amplifier circuitry 1006B and filter circuitry 1006C. In some implementations, the transmit signal path of the RF circuitry 1006 can include filter circuitry 1006C and mixer circuitry 1006A. RF circuitry 1006 can also include synthesizer circuitry 1006D for synthesizing a frequency for use by the mixer circuitry 1006A of the receive signal path and the transmit signal path. In some implementations, the mixer circuitry 1006A of the receive signal path can be configured to down-convert RF signals received from the FEM circuitry 1008 based on a frequency provided by synthesizer circuitry 1006D. The amplifier circuitry 1006B can be configured to amplify the down-converted signals, and the filter circuitry 1006C can be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals can be provided to the baseband circuitry 1004 for further processing. In some implementations, the output baseband signals can be zero-frequency baseband signals, although this is not a requirement. In some implementations, mixer circuitry 1006A of the receive signal path can comprise passive mixers, although the scope of the

[0073] FEM circuitry 1008 can include a receive signal path, which can include circuitry configured to operate on RF signals received from one or more antennas 1010, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1006 for further processing. FEM circuitry 1008 can also include a transmit signal path, which can include circuitry configured to amplify signals for transmission provided by the RF circuitry 1006 for transmission by one or more of the one or more antennas 1010. In various implementations, the amplification through the transmit or receive signal paths can be done solely in the RF circuitry 1006, solely in the FEM circuitry 1008, or in both the RF circuitry 1006 and the FEM circuitry 1008.

[0074] In some implementations, the PMC 1012 can manage power provided to the baseband circuitry 1004. In particular, the PMC 1012 can control power selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 1012 can typically be included when the device 1000 is capable of being powered by a battery, for example when the device is included in a UE. The PMC 1012 can increase the power conversion efficiency from the battery to the circuitry of the device 1000, for example the baseband circuitry 1004. Although the PMC 1012 is included in Figure 1, in some implementations the PMC 1012 can be outside the scope of the device 1000. Figure 10The PMC 1012 is shown coupled only to the baseband circuitry 1004. However, in other implementations, the PMC 1012 can be additionally or alternatively coupled to, and perform similar power management operations for, other components such as, but not limited to, the application circuitry 1002, the RF circuitry 1006, or the FEM circuitry 1008.

[0075] The processors of the application circuitry 1002 and the processors of the baseband circuitry 1004 can be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 1004 can be used to execute Layer 3, Layer 2, or Layer 1 functionality individually or in combination. The processors of the baseband circuitry 1004 can utilize data received from these layers (e.g., packet data) and further execute Layer 4 functionality (e.g., transport communication protocols (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 can include a RRC layer, Layer 2 can include a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, and Layer 1 can include a physical (PHY) layer of the UE / RAN node.

[0076] Figure 11 is a diagram of example interfaces of baseband circuitry in accordance with one or more implementations described herein. As discussed above, Figure 10 The baseband circuitry 1004 of FIG. 10 can include a processor 1004A-1004E and memory 1004G utilized by the processors. The processors 1004A-1004E can be collectively referred to as baseband processors. Each of the processors 1004A-1004E can include a memory interface 1104A-1104E, respectively, for transferring data to / from the memory 1004G. In some aspects, the baseband circuitry 1004, or its components such as the baseband processors, can be a UE or be included in a UE such as the transmitting UE 110-1 or the receiving UE 110-2, described throughout this disclosure.

[0077] The baseband circuitry 1004 can further include one or more interfaces utilized by the baseband circuitry 1004 to communicate with other circuitry / devices, such as an interface to send / receive data to / from memory external to the baseband circuitry 1004 via memory interface 1112, an interface to send / receive data to / from application circuitry 1002 via application circuitry interface 1114, an interface to send / receive data to / from RF circuitry 1006 via RF circuitry interface 1116, and the like. Figure 10 The application circuitry 1002 of FIG. 10 can include a processor 1002A and memory 1002G utilized by the processor. The processor 1002A can be a general- purpose processor, an application specific processor, or another type of processor. The processor 1002A can include a processor core 1002B and a memory interface 1102 for transferring data to and from memory external to the processor 1002A, such as the memory 1002G. In some aspects, the processor 1002A or its components, such as the processor core 1002B, can be a UE or be included in a UE such as the transmitting UE 110-1 or the receiving UE 110-2, described throughout this disclosure. Figure 10wireless hardware communication interface 1118 (e.g., an interface for communicating data to / from near field communication (NFC) components, Bluetooth components, Wi-Fi components, and other communication components), and a power management interface 1120 (e.g., an interface for communicating power or control signals to / from the PMC 1012).

[0078] Embodiments herein can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including executable instructions for causing a machine (e.g., a processor with memory, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc.) to perform acts or blocks of the method according to described embodiments and implementations, and a device or system for concurrent communication using multiple communication technologies.

[0079] Embodiment 1 is an apparatus for a UE and includes a memory and a processor coupled to the memory and configured to cause the UE to sense and select resources for sidelink communication (SL-U) on an unlicensed band based on a clear channel assessment (CCA) operation to be performed, perform the CCA operation for SL-U, and transmit data to another UE using the selected resources for the SL-U when executing instructions stored in the memory.

[0080] Embodiment 2 is an apparatus including the subject matter of Embodiment 1, wherein the selection of the resources includes determining a resource selection window based on an expected CCA time of the CCA operation.

[0081] Embodiment 3 is an apparatus including the subject matter of Embodiment 2, wherein the expected CCA time of the CCA operation is calculated based on a channel access priority class (CAPC) value of the data to be transmitted and a current contention window size (“CW_p”) of the CCA operation.

[0082] Embodiment 4 is an apparatus including the subject matter of any of Embodiments 2-3, wherein the resource selection window has a lower bound between the expected CCA time and a sum of the expected CCA time and a processing time Tproc,1 required for the resource selection for SL-U.

[0083] Embodiment 5 is an apparatus including the subject matter of Embodiment 3, wherein the expected CCA time of the CCA operation is a sum of a defer duration of the CCA operation based on the CAPC value and an estimated backoff period of the CCA operation related to the current contention window size (“CW_p”).

[0084] Embodiment 6 is an apparatus including the subject matter of Embodiment 5, wherein the estimated backoff period of the CCA operation is N a sensing slot period, wherein N is a backoff counter randomly selected by the CCA operation between 0 and the current contention window size (“CW_p”).

[0085] Embodiment 7 is an apparatus including the subject matter of any one of Embodiments 3 or 5, wherein the expected CCA time of the CCA operation is calculated based on a channel occupancy ratio (Roc).

[0086] Embodiment 8 is an apparatus including the subject matter of Embodiment 7, wherein the channel occupancy ratio (Roc) is defined as a percentage of samples measured with a received signal strength indicator (RSSI) measurement satisfying a channel occupancy threshold in a measurement window.

[0087] Embodiment 9 is an apparatus including the subject matter of Embodiment 7, wherein the channel occupancy ratio (Roc) is defined as a percentage of sensing slots out of a number of total sensing slots within a predefined time window that are identified as occupied slots by the CCA operation.

[0088] Embodiment 10 is an apparatus including the subject matter of Embodiment 7, wherein the expected CCA time of the CCA operation is calculated as 16μs + m 9μs + N 9μs / (1-Roc), wherein m is an integer related to the CAPC value and N is another integer randomly selected by the CCA operation between 0 and the current contention window size (“CW_p”).

[0089] Embodiment 11 is an apparatus including the subject matter of Embodiment 2, wherein the resource selection window has an upper bound that is greater than a sum of a minimum selection period and the expected CCA time but does not exceed a remaining packet delay budget (PDB).

[0090] Embodiment 12 is an apparatus including the subject matter of Embodiment 11, wherein the expected CCA time is set to Td + CW_p, wherein Td is a defer period of the CCA operation and CW_p is a current contention window size of the CCA operation.

[0091] Embodiment 13 is an apparatus including the subject matter of Embodiment 11, wherein the expected CCA time is set to Td + CW_p / (1-Roc), wherein Td is a defer period of the CCA operation, CW_p is a current contention window size of the CCA operation, and Roc is a channel occupancy ratio.

[0092] Example 14 is an apparatus including the subject matter of Example 1, wherein the selection of the resources comprises: determining a resource selection window; and obtaining an initial set of candidate resources and excluding candidates based on an indication of a consistent Listen Before Talk (LBT) failure to form an adjusted set of candidate resources.

[0093] Example 15 is an apparatus including the subject matter of Example 14, wherein the indication of a consistent LBT failure is provided from a MAC layer to a physical layer for each RB set.

[0094] Example 16 is an apparatus including the subject matter of Example 15, wherein the processor is further configured to cause the UE to: determine a number of remaining candidate resources in the adjusted set of candidate resources that is less than a predefined threshold; inform the MAC layer of a lack of candidates; and perform a resource pool reselection by the MAC layer.

[0095] Example 17 is an apparatus including the subject matter of Example 1, wherein the processor is configured to cause the UE to receive, from an initiating UE, sidelink control information (SCI) including shared channel occupancy time (COT) information, wherein the shared COT information includes information of a shared COT initiated by the initiating UE. The selection of the resources comprises determining a resource selection window having a start time and an end time, wherein the end time is not later than a remaining COT duration of the COT and a remaining packet delay budget (PDB).

[0096] Example 18 is a method for operating a UE, and the method includes: determining a resource selection window for a sidelink communication (SL-U) on an unlicensed band; obtaining an initial set of candidate resources within the resource selection window; excluding one or more resource blocks from the initial set of candidate resources based on an indication of a consistent Listen Before Talk (LBT) failure from a MAC layer to form an adjusted set of candidate resources; selecting a resource from the adjusted set of candidate resources; and transmitting data to another UE using the selected resource.

[0097] Example 19 is a method including the subject matter of Example 18, and further including: determining a number of remaining candidate resources in the adjusted set of candidate resources that is less than a predefined threshold; informing the MAC layer of a lack of candidates; and performing a resource pool reselection by the MAC layer.

[0098] Example 20 is a baseband procedure for a UE and includes a memory and a processor coupled to the memory and configured to cause the UE, upon execution of instructions stored in the memory, to receive, from an initiating UE, sidelink control information (SCI) including shared channel occupancy time (COT) information, wherein the shared COT information includes information of a shared COT initiated by the initiating UE, determine a resource selection window for sidelink communication (SL-U) on unlicensed spectrum, the resource selection window having an end time no later than a remaining COT duration of the COT or a remaining packet delay budget (PDB), select resources for SL-U during the resource selection window, and transmit data to the initiating UE using the selected resources for SL-U.

[0099] Example 21 is a method including any act or combination of acts as substantially described in the detailed description herein.

[0100] Example 22 is a method as substantially described herein with reference to each of the drawings included herein or any combination thereof, or with reference to each of the paragraphs in the detailed description or any combination thereof.

[0101] Example 23 is a user equipment configured to perform any act or combination of acts as substantially described herein in the detailed description as included in the user equipment.

[0102] Example 24 is a network node configured to perform any act or combination of acts as substantially described herein in the detailed description as included in the network node.

[0103] Example 25 is a non-transitory computer-readable medium storing instructions that, when executed, cause performance of any act or combination of acts as substantially described herein in the detailed description.

[0104] Example 26 is a baseband processor of a user equipment configured to perform any act or combination of acts as substantially described herein in the detailed description as included in the user equipment.

[0105] Example 27 is a baseband processor of a network node configured to perform any act or combination of acts as substantially described herein in the detailed description as included in the user equipment.

[0106] The above description of illustrative examples, implementations, aspects, etc. of the present subject matter described in the Abstract is not intended to be exhaustive or to limit the disclosed aspects to the precise forms disclosed. While specific examples, implementations, aspects, etc. are described in this document, many details are set forth only in connection with the description of examples, implementations, aspects, etc. One skilled in the relevant art, however, will recognize that other analogous aspects or modifications can be employed without departing from the disclosed aspects. Thus, the disclosed aspects are not intended to be limited to the specific examples, implementations, or aspects described herein, but in their breadth and scope, are commensurate with the recited claims.

[0107] To the extent that the subject matter of this disclosure has been described with respect to a variety of examples, implementations, aspects, etc. and corresponding figures, it is to be understood that other similar aspects or modifications can be employed without departing from the disclosed subject matter. Accordingly, the disclosed subject matter is not to be limited to any single example, implementation, or aspect described herein, but is to be accorded the full scope consistent with the breadth and scope of the claims appended hereto.

[0108] In particular, with respect to the various functions performed by the above-described components or structures (assemblies, devices, circuits, systems, etc.), the terminology used to describe such components is intended to correspond to any component or structure that performs the specified function of the described component (e.g., functionally equivalent), unless otherwise indicated, even if not structurally equivalent to the disclosed structure performing the function in the example implementations illustrated herein. Additionally, while a particular feature can have been disclosed with respect to only one of a plurality of implementations, such a feature can be combined with one or more other features of other implementations as can be desired or advantageous for any given or particular application.

[0109] As used herein, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances. Moreover, articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Additionally, to the extent that the terms "includes", "including", "has", "have", "has", "with" or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising". Additionally, where discussion of one or more numbered items (e.g., "first X", "second X", etc.) is made, generally the one or more numbered items can be distinct or they can be the same, but in some instances the context can indicate that they are distinct or that they are the same.

[0110] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as satisfying or exceeding industry or government requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled in a manner that minimizes risks from unauthorized or improper access or use, and privacy responsibilities should be clearly outlined in dealings with users to authorize use.

Claims

1. An apparatus for a user equipment (UE), the apparatus comprising: Memory; and A processor, coupled to the memory and configured to cause the UE to: execute instructions stored in the memory. Based on the Clear Channel Assessment (CCA) operation to be performed, resources for side-link communication (SL-U) on unlicensed frequency bands are sensed and selected; Perform the CCA operation for use with SL-U; and Use the selected resources for the SL-U to send data to another UE.

2. The apparatus of claim 1, wherein the selection of the resource includes determining a resource selection window based on the expected CCA time of the CCA operation.

3. The apparatus of claim 2, wherein the expected CCA time of the CCA operation is calculated based on the Channel Access Priority Class (CAPC) value of the data to be transmitted and the current contention window size ("CW_p") of the CCA operation.

4. The apparatus according to any one of claims 2 to 3, wherein the resource selection window has a lower bound between the expected CCA time and the sum of the expected CCA time and the processing time Tproc,1 required for the resource selection for SL-U.

5. The apparatus of claim 3, wherein the expected CCA time of the CCA operation is the sum of the delay duration of the CCA operation based on the CAPC value and the estimated backoff period of the CCA operation related to the current contention window size ("CW_p").

6. The apparatus of claim 5, wherein the estimated backoff period of the CCA operation is N. The sensing time slot period, where N is a backoff counter randomly selected by the CCA operation between 0 and the current contention window size ("CW_p").

7. The apparatus according to any one of claims 3 or 5, wherein the expected CCA time of the CCA operation is calculated based on the channel occupancy rate (Roc).

8. The apparatus of claim 7, wherein the channel occupancy rate (Roc) is defined as the percentage of samples of received signal strength indicator (RSSI) measurements that meet the channel occupancy threshold within the measurement window.

9. The apparatus of claim 7, wherein the channel occupancy rate (Roc) is defined as the percentage of sensing slots identified as occupied slots by the CCA operation out of a plurality of total sensing slots within a predefined time window.

10. The apparatus of claim 7, wherein the expected CCA time of the CCA operation is calculated to be 16 μs + m. 9μs+N 9μs / (1-Roc), where m is an integer associated with the CAPC value, and N is another integer randomly selected by the CCA operation between 0 and the current competition window size ("CW_p").

11. The apparatus of claim 2, wherein the resource selection window has a sum greater than the minimum selection period and the expected CCA time but not exceeding the upper bound of the remaining packet delay budget (PDB).

12. The apparatus of claim 11, wherein the expected CCA time is set to Td + CW_p, where Td is the delay period of the CCA operation and CW_p is the current contention window size of the CCA operation.

13. The apparatus of claim 11, wherein the expected CCA time is set to Td + CW_p / (1 - Roc), where Td is the delay period of the CCA operation, CW_p is the current contention window size of the CCA operation, and Roc is the channel occupancy rate.

14. The apparatus of claim 1, wherein the selection of the resource comprises: Confirm resource selection window; as well as An initial set of candidate resources is obtained and candidates are excluded based on indications of failure of the Listen Before Talk (LBT) consensus mechanism to form an adjusted set of candidate resources.

15. The apparatus of claim 14, wherein for each RB set, the indication of a consistent LBT failure is provided from the MAC layer to the physical layer.

16. The apparatus of claim 15, wherein the processor is further configured to cause the UE to: Determine the number of remaining candidate resources in the adjusted candidate resource set that is less than a predefined threshold; Notify the MAC layer of insufficient candidates; and The resource pool reselection is performed by the MAC layer.

17. The apparatus of claim 1, wherein the processor is configured to cause the UE to: The UE receives sidelink control information (SCI) including shared channel occupancy time (COT) information, wherein the shared COT information includes information about the shared COT initiated by the UE; and The selection of the resource includes determining a resource selection window with a start time and an end time, wherein the end time is no later than the remaining COT duration and the remaining packet delay budget (PDB) of the COT.

18. A method for operating user equipment (UE), the method comprising: Determine the resource selection window for side-link communication (SL-U) on unlicensed frequency bands; Obtain an initial set of candidate resources within the resource selection window; Based on the indication from the MAC layer that the Listen Before Talk (LBT) consensus failed, one or more resource blocks are excluded from the initial candidate resource set to form an adjusted candidate resource set; Select resources from the adjusted candidate resource set; and Use the selected resources to send data to another UE.

19. The method according to claim 18, further comprising: Determine the number of remaining candidate resources in the adjusted candidate resource set that is less than a predefined threshold; The MAC layer is notified that there are not enough candidates. as well as The resource pool reselection is performed by the MAC layer.

20. A baseband processor for user equipment (UE), the baseband processor comprising: Memory; and A processor, coupled to the memory and configured to cause the UE to: execute instructions stored in the memory. The UE receives sidelink control information (SCI) including shared channel occupancy time (COT) information, wherein the shared COT information includes information on shared COT initiated by the UE. Determine a resource selection window for sidelink communication (SL-U) on unlicensed spectrum, the resource selection window having an end time no later than the remaining COT duration or the remaining packet delay budget (PDB) of the COT; During the resource selection window, select the resources for SL-U; and Use the selected resources for SL-U to send data to the initiating UE.

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