US-20260129650-A1 - Methods and Apparatus for Supporting Sidelink Channel Sharing in Unlicensed Spectrum

US20260129650A1US 20260129650 A1US20260129650 A1US 20260129650A1US-20260129650-A1

Abstract

A first wireless communications device, e.g., a first UE, shares a second portion, e.g., a remaining unused portion, of its sidelink (SL) channel occupancy time (COT), corresponding to unlicensed spectrum, with a second wireless communications device. The first wireless communications device communicates SL COT sharing information to the second wireless communications device via sidelink control information (SCI) communicated over physical sidelink control channel (PSCCH) resources during a first portion of its SL COT. In some embodiments, the SL COT sharing information includes one or more of: i) a channel access priority class value, ii) a COT-sharing indicator value, or iii) a COT duration field value. The SL COT sharing information allows the second wireless communications device to identify the second portion of the COT, which the second wireless communications device is allowed to use for reverse transmission to the first wireless communications.

Inventors

Amitav Mukherjee

Assignees

CHARTER COMMUNICATIONS OPERATING, LLC

Dates

Publication Date: 20260507
Application Date: 20251229

Claims (20)

1 . A method of operating a first communications device, the method comprising: receiving physical sidelink control channel (PSCCH) signals from a second communications device, said received PSCCH signals from the second communications device communicating channel occupancy time (COT) sharing information provided by the second communications device, said COT sharing information including at least: i) a channel access priority class value and ii) a COT duration value; and determining from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device.
2 . The method of claim 1 , wherein said COT sharing information provided the second communications corresponds to a sidelink channel in unlicensed spectrum.
3 . The method of claim 1 , wherein the COT duration value indicates a number of sidelink slots being shared.
4 . The method of claim 1 , wherein said channel access priority class value is a multi-bit value that indicates a channel priority access class of the first communications device.
5 . The method of claim 4 , wherein said channel access priority class value is a two bit.
6 . The method of claim 5 , wherein the COT duration value includes more bits than the multi-bit channel access priority class value.
7 . The method of claim 4 , wherein determining from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device includes: determining a maximum allowed COT for transmission to the second device based on the received channel access priority class and a mapping of different priority class values to different time intervals.
8 . The method of claim 4 , wherein determining from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device includes: using the received COT duration filed value indicating a number of sidelink slots to determine how much of the second communication device's COT duration the first UE can use for transmission by the first device to the second device.
9 . The method of claim 7 , further comprising: transmitting physical sidelink shared channel (PSSCH) signals communicating traffic data to the second communications device during the portion of the second communications device's COT duration the first communications device can use for transmission to the second communications device.
10 . The method of claim 9 , wherein transmitting physical sidelink shared channel (PSSCH) signals communicating traffic data to the second communications device during the portion of the second communications device's COT duration the first communications device can use for transmission to the second communications device includes transmitting sidelink signals to the second UE without any listen before talk (LBT) operation being preformed prior to transmitting the PSSCH signals.
11 . The method of claim 9 , further comprising: transmitting physical sidelink control channel (PSCCH) signals communicating control information to the second communications device during the portion of the second communications device's COT duration the first communications device can use for transmission to the second communications device.
12 . A first communications device, comprising: a wireless receiver; a wireless transmitter; and a processor configured to control the first communications device to: control the receiver to receive physical sidelink control channel (PSCCH) signals from a second communications device, said received PSCCH signals from the second communications device communicating channel occupancy time (COT) sharing information provided by the second communications device, said COT sharing information including at least: i) a channel access priority class value and ii) a COT duration value; and determine from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device.
13 . The first communications device of claim 12 , wherein said COT sharing information provided the second communications corresponds to a sidelink channel in unlicensed spectrum.
14 . The first communications device of claim 12 , wherein the COT duration value indicates a number of sidelink slots being shared.
15 . The first communications device of claim 12 , wherein said channel access priority class value is a multi-bit value that indicates a channel priority access class of the first communications device.
16 . The first communications device of claim 15 , wherein said channel access priority class value is a two bit.
17 . The first communications device of claim 16 , wherein the COT duration value includes more bits than the multi-bit channel access priority class value.
18 . The first communications device of claim 15 , wherein as part of being configured to control the first communications to determine from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device the processor is configured to control the first communications device to: determine a maximum allowed COT for transmission to the second device based on the received channel access priority class and a mapping of different priority class values to different time intervals.
19 . The first communications device of claim 15 , wherein as part of being configured to control the first communications to determine from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device the processor is configured to control the first communications device to: use the received COT duration filed value indicating a number of sidelink slots to determine how much of the second communication device's COT duration the first UE can use for transmission by the first device to the second device.
20 . A non-transitory computer readable medium including machine executable instructions, which when executed by a processor of a first communications device, control the first communications device to perform the steps of: receiving physical sidelink control channel (PSCCH) signals from a second communications device, said received PSCCH signals from the second communications device communicating channel occupancy time (COT) sharing information provided by the second communications device, said COT sharing information including at least: i) a channel access priority class value and ii) a COT duration value; and determining from the received COT sharing information how much of a second communications device's COT duration the first communications device can use for transmission to the second communications device.

Description

RELATED APPLICATIONS The present application is a continuation of U.S. patent application Ser. No. 17/990,217 filed on Nov. 18, 2022 which was published on May 23, 2024 as Publication No. US 2024-0172238 A1, both the application and patent publication being hereby expressly incorporated by reference in their entirety. FIELD The present application relates to communications and, more particularly, to methods and apparatus for supporting sidelink channel sharing and efficient operation in unlicensed spectrum. BACKGROUND Channel access mechanisms were introduced in 3rd Generation Partnership Project (3GPP) Releases 13-15 for Long-Term Evolution (LTE) Licensed Assisted Access (LAA) and its enhancements enhanced LAA/further enhanced LAA (eLAA/FeLAA) that specified downlink (DL) and uplink (UL) LTE operation in unlicensed spectrum, primarily 5 GHz. The channel access schemes are similar to carrier sense multiple access with collision avoidance (CSMA/CA_ and Enhanced Distributed Channel Access (EDCA) channel access used in IEEE 802.11ac/ax. Closely related channel access schemes were introduced in Release 16 for 5G New Radio in unlicensed spectrum (NR-U) for operation in 5 GHz and 6 GHz unlicensed spectrum. In both LTE LAA and NR-U, DL and UL channel access for shared data channels (physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH)) employ a random backoff for channel sensing prior to transmission. The backoff is drawn from a binary exponential contention window (CW). The contention window size has a minimum limit CWmin and a maximum limit CWmax. On the DL, for LTE LAA the CW is reset to CWmin if at least 80% of the Hybrid Automatic Repeat Request (HARQ) acknowledgment (ACK) feedback bits for the last PDSCH subframe were ACKs. For NR-U, reset if at least one HARQ-ACK feedback is ‘ACK’ for PDSCH(s) with transport block based feedback or at least 10% of HARQ-ACK feedbacks is ‘ACK’ for PDSCH code clock group (CBGs) transmitted at least partially on the channel with code block group based feedback. Otherwise, the CW is doubled to the next feasible value with CWmax as the maximum possible value. On the UL, the CW is reset to CWmin for LAA LTE if the New Data Indicator (NDI) bit is toggled in a UL scheduling Downlink Control Information (DCI) or autonomous UL downlink feedback indication (AUL-DFI) indicates an ACK for PUSCH. For NR-U UL, reset if at least one implicit or explicit HARQ-ACK feedback is ‘ACK’ for PUSCH(s) with transport block (TB) based feedback or at least 10% of HARQ-ACK feedbacks are ‘ACK’ for PUSCH CBGs transmitted at least partially on the channel with code block group (CBG) based feedback. Otherwise, the CW is doubled to the next feasible value with CWmax as the maximum possible value. After initiating a channel occupancy (CO), with regard to a DL channel or an UL channel, with random backoff listen-before-talk (LBT), the gNB or UE can share the CO with another device that accesses the channel either without performing any LBT or performs a fixed-duration LBT. In Rel-18, the extension of NR sidelink (SL) operation to unlicensed spectrum (SL-U) in 5 GHz and 6 G Hz will be studied. SL has multiple peer-to-peer communication modes between two or more UEs, unlike DL and UL communication modes between a base station and a UE. SL was introduced in Rel-16 for vehicle-to-everything (V2X) scenarios and enhanced further in Rel-17. SL supports unicast, multicast (groupcast), and broadcast modes. A separate set of NR reference and physical channels have been introduced for SL operation. (See M. Harounabadi, D. M. Soleymani, S. Bhadauria, M. Leyh and E. Roth-Mandutz, “V2X in 3GPP Standardization: NR Sidelink in Release-16 and Beyond,” IEEE Communications Standards Magazine, vol. 5, no. 1, pp. 12-21, March 2021, doi: 10.1109/MCOMSTD.001.2000070) which is hereby expressly incorporated by reference). The set of NR reference and physical channels for SL operation include a Physical Sidelink Broadcast Channel (PSBCH), a Physical Sidelink Feedback Channel (PSFCH), a Physical Sidelink Shared Channel (PSSCH) and a Physical Sidelink Control Channel (PSCCH). Physical Sidelink Broadcast Channel (PSBCH) is for the SL-BCH transport channel where the Master Information Block (MIB) for SL is sent periodically (each 160 ms) and comprises system information for UE-to-UE communication (e.g., SL TDD configuration, in-coverage flag). PSBCH is transmitted along with the Sidelink Primary Synchronization Signal/Sidelink Secondary Synchronization Signal (S-PSS/SSS) in the S-SSB (see synchronization signals). Physical Sidelink Feedback Channel (PSFCH) is for HARQ feedback from a receiver UE to the transmitter UE on the SL for a unicast r groupcast communication. There is no HARQ feedback for broadcast mode. Physical Sidelink Shared Channel (PSSCH) is for user plane data, and Physical Sidelink Control Channel (PSCCH) is for scheduling and resource allocation. Resource pools are defined for SL, where a resour