# US 10,772,125 B2 · Systems and methods for a spatial listen-before-talk protocol > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,772,125 B2 - Document ID: US10772125B2 - Status: Granted - Kind: B2 - Application number: 16/112,444 - Filed: 2018-08-24 - Published: 2019-06-27 - Granted: 2020-09-08 - Earliest claimed: 2017-08-28 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Yisheng Xue; Qingsi Wang; Siddhartha Mallik; Weiliang Zeng; Ahmed Sadek - Web page: https://patentgrep.com/patent/US10772125B2 ## CPC - H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA] - H04B 7/0617: {for beam forming} - H04W 72/0473: {the resource being transmission power} - H04W 74/002: {Transmission of channel access control information} - H04W 74/0816: with collision avoidance - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION ## Abstract A method, apparatus, and computer-readable medium at a transmitting network device or a target network device in a listen-before-talk (LBT) session that employ a spatial LBT procedure is disclosed. The spatial LBT procedure takes into account multiple-input multiple-output (MIMO) configuration information in measuring an effective interference. Accordingly, the spatial LBT procedure enables the transmitting network device or the target network device to more accurately measure an interference and make a more accurate decision on whether a channel is clear, and thus improves the system-wide performance. Also, the spatial LBT procedure allows the transmitting network device or the target/receiving network device to adaptively adjust the LBT power detection threshold when the MIMO configuration is not available. This also enables the network devices to more accurately measure interference and make a more accurate decision on whether the channel is clear, especially when advanced MIMO technologies are deployed in 5G or beyond. ## Claims ### Claim 1 A method for wireless communication at a transmitting network device in a listen-before-talk (LBT) session, comprising: determining multiple input multiple output (MIMO) configuration information for the transmitting network device, wherein the determining comprises determining for the LBT session at least: whether the MIMO configuration information is available; and if the MIMO configuration information is available, at least one of: a MIMO rank, a number of transmit antennas, a number of receive antennas, a transmit beamforming (TxBF) matrix, or a receive beamforming (RxBF) matrix; performing a contention-based access protocol procedure to determine whether a wireless transmission channel is clear for transmitting data to a target network device, based on the determined MIMO configuration information, wherein performing the contention-based access protocol procedure comprises adaptive performing of a spatial LBT procedure, based on the MIMO configuration information; and transmitting a broadcast message, prior to transmitting data to the target network device, the broadcast message including at least part of the MIMO configuration information, when the contention-based access protocol procedure indicates that the wireless transmission channel is clear. ### Claim 2 (depends on 1) The method of claim 1, wherein the contention-based access protocol procedure comprises a clear channel assessment (CCA) procedure or an enhanced CCA (eCCA) protocol procedure and the broadcast message is a request to send (RTS) message for the LBT session. ### Claim 3 (depends on 1) The method of claim 1, wherein the MIMO configuration information is embedded in a header of an existing broadcast message. ### Claim 4 (depends on 1) The method of claim 1, wherein the wireless transmission channel is one of a licensed frequency band, an unlicensed frequency band, or a shared frequency band for an asynchronous wireless system. ### Claim 5 (depends on 1) The method of claim 1, wherein the adaptive performing of the spatial LBT procedure further comprises: computing an effective interference measurement based at least in part on the TxBF matrix and the RxBF matrix of the MIMO configuration information; and comparing the effective interference measurement with a default LBT power detection (PD) threshold to determine if the wireless transmission channel is clear. ### Claim 6 (depends on 5) The method of claim 5, wherein the adaptive performing of the spatial LBT procedure further comprises: computing an omni-directional preamble-based interference from a second transmitting network device to the transmitting network device in addition to the effective interference measurement. ### Claim 7 (depends on 1) The method of claim 1, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold for the transmitting network device when only a part of the MIMO configuration information is available that does not allow the transmitting network device to estimate an effective interference level but sufficient to determine that an ongoing or incoming data transmission is of a rank lower than a full rank of the transmitting network device. ### Claim 8 (depends on 7) The method of claim 7, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold when a transmit power is lower than needed for the full rank of the transmitting network device for an ongoing or an incoming data transmission and when the MIMO configuration information is not available. ### Claim 9 (depends on 1) The method of claim 1, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold when a lower MIMO rank is determined from a blind signal processing on an ongoing or incoming data transmission while rank information is not present in the MIMO configuration information. ### Claim 10 (depends on 1) The method of claim 1, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold when a low MIMO rank is determined from a static MIMO configuration without listening to the wireless transmission channel or when a MIMO configuration of the transmitting network device is asymmetric. ### Claim 11 (depends on 1) The method of claim 1, wherein the adaptive performing of the spatial LBT procedure further comprises: using an omni-directional preamble-based interference measurement for LBT PD threshold when the MIMO configuration information is not available. ### Claim 12 An apparatus for wireless communication at a transmitting network device in a listen-before-talk (LBT) session, comprising: means for determining multiple input multiple output (MIMO) configuration information for the transmitting network device; means for performing a contention-based access protocol procedure to determine whether a wireless transmission channel is clear for transmitting data to a target network device, based on the determined MIMO configuration information, wherein the content-based access protocol procedure comprises a clear channel assessment (CCA) procedure or an enhanced CCA (eCCA) protocol procedure and the broadcast message comprises a request to send (RTS) message for the LBT session and wherein the means to perform the CCA or eCCA procedure comprises adaptive performing of a spatial LBT procedure, based on the MIMO configuration information; and means for transmitting a broadcast message, prior to transmitting data to the target network device, the broadcast message including at least part of the MIMO configuration information, when the contention-based access protocol procedure indicates that the wireless transmission channel is clear. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the adaptive performing of the spatial LBT procedure further comprises: computing an effective interference measurement based at least in part on the TxBF matrix and the RxBF matrix of the MIMO configuration information; and comparing the effective interference measurement with a default LBT power detection (PD) threshold to determine if the wireless transmission channel is clear. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the adaptive performing of the spatial LBT procedure further comprises: computing an omni-directional preamble-based interference from a second transmitting network device to the transmitting network device in addition to the effective interference measurement when the MIMO configuration information is available. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold for the transmitting network device when only a part of the MIMO configuration information is available that does not allow the transmitting network device to estimate an effective interference level but sufficient to determine that an ongoing or incoming data transmission is of a rank lower than a full rank of the transmitting network device. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the adaptive performing of the spatial LBT procedure further comprises: using a larger LBT PD threshold when a transmit power is lower than needed for the full rank of the transmitting network device for an ongoing or an incoming data transmission and when the MIMO configuration is not available. ### Claim 17 (depends on 12) The apparatus of claim 12, wherein the adaptive performing of the spatial LBT procedure further comprises one of: using a larger LBT PD threshold when a lower MIMO rank is determined from a blind signal processing on an ongoing or incoming data transmission while rank information is not present in the MIMO configuration information; and using a larger LBT PD threshold when a low MIMO rank is determined from a static MIMO configuration without listening to the wireless transmission channel or when a MIMO configuration of the transmitting network device is asymmetric. ### Claim 18 (depends on 12) The apparatus of claim 12, wherein the adaptive performing of the spatial LBT procedure further comprises: using an omni-directional preamble-based interference measurement for LBT PD threshold when the MIMO configuration information is not available. ### Claim 19 An apparatus for wireless communication at a transmitting network device, comprising: a memory; and at least one processor coupled to the memory and configured to: to determine multiple input multiple output (MIMO) configuration information for the transmitting network device; to perform a content-based access protocol procedure to determine whether a wireless transmission channel is clear for transmitting data to a target network device, based on the determined MIMO configuration information, wherein the contention-based access protocol procedure comprises a clear channel assessment (CCA) protocol procedure or an enhanced CCA (eCCA) protocol procedure and the broadcast message is a request to send (RTS) message for the LBT session and wherein means to perform the CCA or eCCA procedure comprises adaptive performing of a spatial LBT procedure, based on the MIMO configuration information; and to transmit a broadcast message, prior to transmitting data to the target network device, the broadcast message including at least part of the MIMO configuration information, when the content-based access protocol procedure indicates that the wireless transmission channel is clear. ### Claim 20 A method for wireless communication at a target network device in a listen-before-talk (LBT) session, comprising: receiving from a transmitting network device a first broadcast message over a wireless transmission channel; determining first multiple input multiple output (MIMO) configuration information of the transmitting network device from the received first broadcast message; performing a contention-based access protocol procedure to determine whether the wireless transmission channel is clear for transmitting a signal to the transmitting network device, based on the determined MIMO configuration information, wherein the contention-based access protocol procedure comprises a clear channel assessment (CCA) or an enhanced CCA (eCCA) protocol and the first broadcast message is a request to send (RTS) message for the LBT session and wherein the performing of the CCA or eCCA procedure further comprises adaptive performing of a spatial LBT procedure, based on the first MIMO configuration information; and transmitting a second broadcast message to the transmitting network device, the second broadcast message including second MIMO configuration information based on the determined first MIMO configuration information, when the first MIMO configuration information is available from the received first broadcast message and when the contention-based access protocol procedure indicates that the wireless transmission channel is clear for transmission. ### Claim 21 (depends on 20) The method of claim 20, wherein the adaptive performing of the spatial LBT procedure further comprises one or more of: computing an effective interference measurement based at least in part on the TxBF matrix and the RxBF matrix of the first MIMO configuration information when the first MIMO configuration information is available; comparing the effective interference measurement with a default LBT power detection (PD) threshold to determine if the wireless transmission channel is clear; computing an omni-directional preamble-based interference from a second transmitting network device to the target network device in addition to the effective interference measurement when the first MIMO configuration information is available; using a larger LBT PD threshold when only a part of the first MIMO configuration information is available that does not allow the target network device to estimate an effective interference level but sufficient to determine that an ongoing or incoming data reception is of a rank lower than a full rank of the target network device. ### Claim 22 (depends on 20) The method of claim 20, wherein the adaptive performing of the spatial LBT procedure further comprises one or more of: using a larger LBT PD threshold when a receive power is lower than needed for a full rank of the target network device for an ongoing or an incoming data reception; using a larger LBT PD threshold when a lower MIMO rank is determined from a blind signal processing on an ongoing or incoming data reception while rank information is not present in the first MIMO configuration information; using a larger LBT PD threshold when a low MIMO rank is determined from a static MIMO configuration indicated in the first MIMO configuration information without listening to the wireless transmission channel or when a MIMO configuration of the target network device is asymmetric; and using an omni-directional preamble-based interference measurement for LBT PD threshold when the first MIMO configuration information is not available.