# US 2023/0057052 A1 · Techniques for reference signal bundling in sidelink channels > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0057052 A1 - Document ID: US20230057052A1 - Status: Published application - Kind: A1 - Application number: 17/405,899 - Filed: 2021-08-18 - Published: 2023-02-23 - Earliest claimed: 2021-08-18 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Ahmed Elshafie; Hung Dinh Ly; Seyedkianoush Hosseini; Wei Yang - Web page: https://patentgrep.com/patent/US20230057052A1 ## CPC - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 25/0224: {using sounding signals} - H04L 25/0202: {Channel estimation} - H04L 25/0204: {of multiple channels} - H04W 92/18: between terminal devices - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Methods, systems, and devices for wireless communication are described, including techniques for utilizing implicit or explicit signaling to indicate a cancellation of demodulation reference signal (DMRS) bundling. A first user equipment (UE) may perform DMRS bundling across physical sidelink channels transmitted to a second UE to enable the second UE to perform joint channel estimation. In some examples, based on a detected change, either at the first UE or the second UE, the first UE may signal to the second UE that the DMRS bundling is canceled. In some examples, the detected change may be a resource allocation change, a physical channel configuration change, a change in a quasi-colocation (QCL) relationship at the first UE, or a change in a transmission configuration indicator (TCI) state at the first UE. Additionally or alternatively, the first UE or the second UE may request the cancellation based on detected changes. ## Claims ### Claim 1 A method for wireless communication at a first user equipment (UE), comprising: transmitting, to a second UE, first control signaling indicating a joint channel estimation procedure for a sidelink connection based at least in part on a set of reference signals from the second UE; determining a change in one or more channel parameters of the sidelink connection after the first control signaling is transmitted; transmitting, to the second UE, second control signaling indicating a cancellation of the joint channel estimation procedure for the sidelink connection based at least in part on determining the change in the one or more channel parameters; and transmitting one or more reference signals of the set of reference signals based at least in part on receiving the second control signaling, at least one reference signal associated with a channel estimation procedure for the sidelink connection. ### Claim 2 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of a resource allocation associated with the set of reference signals, wherein the change in the one or more channel parameters comprises the resource allocation, and wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the resource allocation. ### Claim 3 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of one or more resource blocks allocated for a sidelink feedback channel, wherein the change in the one or more channel parameters comprises the one or more resource blocks allocated for the sidelink feedback channel, and wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the one or more resource blocks. ### Claim 4 (depends on 3) The method of claim 3, wherein a resource allocation associated with one or more reference signals of the set of reference signals is based at least in part on a mapping of the one or more resource blocks allocated for the sidelink feedback channel. ### Claim 5 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of a quasi-colocation relationship at the first UE, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the quasi-colocation parameter. ### Claim 6 (depends on 5) The method of claim 5, wherein the indication of the quasi-colocation relationship is a last indication of a set of indications of the quasi-colocation relationship. ### Claim 7 (depends on 5) The method of claim 5, wherein the quasi-colocation relationship is different from a previous quasi-colocation relationship, and the change in the one or more channel parameters comprises a change from the previous quasi-colocation relationship to the quasi-colocation relationship. ### Claim 8 (depends on 5) The method of claim 5, wherein the change in the one or more channel parameters comprises the quasi-colocation relationship. ### Claim 9 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of a transmission configuration indicator state for the first UE, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the transmission configuration indicator state. ### Claim 10 (depends on 9) The method of claim 9, wherein the indication of the transmission configuration indicator state is a last indication of a set of indications of the transmission configuration indicator state for the first UE. ### Claim 11 (depends on 9) The method of claim 9, wherein the transmission configuration indicator state is different from a previous transmission configuration indicator state, and the change in the one or more channel parameters comprises a change from the previous transmission configuration indicator state to the transmission configuration indicator state. ### Claim 12 (depends on 9) The method of claim 9, wherein the change in the one or more channel parameters comprises the transmission configuration indicator state. ### Claim 13 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of a phase coherency identifier, a continuity identifier, or both, associated with the set of reference signals, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the phase coherency identifier, the continuity identifier, or both. ### Claim 14 (depends on 1) The method of claim 1, further comprising: receiving, from the second UE, signaling indicating a request to cancel the first joint channel estimation procedure, wherein the change in the one or more channel parameters is determined based at least in part on receiving the signaling. ### Claim 15 (depends on 14) The method of claim 14, further comprising: identifying one or more coherency process identifiers in the signaling, each coherency process identifier associated with a respective reference signal of the set of reference signals; and identifying the request to cancel the joint channel estimation procedure based at least in part on identifying the one or more coherency process identifiers. ### Claim 16 (depends on 1) The method of claim 1, further comprising: deactivating a power amplifier at the first UE based at least in part on transmitting the second control signaling. ### Claim 17 (depends on 1) The method of claim 1, wherein transmitting the second control signaling comprises: transmitting, in the second control signaling, an indication of one or more coherency process identifiers, each coherency process identifier associated with a respective reference signal of the set of reference signals, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is based at least in part on the one or more coherency process identifiers. ### Claim 18 (depends on 1) The method of claim 1, wherein: the first control signaling comprises a first radio resource control message, a first medium access control control element, a first sidelink control information message, or any combination thereof; and the second control signaling comprises a second radio resource control message, a second medium access control control element, a second sidelink control information message, or any combination thereof. ### Claim 19 A method for wireless communication at a first user equipment (UE), comprising: receiving, from a second UE, first control signaling indicating a joint channel estimation procedure for a sidelink connection based at least in part on a set of reference signals from the second UE; receiving, from the second UE, second control signaling indicating a cancellation of the joint channel estimation procedure for the sidelink connection based at least in part on a change in one or more channel parameters; monitoring for one or more reference signals of the set of reference signals based at least in part on transmitting the second control signaling; and performing a channel estimation procedure for the sidelink connection using at least one reference signal received based at least in part on monitoring for the one or more reference signals. ### Claim 20 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of a resource allocation associated with the set of reference signals, wherein the change in the one or more channel parameters comprises the resource allocation, and wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the resource allocation. ### Claim 21 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of one or more resource blocks allocated for a sidelink feedback channel, wherein the change in the one or more channel parameters comprises the one or more resource blocks allocated for the sidelink feedback channel, and wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the one or more resource blocks. ### Claim 22 (depends on 21) The method of claim 21, wherein a resource allocation associated with one or more reference signals of the set of reference signals is based at least in part on a mapping of the one or more resource blocks allocated for the sidelink feedback channel. ### Claim 23 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of a quasi-colocation relationship at the second UE, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the quasi-colocation parameter. ### Claim 24 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of a transmission configuration indicator state for the second UE, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the transmission configuration indicator state. ### Claim 25 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of a phase coherency identifier, a continuity identifier, or both, associated with the set of reference signals, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the phase coherency identifier, the continuity identifier, or both. ### Claim 26 (depends on 19) The method of claim 19, further comprising: transmitting, to the second UE, signaling indicating a request to cancel the first joint channel estimation procedure, wherein the change in the one or more channel parameters is based at least in part on transmitting the signaling. ### Claim 27 (depends on 26) The method of claim 26, wherein transmitting the signaling comprises: transmitting, in the signaling, one or more coherency process identifiers, each coherency process identifier associated with a respective reference signal of the set of reference signals, wherein the request to cancel the joint channel estimation procedure is indicated based at least in part on the one or more coherency process identifiers. ### Claim 28 (depends on 19) The method of claim 19, further comprising: identifying, in the second control signaling, an indication of one or more coherency process identifiers, each coherency process identifier associated with a respective reference signal of the set of reference signals, wherein the cancellation of the joint channel estimation procedure for the sidelink connection is indicated based at least in part on the one or more coherency process identifiers. ### Claim 29 An apparatus for wireless communication at a first user equipment (UE), comprising: a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: transmit, to a second UE, first control signaling indicating a joint channel estimation procedure for a sidelink connection based at least in part on a set of reference signals from the second UE; determine a change in one or more channel parameters of the sidelink connection after the first control signaling is transmitted; transmit, to the second UE, second control signaling indicating a cancellation of the joint channel estimation procedure for the sidelink connection based at least in part on determining the change in the one or more channel parameters; and transmit one or more reference signals of the set of reference signals based at least in part on receiving the second control signaling, at least one reference signal associated with a channel estimation procedure for the sidelink connection. ### Claim 30 An apparatus for wireless communication at a first user equipment (UE), comprising: a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: receive, from a second UE, first control signaling indicating a joint channel estimation procedure for a sidelink connection based at least in part on a set of reference signals from the second UE; receive, from the second UE, second control signaling indicating a cancellation of the joint channel estimation procedure for the sidelink connection based at least in part on a change in one or more channel parameters; monitor for one or more reference signals of the set of reference signals based at least in part on transmitting the second control signaling; and perform a channel estimation procedure for the sidelink connection using at least one reference signal received based at least in part on monitoring for the one or more reference signals.