# US 2021/0243073 A1 · Beam failure detection in a second band based on measurements in a first band > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0243073 A1 - Document ID: US20210243073A1 - Status: Published application - Kind: A1 - Application number: 17/158,656 - Filed: 2021-01-26 - Published: 2021-08-05 - Earliest claimed: 2020-01-31 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Hamed PEZESHKI; Arumugam CHENDAMARAI KANNAN; Tao LUO - Web page: https://patentgrep.com/patent/US20210243073A1 ## 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)} - G06N 3/0464: Convolutional networks [CNN, ConvNet] - G06N 3/09: Supervised learning - G06N 20/00: Machine learning - H04B 7/06964: {Re-selection of one or more beams after beam failure} - H04B 17/328: {Reference signal received power [RSRP]; Reference signal received quality [RSRQ]} - H04L 5/0023: {Time-frequency-space} - H04L 5/0085: {when channel conditions change} - H04L 41/0668: by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure - H04L 41/16: using machine learning or artificial intelligence - G06N 3/044: Recurrent networks, e.g. Hopfield networks - G06N 3/045: Combinations of networks - G06N 3/08: Learning methods - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS - H04B: TRANSMISSION ## Abstract Certain aspects of the present disclosure provide techniques for beam failure detection in a second band based on measurements in a first band. A method that may be performed by a user equipment (UE) includes receiving one or more reference signals (RSs) on a first radio frequency band and initiating a beam failure recovery on a second radio frequency band based, at least in part, on the one or more RSs on the first radio frequency band. The UE may measure the one or more RSs on the first radio frequency band and perform beam failure detection (BFD) for the second radio frequency band based, at least in part, on one or more measurements of the one or more RSs on the first radio frequency band. ## Claims ### Claim 1 A method for wireless communications by a user equipment (UE), comprising: receiving one or more reference signals (RSs) on a first radio frequency band; and initiating a beam failure recovery procedure for a second radio frequency band based, at least in part, on the one or more RSs received on the first radio frequency band. ### Claim 2 (depends on 1) The method of claim 1, further comprising: measuring the one or more RSs on the first radio frequency band; and performing beam failure detection (BFD) for the second radio frequency band based, at least in part, on one or more measurements of the one or more RSs on the first radio frequency band. ### Claim 3 (depends on 2) The method of claim 2, wherein performing BFD for the second radio frequency band comprises: estimating one or more channel parameters of the second radio frequency band using a machine learning (ML) algorithm with the one or more measurements of the one or more RSs on the first radio frequency band as input; and comparing the estimated one or more channel parameters of the second radio frequency band to a BFD threshold for the second radio frequency band. ### Claim 4 (depends on 3) The method of claim 3, wherein performing BFD for the second radio frequency band comprises: detecting beam failure for the second radio frequency band when the estimated one or more channel parameters of the second radio frequency band are below the BFD threshold for the second radio frequency band for at or above a threshold number of measurement instances. ### Claim 5 (depends on 3) The method of claim 3, wherein performing BFD for the second radio frequency band comprises: requesting one or more RSs on the second radio frequency band when the estimated one or more channel parameters of the second radio frequency band are within a predefined margin of the BFD threshold for the second radio frequency band; measuring the one or more RSs on the second radio frequency band; and comparing one or more measurements of the one or more RSs on the second radio frequency band to the BFD threshold for the second radio frequency band. ### Claim 6 (depends on 5) The method of claim 5, wherein requesting the one or more RSs on the second radio frequency band comprises requesting a base station (BS) to transmit one or more on-demand beam failure detection (BFD) RSs on the second radio frequency band. ### Claim 7 (depends on 2) The method of claim 2, wherein the one or more measurements on the first radio frequency band comprises one or more reference signal receive power (RSRP) measurements, one or more positioning measurements, one or more raw channel measurements, one or more channel impulse response (CIR) measurements, one or more angle of departure (AoD) measurements, one or more delay measurements, or a combination thereof. ### Claim 8 (depends on 2) The method of claim 2, wherein the estimated one or more channel parameters comprises estimated one or more reference signal receive power (RSRP) values. ### Claim 9 (depends on 1) The method of claim 1, wherein the first radio frequency band is in a sub-6 GHz radio frequency range and the second radio frequency band is in a millimeter wave (mmW) radio frequency range. ### Claim 10 A method for wireless communications by a base station (BS), comprising: sending a first one or more reference signals (RSs) to a user equipment (UE) on a first radio frequency band; receiving a request from the UE, in response to the first one or more RSs on the first radio frequency band, to send a second one or more RSs on a second radio frequency band; and sending the second one or more RSs to the UE on the second radio frequency band. ### Claim 11 (depends on 10) The method of claim 10, further comprising: receiving, from the UE, a beam failure recovery request message for the second radio frequency band. ### Claim 12 (depends on 10) The method of claim 10, wherein the first radio frequency band is in a sub-6 GHz radio frequency range and the second radio frequency band is in a millimeter wave (mmW) radio frequency range. ### Claim 13 (depends on 10) The method of claim 10, wherein receiving the request from the UE to send the second one or more RSs on the second radio frequency band comprises receiving the request on a physical uplink control channel (PUCCH). ### Claim 14 (depends on 10) The method of claim 10, wherein receiving the request from the UE to send the second one or more RSs on the second radio frequency band comprises receiving a request, from the UE, to transmit one or more on-demand beam failure detection (BFD) RSs on the second radio frequency band. ### Claim 15 An apparatus for wireless communications, comprising: a memory; and at least one processor coupled with the memory, the memory and processor configured to: receive one or more reference signals (RSs) on a first radio frequency band; and initiate a beam failure recovery procedure for a second radio frequency band based, at least in part, on the one or more RSs received on the first radio frequency band. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the memory and processor are further configured to: measure the one or more RSs on the first radio frequency band; and perform beam failure detection (BFD) for the second radio frequency band based, at least in part, on one or more measurements of the one or more RSs on the first radio frequency band. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the memory and processor are further configured to: estimate one or more channel parameters of the second radio frequency band using a machine learning (ML) algorithm with the one or more measurements of the one or more RSs on the first radio frequency band as input; and compare the estimated one or more channel parameters of the second radio frequency band to a BFD threshold for the second radio frequency band. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the memory and processor are configured to: detect beam failure for the second radio frequency band when the estimated one or more channel parameters of the second radio frequency band are below the BFD threshold for the second radio frequency band for at or above a threshold number of measurement instances. ### Claim 19 (depends on 17) The apparatus of claim 17, wherein the memory and processor are configured to: request one or more RSs on the second radio frequency band when the estimated one or more channel parameters of the second radio frequency band are within a predefined margin of the BFD threshold for the second radio frequency band; measure the one or more RSs on the second radio frequency band; and compare one or more measurements of the one or more RSs on the second radio frequency band to the BFD threshold for the second radio frequency band. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the memory and processor are configured to request a base station (BS) to transmit one or more on-demand beam failure detection (BFD) RSs on the second radio frequency band. ### Claim 21 (depends on 16) The apparatus of claim 16, wherein the one or more measurements on the first radio frequency band comprises one or more reference signal receive power (RSRP) measurements, one or more positioning measurements, one or more raw channel measurements, one or more channel impulse response (CIR) measurements, one or more angle of departure (AoD) measurements, one or more delay measurements, or a combination thereof. ### Claim 22 (depends on 16) The apparatus of claim 16, wherein the estimated one or more channel parameters comprises estimated one or more reference signal receive power (RSRP) values. ### Claim 23 (depends on 15) The apparatus of claim 15, wherein the first radio frequency band is in a sub-6 GHz radio frequency range and the second radio frequency band is in a millimeter wave (mmW) radio frequency range. ### Claim 24 An apparatus for wireless communications, comprising: a memory; and at least one processor coupled with the memory, the memory and processor configured to: send a first one or more reference signals (RSs) to a user equipment (UE) on a first radio frequency band; receive a request from the UE, in response to the first one or more RSs on the first radio frequency band, to send a second one or more RSs on a second radio frequency band; and send the second one or more RSs to the UE on the second radio frequency band. ### Claim 25 (depends on 24) The apparatus of claim 24, wherein the memory and processor are configured to: receive, from the UE, a beam failure recovery request message for the second radio frequency band. ### Claim 26 (depends on 24) The apparatus of claim 24, wherein the first radio frequency band is in a sub-6 GHz radio frequency range and the second radio frequency band is in a millimeter wave (mmW) radio frequency range. ### Claim 27 (depends on 24) The apparatus of claim 24, wherein the memory and processor are configured to receive the request on a physical uplink control channel (PUCCH). ### Claim 28 (depends on 24) The apparatus of claim 24, wherein the memory and processor are configured to receive a request, from the UE, to transmit one or more on-demand beam failure detection (BFD) RSs on the second radio frequency band.