# US 11,310,858 B2 · Method and apparatus for managing radio link in unlicensed band > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,858 B2 - Document ID: US11310858B2 - Status: Granted - Kind: B2 - Application number: 16/639,524 - Filed: 2018-08-14 - Published: 2020-07-23 - Granted: 2022-04-19 - Earliest claimed: 2017-08-16 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Joonkui Ahn; Sukhyon Yoon; Hanjun Park; Changhwan Park; Seonwook Kim - Web page: https://patentgrep.com/patent/US11310858B2 ## CPC - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04W 76/18: Management of setup rejection or failure - 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 27/0006: {Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio (for spectrum sharing between different networks H04W16/14)} - H04W 24/08: Testing, {supervising or monitoring} using real traffic - H04W 48/16: Discovering, processing access restriction or access information - H04W 48/20: Selecting an access point - H04W 56/00: Synchronisation arrangements - H04B 7/0617: {for beam forming} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION ## Abstract A method for managing a radio link in an unlicensed band is provided. An apparatus attempts to receive a discovery reference signal (DRS) in a serving cell that is operated in the unlicensed band. The apparatus determines that a radio link to the serving cell has failed if the DRS is not received for a predetermined time. ## Claims ### Claim 1 A method for managing a radio link by a wireless device in an unlicensed band, the method comprising: receiving information from a base station, wherein the information informs a time duration for receiving a discovery reference signal (DRS), a first number of DRS receptions for determining radio link failure, and a second number of DRS receptions for determining beam recovery; attempting to receive the DRS in a serving cell operating in the unlicensed band within the time duration; declaring a radio link with the serving cell has failed based on the DRS not being received more than the first number within the time duration; and performing a beam recovery procedure based on the DRS not being received more than the second number within the time duration. ### Claim 2 (depends on 1) The method of claim 1, wherein the DRS includes a downlink (DL) signal for maintaining synchronization with the serving cell. ### Claim 3 (depends on 2) The method of claim 2, wherein the DRS includes at least one of a synchronization signal/physical broadcast channel (SSB) block and a channel state information-reference signal (CSI-RS). ### Claim 4 (depends on 1) The method of claim 1, wherein, if reception quality of the received DRS is lower than a reception threshold even if the DRS is received, it is regarded that the DRS is not received. ### Claim 5 (depends on 4) The method of claim 4, further comprising: measuring DL reception quality of the serving cell; and determining that the radio link with the serving cell has failed if the DL reception quality is lower than a DL threshold. ### Claim 6 (depends on 5) The method of claim 5, wherein the reception threshold is less than the DL threshold. ### Claim 7 (depends on 1) The method of claim 1, further comprising: performing cell reselection for selecting a new cell if it is determined that the radio link with the serving cell has failed. ### Claim 8 A device for managing a radio link in an unlicensed band, the device comprising: a transceiver configured to transmit and receive a radio signal; and a processor operatively coupled with the transceiver and configured to: receive information from a base station, wherein the information informs a time duration for receiving a discovery reference signal (DRS), a first number of DRS receptions for determining radio link failure, and a second number of DRS receptions for determining beam recovery; attempt to receive the DRS in a serving cell operating in the unlicensed band within the time duration; declare a radio link with the serving cell has failed based on the DRS not being received more than the first number within the time duration; and perform a beam recovery procedure based on the DRS not being received more than the second number within the time duration. ### Claim 9 (depends on 8) The device of claim 8, wherein the DRS includes a downlink (DL) signal for maintaining synchronization with the serving cell. ### Claim 10 (depends on 9) The device of claim 9, wherein the DRS includes at least one of a synchronization signal/physical broadcast channel (SSB) block and a channel state information-reference signal (CSI-RS). ### Claim 11 (depends on 8) The device of claim 8, wherein, if reception quality of the received DRS is lower than a reception threshold even if the DRS is received, it is regarded that the DRS is not received. ### Claim 12 (depends on 11) The device of claim 11, wherein the processor is configured to: measure DL reception quality of the serving cell; and determine that the radio link with the serving cell has failed if the DL reception quality is lower than a DL threshold. ### Claim 13 (depends on 12) The device of claim 12, wherein the reception threshold is less than the DL threshold.