# US 11,121,765 B2 · Method and apparatus for signal configuration for mobile base station > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,121,765 B2 - Document ID: US11121765B2 - Status: Granted - Kind: B2 - Application number: 16/681,736 - Filed: 2019-11-12 - Published: 2020-05-14 - Granted: 2021-09-14 - Earliest claimed: 2018-11-13 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Ji Hyung Kim; Mi Young Yun - Web page: https://patentgrep.com/patent/US11121765B2 ## CPC - H04B 7/18541: {for handover of resources} - H04B 7/18513: {Transmission in a satellite or space-based system} - H04B 17/382: for resource allocation, admission control or handover - H04W 36/083: {wherein at least one of the access points is a moving node} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 56/0065: {using measurement of signal travel time} - H04W 72/27: between access points - H04W 74/006: {in the downlink, i.e. towards the terminal} - H04W 76/27: Transitions between radio resource control [RRC] states - H04W 80/02: Data link layer protocols - H04W 84/06: Airborne or Satellite Networks (space-based or airborne stations H04B7/185) - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A handover method for a satellite base station, performed by a terminal, may comprise selecting at least one candidate satellite base station; performing signal strength measurement on a first candidate satellite base station among the at least one candidate satellite base station; in response to determining that the first candidate satellite base station is available according to a result of the signal strength measurement, selecting the first candidate satellite base station as a target satellite base station; and in response to determining that the first candidate satellite base station is not available according to the result of the signal strength measurement, performing signal strength measurement on a second candidate satellite base station among the at least one candidate satellite base station. ## Claims ### Claim 1 A timing adjustment method with a satellite base station, performed by a terminal, the timing adjustment method comprising: receiving a reference time delay value from the satellite base station; receiving a timing advance command from the satellite base station; and calculating an actual time delay value between the terminal and the satellite base station by using the reference time delay value and a value included in the timing advance command, and updating a timing advance value of the terminal for the satellite base station by using the calculated actual time delay value, wherein the value included in the timing advance command for initial access, timing advance maintenance, handover, or beam switching has a positive or negative value depending on the reference time delay value, and wherein the reference time delay value is received from the satellite base station through at least one of a physical downlink control channel (PDCCH), a radio resource control (RRC) signaling, and a medium access control (MAC) control element (CE), or received from the satellite base station as included in ephemeris of the satellite base station. ### Claim 2 (depends on 1) The timing adjustment method according to claim 1, wherein the reference time delay value is a representative time delay value between the satellite base station and the terminal, which corresponds to a specific time point, a specific time interval, or a specific position of the satellite base station. ### Claim 3 (depends on 1) The timing adjustment method according to claim 1, wherein when a new time delay value replacing the reference time delay value is received in a slot n, the terminal uses the new time delay value from a beginning of a slot (n+k+1) for calculating the actual time delay value between the terminal and the satellite base station, wherein each of n and k is an integer equal to or greater than 0. ### Claim 4 (depends on 3) The timing adjustment method according to claim 3, wherein k is defined as k=[Nslotsubframe,μ·(NT,1+NT,2+NTA,max+0.5)/Tsf], NT,1 is a time length of N1 symbols corresponding to a physical downlink shared channel (PDSCH) reception time for processing capability of the terminal when an additional PDSCH demodulation reference signal (DM-RS) is configured, NT,2 is a time length of N2 symbols corresponding to a physical uplink shared channel (PUSCH) preparation time for processing capability of the terminal, NTA,max is a maximum time delay within a cell of the satellite base station, Nslotsubframe,μ is a number of slots per subframe, and Tsf is a time length of a subframe of 1 msec. ### Claim 5 (depends on 2) The timing adjustment method according to claim 2, wherein the reference time delay value is set to a maximum time delay between the satellite base station and the terminal, a minimum time delay between the satellite base station and the terminal, or a time delay between a center of a cell and the satellite base station. ### Claim 6 A method for receiving signals from a first satellite base station and a second satellite base station, performed by a terminal, the method comprising: obtaining information on a first bandwidth part (BWP) of the first satellite base station that is a serving base station, and information on a second BWP of the second satellite base station; providing information on a current position of the terminal to the first satellite base station; obtaining an estimated time delay value between the terminal and the second satellite base station from the first satellite base station; and estimating a time point at which a signal of the second satellite base station arrives at the terminal based on the estimated time delay value, and monitoring the second BWP for a period within a predetermined time range from the estimated time point, wherein the first satellite base station and the second satellite base station transmit signals at a same time. ### Claim 7 (depends on 6) The method according to claim 6, wherein the information on the first BWP and the information on the second BWP are received from one of the first satellite base station and the second satellite base station through at least one of a physical downlink control channel (PDCCH), a medium access control (MAC) control element (CE), and a radio resource control (RRC) signaling, or received respectively from the first satellite base station and the second satellite base station through at least one of a PDCCH, a MAC CE, and an RRC signaling. ### Claim 8 (depends on 6) The method according to claim 6, wherein the information on the first BWP is received from the first satellite base station as included in ephemeris of the first satellite base station, and the information on the second BWP is received from the second satellite base station as included in ephemeris of the second satellite base station. ### Claim 9 (depends on 6) The method according to claim 6, wherein a guard band is configured between the first BWP and the second BWP. ### Claim 10 (depends on 6) The method according to claim 6, wherein each of the first BWP and the second BWP is configured periodically, semi-persistently, or semi-periodically. ### Claim 11 (depends on 6) The method according to claim 6, wherein the obtaining of the estimated time delay value further comprises: receiving a difference value between a reference time delay value of the first satellite base station and the estimated time delay value from the first satellite base station; and calculating the estimated time delay value using the difference value and the reference time delay value. ### Claim 12 (depends on 11) The method according to claim 11, wherein the reference time delay value is a representative time delay value between the first satellite base station and the terminal, which corresponds to a specific time point, a specific time interval, or a specific position of the first satellite base station. ### Claim 13 A timing adjustment method with a satellite base station, performed by a terminal, the timing adjustment method comprising: receiving, from the satellite base station, information related to a position of the satellite base station or a delay time (v) between the satellite base station and the terminal; when receiving the information related to the position of the satellite base station from the satellite base station, calculating the delay time (v) based on a position of the terminal and the position of the satellite base station; and transmitting a physical random access channel (PRACH) at a time (t−v) earlier by the delay time v than a configured transmission time t of the PRACH. ### Claim 14 (depends on 13) The timing adjustment method according to claim 13, further comprising, when an initial access by the transmission of the PRACH fails, re-transmitting the PRACH at a time (t−v−toffset) or (t−v+toffset) by applying a time offset toffset.