Measurement configuration in non-terrestrial network (NTN)
A method includes receiving a measurement configuration from a serving cell of a user equipment (UE) in a non-terrestrial network (NTN) providing mobile communication service based on satellites. The satellites can be low Earth orbiting (LEO) satellites, geostationary Earth orbiting (GEO) satellites, and the like. The measurement configuration indicates a first synchronization signal block (SSB) based measurement timing configuration (SMTC) and a second SMTC. The first SMTC specifies first SMTC windows aligning with SSB signals from the serving cell of the UE. The second SMTC specifies second SMTC windows aligning with SSB signals from a first neighbor cell of the UE. The serving cell is associated with a first flying object, and the first neighbor cell is associated with a second flying object. The UE performs a measurement based on the first SMTC corresponding to the serving cell and the second SMTC corresponding to the first neighbor cell.
1. A method, comprising:
receiving a measurement configuration from a serving cell of a user equipment (UE) in a non-terrestrial network (NTN) providing mobile communication service based on satellites belonging to the NTN, the satellites being low Earth orbiting (LEO) satellites or geostationary Earth orbiting (GEO) satellites, the measurement configuration indicating a first synchronization signal block (SSB) based measurement timing configuration (SMTC) and a second SMTC, the first SMTC specifying first SMTC windows aligning with SSB signals from the serving cell of the UE, the second SMTC specifying second SMTC windows aligning with SSB signals from a first neighbor cell of the UE, the serving cell associated with a first satellite, the first neighbor cell associated with a second satellite, a third SMTC that specifies third SMTC windows aligning with SSB signals of a second neighbor cell of the UE operating on a second carrier, and a fourth SMTC that specifies fourth SMTC windows aligning with SSB signals of a third neighbor cell of the UE operating on the second carrier, and wherein the measurement configuration further indicates a first measurement gap configuration corresponding to the second neighbor cell and a second measurement gap configuration corresponding to the third neighbor cell, the first measurement gap specifying measurement gaps that are aligned with the third SMTC windows, the second measurement gap specifying measurement gaps that are aligned with the fourth SMTC windows;
performing a measurement based on the first SMTC corresponding to the serving cell and the second SMTC corresponding to the first neighbor cell; and
performing a measurement on the second carrier based on the first measurement gap configuration, the second measurement gap configuration, the third SMTC, and the fourth SMTC
receiving information indicating a position of the second satellite associated with the first neighbor cell from the serving cell;
determining an SMTC offset based on the position of the second satellite associated with the first neighbor cell, the SMTC offset being based on a timing of the serving cell, the SMTC offset being one of:
a time offset with respect to the first SMTC,
a time offset with respect to the second SMTC, or
a time offset indicating a starting position of an SMTC window within a periodicity of the second SMTC; and
reporting a service link propagation delay difference between the serving cell and the first neighbor cell based on the SMTC offset.
2. The method of claim 1 , wherein the serving cell and the first neighbor cell operates on a first carrier.
3. The method of claim 1 , wherein the information indicating the position of the second satellite includes one of:
position-velocity-time (PVT) information of the second satellite, or
orbital ephemeris parameters of the second satellite.
4. The method of claim 3 , wherein the information further indicates a feeder link delay of the first neighbor cell.
5. The method of claim 1 , further comprising:
determining a measurement gap offset based on a position of a third satellite associated with the second neighbor cell, the measurement gap offset being based on a timing of the serving cell, the measurement gap offset being one of:
a time offset with respect to the first measurement gap configuration corresponding to the second neighbor cell,
a time offset with respect to the first SMTC,
a time offset indicating a starting position of a measurement gap within a periodicity of the first measurement gap configuration corresponding to the second neighbor cell; and
transmitting the measurement gap offset to the serving cell.
6. The method of claim 5 , further comprising:
receiving from the serving cell an updated measurement configuration indicating:
a fifth SMTC corresponding to the first neighbor cell of the UE and determined based on the SMTC offset, and
a third measurement gap configuration corresponding to the second neighbor cell and determined based on the measurement gap offset.
7. The method of claim 6 , wherein the updated measurement configuration indicates the fifth SMTC by providing the SMTC offset and the third measurement gap configuration by providing the measurement gap offset.
8. The method of claim 6 , wherein the updated measurement configuration is received using a MAC CE or RRC signaling.
9. The method of claim 6 , further comprising:
transmitting a MAC CE, a HARQ feedback, or an RNTI to the serving cell to confirm reception of the updated measurement configuration.
10. The method of claim 5 , further comprising:
receiving from the serving cell a confirmation corresponding to one of the SMTC offset and the measurement gap offset.
11. The method of claim 1 , further comprising:
transmitting information indicating a location of the UE to the serving cell; and
receiving an update indicating an SMTC offset corresponding to one of the first, second, and third neighbor cells and a measurement gap offset corresponding to one of the second and third neighbor cells.
12. The method of claim 1 , further comprising:
receiving periodically an update of an ephemeris, PVT information, and/or a feeder link delay of the second satellite associated with the first neighbor cell from the serving cell through one or a combination of a system information block (SIB), a radio resource control (RRC) signaling, and a MAC control element (CE).
13. The method of claim 1 , further comprising:
determining an SMTC offset corresponding to the first neighbor cell based on a long-term ephemeris of the second satellite;
determining a measurement gap offset corresponding to the second neighbor cell based on a long-term ephemeris of a third satellite associated with the second neighbor cell; and
transmitting the SMTC offset and the measurement gap offset to the serving cell.
14. The method of claim 1 , further comprising:
transmitting an SMTC offset and a measurement gap offset in response to one of:
an SSB signal moving out of the measurement gaps specified by one of the first and second measurement gap configurations,
a request from the serving cell,
a propagation delay of one of the first, second, and third neighbor cells changing by an amount equal to a threshold,
expiry of a timer, and
a location change of the UE by a certain margin.
15. The method of claim 1 , wherein the SSB signals of the second neighbor cell include:
a sequence of periodically transmitted first SSB bursts, and for each first SSB burst overlapping with the measurement gaps of the first measurement gap configuration, a second SSB burst that is adjacent to the respective first SSB burst in time domain.
16. An apparatus, comprising circuitry configured to:
receive a measurement configuration from a serving cell of a user equipment (UE) in a non-terrestrial network (NTN) providing mobile communication service based on satellites belonging to the NTN, the satellites being low Earth orbiting (LEO) satellites or geostationary Earth orbiting (GEO) satellites, the measurement configuration indicating a first synchronization signal block (SSB) based measurement timing configuration (SMTC) and a second SMTC, the first SMTC specifying first SMTC windows aligning with SSB signals from the serving cell of the UE, the second SMTC specifying second SMTC windows aligning with SSB signals from a first neighbor cell of the UE, the serving cell associated with a first satellite, the first neighbor cell associated with a second satellite, a third SMTC that specifies third SMTC windows aligning with SSB signals of a second neighbor cell of the UE operating on a second carrier, and a fourth SMTC that specifies fourth SMTC windows aligning with SSB signals of a third neighbor cell of the UE operating on the second carrier, and wherein the measurement configuration further indicates a first measurement gap configuration corresponding to the second neighbor cell and a second measurement gap configuration corresponding to the third neighbor cell, the first measurement gap specifying measurement gaps that are aligned with the third SMTC windows, the second measurement gap specifying measurement gaps that are aligned with the fourth SMTC windows;
perform a measurement based on the first SMTC corresponding to the serving cell and the second SMTC corresponding to the first neighbor cell; and
perform a measurement on the second carrier based on the first measurement gap configuration, the second measurement gap configuration, the third SMTC, and the fourth SMTC
receive information indicating a position of the second satellite associated with the first neighbor cell from the serving cell;
determine an SMTC offset based on the position of the second satellite associated with the first neighbor cell, the SMTC offset being based on a timing of the serving cell, the SMTC offset being one of:
a time offset with respect to the first SMTC,
a time offset with respect to the second SMTC, or
a time offset indicating a starting position of an SMTC window within a periodicity of the second SMTC; and
report a service link propagation delay difference between the serving cell and the first neighbor cell based on the SMTC offset.
17. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method, the method comprising:
receiving a measurement configuration from a serving cell in a non-terrestrial network (NTN) at a user equipment (UE), the NTN providing mobile communication service based on satellites belonging to the NTN, the satellites being low Earth orbiting (LEO) satellites or geostationary Earth orbiting (GEO) satellites, the measurement configuration indicating a first synchronization signal block (SSB) based measurement timing configuration (SMTC) and a second SMTC, the first SMTC specifying first SMTC windows aligning with SSB signals from the serving cell of the UE, the second SMTC specifying second SMTC windows aligning with SSB signals from a first neighbor cell of the UE, the serving cell associated with a first satellite, the first neighbor cell associated with a second satellite, a third SMTC that specifies third SMTC windows aligning with SSB signals of a second neighbor cell of the UE operating on a second carrier, and a fourth SMTC that specifies fourth SMTC windows aligning with SSB signals of a third neighbor cell of the UE operating on the second carrier, and wherein the measurement configuration further indicates a first measurement gap configuration corresponding to the second neighbor cell and a second measurement gap configuration corresponding to the third neighbor cell, the first measurement gap specifying measurement gaps that are aligned with the third SMTC windows, the second measurement gap specifying measurement gaps that are aligned with the fourth SMTC windows;
performing a measurement based on the first SMTC corresponding to the serving cell and the second SMTC corresponding to the first neighbor cell; and
performing a measurement on the second carrier based on the first measurement gap configuration, the second measurement gap configuration, the third SMTC, and the fourth SMTC
receiving information indicating a position of the second satellite associated with the first neighbor cell from the serving cell;
determining an SMTC offset based on the position of the second satellite associated with the first neighbor cell, the SMTC offset being based on a timing of the serving cell, the SMTC offset being one of:
a time offset with respect to the first SMTC,
a time offset with respect to the second SMTC, or
a time offset indicating a starting position of an SMTC window within a periodicity of the second SMTC; and
reporting a service link propagation delay difference between the serving cell and the first neighbor cell based on the SMTC offset.