Cell selection and reselection criteria for non-terrestrial network (NTN) networks
Techniques discussed herein facilitate cell selection and/or reselection in scenarios involving one or more Non-Terrestrial Network (NTN) cells. One example embodiment is a User Equipment (UE) device comprising a processor configured to perform operations comprising: determining one or more suitable cells for one of a cell selection procedure or a cell re-selection procedure, wherein the one or more suitable cells comprise a first cell associated with a satellite of a NTN; determining a ranking for each cell of the one or more suitable cells, wherein the ranking for the first cell is based at least in part on a location of the UE, ephemeris data of the satellite, and one or more additional parameters; selecting a highest ranked cell of the one or more suitable cells based on the determined rankings for each cell of the one or more suitable cells; and camping on the highest ranked cell.
1. A User Equipment (UE) comprising a memory and a baseband processor configured to, when executing instructions stored in the memory, perform operations comprising:
receiving a broadcast signal indicating ephemeris data of a satellite of a non-terrestrial network (NTN);
determining one or more suitable cells for one of a cell selection procedure or a cell re-selection procedure, wherein the one or more suitable cells comprise a first cell associated with the satellite of the non-terrestrial network (NTN);
determining a ranking for each cell of the one or more suitable cells, wherein the ranking for the first cell is based at least in part on a location of the UE, the ephemeris data, and one or more additional parameters;
selecting a highest ranked cell of the one or more suitable cells based on the determined ranking for each cell of the one or more suitable cells; and
camping on the highest ranked cell.
2. The UE of claim 1 , wherein the ephemeris data indicates a time at which a feeder link change will occur and the operations further comprise determining the ranking based on the time of the feeder link change.
3. The UE of claim 1 , wherein the operations further comprise
receiving Non-Access Stratum (NAS) signaling of a database comprising initial parameters for the NTN; and
determining the ranking based on the initial parameters for the NTN.
4. The UE of claim 1 , wherein the one or more suitable cells further comprise at least one terrestrial network (TN) cell, and wherein the one or more additional parameters indicate a priority of the first cell relative to the at least one TN cell, wherein the ranking for the first cell is based at least in part on the priority of the first cell relative to the at least one TN cell.
5. The UE of claim 4 , wherein the priority is indicated via at least one of a Master Information Block (MIB), a System Information Block Type 1 (SIB1), a SIB3, or a SIB4.
6. The UE of claim 4 , wherein the priority is indicated via a Non-Access Stratum (NAS) message passed to an Access Stratum (AS).
7. The UE of claim 1 wherein the one or more suitable cells further comprise at least one terrestrial network (TN) cell, and wherein the ranking for the first cell is based at least in part on stored priority information for NTN cells relative to TN cells.
8. A method, comprising:
determining one or more suitable cells for one of a cell selection procedure or a cell re-selection procedure, wherein the one or more suitable cells comprise a first cell associated with a satellite of a non-terrestrial network (NTN);
receiving signaling indicating at least one scaling factor associated with a distance to the satellite, an elevation angle of the satellite, a common delay associated with the first cell, a differential delay associated with the first cell and a user equipment (UE), a speed of the UE, or a mobility state of the UE;
determining a ranking for each cell of the one or more suitable cells, wherein the ranking for the first cell is based at least in part on the at least one scaling factor, a location of a UE, ephemeris data of the satellite, and one or more additional parameters;
selecting a highest ranked cell of the one or more suitable cells based on the determined ranking for each cell of the one or more suitable cells; and
camping on the highest ranked cell.
9. The method of claim 8 , wherein the scaling factor is associated with a hysteresis parameter that specifies a hysteresis value for the ranking for the first cell.
10. The method of claim 8 , wherein the signaling comprises one of a System Information Block Type 2 (SIB2) Information Element (IE), a dedicated IE for NTN, or Radio Resource Control (RRC) signaling via a terrestrial node.
11. The method of claim 8 , further comprising determining that the first cell is a suitable cell based on at least one of (i) a cell selection received level value for the first cell being greater than zero or (ii) a cell selection quality level for the first cell being greater than zero.
12. The method of claim 8 , wherein the one or more suitable cells further comprise at least one terrestrial network (TN) cell, and wherein the ranking for the first cell is based at least in part on stored priority information for NTN cells relative to TN cells.
13. A baseband processor configured to perform operations comprising:
determining one or more suitable cells for one of a cell selection procedure or a cell re-selection procedure, wherein the one or more suitable cells comprise a first cell associated with a satellite of a non-terrestrial network (NTN);
determining a ranking for each cell of the one or more suitable cells, wherein the ranking for the first cell is based at least in part on a location of a UE, ephemeris data of the satellite, a configuration of the NTN, and one or more additional parameters;
selecting a highest ranked cell of the one or more suitable cells based on the determined ranking for each cell of the one or more suitable cells; and
controlling operation of a transceiver to camp on the highest ranked cell.
14. The baseband processor of claim 13 , wherein the one or more additional parameters comprise at least one of: a distance to the satellite, an elevation angle of the satellite, a common delay associated with the first cell, a differential delay associated with the first cell and the UE, a speed of the UE, or a mobility state of the UE.
15. The baseband processor of claim 13 , wherein the configuration of the NTN characterizes the satellite as one of medium earth orbit (MEO), low earth orbit (LEO), high altitude platform station (HAPS), or geostationary orbit (GEO).
16. The baseband processor of claim 13 , wherein the operations further comprise determining the one or more additional parameters based on information provided via Non-Access Stratum (NAS) signaling.
17. The baseband processor of claim 13 , wherein the operations comprise
receiving signaling of an intra-NTN prioritization that prioritizes different NTN configurations; and
determining the ranking based on the intra-NTN prioritization.
18. The baseband processor of claim 17 , wherein the intra-NTN prioritization is indicated via at least one of a Master Information Block (MIB), a System Information Block Type 1 (SIB1), a SIB3, or a SIB4.
19. The baseband processor of claim 17 , wherein the intra-NTN prioritization is indicated via a Non-Access Stratum (NAS) message passed to an Access Stratum (AS).
20. The baseband processor of claim 13 , wherein the one or more suitable cells further comprise at least one terrestrial network (TN) cell, and wherein the ranking for the first cell is based at least in part on stored priority information for NTN cells relative to TN cells.