User equipment, base station, and AMF system
Provided are a user equipment (UE), a base station, and an AMF (Access and Mobility Management Function) system, as well as corresponding methods and integrated circuits. The UE determines, based on a signal strength measurement or a position in combination with either of a list of cell IDs of earth moving cells and a timing or a stored mapping between geographical areas and tracking areas whether the UE is located in a registration area that has been indicated to the UE by the AMF and in which the UE is paged by the base station.
1 . A user equipment, UE, comprising:
a transceiver, which, in operation,
transmits a registration request including an indication of a first location of the UE, the indication of the first location being stored in the UE, and
receives a registration accept message including a list of one or more tracking areas forming a registration area, the list of one or more tracking areas including the indication of the first location of the UE, and
circuitry, which, in operation, determines, based on an indication of a second location of the UE and the list of one or more tracking areas corresponding to a plurality of prestored geographical areas, whether or not the UE is located in the registration area at the second location, the one or more tracking areas of the list corresponding to one or more cell IDs of earth moving cells forming the registration area per each time interval such that the registration area for the UE need not be updated each time the earth moving cells, which constitute the registration area, change,
wherein the circuitry, when determining that the UE is not located in the registration area at the second location and when received signal strengths of a plurality of candidate cells for a newly visited cell are substantially the same,
determines, based on a measurement of the second location, a geographical area in which the UE is located out of the plurality of prestored geographical areas, and
selects one candidate cell included in the determined geographical area as the newly visited cell,
wherein the registration request includes a cell ID of a last cell that has been visited by the UE and a timestamp indicating a first time instant at which the UE has been located within the last cell, and
the circuitry, in operation, determines whether or not the UE is located in the registration area at the second location based on:
a list of cell IDs of the earth moving cells or cell sections of the earth moving cells, an indication of a second time instant when the earth moving cells form the registration area, coverage area information indicating, for each of the earth moving cells, a coverage area of the cell or cell section relative to a satellite location of a satellite generating the cell and ephemeris data of the satellite, and the measurement of the second location of the UE, wherein the list of cell IDs of the earth moving cells and the indication of the second time instant are included in an indication of the registration area,
wherein the indication of the registration area includes:
a plurality of lists of cell IDs of the earth moving cells or cell sections of the earth moving cells including said list of cell IDs, and
a plurality of indications of time intervals including said time interval respectively indicating, for each of the plurality of lists of cell IDs, the time interval when the earth moving cells or cell sections respectively indicated by the list of cell IDs, form the registration area,
wherein the plurality of lists of cell IDs with the associated time intervals define the registration area itself as time-indexed frozen sets of earth moving cells.
2 . The UE according to claim 1 , wherein the transceiver, in operation, receives the coverage area information within system information.
3 . The UE according to claim 1 , wherein the coverage area information includes, for each of the earth moving cells:
a satellite beam direction of each beam forming the cell and a radius or diameter of the coverage area, or
a polygon defining the coverage area in a non-overlapping manner, or
a center and a radius of the coverage area.
4 . The UE according to claim 1 , wherein the transceiver, in operation, receives a paging message within the registration area.
5 . The UE according to claim 1 , wherein, if the circuitry determines that the UE is not located in the registration area at the second location, the transceiver, in operation, transmits a second registration request including at least one of:
an indication of the second location of the UE, or
a cell ID of the newly visited cell and a timestamp indicating a third time instant at which the UE has been located within the newly visited cell.
6 . A communication method for a user equipment, UE, comprising:
transmitting a registration request including an indication of a first location of the UE;
storing the indication of the first location in the UE;
receiving a registration accept message including a list of one or more tracking areas forming a registration area, the list of one or more tracking areas including the indication of the first location of the UE;
determining, based on an indication of a second location of the UE and the list of one or more tracking areas corresponding to a plurality of prestored geographical areas, whether or not the UE is located in the registration area at the second location, the one or more tracking areas of the list corresponding to one or more cell IDs of earth moving cells forming the registration area per each time interval such that the registration area for the UE need not be updated each time the earth moving cells, which constitute the registration area, change;
when determining that the UE is not located in the registration area at the second location and when received signal strengths of a plurality of candidate cells for a newly visited cell are substantially the same,
determining, based on a measurement of the second location, a geographical area in which the UE is located out of the plurality of prestored geographical areas, and
selecting one candidate cell included in the determined geographical area as the newly visited cell;
wherein the registration request includes a cell ID of a last cell that has been visited by the UE and a timestamp indicating a first time instant at which the UE has been located within the last cell; and
determining whether or not the UE is located in the registration area at the second location based on:
a list of cell IDs of the earth moving cells or cell sections of the earth moving cells, an indication of a second time instant when the earth moving cells form the registration area, coverage area information indicating, for each of the earth moving cells, a coverage area of the cell or cell section relative to a satellite location of a satellite generating the cell and ephemeris data of the satellite, and the measurement of the second location of the UE, wherein the list of cell IDs of the earth moving cells and the indication of the second time instant are included in an indication of the registration area;
wherein the indication of the registration area includes:
a plurality of lists of cell IDs of the earth moving cells or cell sections of the earth moving cells including said list of cell IDs, and
a plurality of indications of time intervals including said time interval respectively indicating, for each of the plurality of lists of cell IDs, the time interval when the earth moving cells or cell sections respectively indicated by the list of cell IDs, form the registration area,
wherein the plurality of lists of cell IDs with the associated time intervals define the registration area itself as time-indexed frozen sets of earth moving cells.