Method and apparatus for measurement reporting in carrier aggregation wireless communication systems
When detecting occurrence of an event for transmitting a measurement report of a radio condition of a cell at a frequency set for a base station apparatus, to the base station apparatus ( 3 ) communicating with a terminal apparatus ( 2 ), the terminal apparatus ( 2 ) in a wireless communication system ( 1 ) creates a measurement report including information indicating radio conditions of cells at a frequency at which the event occurred and at another different frequency. The base station apparatus ( 3 ) controls whether or not to perform handover of the terminal apparatus ( 2 ) to another cell, on the basis of the measurement report transmitted from the terminal apparatus ( 2 ). Thereby, there is provided a wireless communication system in which a base station apparatus and the terminal apparatus are communicable with each other using multiple frequencies, the wireless communication system being capable of shortening time required for handover.
1. A terminal apparatus comprising:
a transceiver, which, in operation, communicates with a base station apparatus; and
control circuitry coupled to the transceiver, wherein the control circuitry, in operation,
detects occurrences of an event in a cell among multiple cells including both serving cells, which are aggregately used by the transceiver to communicate with the base station apparatus on serving frequencies, and non-serving cells, which are not presently used by the transceiver to communicate with the base station apparatus;
measures radio conditions of the serving cells and the non-serving cells; and
in response to detection of an occurrence of the event,
creates a measurement report indicating radio conditions of the best non-serving cell selected from the non-serving cells based on reference signal received power (RSRP) on one of the serving frequencies, the measurement report excluding radio conditions of non-selected non-serving cell(s) for which the radio conditions are measured; and
transmits the measurement report to the base station apparatus.
2. The terminal apparatus according to the claim 1 ,
wherein the measurement report includes a list of the best non-serving cells in order of decreasing RSRP.
3. The terminal apparatus according to claim 1 ,
wherein a policy for deciding the multiple cells, for which radio conditions are measured, is set in the terminal apparatus.
4. The terminal apparatus according to claim 1 ,
wherein the best non-serving cell is a cell judged to have a higher RSRP in comparison with a reference RSRP.
5. The terminal apparatus according to claim 1 ,
wherein the measurement report additionally indicates radio conditions of the serving cells on the serving frequencies.
6. The terminal apparatus according to claim 1 ,
wherein the serving frequencies include a primary frequency and a secondary frequency, wherein the control circuitry, in operation, determines whether to create the measurement report additionally indicating radio conditions of a cell on the primary frequency, or to create the measurement report additionally indicating radio conditions of the cell on the primary frequency and of a cell on the secondary frequency.
7. The terminal apparatus according to claim 5 ,
wherein the radio conditions of the serving cells and of the best non-serving cell are combined in one measurement report.
8. A wireless communication method comprising:
a terminal apparatus communicating with a base station apparatus;
the terminal apparatus detecting occurrences of an event in a cell among multiple cells including both serving cells, which are aggregately used by the transceiver to communicate with the base station apparatus on serving frequencies, and non-serving cells, which are not presently used by the transceiver to communicate with the base station apparatus;
the terminal apparatus measuring radio conditions of the serving cells and the non-serving cells;
the terminal apparatus, in response to detection of an occurrence of the event, creating a measurement report indicating radio conditions of the best non-serving cell selected from the non-serving cells based on reference signal received power (RSRP) on one of the serving frequencies, the measurement report excluding radio conditions of non-selected non-serving cell(s) for which the radio conditions are measured; and
the terminal apparatus transmitting the measurement report to the base station apparatus.
9. The method according to the claim 8 ,
wherein the measurement report includes a list of the best non-serving cells in order of decreasing RSRP.
10. The method according to claim 8 ,
wherein a policy for deciding the multiple cells, for which radio conditions are measured, is set in the terminal apparatus.
11. The method according to claim 8 ,
wherein the best non-serving cell is a cell judged to have a higher RSRP in comparison with a reference RSRP.
12. The method according to claim 8 ,
wherein the measurement report additionally indicates radio conditions of the serving cells on the serving frequencies.
13. The method according to claim 8 ,
wherein the serving frequencies include a primary frequency and a secondary frequency, wherein the method further comprises the terminal apparatus determining whether to create the measurement report additionally indicating radio conditions of a cell on the primary frequency, or to create the measurement report additionally indicating radio conditions of the cell on the primary frequency and of a cell on the secondary frequency.
14. The method according to claim 8 ,
wherein the radio conditions of the serving cells and of the best non-serving cell are combined in one measurement report.