Terminal, transmitting device, reception quality reporting method and reception method
A terminal which is capable of selecting appropriate transmission points while reducing the overhead for channel state information (CSI) reporting is provided. A measuring unit ( 303 ) uses a plurality of reference signals from a plurality of transmission points to measure a first reception quality with respect to each of the plurality of reference signals. A receiving unit ( 301 ) receives a first piece of information concerning at least one specific reference signal among the plurality of reference signals, and the measuring unit ( 303 ) uses the specific reference signal to measure a second reception quality on the basis of the first piece of information. A transmitting unit ( 304 ) reports the first reception quality, which satisfies a predetermined condition, and the second reception quality.
1. A terminal comprising integrated circuits configured to:
measure, using a plurality of channel state information reference signals (CSI-RSs) from a plurality of first transmission points of a first cell of a first macro base station and having a first cell identifier of the first macro base station, a reception power for each of the plurality of CSI-RSs, the plurality of CSI-RSs being indicated in a candidate list transmitted from the first macro base station;
report the reception power for first CSI-RSs corresponding to the reception power that satisfies a first reporting condition along with an identification of the first CSI-RSs;
receive first information specifying at least one CSI-RS selected by the first macro base station among the first CSI-RSs for which the report has been transmitted;
measure channel state information (CSI) for the at least one specified CSI-RS;
report the CSI for the specified at least one CSI-RS to the first macro base station;
wherein for a handover to a second cell of a second macro base station with a plurality of second transmission points using a second cell identifier of the second macro base station, the second cell identifier is different from the first cell identifier;
the reception power for a cell specific reference signal (CRS) is measured from one of the plurality of second transmission points;
when the reception power for the CRS satisfies a second reporting condition, the reception power for each of the plurality of CSI-RSs is measured from the plurality of second transmission points for transmission in a handover completion message;
the reception power for the CRS satisfying the second reporting condition is reported along with an identification of the second cell corresponding to the reception power satisfying the second reporting condition;
an instruction for the handover and second information necessary for the handover is received after the report of the reception power for the CRS along with the identification of the second cell; and
the handover completion message is transmitted including the reception power for the each of the plurality of CSI-RSs from the plurality of second transmission points.
2. The terminal according to claim 1 , wherein the CSI is reported when a report request for the reception power for the at least one specified CSI-RS is received.
3. The terminal according to claim 1 , wherein the candidate list indicates configuration information on the plurality of CSI-RSs.
4. The terminal according to claim 1 , wherein the reception power for the plurality of CSI-RSs is measured in a resource group that is set at a timing of a predetermined period, and no data signal is assigned in the resource group.
5. The terminal according to claim 4 , wherein the plurality of CSI-RSs are assigned to mutually different resources in the resource group.
6. The terminal according to claim 4 , wherein a transmission period of the plurality of CSI-RSs is an integer multiple of the predetermined period.
7. The terminal according to claim 1 , wherein:
the terminal performs communication using a plurality of component carriers;
when a specific component carrier is newly added to the terminal, the reception power is measured using the plurality of CSI-RSs from the plurality of first transmission points in a frequency of the specific component carrier;
the reception power for at least one CSI-RS satisfying a predetermined condition is reported to the first macro base station; and
the at least one CSI-RS is mapped in the specific component carrier, and the CRS is not mapped in the specific component carrier.
8. The terminal according to claim 1 , wherein:
the reception power for second CSI-RSs satisfying a third reporting condition relating to uplink is reported along with an identification of the second CSI-RSs corresponding to the reception power satisfying the third reporting condition; and
a third information specifying at least one CSI-RS selected by the first macro base station is received among the second CSI-RSs for which the report has been transmitted.
9. The terminal according to claim 1 , wherein an amount of information used for indicating the reception power is smaller than the amount of information used for indicating the CSI.
10. The terminal according to claim 1 , wherein a measurement period of the reception power is longer than a measurement period of the CSI.
11. A reception quality reporting method comprising:
measuring, using a plurality of channel state information reference signals (CSI-RSs) from a plurality of first transmission points of a first cell of a first macro base station and having a first cell identifier of the first macro base station, a reception power for each of the plurality of CSI-RSs, the plurality of CSI-RSs being indicated in a candidate list transmitted from the first macro base station;
reporting the reception power for first CSI-RSs corresponding to the reception power that satisfies a first reporting condition along with an identification of the first CSI-RSs;
receiving first information specifying at least one CSI-RS selected by the first macro base station among the first CSI-RSs for which the report has been transmitted;
measuring channel state information (CSI) for the at least one specified CSI-RS;
reporting the CSI for the specified at least one CSI-RS to the first macro base station;
wherein for a handover to a second cell of a second macro base station with a plurality of second transmission points using a second cell identifier of the second macro base station, the second cell identifier is different from the first cell identifier;
measuring the reception power for a cell specific reference signal (CRS) from one of the plurality of second transmission points;
measuring, when the reception power for the CRS satisfies a second reporting condition, the reception power for each of the plurality of CSI-RSs from the plurality of second transmission points for transmission in a handover completion message;
reporting the reception power for the CRS satisfying the second reporting condition along with an identification of the second cell corresponding to the reception power satisfying the second reporting condition;
receiving an instruction for the handover and second information necessary for the handover after the report of the reception power for the CRS along with the identification of the second cell; and
transmitting the handover completion message including the reception power for the each of the plurality of CSI-RSs from the plurality of second transmission points.