Reference signal arrangement method and wireless communication base station apparatus
A wireless communication base station apparatus which is able to prevent deterioration in the throughput of LTE terminals even when LTE terminals and LTE+ terminals coexist. In this apparatus, based on the mapping pattern of the reference signals used only in LTE+ terminals, a setting unit ( 105 ) sets, in each subframe, the resource block groups where the reference signals used only by the LTE+ terminals are mapped. For symbols mapped to the antennas ( 110 - 1 to 110 - 4 ), an mapping unit ( 106 ) maps, to all the resource blocks within one frame, cell specific reference signals used for both LTE terminals and LTE+ terminals. For the symbols mapped to the antennas ( 110 - 5 to 110 - 8 ), the mapping unit ( 106 ) maps, to the plurality of resource blocks, of which part of the resource block groups is comprised, in the same subframe within one frame, the cell specific reference signals used only for LTE+ terminals, based on the setting results inputted from the setting unit ( 105 ).
1. A radio communication apparatus comprising:
a mapping section configured to map a first reference signal for computing a channel quality indicator (CQI) in a subframe; and
a transmitting section configured to transmit the mapped first reference signal to a first terminal for a first communication system,
wherein the first reference signal is not transmitted in a subframe where a transmission of the first reference signal collides with a transmission of physical broadcast channel (PBCH) or system information block 1 (SIB 1 ), and
said mapping section further maps a third reference signal for computing a CQI in all subframes, and said transmitting section further transmits the mapped third reference signal to the first terminal for the first communication system and to a second terminal for a second communication system.
2. The radio communication apparatus according to claim 1 , wherein said mapping section maps a second reference signal for demodulating data in a resource block upon which the data is mapped, and said transmitting section transmits the mapped second reference signal to the first terminal.
3. The radio communication apparatus according to claim 2 , wherein the second reference signal is a UE-specific reference signal.
4. The radio communication apparatus according to claim 1 , wherein the third reference signal is a cell-specific reference signal.
5. The radio communication apparatus according to claim 1 , wherein the third reference signal is used for demodulating the PBCH or a downlink control channel.
6. The radio communication apparatus according to claim 1 , wherein the first reference signal is mapped such that a number of symbols of the first reference signal per resource block is lower than a number of symbols of the third reference signal per resource block.
7. The radio communication apparatus according to claim 1 , wherein a maximum number of antenna ports of a base station for the first terminal in the first communication system is larger than a maximum number of antenna ports of a base station for the second terminal in the second communication system.
8. The radio communication apparatus according to claim 1 , wherein the first communication system is a LTE-Advanced, and the second communication system is a LTE.
9. The radio communication apparatus according to claim 1 , wherein the first reference signal is mapped with a set period.
10. The radio communication apparatus according to claim 1 , wherein the first reference signal is mapped with an interval, which is the same as (i) an interval of retransmissions in a HARQ or a number of HARQ processes, (ii) an integer multiple of an interval of retransmissions in a HARQ or an integer multiple of a number of HARQ processes, or (iii) 1/N of an interval of retransmissions in a HARQ or 1/N of a number of HARQ processes, where N is a positive integer.
11. The radio communication apparatus according to claim 1 , wherein the first reference signal is mapped with a same period as a period, with which a CQI is reported, or with a period which is an integer multiple of a period, with which a CQI is reported.
12. The radio communication apparatus according to claim 1 , wherein the first reference signal is mapped with a same period as a period of semi-persistent scheduling (SPS) transmission, or with a period which is 1/N of a period of SPS transmission, where N is a positive integer.
13. The radio communication apparatus according to claim 1 , wherein the first reference signal is a cell-specific reference signal.
14. The radio communication apparatus according to claim 1 , wherein the first reference signal is a channel state information-reference signal (CSI-RS).
15. A radio communication method comprising:
mapping a first reference signal for computing a channel quality indicator (CQI) in a subframe; and
transmitting the mapped first reference signal to a first terminal for a first communication system,
wherein the first reference signal is not transmitted in a subframe where a transmission of the first reference signal collides with a transmission of physical broadcast channel (PBCH) or system information block 1 (SIB 1 ), and
the method further comprises:
mapping a third reference si mal for computing a CQI in all subframes; and
transmitting the mapped third reference signal to the first terminal for the first communication system and to a second terminal for a second communication system.