Communication apparatus and control signal mapping method
A communication apparatus includes control circuitry and a transmitter. In operation, the control circuitry selects a Demodulation Reference Signal (DMRS) mapping pattern from among a plurality of DMRS mapping patterns. The DMRS mapping patterns include a first DMRS mapping pattern with first DMRS resource elements to which first DMRSs in a first half of a subframe are mapped and second DMRS resource elements to which second DMRSs in a second half of the subframe are mapped. Also, in operation, the transmitter transmits downlink control information that includes a plurality of bits indicating the selected DMRS mapping pattern.
1. A communication apparatus comprising:
control circuitry which, in operation, selects a Demodulation Reference Signal (DMRS) mapping pattern from among a plurality of DMRS mapping pattern candidates, wherein the plurality of DMRS mapping pattern candidates includes a first DMRS mapping pattern with first DMRS resource elements to which first DMRSs in a first half of a subframe are mapped and second DMRS resource elements to which second DMRSs in a second half of the subframe are mapped; and
a transmitter which, in operation, transmits mapping pattern candidates information relating to the plurality of DMRS mapping pattern candidates via higher layers and transmits downlink control information that includes a plurality of bits indicating the selected DMRS mapping pattern.
2. The communication apparatus according to claim 1 , wherein in the first DMRS mapping pattern, a number of the first DMRS resource elements in the first half of the subframe is larger than a number of the second DMRS resource elements in the second half of the subframe.
3. The communication apparatus according to claim 1 , wherein the first DMRS mapping pattern defines at least two adjacent OFDM symbols to which a DMRS is mapped.
4. The communication apparatus according to claim 1 , wherein the first DMRS mapping pattern defines a smaller number of resources in a frequency domain to which the second DMRSs are mapped than a number of resources in the frequency domain to which the first DMRSs are mapped.
5. The communication apparatus according to claim 1 , wherein the DMRS mapping pattern is selected for each of a plurality of user terminals.
6. The communication apparatus according to claim 1 , wherein the control circuitry, in operation, selects the DMRS pattern for each of a plurality of subframes.
7. The communication apparatus according to claim 1 , wherein the plurality of DMRS mapping pattern candidates is shared between the communication apparatus and a terminal apparatus.
8. The communication apparatus according to claim 1 , wherein the transmitter, in operation, transmits a downlink signal that includes DMRSs mapped according to the selected DMRS mapping pattern.
9. A communication method comprising:
selecting a Demodulation Reference Signal (DMRS) mapping pattern from among a plurality of DMRS mapping pattern candidates, wherein the plurality of DMRS mapping pattern candidates includes a first DMRS mapping pattern with first DMRS resource elements to which first DMRSs in a first half of a subframe are mapped and second DMRS resource elements to which second DMRSs in a second half of the subframe are mapped; and
transmitting mapping pattern candidates information relating to the plurality of DMRS mapping pattern candidates via higher layers and transmitting downlink control information that includes a plurality of bits indicating the selected DMRS mapping pattern.
10. The communication method according to claim 9 , wherein in the first DMRS mapping pattern, a number of the first DMRS resource elements in the first half of the subframe is larger than a number of the second DMRS resource elements in the second half of the subframe.
11. The communication method according to claim 9 , wherein the first DMRS mapping pattern defines at least two adjacent OFDM symbols to which a DMRS is mapped.
12. The communication method according to claim 9 , wherein the first DMRS mapping pattern defines a smaller number of resources in a frequency domain to which the second DMRSs are mapped than a number of resources in the frequency domain to which the first DMRSs are mapped.
13. The communication method according to claim 9 , wherein the DMRS mapping pattern is selected for each of a plurality of user terminals.
14. The communication method according to claim 9 , comprising selecting the DMRS pattern for each of a plurality of subframes.
15. The communication method according to claim 9 , wherein the plurality of DMRS mapping pattern candidates is shared between a communication apparatus and a terminal apparatus.
16. The communication method according to claim 9 , further comprising transmitting a downlink signal that includes DMRSs mapped according to the selected DMRS mapping pattern.
17. The communication apparatus according to claim 1 , wherein the downlink control information is transmitted on a Physical Downlink Control Channel (PDCCH) or an Enhanced Physical Downlink Control Channel (EPDCCH).
18. The communication apparatus according to claim 1 , wherein each of the plurality of DMRS mapping patterns has a different density of DMRSs in a frequency domain.
19. The communication apparatus according to claim 1 , wherein DMRS resource elements in which DMRSs are not assigned are used to transmit data.