Communication apparatus and communication method
The present disclosure provides a method of generating codebook in a wireless communication system with multiple antenna arrays, as well as a wireless communication system, base station and terminal using the codebook for communication. The method comprises steps of: providing a basic codebook which contains multiple pre-coding matrices; and assigning phase offsets to certain pre-coding matrices in the basic codebook to form a codebook with phase offset. The feedback overhead from a client to a base station side is reduced and a good precision of feedback for multi-antenna array is kept by applying the method of generating codebook and using the generated codebook in the wireless communication system, base station and terminal.
1. A communication apparatus comprising:
circuitry which, in operation, stores a plurality of extended precoding matrices; and
a transmitter which, in operation, transmits control information including a precoding matrix indicator (PMI) that identifies an extended precoding matrix selected from the plurality of extended precoding matrices;
wherein the extended precoding matrix is generated by combining a first precoding matrix (w m ) and a second precoding matrix, the first precoding matrix (w m ) including four elements having m times 2π/32 of a phase difference between each element, and the second precoding matrix being generated by multiplexing the first precoding matrix with a phase offset, wherein m is an integer.
2. The communication apparatus according to claim 1 , wherein phases of each element of the first precoding matrix (w m ) are 0, 2π/32×m, 4π/32×m and 6π/32×m.
3. The communication apparatus according to claim 1 , wherein the first precoding matrix (w m ) is selected from 32 precoding matrices.
4. The communication apparatus according to claim 1 , wherein the extended precoding matrix includes a matrix having a size of 1 by 8.
5. The communication apparatus according to claim 1 , wherein the phase offset is selected from 0, π/2, π and 3π/2.
6. A communication method comprising:
storing a plurality of extended precoding matrices;
transmitting control information including a precoding matrix indicator (PMI) that identifies an extended precoding matrix selected from the plurality of extended precoding matrices;
wherein the extended precoding matrix is generated by combining a first precoding matrix (w m ) and a second precoding matrix, the first precoding matrix (w m ) including four elements having m times 2π/32 of a phase difference between each element, and the second precoding matrix being generated by multiplexing the first precoding matrix with a phase offset, wherein m is an integer.
7. The communication method according to claim 6 , wherein phases of each element of the first precoding matrix (w m ) are 0, 2π/32×m, 4π/32×m and 6π/32×m.
8. The communication method according to claim 6 , wherein the first precoding matrix (w m ) is selected from 32 precoding matrixes.
9. The communication method according to claim 6 , wherein the extended precoding matrix includes a matrix having a size of 1 by 8.
10. The communication method according to claim 6 , wherein the phase offset is selected from 0, π/2, it and 3π/2.