Apparatus and method for communication
View Patent ↗An eigen value expansion section 103 calculates eigen values and eigen vectors in a correlation matrix or covariance matrix of input signals. When the ratio between a maximum eigen value and other eigen values is equal to or lower than a threshold, an assignment method selection section 104 selects a code assignment method whereby systematic bits are transmitted with their respective eigen vectors. As a result, a communication apparatus 100 transmits a systematic bit X with the respective eigen vectors. On the other hand, when the ratio between a maximum eigen value and other eigen values is greater than the threshold, the assignment method selection section 104 selects a code assignment method whereby systematic bits are transmitted with only the eigen vector having the maximum eigen value. As a result, the communication apparatus 100 transmits the systematic bit X with only the eigen vector having the maximum eigen value. This makes it possible to obtain an effect of improving sufficient communication quality even when the difference between the maximum eigen value and other eigen values is large in a communication system which combines a turbo code and MIMO.
1. A communication apparatus used in a system which transmits/receives independent signals using an array antenna for both transmission and reception with a plurality of eigen vectors, comprising:
a turbo coding section that carries out turbo coding on transmission data and obtains coded data of a systematic bit and a parity bit;
an eigen value calculation section that calculates an eigen value of said each eigen vector;
an assignment method selection section that selects an assignment method of coded data to be transmitted with said each eigen vector based on the ratio between a maximum eigen value and other eigen values; and
a transmission section that transmits predetermined coded data with said each eigen vector based on the selected assignment method.
2. The communication apparatus according to claim 1 , wherein when the ratio between the maximum eigen value and other eigen values is greater than a predetermined threshold, said assignment method selection section selects a first assignment method whereby the systematic bit is transmitted only from an eigen vector having a maximum eigen value and selects a second assignment method whereby the systematic bit is transmitted from all eigen vectors when the ratio between the maximum eigen value and other eigen values is equal to or lower than said threshold.
3. The communication apparatus according to claim 2 , further comprising a repetition section that repeats parity bits, wherein when said assignment method selection section selects said first assignment method, said transmission section transmits parity bits after said repetition from an eigen vector having other than the maximum eigen value.
4. The communication apparatus according to claim 3 , further comprising a puncturing section that punctures parity bits,
wherein said repetition section repeats punctured parity bits, and
when said assignment method selection section selects said first assignment method, said transmission section transmits systematic bits and remaining parity bits through said puncturing from an eigen vector having a maximum eigen value and transmits parity bits after said repetition from eigen vectors other than the maximum eigen value.
5. The communication apparatus according to claim 1 , wherein said transmission section transmits an assignment method indication command indicating the assignment method selected by said assignment method selection section from an eigen vector having a maximum eigen value.
6. A communication apparatus used in a system which transmits/receives independent signals using an array antenna for both transmission and reception with a plurality of eigen vectors, which carries out radio communication with the communication apparatus according to claim 5 , comprising:
an assignment method decision section that extracts an assignment method indication command from a signal transmitted with an eigen vector having a maximum eigen value and decides the assignment method of coded data corresponding to the respective eigen vectors; and
a turbo decoding section that carries out turbo decoding on the coded data transmitted with the respective eigen vectors based on the decision result of said assignment method decision section.
7. A communication method used in a system which transmits/receives independent signals using an array antenna for both transmission and reception with a plurality of eigen vectors, comprising:
a step of carrying out turbo coding on transmission data and obtaining coded data of systematic bits and parity bits;
a step of calculating eigen values of said respective eigen vectors;
a step of selecting an assignment method of coded data transmitted from said respective eigen vectors based on the ratio between a maximum eigen value and other eigen values; and
a step of transmitting predetermined coded data with said respective eigen vectors based on the selected assignment method.