研究期間：10108~10207;It has been shown that the multiple-antenna system has superior capacity to the single-antenna system. Among the channel codes for the multiple transmitter antennas system, which are called space-time codes, unitary space-time modulation which is a kind of noncoherent space-time block codes attracts much attention. We have obtained some satisfactory results of noncoherent coding. However, noncoherent block-coded modulation which is based on multilevel coding has bad error rate if the block is short. Short noncoherent block codes are important since in the case of short blocks, the rate loss caused by the pilot signal for coherent decoding is significant. In the first year of this project, we will study short noncoherent block codes. Instead of using multilevel coding, we will use algorithms to find codewords of a code which has large minimum noncoherent distance. Possible approaches include to find codewords based on the chosen constellation, or based on the given minimum noncoherent distance. According to our initial results, the obtained noncoherent block codes for the single-antenna system have excellent minimum noncoherent distance as well as error rates, so further research on this subject is necessary. In the second year of this project, we will do further applications of the obtained short block codes and algorithms, including longer noncoherent block codes serially concatenated with outer codes, noncoherent trellis coded modulation and differential encoding. We will search for noncoherent block and trellis codes whose symbols of trellis branches are codewords of short block codes obtained in the first year, and modify algorithms to find short noncoherent block codes suitable for generalized differential encoding.
