Study On Cooperative Coding And Diversity Technology With Polar Codes

Cooperative commnunication and space diversity are two important techniques in multipleuser wireless communication. Cooperative communication is that, each of the adjacent nodescommunicates with others by sharing each antenna in the established manner, and can obtain thespatial diversity gain so as to improve the performance of the system. Space-time block code is aspace-time coding method to provide sufficient space diversity gain, but it can not provideenough coding gain. Polar codes are the first class of provably capacity-achieving codes withlow encoding and decoding complexity, which are based on channel polarization theory. Thecombiniation of the cooperative communication and space diversity techniques with polar codeswill not only provide diversity gain but also provide large coding gain.First, the thesis studies the application of polar codes in cooperative communication. Twocooperative coding schemes using Polar codes are proposed with the classical three-nodes relaychannel model. One is the cooperative coding scheme with amplify-forward (AF), and the otheris the cooperative coding scheme with decode-forward (DF) modes. By numerical analysis, theperformances of the proposed schemes are discussed under different code length, differentcoding rate, and different distance between nodes. The comparison of the proposed schemes withthose schemes using low density parity check codes (LDPC) is also presented under the samecondition. The results show that polar cooperative coding scheme has a better performance. Thepolar cooperative coding scheme has been enhanced to the LDPC cooperative coding schemewith greater than2dB when the coding rate is0.25. Similarly, the smaller the distance betweenrelay and source, the better the performance of the system is. The position of the relay node iscritical in the cooperative coding scheme.Further, the thesis studies the application of Polar codes in space diversity system. In order toimprove the bir-error-rate (BER) performance of space-time block code, a concatenated schemewith Polar codes and space-time block code is proposed. The block diagram and the decodinganalysis of the concatenated scheme are given. The BER performances of the proposedconcatenated scheme are presented by numerical simulation under the different code length,coding rate, and the different number of the receiver antenna. The result show that, theperformance of the Polar-STBC concatenated scheme is improved as the increasing of the codelength and the decreasing of coding rate; compared with STBC coding, the scheme can obtain significant coding gain; for example, the coding gain is about9dB when coding rate is0.5andBER is10-4.