Transmit diversity based on multiplicative transformation for non-binary LDPC codes in MIMO systems

In order to achieve reliable communication, transmit diversity is commonly used in multiple antenna systems. Currently, to obtain transmit diversity, space-time code is usually used. In this paper, a new multiplicative transformation scheme is proposed for multiple antenna systems with non-binary low-density parity-check (LDPC) codes. It is shown that this scheme can provide transmit diversity. In the scheme, for the first antenna, the modulated LDPC codeword is directly applied, while for the second antenna, before modulation, a multiplicative transformation is used, where the multiplication is defined in the same Galois field as that used to construct the nonbinary LDPC code. The performance of the proposed system is analyzed, and it is shown that, compared with phase sweeping transmit diversity (PSTD) and Alamouti's space-time block code (STBC), the proposed system not only provides transmit diversity, but also achieves good gain. Simulation results further prove the increased performance in both block fading and slow fading channels.