Abstract : In this article, we study the coding advantage of spacetime-frequency block codes (STFBCs). Since in MIMO-OFDM coding there is the potential of exploiting space, time and frequency diversities and as the frequency tones of OFDM modulation are relatively substantial, the intricate structure of STFBCs makes it almost impossible to optimize the parameters of the code as the number of symbols increases in each block. Consequently, we investigate how to optimize the code parameters independently to reduce the computational complexity. Furthermore, code permutation is an important part of the STFBCs. However, due to elaborate structure of the STFBCs, it is very hard to calculate the optimum permutation. Therefore, we put forth a technique to decompose the coding advantage of the STFBCs. Using this technique, the permutation parameter can be easily introduced and optimized for STFBCs. We then design a novel STFBC based on any given STBC and apply the proposed scheme on the proposed STFBC to illustrate the application of this technique by designing the optimum permutation for the code. Simulation results confirm that the proposed STFBC outperforms the best existing STFBCs in the literature.
Index terms : Coding advantage, digital wireless communications, fading channel, MIMO-OFDM, space-time-frequency coding