On the design of space-frequency codes from super-orthogonal space-time trellis codes via mapping

This paper describes how to construct a class of Space-frequency (SF) codes by mapping the Super-orthogonal space-time trellis (SOSTT) codes across OFDM subcarriers. Two mapping methods are employed: conventional repetition mapping and the proposed mapping methods with the design criteria of achieving full diversity including spatial and frequency at the maximum possible transmission, rate. The proposed mapping method appears to outperform the conventional mapping counterpart with respect to coding gain when constructing the SF codes mapped from SOSTT codes. Simulation results show the performance gain of 0.5-3 dB under frequency-selective fading channels. In addition, the constructed SF codes mapped with both mapping methods are compared to the existing commonly known SF codes, i.e. the Space-time trellis (STT) codes mapped with conventional mapping method. Apparently the SOSTT codes are superior to the STT codes in single-carrier narrowband wireless channel, the mapped SOSTT codes do not offer the same advantage over the mapped STT codes under the severely-frequency-selective fading channel when the codes having large number of states. Nevertheless, some performance improvement is observed for codes with small number of states.