Full-diversity space-frequency trellis codes designing method

This paper introduces a method to design space-frequency trellis codes for a system that combines space-time coding with orthogonal frequency division multiplexing (OFDM) to realize broad-band wireless communications. It has been pointed out in the literature that the frequency-selective fading, which usually occurs in such combined system, turns out to produce a beneficial effect on the error rate performance by providing the frequency diversity in addition to the spatial diversity. This enables space-frequency codes to exploit greater diversity than the space-time codes. However, exhaustive search for space-frequency trellis codes is impractical. The only existing heuristic design method has a drawback in the spectral efficiency, and in turn degrades the coding gain (energy efficiency,) which is also the primary purpose of space-frequency coding. We propose a practical method to design the space-frequency codes that exploit full diversity while maximizes the coding gain at a desired spectral efficiency. The simulation results show the superior error rate performance of the codes designed by the proposed method.