Performance analysis of bit-interleaved space-time coding for OFDM in block fading channels

The performance of a bit-interleaved space-time coding (BISTC) scheme is investigated for OFDM systems. The BISTC scheme considered here concatenates bit-interleaved coded modulation (BICM) with the well-known space-time trellis code (STTC) of V. Tarokh et al. (see IEEE Trans. Info. Theory, p.1456-67, 1999). The codeword of the BISTC system spans space, time and frequency dimensions, while spatial and temporal/frequency diversity are conveniently decoupled and exploited separately by the STTC and BICM, respectively. Performance analyses based on both pairwise error probability (PEP) and error bounds are conducted over a more general block fading channel that possesses both frequency and time diversity, and of which the fast and quasi-static fading channels are two instances. An improved error bound, assisted by a limitation and uniform interleaver approach, is derived and shown to provide much more accurate error rate estimation than the standard union bound in block fading channels. Both simulation and error bound analysis indicate that BISTC is efficient in taking advantage of available diversity. Simulation results also show that iterative decoding/demodulation (IDD) in BISTC allows the frame error rate performance to approach the theoretical bound.