On performance limits of MIMO-OFDM systems over block-fading channels

We investigate the effect of system parameters on performance limits of space-time-frequency coded OFDM systems over block-fading channels. For this purpose, we obtain a sphere packing lower bound on average word error probability of space-time-frequency codes. This bound not only determines the merit of codes in the sense of error performance, but it also provides a tool to explore the performance limits of system in terms of parameters such as number of antennas, coherence time, coherence bandwidth, delay constraint, system bandwidth, and number of channel taps. It is also shown how these parameters affect the mean and the variance of instantaneous channel capacity, the outage probability, and the maximum achievable diversity of the system.