Coded diversity schemes on block fading Rayleigh channels

This paper considers coded diversity schemes on block fading Rayleigh channels. Based on random coding techniques we analyze the performance of binary block codes on such channels. New upper and lower bounds to the error probability are derived. The new upper bound, that is tighter than previously known results, reveals that the maximum diversity order achieved in a block fading channel with finite interleaving is dictated not only by the number of diversity channels L but also by the code rate R, and that the performance can be only marginally improved by increasing the block length of the code. Furthermore, it was found that low rate codes can effectively exploit the available diversity. For diversity order of L, codes of rate 1/L are in particular advantageous. The gains over conventional diversity schemes are shown to be significant (3-6 dB). Examples of systems that our model can be used for are the GSM or PCS1900, and the ATDMA proposal for UMTS. These systems employ slow frequency hopping TDMA.