On Improved Bounds on Coded Communications over Interleaved Fading Channels, with Applications to Turbo Codes

We study here rigorous analytical upper bounds on the block and bit error probabilities of ML decoded block codes, operating over fully interleaved Rician fading channels. The proposed improved bounding technique is a modified and generalized version of the recently introduced bounds for the AWGN channel by Duman and Salehi, which are based on modifying the classical Gallager technique. The advantage of the improved upper bounds over the ubiquitous union bounds is demonstrated for some ensembles of turbo codes, and it is especially pronounced in the rate region exceeding the cutoff rate. The upper bounds are also compared with computer simulations of efficiently and iteratively decoded turbo codes, demonstrating a good match. Hence, the improved bounds here can also be used as a fast technique to approximately assess the performance of efficient iterative decoding algorithms. The upper bounds are also calculated for several orders of space diversity and in this case as well, they closely approximate the simulated performance of the iterative decoding.