Turbo decoding for wireless systems with imperfect channel estimates

A new metric for turbo decoding on Rayleigh fading channels with noisy channel estimates is derived. By including the error variance of the channel estimate in the decoder metric derivation, we calculate the correct channel reliability factor for this case. Simulations show that the signal-to-noise ratio gain of using this new metric, compared to ignoring the uncertainty of the channel estimate, may be as large as 1 dB at a bit error probability of 10/sup -3/. This gain is obtained without any complexity increase.