An adaptive MLSD receiver using colored noise diversity

A persurvivor processing (PSP) maximum likelihood sequence detection (MLSD) receiver is developed for a fast time-varying frequency selective Rayleigh fading channel with colored additive auto-regressive (AR) noise. The noise correlation is used to considerably enhance the performance of the communications. The new PSP-MLSD algorithm detects the input data and jointly estimates of the noise and channel parameters all together. A new maximum likelihood criterion is proposed based on the noise model. This criterion has some appropriate properties, e.g., it has a unique joint minimum at the true values of the channel parameters and the noise parameters. The proposed structure can be viewed as a traditional PSP-MLSD receiver combined with an adaptive whitening filter. In a colored noise environment, this scheme offers faster tracking property, more accurate estimation of the channel and a substantially lower error probability compared with the traditional PSP-MLSD structure. The signal-to-noise-ratio (SNR) improvement achieved by the proposed receiver, which can be called the noise diversity gain, is almost equal to the ratio of the energy of the additive noise to the energy of the unpredictable noise component.