Discrete-time model for digital communications over a frequency-selective Rician fading WSSUS channel

The paper develops a discrete-time model for digital communications via a frequency-selective Rician fading, wide-sense-stationary uncorrelated-scattering (WSSUS) channel with arbitrary pulse shaping and receiver filtering. As a special case, the discrete-time model is also applicable to a frequency-selective Rayleigh fading WSSUS channel. The model is expressed in the form /spl Xi//sub k/=N/sub k/+/spl Sigma/b/sub k-m/g/sub m/(t), where /spl Xi//sub k/ is the complex-valued receiver output, b/sub k-m/ is the transmitted symbol, N/sub k/ is the complex-valued output noise due to AWGN, and g/sub m/(t) is the time-varying gain of b/sub k-m/. Statistical characteristics of N/sub k/ and g/sub m/(t) are derived. It is found that {N/sub k/} is a zero-mean complex Gaussian sequence, and g/sub m/(t)s/spl forall/m follow a wide-sense-stationary, jointly complex Gaussian random process. Simple closed-form formulas computing statistical parameters of N/sub k/ and g/sub m/(t)s are derived. Several aspects regarding the use of the proposed model to analytic works and efficient computer simulations are discussed. Finally, three illustrative examples are given.