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 Ξ_k=N_k+Σb_k-mg_m(t), where Ξ_k is the complex-valued receiver output, b_k-m is the transmitted symbol, N_k is the complex-valued output noise due to AWGN, and g_m(t) is the time-varying gain of b_k-m. Statistical characteristics of N_k and g _m(t) are derived. It is found that {N_k} is a zero-mean complex Gaussian sequence, and g_m(t)s∀m follow a wide-sense-stationary, jointly complex Gaussian random process. Simple closed-form formulas computing statistical parameters of N_k and g_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