Inner-outer factorization for rayleigh fading channel modeling

Abstract

The paper first deals with the design of Rayleigh fading channel simulators based on a Moving Average (MA) model. We present a new approach to estimate the model parameters based on the inner-outer factorization. The core of the approach consists of assimilating an infinite-order MA model to the outer spectral factor of the channel power spectral density (PSD). This outer factor, which leads to a causal minimum-phase filter, is first evaluated inside the unit disk of the z-plane. Then, we propose to compute the Taylor expansion coefficients of the outer factor since they coincide with the model parameters. This has two advantages: unlike other simulation techniques, the first p parameters remain unchanged when one increases the model order from p to p+1; in addition, our approach offers the possibility of selecting an appropriate model order for a given mean error bound. Then, we extend this approach to ARMA models to weaken the oscillatory deviations from the theoretical PSD in the case of AR models, or low peaks at the Doppler frequencies for MA models. A comparative study with existing channel simulation approaches points out the relevance of our ARMA model-based method.