The impact of antenna arrays on the indoor radio estimation using the SAGE algorithm

Space-alternating generalized expectation-maximization (SAGE) algorithm is proposed to compute the jointly maximum-likelihood estimate of the relative delay, incidence azimuth, and complex amplitude, which are considered the character parameters of impinging waves in indoor radio environments. The maximization processes of SAGE algorithm can be separated into several individual procedures which can be performed sequentially to reduce the computational complexity. To study the impact of the antenna arrays on the performance of the estimation, different receive antenna arrays, such as linear array, circular array and triangle array, are applied to evaluate the resolution, accuracy and the mean convergence rate of the SAGE method with different receive antenna arrays by synthetic simulation. Unlike the uniform distribution usually used in the outdoor mobile channel model to evaluate the radio channel estimation methods previously, in the indoor circumstance the angular spread of the impinging signals is supposed to distribute as the clustered “double Poisson” time-of-arrival model, and the angular distribution is also clustered with uniformly distributed clusters and arrivals within clusters that have a Laplacian distribution. Finally, the applicability of the SAGE algorithm (with virtual circular array) to real indoor propagation environments is demonstrated.