The effect of measurement error on the estimation of channel parameters and a novel way to prevent estimation failure

For the mobile radio channel parameter estimation, the Space-Alternating Generalized Expectation-maximization (SAGE) algorithm is a popular scheme to estimate the individual path parameters, i.e., the relative delay, incidence azimuth, Doppler frequency, and complex amplitude of impinging waves. Because of the constraint of bandwidth of channel sounding signal and the limitation of the number of antennas, it is impossible to separate every individual path exactly especially when the paths are close in the spatial domain as well as in the time domain. Furthermore the measurement errors including measurement noise and thermal noise make it more difficult to separate each path in the received sounding signal constructed with multipath delay. In this study we modelled the measurement errors of channel sounding system as an Additive White Gaussian Noise (AWGN) and present the effects of measurement errors on the estimation of channel parameters using SAGE algorithm. We demonstrate that the measurement error causes the estimation failure and the impact of the error on the antenna pattern is most pronounced. We introduce a novel method to prevent the estimation failure when using SAGE algorithm. The simulation results are presented to compare the estimation results between with and without proposed method.