A technique for nonlinear echo cancellation in wireless netwoks

Abstract

The echo cancellation technique in wireless telephones mostly uses the echo canceller to be placed in the wireless handset. This scheme has an inherent disadvantage as much processing has to be done in the handset thereby causing higher costs for the handset and more power consumption. Schemes have been proposed in earlier works to solve the problem by placing the echo canceller in the base station rather than in the handset. The echo generated in a wireless network is essentially nonlinear as the handset and the base station include speech codecs which produce nonlinear distortion in the mobile signal. In this paper, an echo cancellation technique based on adaptive Volterra filters has been proposed for cancellation of nonlinear echo due to codecs. Simulation results for the proposed echo cancellation scheme are presented and compared with the performance of a linear echo cancellation (LMS) scheme. The echo-cancelled speech quality was perceptually better as compared to that obtained using the LMS algorithm when implemented on a TMS 320C6711 DSK.