Time varying equalization of doubly selective channel

Abstract

Inter symbol interference and rapid time variations makes doubly selective channels difficult to equalize. The rapid time variations entail a receiver that also adapts itself to the channel variation. This increases the implementation complexity requirement for the receiver. Therefore faster techniques are much needed to establish real time communication over such severe channels. The focus of this research report is on faster equalization techniques for doubly selective channels. The block equalization technique was used as it emphases on low complexity equalization. MMSE equalizer is reformulated as the problem solving a system of linear equations. This allows the application of algorithms from linear algebra predominantly iterative methods for solution of system of linear equations. Jacobi, Gauss Seidel, Steepest Descent and Conjugate Gradient are used. Jacobi and Gauss Seidel are good for square matrices of lower order, but worse for higher order matrices. Steepest Descent takes more time and more number of iterations to converge than Conjugate Gradient. This report concludes by proposing the Conjugate Gradient method is suitable for low complexity block equalization problem from the perspective of run time and bit error rate.