Stable pole-zero modeling of long FIR filters with application to the MMSE-DFE

The problem of approximating a long FIR filter by a reduced-parameter stable pole–zero filter is addressed in this paper. We derive a computationally efficient order-recursive algorithm that achieves this task with high accuracy. Our main emphasis is on applying this algorithm to reduce the implementation complexity of the decision feedback equalizer’s long FIR feedforward and feedback filters encountered in high-speed data transmission on digital subscriber loops.