Zero-forcing decision-feedback equalizer for packet data transmission

For communication over channels subject to fast time-variation, e.g., the HF channel, the information symbols are arranged in the form of blocks separated by known symbols. The known receiver for this system is the nonlinear data-directed estimator (NDDE). An appropriate zero-forcing decision-feedback equalizer which has better performance and lower complexity is derived. Whereas the NDDE uses the Levinson algorithm to solve M/2 Toeplitz systems of decreasing order (where M is the number of symbols per block), the author´s equalizer needs to process only one Toeplitz system. The Schur algorithm, proposed for Cholesky factorization, allows further reduction in the complexity of the process