JOINT EQUALIZATION AND CODING FOR INTERSYMBOL INTERFERENCE CHANNELS

We present a novel scheme that combines decision feedback equalization (DFE) with high-rate error-detection coding in an efficient manner, T he proposed scheme is shown to considerably outperform the conventiona l practice on channels with high SNR, such as those encountered in twi sted-pair telephonia systems. In order to analyze the performance of o ur method, we introduce an approximate mathematical model taking into account the error propagation phenomenon. Based on this model, upper a nd lower bounds on the overall probability of error are developed. The se show that a simple low-redundancy error-detecting code, when proper ly integrated with the equalizer, can make the overall probability of error several orders of magnitude lower than that obtained with the co nventional DFE, or with a DFE followed by an error-correcting code. Co mputer simulations of the proposed method have been performed for seve ral channels, including the so-called high-bit-rate digital subscriber line (HDSL) test-loop #4, which is known to have a considerable amoun t of intersymbol interference. For all these channels, our results sho w that a reduction in the probability of error by more than three orde rs of magnitude can be obtained using codes of rate 0.96 and above. Th is, in turn, translates into power savings (coding gain) of 2.5 to 3 d B.