Correlation Receivers Minimizing Intersymbol Interference

Abstract

The problem considered here is that of binary pulse communication operating in a white noise environment -wherein interfering signal pulses are generated by any of the following causes t (1) A signaling rate larger than channel bandwidths, causing pulse spill over into succeeding bands. (2) Go-channel interference or cross talk on carrier systems. (3) Signal echoes or reflections due to antenna location or mismatch of high frequency components. The optimum correlation receiver is found to be a linear combination of the desired signal pulse plus the interfering pulse. In severe cases significant improvement can be had over a correlation receiver using only the desired signal pulse. For the cause (l) above, prior receiver decisions may be used to improve the design. In particular, the immediately preceding overall receiver decision is used to select one of two parallel component correlation operations whose designs are based on a priori knowledge of the preceding transmission. It can then be shown that this is equivalent to a single correlation operation with dual decision levels, wherein the preceding receiver output controls the selection of the decision level to be utilized next. The resulting performance of this type of receiver is superior t© the correlator composed of the linear sum of signal plus interference pulses. A similar investigation was performed for the ease of Rayleigh fading on the interfering pulse. Analytical equations are established for determining the necessary solutions; however, numerical complexity precludes definitive results at this tim