Crosstalk-based CPM for wireless personal communications

Abstract

The Viterbi decoder is an efficient implementation of the maximum likelihood sequence estimator for continuous phase modulation (CPM) signals in an additive white Gaussian noise channel, therefore its performance analysis is of interest when co-channel and adjacent channel interference (ACI) are also present. Much research has recently been done in this field, towards the goal of finding more bandwidth-efficient CPM modulations for wireless personal communications (PCS). The work described in this paper gives a new and relatively simple approach for performance analysis. It uses the crosstalk approach which was used for analysis of simpler detectors for specific CPM cases, but broadens this approach substantially, to take into account more general CPM cases. The crosstalk approach when combined with an equivalent white Gaussian noise model gives very close approximations to previous analytic results, while requiring much less computer time. This work considers many CPM schemes in an adjacent channel interference and white Gaussian noise environment. The results are compared (when possible) to previous works, and many new CPM modulation schemes are also examined. Some of these new schemes give surprisingly good results, which should be of interest to those searching for bandwidth-efficient CPM signals, for use in PCS systems. One of the new schemes allows an ACI user to be 62 dB greater than the desired user at a frequency separation equal to 1.5 times the bit rate, with just a 2 dB degradation. >