UP Paper 1333 US-W-PDOWN
A New Finite Series Representation for Continuous Phase Modulation
Wylie-Green,MarilynnNokia
The Laurent Decomposition expresses any binary single-h continuous phase modulated signal as the summation of a finite number of linearly modulated pulse amplitude modulated waveforms, and the resulting signal space is so constructed that the CPM signal can usually be synthesized with a reasonable degree of accuracy by using only the “main” PAM component pulse. This derivation has been very useful for reduced complexity demodulation of binary CPM signals. Subsequent to Laurent’s work, it was shown that commensurate expressions could be obtained for multilevel and multi-h CPM, but with an exponential increase in the total number of PAM component pulses in the signal representation. In this paper, we show that by expressing any CPM signal as an equivalent binary multi-h CPM signal, that we can derive a generalization of Laurent’s result which can be applied to all variants of CPM that use non-integer modulation indices. Most notably, the component pulses are naturally ranked in order of decreasing signal energy, so that over each symbol interval there is a single “main pulse” that can be used as a good first-order approximation of the CPM signal.