| Two families of coded modulation schemes based on Continuous Phase Modulation (CPM) have been designed and analyzed in this work. The first involves the use of finite-state outer-codes (FSOC-CPM), and the second involves the use of filters after the modulator (filtered CPM). FSOC-CPM codes have a constant envelope, while filtered CPM signals do not.;CPM signals may be precoded by a convolutional outer code followed by a mapping rule. The result is often a more powerful trellis code than CPM alone. However, better codes may be obtained by a more general finite-state machine than the convolutional code generator. Based on this idea, new codes and design rules for outer-codes with rates 1/2 and 2/3 are presented. Previously published results are matched for full response CPM but are usually exceeded for partial response signals.;Filters may be designed that limit the transmitted spectrum of the CPM signals, and allow concentration of signal power in regions of the signal spectrum that carry relatively large amounts of information. We have extended the concept of faster-than-Nyquist signalling to brickwall filtering of CPM signals. Large gains in energy and bandwidth are possible through the proper design of these filters. We have developed techniques that yield upper bounds for the minimum distance of these signals. Practical filters have performance estimates that are very close to that obtained with brickwall filtering.;Our work on filtered CPM suggests that CPM signals may not really be "bandwidth efficient". We have defined the concept of information bandwidth of a modulation. |
