Optimal design of CPM decoders based on state-space partitioning

The joint optimization of decoder complexity and error performance is considered for partial-response continuous phase modulation (CPM). The operation of the decoder is defined by a state-space partition (SSP), by which the states are divided into C classes. Proceeding breadth-first in the trellis, the decoder selects the single best path for each state-class. A novel decoder design criterion is formulated, based on two parameters: C, which determines the computational effort, and a distance parameter d´_min, which characterizes the error event probability. A systematic procedure for obtaining the optimal SSP subject to the new criterion is presented