Turbo-detected coded continuous-phase modulation for military UHF satellite communications

Abstract

The joint iterative demodulation and decoding of coded continuous-phase modulation (CPM) has been shown to offer near-optimal performance for constant envelope signalling in additive white Gaussian noise. An in-depth trade study of the parameters for such a system is used to derive the optimal waveform parameters for a variety of channels. In particular, the optimal parameters are selected for the military 25-kHz UHF follow-on (UFO) satellite communications (SATCOM) channel. A set of four waveforms are defined for that application that provide a range of power-efficient and bandwidth-efficient solutions, with data rates from 56 kbps to 80 kbps. Each operates within the typical link margins available for UHF SATCOM and meets typical (MIL-STD-188-181B) adjacent channel interference specifications. The implementation of a prototype modem using commercial off-the-shelf (COTS) hardware is described.