Space-time coded systems with continuous phase frequency shift keying

A space-time (ST) trellis encoded scheme with M-ary continuous phase frequency shift keying with a modulation index of 1/M (M-CPFSK) is presented. A ST-M-CPFSK system model that incorporates the Rimoldi decomposition of CPFSK is developed. The Rimoldi decomposition separates the non-memory component of CPFSK from the memory component. The latter can be represented as a continuous phase encoder (CPE) and implemented with a ring convolutional encoder. The ST codes used here are linear ring convolutional codes. This allows the ST encoder and the CPE to be combined into one encoder, which can be represented by a single trellis and is easily implemented using delay elements, modulo-M adders and scalar multipliers.