Externally encoded space-time coded systems with continuous phase frequency shift keying

We present an externally encoded space-time (ST) trellis scheme using M-ary continuous phase frequency shift keying with modulation index equal to 1/M (M-CPFSK). The ST-M-CPFSK model given in R.L. Maw et al, (1998) is used. It incorporates the Rimoldi decomposition [B.E. Rimoldi, 1998] of CPFSK, and combines the ST encoder and CPFSK encoding into a single trellis encoder on the ring of integers modulo-M (Z_M). The external error correction codes are linear ring convolutional codes on Z_M. This allows the external encoder to be incorporated into a combined trellis encoder that is easily implemented with delay elements, modulo-M adders and scalar multipliers.