Abstract
For Rayleigh fading channels, the primary code design criterion for a trellis coded modulation scheme is to maximize its effective code length (ECL). This paper concerns the design of optimal (2,1) Z 2 -convolutional encoders (CE) which, when combined with the continuous phase encoder (CPE) of CPFSK scheme, reaches the upper bound of ECL of a generic trellis coded modulation scheme. We develop sufficient conditions for the optimality of such a CE and the upper bound of the complexity for the test of these sufficient conditions is also shown. © 1998 IEEE.