Effective Channel Coding Using Quaternary Encoders and Continuous Phase Modulation

A generic CPM scheme can be decomposed into a continuous-phase encoder (CPE) and a memoryless modulator (MM). The CPE can be combined with a channel encoder (CE). This creates an extended CE, as the CPE is now an extension of the CE. In this paper, a 1⁄2 rate quaternary CE is combined with a quaternary CPE. The CE used here is a convolutional encoder, thus, the extended CE is also a convolutional encoder. The paper explains the design of an effective serially interleaved concatenated channel coded scheme, where the inner encoder is the extended CE and the outer encoder is a convolutional encoder. A BER of 2.8X10 at 0.6dB SNR in an AWGN channel is obtainable.