Performance and Power Spectrum Calculations for Convolutionally Coded Generalized MSK with Two Symbol Periods Pulse Shape Duration

We show that by applying a cascaded convolutional encoder using two stages of coding, the last being a double repetition code, to "preceded" generalized minimum-shift keying (MSK) signals with pulse shape of duration two symbol periods a significant improvement in power and spectral efficiency is achieved. With only a double repetition code, it is shown that the signal has a power spectrum identical to uncoded MSK-like. When outer encoder is applied to improve the power efficiency, the bandwidth expansion is just a reciprocal of the outer encoder rate. It is demonstrated that considering performance, bandwidth and receiver complexity, generalized MSK signal coded using our special cascaded convolutional codes is an improvement over MSK and generalized MSK coded with "optimum" convolutional codes for the same code rate and receiver complexity reported previously for the same modulation scheme.