NONCOHERENT BLOCK DEMODULATION OF MSK WITH INHERENT AND ENHANCED ENCODING

The study considers noncoherent demodulation and coding of minimum shift keying (MSK). Using the framework of noncoherent maximum-likelihood block estimation (N-MLBE), it is shown that there is a close relation between known noncoherent MSK demodulation structures, such as envelope and differential receivers, and schemes derived from the N-MLBE principle. When the observation interval is increased, the performance of MSK with N-MLBE tends to that of binary coherently detected orthogonal BFSK. Furthermore, a new demodulation strategy, reduced block noncoherent estimation (RBNE) is introduced and shown to improve the performance of noncoherent MSK, beyond that of coherently detected orthogonal FSK. When PBNE is used with MSK and the observation interval is increased, the performance approaches that of antipodal signaling. The key feature that makes all these structures give an improved performance is multi-symbol noncoherent processing with exploitation of the MSK inherent coding properties induced by its phase continuity. Further performance improvement by the use of binary block codes is considered for MSK with N-MLBE. It is shown that simple binary block codes with low bandwidth expansion which exploit the inherent MSK memory can give significant gains.