NONLINEAR MULTI-H PHASE CODES FOR CPFSK SIGNALING

Two novel trellis-coding techniques, called nonlinar multi-h signaling and nonlinear asymmetrical multi-h signaling, which achieve higher co nstraint length than ordinary multi-h signals, are introduced with CPF SK signals, In contrast to ordinary multi-h signaling where the modula tion index is changed at the end of every symbol interval, nonlinear m ulti-h signals are constructed by changing the modulation index based on the previous symbol, and the current symbol interval, A class of no nlinear asymmetrical multi-h signals, which change the modulation inde x based on the current symbol too, is then constructed by extending no nlinear multi-h signals and combining them with asymmetrical multi-h s ignals. Binary full-response nonlinear multi-h and nonlinear asymmetri cal multi-h CPFSK signals are constructed and analyzed. Minimum Euclid ean distances and spectral properties of these signals are calculated at different phase states and various selected modulation index patter ns, Numerical results indicate that nonlinear multi-h and nonlinear as ymmetrical multi-h signals achieve significantly higher distance than other existing multi-h formats reported in the literature.