Multipple trellis codes for multi-h phase coded modülation

Continuous phase modulation (CPM) is a very attractive digital modulation technique for the transmission of digital information over band and/or power limited channels. The phase continuity provides to CPM signals good spectral properties and some error correction possibilities. Multi-/i phase coded modulation technique (MHPM) has received a great deal of attention for application in satellite modems due to its power and bandwidth efficiency which are even better than that of CPM. MHPM is a special case of CPM where the modulation index (h) is periodically changed for successive signalling intervals. In this thesis, multiple trellis codes are designed for the systems which use MHPM technique, in order to increase their error performances over gaussian and fading channels. »Since their trellis structures are time-variant, MHPM schemes can not be decomposed as CPM schemes into a ti me-invariant continuous phase encoder (CPE) followed by a memoryless modulator (MM), over one symbol interval. A new representation for M-ary MHPM is intro duced to overcome this problem, namely to obtain a time invariant CPE followed by a time invariant MM. We simply consider k consecutive symbol intervals together during the constitution of the CPE where k is the number of different modulation indexes. The outputs of this fc-CPE are then mapped to multiple signal set consti tuted by k consecutive MHPM signals. This kind of decomposition makes easier the optimal combination of an external encoder with MHPM. Since the CPE is linear over a finite field, the cascade of an external convolutional encoder with the CPE can be reduced to an equivalent single convolutional encoder. The set partitioning method is applied to the multiple MHPM trellis structures to maximize the Euclide an distances between all signal pairs originating from and merging to the same state. The proposed multiple coded MHPM systems for the gaussian channels which use 4 and 8 state decoding trellis provide significant asymptotic coding gains with respect to the corresponding uncoded MHPM and related CPM systems. The design of mul tiple trellis codes for MHPM is also realized for the fading channels which request different design criteria such as the effective code length and the product distance. It is shown by analytical methods and by means of computer simulation that these new coded MHPM systems significantly outperform their uncoded counterparts in this type of channels.