880-01As a benchmark for comparing various coded modulation designs, we consider the cutoff rate of coded modulation. In Chapter II, we first derive general expressions for the cutoff rates of M-PSK, M-DPSK and QAM over a Rayleigh fading channel. An interesting result that we have obtained is the following: coherent detection of DPSK does not always provide better performance than differentially coherent detection of DPSK in coded modulation. Then, cutoff rates of power controlled BPSK/QPSK and M-ary orthogonal signaling for CDMA mobile communications systems are obtained. It is shown that the coded modulation performance is not very sensitive to the variation of the power control variance. For M-ary orthogonal signaling, the optimum code rate selection problem is discussed.
In Chapter Ⅲ, design of communication systems based on the cutoff rate is addressed. Specifically, we consider the European terrestrial DAB (digital audio broadcasting) system, where π/4-DPSK and punctured convolutional coding are used. Several strategies for designing receivers are proposed: in particular, a strategy for the code rate selection, which acts better than the existing one, is presented based on the cutoff rate. In addition, cutoff rate for the coded modulation of European DVB (digital video broadcasting) systems and that of the American ATSC (advanced television system committee) systems are compared.
In Chapter Ⅳ, we develop a cost effective demodulator for MSK that is considerably simpler to implement than existing ones. The proposed demodulator for MSK is based on a multi-symbol-based technique and its performance tightly approaches that of coherent detection. Availability of the proposed receiver for demodulating GMSK is also investigated through computer simulation.
