Backward Compatible Modulation Schemes for Improving Spectrum Efficiency in DAB Systems

In this study, a new physical layer transmission technique is proposed with the spectrum efficiency up to two times of that of the Eureka-147 DAB system. The proposed technique comprises the modulation and demodulation schemes. In the modulation, non-uniform-phased 16-level amplitude/phase shift keying (16APSK) is adopted to replace the quadrature-phase-shift-keying (QPSK) in the Eureka 147 DAB system. Besides, in the demodulation, a simpler two-level differential amplitude-shift-keying (2DASK) detector with non-division operation is proposed to achieve low costs of hardware implementation. Furthermore, in order to guarantee backward compatibility of the original DAB receiver, the DQPSK-liked signaling constellation is designed. A software simulation platform is developed using Simulink/Matlab for evaluating the performances of DAB systems in multipath fading channels.