A Time-Delay Overlapping Modulation-Based High Spectral Efficiency and Secure DCSK System

In this paper, a new high spectral efficiency differential-chaos-shift-keying system based on the time-delay overlapping modulation technology (TDOP-DCSK) is proposed. In this system, the binary bits are conveyed by multiple chaotic carriers which are delayed in turn and overlapped directly in time domain, and demodulated via solving the equation system. Benefiting from the time-delay overlapping modulation, TDOP-DCSK can offer higher spectral efficiency, data transmission rate and energy efficiency. Meanwhile, as multiple information-bearing chaotic signals are delayed and overlapped, the correlation between the reference and information-bearing signal is weakened, which brings a higher security level. The spectral efficiency, energy efficiency and security are analyzed, and the analytical BER expressions are derived over both additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. In addition, effects of various system parameters on the system performance are discussed, and the BER comparison between TDOP-DCSK and the traditional DCSK system is implemented to discover the means of TDOP-DCSK symbol constitution. The simulation results verify superiorities and show broad prospects of TDOP-DCSK.