Performance Analysis of an Overlap-Based CSS System

Overlap is one of the techniques for increasing bit rate in Chirp Spread Spectrum (CSS). Although more overlaps can offer higher data throughput, more Inter-Symbol Interference (ISI) occurs, resulting in serious Bit Error Rate (BER) performance degradation. In this paper, the authors analyze the influence of the overlap on CSS systems and express the maximum number of overlapped symbols that does not incur the ISI, in terms of the chirp bandwidth and chirp duration. The analysis results are verified by BER performance simulation of Direct Modulation Differential Phase Shift Keying (DM-DPSK) that is a typical modulation method used in CSS.