A Closed-Form BER Expression for Overlap-Based CSS System Design

Overlap is one of the techniques for increasing bit rate in chirp spread spectrum (CSS). More overlaps can offer higher data throughput; however, they may cause more intersymbol interference (ISI) at the same time, resulting in serious bit error rate (BER) performance degradation. Thus, the number of overlaps should be decided according to the required BER performance. In this paper, we derive a closed form expression for BER of the overlap-based CSS system, exploiting the approximated Gaussian Q function. The derived BER expression includes the number of overlaps as a parameter, and thus, would be very useful in determining the number of overlaps for a specified BER. The numerical results demonstrate that the BER derived in a closed form closely agrees with the simulated BER.