Noncoherent Multiuser Chirp Spread Spectrum: Performance with Doppler and Asynchronism

TL;DR

This paper analyzes multiuser noncoherent chirp spread spectrum performance under Doppler and asynchronism, deriving BER expressions and demonstrating the advantages of new nonlinear chirp designs over traditional linear chirps.

Contribution

It introduces analytical BER expressions for noncoherent multiuser BCSS considering Doppler and asynchronism, and shows the superior performance of novel nonlinear chirp signals.

Findings

Nonlinear chirps outperform linear chirps under Doppler and asynchronism.

Derived BER expressions match simulation results.

Nonlinear chirp designs reduce multiuser interference effects.

Abstract

In this paper, we investigate multi user chirp spread spectrum with noncoherent detection as a continuation of our work on coherent detection in [1]. We derive the analytical bit error ratio (BER) expression for binary chirp spread spectrum (BCSS) in the presence of multiple access interference (MAI) caused by correlation with other user signals because of either asynchronism or Doppler shifts, or both, and validate with simulations. To achieve this we analyze the signal cross correlations, and compare traditional linear chirps with our recently-proposed nonlinear chirps introduced in [1] and with other nonlinear chirps from the literature. In doing so we illustrate the superior performance of our new nonlinear chirp designs in these practical conditions, for the noncoherent counterpart of [1].