Efficient Communications for Overlapped Chirp-Based Systems
Thuy M. Pham, André Noll Barreto, Gerhard Fettweis
Abstract
In this letter, we consider the problem of increasing the spectral efficiency of a chirp-based communication system. Existing radar systems employ non-overlapping chirps with a large time-bandwidth product, and a modulation of these chirps for communications systems results in low spectral efficiency. Chirp overlapping can enhance the data rate, but it suffers from performance degradation due to intersymbol interference (ISI). In this letter, we derive a useful bit error rate (BER) expression to analyze the performance of a system with a finite number of overlapped chirps. Additionally, we investigate the conditions in which the ISI can be reduced while approaching the Nyquist signaling rate. We then propose simple linear equalization techniques to compensate for the ISI, allowing us to achieve faster-than-Nyquist signaling. We demonstrate the effectiveness of our approach by extensive analytical and numerical results.