Frequency-Shift Chirp Spread Spectrum Communications With Index Modulation

This article introduces a novel frequency-shift chirp spread spectrum (FSCSS) system with index modulation (IM). By using combinations of orthogonal chirp signals for message representation, the proposed FSCSS with index modulation (FSCSS-IM) system is very flexible to design and can achieve much higher data rates than the conventional FSCSS system under the same bandwidth. The article presents optimal detection algorithms, both coherently and noncoherently, for the proposed FSCSS-IM system. Furthermore, a low-complexity noncoherent detection algorithm is also developed to reduce the computational complexity of the receiver, which is shown to achieve near-optimal performance. The results are presented to demonstrate that the proposed system, while enabling much higher data rates, enjoys similar bit-error performance as that of the conventional FSCSS system.