Fractional Chirp Rate Based Non-Orthogonal Transmission for Chirp Spread Spectrum Modulation
Runxin Zhang, Shun Zhang, Xiaobo Wang, Yunzhou Zhu · 2023
As one of the emerging technologies, chirp spread-spectrum (CSS) modulation finds extensive adoption in Internet of Things (IoT) networks, including notable examples like Long-Range (LoRa). In order to enhance the capacity of CSS modulation based IoT networks, this paper introduces a novel non-orthogonal transmission scheme named fractional chirp rate based CSS (FCR-CSS). FCR-CSS explores the dimension of chirp rate in CSS signals. In contrast to conventional LoRa that relys on distinct spreading factors (SF), FCR-CSS harnesses varying chirp rates to enable concurrent transmission by multiple users while utilizing the same SF. Interference analysis shows that in the proposed system, the energy dispersion of interference signal guarantees the correct demodulation of interested signal. Both analytical and simulation results substantiate the considerable capacity enhancement achievable through FCR-CSS, all the while maintaining a satisfactory bit error rate (BER) performance.