Design of Noncoherent and Coherent Receivers for Chirp Spread Spectrum Systems

LoRaWAN is a prominent communication standard to enable reliable low-power, long-range communications for the Internet of Things (IoT). The modulation technique used in LoRaWAN, commonly known as LoRa modulation, based on principle chirp spread spectrum (CSS). main objective this article design practical, low-complexity coherent receiver recently proposed CSS-based scheme, called phase-shift keying CSS (PSK-CSS), that embeds extra information bits starting phases conventional symbols. To end, novel method perform coarse timing and frequency synchronization makes use preamble consisting both up down chirps shape pulse shaping and/or receive (matched) filters. Furthermore, fine synchronization, timing, phase loop filters are designed simple first-order second-order phase-locked (PLL) circuits with dynamic gain control. A natural outcome our practical noncoherent can be LoRa/CSS system has better performance lower computational complexity compared other existing designs. Extensive simulation results presented demonstrate excellent merits design. In particular, bit-error-rate (BER) higher-rate PSK-CSS obtained only 0.25 dB worse than ideal co-coherent receiver, whereas it enjoys about 0.75-dB power over detection system. Thanks carried by symbols, implemented quadrature (QPSK) delivers additional 23.44% 18.75% data rate spreading factors (SFs) 8 10, respectively.