Demodulation of Frequency Shift Chirp Spreading spectrum with Cyclic Prefix

The rapid development of the Internet of Things (IoT) puts forward many requirements for wireless communication technology. Low Power Wide Area Networks (LPWAN) are designed for low bandwidth, low power, long-range and large number of connected IoT applications. As one of the LPWAN, Low Power Long Range Transceiver (LoRa) described as a Frequency Shift Chirp Modulation (FSCM), is widely concerned and studied. In this paper, the performance of Lora modulation in the fading channel is analyzed. Because the delay spread of the multipath signal will propagate to the next symbol, which will cause intersymbol interference (ISI) and result in performance degradation of the system, the FSCM signal with Cyclic Prefix (CP) is introduced. The effectiveness of CP to resist ISI is proved by theoretical analysis and performance simulation. At the same time, the rake receiver is introduced, The performance of the system is greatly improved by the rake reception of multipath signals.