Research On High Throughput Adaptive Frequency Hopping System Based On LoRa Backscatter

To make people live better,IoT(Internet of Things)technologies utilize ubiquitous sensing to get information from natural environment and human movements.However,the simultaneous works based on millions of nodes consume huge energy,which limits the development and widespread deployment of IoT network.Low-power Wide-Area Network(LPWAN)technology,which are low power consumption and high coverage rate,are getting more and more attraction from both academia and industry.Among them,the LoRaWAN network is highly respected and widely deployed for its excellent long-distance transmission performance and openness.RF backscatter communication systems is a low-power technology to allow passive tag free-ride ambient RF signal to transmit its information.I chose the LoRaWAN as our fundamental platform to study the LoRa backscatter system and found the existing problems in state-of-art design.(1)The throughput of passive LoRa tag is limited because of strict power constraint;(2)The backscatter communication system is unstable.The energy intensity of the backscatter signal is much lower than excitation signal,which is easy inferenced by environmental noises.To address the above problems,this paper proposes H^2-B LoRa.It is a frequency hopping LoRa backscatter system with performance as high-throughput,noise-tolerable.The contribution are as follow.(1)I built a high-throughput coding scheme and a fine-grained IF signal generator in this paper for frequency-shifting modulation(FSK)on LoRa backscatter tag.The highest throughput of the H^2-B LoRa system is 24.76 Kbps,which is two orders of magnitude higher than that of the phase coded LiteNap system,and four times higher than that of the PLoRa system.(2)I proposed a backscattered adaptive anti-interference frequency hopping system.The system proposes a self-synchronization method,channel estimation for channel adaptive update and three channel-coding methods.Experimental results show that proposed system is stable.When the signal-to-noise ratio is-10 dBm,the stability of the H^2-B LoRa system is improved by 3%,45%and 85%respectively with the different channel-coding algorithm with the comparison to the PLoRa system.