Efficient and Scalable: Physical Layer Design to Taming Interference in Large-Scale Concurrent Backscatter Communications

The ever-increasing number of IoT devices can communicate with ultra-low power consumption through backscattering technology, which opens up more possibilities for ubiquitous IoT communication. However, large-scale tag communication brings certain challenges. In this study, we propose a scheme that uses the successive interference cancellation (SIC) algorithm based on concatenated convolutional coding and iterative decoding design, to address interference issues that may arise from multiple tag communication. The channel is modeled as MISO in the Rayleigh fading environment. Our system employs Walsh codes for spreading to achieve direct serial code division multiple access (DS-CDMA) and combines iterative decoding to enhance anti-interference capability. The SIC algorithm is applied to detect and decode tags separately while eliminating interference from other tags to improve decoding accuracy. Our proposed scheme successfully achieves concurrent communication of 90+ tags with notable BER results. Moreover, when nodes transmit data at 400 kbps, the throughput reaches 33 Mbps, which is 1.5 times higher than the throughput of the scheme without the SIC algorithm.