MegaScatter: Large-Scale and Ubiquitous Backscatter Network via Multi-Domain Fusion

With the rapid growth of the Internet of Things (IoT), the demand for low-power and concurrent transmission capabilities has surged. This paper presents MegaScatter, a large-scale and ubiquitous backscatter network that supports concurrent communication for thousands of backscatter tags demodulating with only two receiver antennas. The core idea of MegaScatter is to integrate Orthogonal Frequency-Division Multiple Access (OFDMA) and spatial-domain pseudo-orthogonal techniques to resolve signal collisions in tags' subcarrier transmissions. Additionally, it employs a time-domain training sequence for accurate channel state and frequency offset estimation and uses orthogonal codewords for harmonic interference cancellation. Our experimental prototype effectively decouples signal collisions within the same subcarrier, enabling 5x concurrent data transmission using only two antennas. Simulations show that the system supports concurrent transmission from 9800 tags across 980 subcarriers, achieving a total throughput of 543.9 Mbps with a 2-antenna receiver. Compared to state-of-the-art systems, these advancements represent a 10× increase in concurrency and a 9.3× improvement in throughput.