Efficient Hierarchical Multiple Access for Ambient Backscatter Wireless Networks

Abstract

Ambient backscatter communication (AmBC) enables information delivery over an ambient RF signal without carrier generation and has emerged as a promising technology to build up the self- sustainable Internet-of-Things (IoT). However, when a strong ambient signal appears, multiple backscatter nodes may initiate data transmission simultaneously, causing severe contention and wasting the precious transmission opportunity. The nondeterministic and sporadic nature of ambient signals makes it a great challenge for efficient multiple access design in ambient backscatter aided wireless network (AmBWN). Moreover, the stringent energy supply and ultra-low-cost design of the backscatter transmitter makes most multiple access schemes no longer suitable for AmBWN. To fully share carrier resources for backscattering, we resort to the non-orthogonal multiple access (NOMA) to allow multiple devices in the same regime to transmit over an ambient signal with low latency. Moreover, we propose a hierarchical multiple access scheme, which allows beamforming based spatial division multiple access among groups, and NOMA for multiple users access within a group. The evaluation result shows latency and SINR can be significantly improved with minimal overhead at the transmitter.