Multi-Dimensional Sparse-Coded Ambient Backscatter Communication for Massive IoT Networks

Abstract

In this paper, we propose a multi-dimensional sparse-coded ambient backscatter communication (MSC-AmBC) system for long-range and high-rate massive Internet of things (IoT) networks. We utilize the characteristics of the ambient sources employing orthogonal frequency division multiplexing (OFDM) modulation to mitigate strong direct-link interference and improve signal detection of AmBC at the reader. Also, utilization of the sparsity originated from the duty-cycling operation of batteryless RF tags is proposed to increase the dimension of signal space of backscatter signals to achieve either diversity or multiplexing gains in AmBC. We propose optimal constellation mapping and reflection coefficient projection and expansion methods to effectively construct multi-dimensional constellation for high-order backscatter modulation while guaranteeing sufficient energy harvesting opportunities at these tags. Simulation results confirm the feasibility of the long-range and high-rate AmBC in massive IoT networks where a huge number of active ambient sources and passive RF tags coexist.

Adaptive Transmission Repetition and Combining in Bistatic WiFi Backscatter Communications

“…There have been a number of proposals to resolve contention between multiple RFID tags [22]- [25]. Some attempts have also been made for ambient backscatter communication [2], [26]. The proposed scheme can be combined with a wide range of such proposals, thus still benefiting from transmission repetition for robust communication in multi-tag environments.…”