Noncoherent Detection for Ambient Backscatter Communications Over OFDM Signals

Donatella Darsena

doi:10.1109/access.2019.2950601

Abstract

Backscattering communications have been recently proposed as an effective enabling technology for massive Internet of Things (IoT) development. A novel application of backscattering, called ambient backscattering (AmBC), has been gaining much attention, wherein backscattering communications exploit existing RF signals without the need for a dedicated transmitter. In such a system, data demodulation process is strongly complicated by the random nature of the illuminating signal, as well as by the presence of the direct-link interference (DLI) from the legacy system. To overcome these shortcomings, one can resort to noncoherent detection strategies, aimed at reducing or even nullifying the amount of a priori information needed to reliably perform signal demodulation. In this paper, we investigate noncoherent detection strategies for backscatter communications over ambient OFDM signals and solve the noncoherent maximum-likelihood (ML) detection problem for a general Q-ary signal constellation. Additionally, we derive a suboptimal detector, which takes the form of the classical energy-detector (ED), whose performance is evaluated in closed-form. Finally, the performance of the proposed detectors is corroborated through Monte Carlo simulations.

Highlights

With the advent of Internet of Things (IoT) [1], [2], where Internet extends into the real world [3] and billions of devices sense the surrounding environment and communicate without human intervention, a key issue is the search for energyefficient reliable sensing communication protocols, which can support large-scale and seamless deployment by relaxing battery constraints
The channel taps are modeled as circularly-symmetric complex Gaussian random variables, with path-losses given by [45], [46] σi2k = c2/(4π fcζik )2, for (i, k) ∈ {(1, 2), (2, 4), (1, 4)}, where c = 3·108 m/s is the light speed
This paper dealt with noncoherent detection problem for backscatter communications over ambient Orthogonal Frequency Division Multiplexing (OFDM) signals

Summary

INTRODUCTION

With the advent of Internet of Things (IoT) [1], [2], where Internet extends into the real world [3] and billions of devices sense the surrounding environment and communicate without human intervention, a key issue is the search for energyefficient reliable sensing communication protocols, which can support large-scale and seamless deployment by relaxing battery constraints. For this reason, backscattering communications [4]–[8] have been recently proposed as an effective enabling technology for massive IoT development.

Darsena

SYSTEM MODEL

SUBOPTIMAL ENERGY DETECTOR FOR

NUMERICAL RESULTS

CONCLUSION