Performance Characterization of Relaying Using Backscatter Devices

TL;DR

This paper analyzes the error performance of backscatter communication relays under ambient interference, comparing amplify-and-forward and decode-and-forward schemes with optimized power allocation.

Contribution

It is the first to compare AF and DF backscatter relaying performance analytically considering energy detection and power optimization.

Findings

DF with optimal power performs similarly to AF.

AF outperforms DF with imperfect OOK reflection coefficients.

Analytical BER expressions derived for backscatter relays.

Abstract

In this paper, we examine the error performance of backscatter communication in the presence of ambient interference, where the backscatter device acts as a relay. Specifically, the performance comparison of amplify-and-forward (AF) and decode-and-forward (DF) backscatter relaying is considered for the first time. Considering energy-based detection for on-off keying (OOK) modulation, we derive the statistics of the received signal power, from which the detection thresholds and corresponding bit error rates (BER) are obtained analytically. For the DF scheme, we allow the source node to transmit continuous-wave signals during the relay-to-destination transmission phase to power the backscatter relay. Under a total power budget constraint at the source, we optimize the power allocation for the transmissions in the source-to-relay and relay-to-destination phases. Numerical analysis shows that the DF scheme with optimal power allocation performs similarly compared to the AF scheme, despite the added complexity of the decoding operation. On the other hand, the AF scheme significantly outperforms the DF scheme when the reflection coefficients at the backscatter device do not correspond to perfect OOK. These results provide valuable insights into the design and deployment of backscatter nodes with the goal of improving coverage.