On the Achievable Rate of Bi-Static Modulated Re-Scatter Systems

TL;DR

This paper analyzes the achievable data rate in a bi-static modulated re-scatter system combining legacy MIMO links with a multi-antenna re-scatter node, demonstrating enhanced capacity and examining the effects of channel estimation errors.

Contribution

It introduces a model for a combined legacy MIMO and re-scatter system, deriving achievable rate bounds and analyzing the impact of channel estimation errors with joint decoding.

Findings

Achievable sum rate exceeds that of the legacy system alone.

Channel estimation errors impact the achievable rate.

Joint decoding with interference cancellation improves performance.

Abstract

In ambient re-scatter communications, devices convey information by modulating and re-scattering the radio frequency signals impinging on their antennas. In this correspondence, we consider a system consisting of a legacy modulated continuous carrier multiple-input-multiple-output (MIMO) link and a multi-antenna modulated re-scatter (MRS) node, where the MRS node modulates and re-scatters the signal generated by the legacy transmitter. The receiver seeks to decode both the original message and the information added by the MRS. We show that the achievable sum rate of this system exceeds that which the legacy system could achieve alone. We further consider the impact of channel estimation errors under the least squares channel estimation and study the achievable rate of the legacy and MRS systems, where a linear minimum mean square error receiver with successive interference cancellation is utilized for joint decoding.