# Channel Estimation for Ambient Backscatter Communication Systems with Massive-Antenna Reader

## TL;DR

This paper addresses the challenge of channel estimation in ambient backscatter communication systems with massive-antenna readers, proposing a joint estimation method and analyzing its theoretical limits.

## Contribution

It introduces a two-step joint estimation approach for channel gains and DoAs in AmBC systems with large antenna arrays, including a refinement process and CRLB analysis.

## Key findings

- The proposed method effectively estimates channels and DoAs.
- CRLBs provide theoretical bounds for estimation accuracy.
- Simulations confirm the efficiency and validity of the approach.

## Abstract

Ambient backscatter, an emerging green communication technology, has aroused great interest from both academia and industry. One open problem for ambient backscatter communication (AmBC) systems is channel estimation for a massive-antenna reader. In this paper, we focus on channel estimation problem in AmBC systems with uniform linear array (ULA) at the reader which consists of large number of antennas. We first design a two-step method to jointly estimate channel gains and direction of arrivals (DoAs), and then refine the estimates through angular rotation. Additionally, Cramer-Rao lower bounds (CRLBs) are derived for both the modulus of the channel gain and the DoA estimates. Simulations are then provided to validate the analysis, and to show the efficiency of the proposed approach.