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Experimental Demonstration of Backscatter Channel Estimation by MIMO Reader

Contact: Deepak Mishra
Examiner: Deepak Mishra

Background:

Backscatter communication (BSC) is emerging as a promising technology that can help in practically realizing the ubiquitous deployment of low-cost sustainable wireless devices in Internet of Things (IoT). This technology thrives on its capability to use low-power passive devices like envelope detectors, dividers, comparators, and impedance controllers, instead of more costly and bulkier conventional radio frequency (RF) chain components such as local oscillators, mixers, and converters [1]. The BSC systems generally comprise a power-unlimited reader and low-power tags. As the tag does not have its own transmission circuitry, it relies on the carrier transmission from the emitter for first powering itself and then backscattering its data to the reader by appending information to the backscattered carrier. Despite the several merits, the limited BSC range and low achievable bit rate are two major fundamental bottlenecks of this technology [2]. The main purpose of this project is to analyze the efficacy of a full-duplex multiple-input-multiple-output (MIMO) reader in combating these limitations of monostatic BSC systems. Specifically, it will be involving a study on the optimal utilization of the available energy resources at multiantenna reader for accurately estimating the backscattered channel and then using this information for efficiently decoding the reflected signal from tag to enable longer range quality-of-service (QoS) aware BSC.

Objectives:

This Master thesis project will be first focusing on the prototype implementation of basic monostatic BSC between a singe antenna semi-passive tag and a full-duplex antenna array reader. Specifically, this setup will comprise of multiantenna reader implemented using USRP kit, off-of-the-shelve backscattering device, and basic measurement units. Thereafter, this BSC setup will be used to conduct hardware experiments for validating the performance of a recently proposed channel estimation protocol [3], that involves obtaining least-squares estimate (LSE) of the tag-to-reader channel directly from the backscattered signal, without requiring any feedback from tag. This LSE will finally be employed in designing of the precoder and combiner at the reader for optimally decoding the backscattered signal from the tag.

Prerequisites:

The student needs to have a good background in multiantenna wireless communications, antenna theory, and embedded systems.

References

[1] C. Xu, L. Yang and P. Zhang, "Practical Backscatter Communication Systems for Battery-Free Internet of Things: A Tutorial and Survey of Recent Research", in IEEE Signal Processing Magazine, vol. 35, no. 5, pp. 16-27, Sept. 2018.
[2] A. Bletsas, P. N. Alevizos and G. Vougioukas, "The Art of Signal Processing in Backscatter Radio for µW (or Less) Internet of Things: Intelligent Signal Processing and Backscatter Radio Enabling Batteryless Connectivity", in IEEE Signal Processing Magazine, vol. 35, no. 5, pp. 28-40, Sept. 2018.
[3] D. Mishra and E. G. Larsson, "Optimizing reciprocity-based backscattering with a full-duplex antenna array reader", in Proc. IEEE Int. Workshop Signal Process. Adv. Wireless Commun. (SPAWC), Kalamata, Greece, June 2018, pp. 1-5.

Page responsible: Danyo Danev
Last updated: 2018 11 21   15:41


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