Integrated Communication and Positioning Design in RIS-empowered OFDM System: a Correlation Dispersion Scheme

TL;DR

This paper introduces a novel RIS-assisted OFDM system that enhances indoor communication and positioning by optimizing phase coefficients to differentiate channel responses, effectively improving accuracy in noisy environments.

Contribution

It proposes a new integrated design using correlation dispersion to improve indoor positioning and communication in RIS-empowered OFDM systems, considering imperfect channel information.

Findings

Outperforms existing methods in high-noise environments.

Effectively differentiates CFROPs for accurate positioning.

Works better with prior location information.

Abstract

In this paper, we propose a novel integrated communication and positioning design for orthogonal frequency division multiplexing system aided by a reconfigurable intelligent surface (RIS) in indoor circumstances. The channel frequency responses on pilots (CFROPs) of places of interest are used for online mapping with the offline CFROP database. We transform the objective of minimizing the similarity of different CFROPs into creating a differentiated database by optimizing the phase coefficients of RIS. Imperfect channel state information is considered due to time-varying caused by the two-stage mapping. We formulate a universal optimization problem for maximizing either the average or the minimum virtual distance of CFROPs. The communication service requirements are converted as constraints. A moderate case is discussed to reduce computational complexity with minor accuracy loss. A special property called correlation dispersion is analyzed. It is capable of eliminating the spatial consistency that incurs inaccuracy to traditional positioning methods. The property and the moderate case complement each other well with clear and logical physical interpretation. The particular characteristic makes our design outperform others especially in high-level-noise environments. It works even better when the prior information of user's potential location is available. The validity of our design is confirmed by numerical results.