Performance Analysis and Mitigation Method for I/Q Imbalance-Impaired Time Reversal-Based Indoor Positioning Systems

Abstract

Time reversal-based indoor positioning system (TRIPS) is a promising technology for the centimeteraccuracy indoor positioning, since it exploits the rich multipath propagation in indoor environments as a specific signature for each location. In TRIPS, a database is first constructed via channel probing. Well-calibrated devices are usually assumed in this process, i.e., no hardware impairments. However, a low cost terminal to be located, whose typical impairment is the I/Q imbalance (IQI) at the front-end transmitter, can significantly influence the TRIPS performance. More specifically, IQI creates an interference image of the signal that reduces the metric value used in TRIPS and hence decreases the localization accuracy. In this paper, we analytically investigate the impact of the IQI on the metric of TRIPS. A closed-form approximation of the localization metric inherent to the IQI is derived. In order to improve the TRIPS performance, an effective IQI mitigation method is proposed. Numerical simulations are carried out to validate the derived analytical expression under the IQI impact and the proposed compensation method. Index terms-Indoor positioning system, time reversal, I/Q imbalance, OFDM.

Focusing gain analysis of time-reversal precoding in MISO OFDM communication systems

“…Recently, TR has been claimed to be a promising candidate for 5G communication systems, where massive multipath (one of the major challenges in modern wireless communications) is exploited to enhance the communication link instead of trying to remove them [14]. TR is also shown to be an interesting technology to provide physical layer security [15], centimeteraccuracy indoor localization [16][17][18], event detection through a wall [19], and monitoring of vital signs [20]. It is worth noticing that almost all TR-based applications referred here are in the TD.…”