Direct path detection using multipath interference cancelation for communication-based positioning system

Jiaxin Yang,Sung Ik Park,Xianbin Wang,Heung Mook Kim

doi:10.1186/1687-6180-2012-188

Abstract

Abstract Abstract Recent development in wireless communication-based positioning technology brings significant challenge of detecting the weak signal component arriving from the direct propagation path for time-of-arrival (TOA)-based approach. Due to the common obstruction of the direct propagation path in dense multipath environments, identification of the weak direct path in these environments can be very difficult via the classical correlation-based estimator in the presence of interference from significant later arriving multipath components. A new direct path detection scheme using the multipath interference cancelation is presented in this article. For data communication purpose, an iterative estimator with improved accuracy for joint channel and data estimation is first developed; based on which, the interference of multipath components are reconstructed and subtracted from the original received signal. With the aid of the detected data, an enhanced preamble is formulated. The accuracy of direct path detection is substantially improved by using the correlation between the multipath interference-suppressed signal and the enhanced preamble. Semi-analytical expression of the performance of the iterative estimator is derived. The analysis enables the system to determine an automatic stopping criterion to reduce the computational complexity of the iterative process. The performance of the direct path detection is also analyzed in terms of the signal-to-interference-noise ratio (SINR) and compared with that of the conventional approach. Computer simulation results show the superiority of the proposed direct path detection. The accuracy of the positioning system using the proposed method is also evaluated in dense multipath environments.

Highlights

Positioning techniques using wireless communication signals have attracted considerable attention, especially in dense multipath environments where the Global Positioning System (GPS) is often unreliable [1,2]
// No peak selected after interference cancelation k = m0; else if m0 < m0 // A peak prior to m0 is detected after interference cancelation k = m0; else k = m0; end end Performance analysis of the proposed direct path detection method To show the superiority of the proposed approach, we evaluate the signal-to-interference-noise ratio (SINR) of the correlation output in (36) of the proposed method and compare it with (6)
Based on the channel estimation and data detection results provided by the proposed iterative estimator, the interference from later arriving multipath components is reconstructed and removed from the original received signal

Summary

Introduction

Positioning techniques using wireless communication signals have attracted considerable attention, especially in dense multipath environments where the Global Positioning System (GPS) is often unreliable [1,2]. The new direct path detection is based on the cross-correlation between the multipath interference-suppressed signal and the enhanced preamble. 1. m-sequence exhibits excellent correlation properties [32] such that the interference components from the LPs in (5) have been minimized by the preamble itself In this case, the performance gain of the proposed direct path detection over the classical estimator will serve as a lower bound for other cases. To address the aforementioned challenges, we propose a new direct path detection scheme based on multipath interference cancelation and data-aided method . We extend the analysis to the proposed iterative estimator in OFDM-based communication system with MPSK modulation We use both time and frequency domains’ signals analysis to derive a semi-analytical result of the estimation error.

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Conclusion