A TDOA location scheme in OFDM based WMANs

A time difference of arrival (TDOA) location scheme for the orthogonal frequency division multiplexing (OFDM) based wireless metropolitan area networks (WMANs) is presented. A novel TDOA estimation algorithm for OFDM signals is proposed and adopted in this scheme. The algorithm enhances the location performance by utilizing the information in the time and frequency domains obtained from the received location OFDM signals. The simulations are implemented with an 802.16e configuration considering an outdoor wireless scenario. The simulation results show that the scheme can meet the E911 requirements in even complex multipath channel conditions, and outperform the location schemes with traditional correlation detection TDOA estimations.

I. Introduction

Location schemes have been adopted in the available wireless networks to implement the promising location based services (LBS). Among the schemes, as those employed in the 3GPP and specifications [1], [2], the assisted GPS (A-GPS) and time difference of arrival (TDOA) based schemes are preferred. The A-GPS schemes demand additional GPS receivers at the mobile terminals (MTs), which leads to an increased cost, size, and power consumption. In contrast, the TDOA based schemes demand no additional devices at the MTs. Further more, the TDOA based schemes are more suitable for urban applications where the satellite signals are subject to blockage. Clearly, the TDOA based location schemes are practical and likely to be widely adopted in the future OFDM based wireless metropolitan area networks (WMANs).