Maximum likelihood TOA and OTDOA estimation with first arriving path detection for 3GPP LTE system

Abstract

The US Federal Communications Commission (FCC) has mandated wireless network operators and mobile devices to provide accurate location information for E‐911. Requirements for time of arrival (TOA) and time difference of arrival (TDOA) measurements have been specified in 3GPP LTE Rel. 9 to ensure accurate user equipment (UE) positioning even under bad conditions (e.g. with channel quickly varying and SNR being as low as −13 dB). To fulfil these requirements, it is vital to accurately estimate the first signal arriving path. In this work, we first derive ‐ without any approximation ‐ the Cramér–Rao lower bound (CRLB) of the LTE TOA and TDOA measurements based on the different pilots, which is shown to be as low as a few metres for SNR = −13 dB. The achievable performance of the LTE system is compared with the FCC and 3GPP requirements, and the impact of mobile multipath channels on the measurements is analysed. Then, we describe practical low‐complexity methods for LTE TOA and TDOA measurements with enhanced first arriving path detection. The maximum likelihood based correlation profile is used as detection metric. After grossly determining the signal region by a moving window, three methods, namely, peak detection, SNR‐based threshold and adaptive threshold based on noise floor and metric peak value are employed to estimate the first arriving path. Simulation results show that the proposed adaptive threshold‐based method can meet all 3GPP requirements under various realistic mobile channels, and can in some cases achieve a performance close to the CRLB. Copyright © 2014 John Wiley & Sons, Ltd.

A Survey of Enabling Technologies for Network Localization, Tracking, and Navigation

“…1) mmWave and massive MIMO: In 3GPP Release 9, PRS was defined so that the TOA can be measured between BS and mobile [46]. Many mobile device and service providers are investigating the localization performance with PRS.…”

Reduced‐complexity simply/doubly differential primary synchronization for LTE systems

“…where u stands for the fine adjustment frequency determined from the Equation 10. The SD metric M u SD in Equation 11 must be calculated for the 3 u values.…”

“…Several researches have been done on this issue. Some approaches propose new synchronization signals that are not compliant with the LTE signal, while others exploit dedicated synchronization signals and tailor specific metrics to them . The approaches in the previous studies accomplish symbol start detection in a Cyclic Prefix (CP)–based blind manner.…”

“…In the previous studies, maximum likelihood–based correlation metric was used to grossly determine the time of arrival. For fine time synchronization, three methods were used,, namely, peak detection, signal‐to‐noise ratio (SNR)–based threshold, and adaptive threshold based on noise floor and metric peak value. Then, joint detection of fine PSS start and S‐ID was achieved exploiting a suitable reduced‐rank representation of the channel frequency response to mitigate the impact of multipath distortion .…”

“…Some approaches propose new synchronization signals that are not compliant with the LTE signal, 4,5 while others exploit dedicated synchronization signals and tailor specific metrics to them. [6][7][8][9][10][11][12][13][14] The approaches in the previous studies [6][7][8] accomplish symbol start detection in a Cyclic Prefix (CP)-based blind manner. Then, the S-ID is determined through cross-correlation between the 3 local known ZC sequence candidates and the Frequency Domain (FD)-extracted OFDM symbols.…”