Time-Delay Estimation in the Multi-Path Channel based on Maximum Likelihood Criterion

• Shengdong Xie,
• Aiqun Hu,
• Yi Huang,

Vol. 6, No. 4, April 24, 2012
10.3837/tiis.2012.04.006, Download Paper (Free):

• Multi-path propagation channel
• time-delay estimation
• maximum likelihood criterion
• subspace fitting algorithm
• CRLB

Abstract

To locate an object accurately in the wireless sensor networks, the distance measure based on time-delay plays an important role. In this paper, we propose a maximum likelihood (ML) time-delay estimation algorithm in multi-path wireless propagation channel. We get the joint probability density function after sampling the frequency domain response of the multi-path channel, which could be obtained by the vector network analyzer. Based on the ML criterion, the time-delay values of different paths are estimated. Considering the ML function is non-linear with respect to the multi-path time-delays, we first obtain the coarse values of different paths using the subspace fitting algorithm, then take them as an initial point, and finally get the ML time-delay estimation values with the pattern searching optimization method. The simulation results show that although the ML estimation variance could not reach the Cramer-Rao lower bounds (CRLB), its performance is superior to that of subspace fitting algorithm, and could be seen as a fine algorithm.

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