Title page for etd-0729108-230746


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URN etd-0729108-230746
Author Chia-Hung Kao
Author's Email Address No Public.
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Department Electrical Engineering
Year 2007
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Estimation of Signal Arrival Time Using 2-D Simulated
Annealing and Modified GML Algorithm
Date of Defense 2008-06-26
Page Count 51
Keyword
  • UWB
  • signal arrival time
  • generalized maximum likelihood
  • simulated annealing
  • Abstract The main purpose of this thesis is to combine modified GML algorithm with 2-D simulated annealing for estimation of signal arrival time in the UWB systems.In a dense multipath environment, the generalized maximum-likelihood (GML) algorithm can be used for the time-of-arrival (TOA) estimation. Nevertheless, the GML algorithm usually takes a long period of time, and sometimes fails to converge. Hence, a modified GML (MGML) algorithm is investigated. Two threshold parameters need to be determined in using the estimation algorithm. One threshold is to decide the arrival time range of estimated path, and the other, an amplitude threshold, is to judge whether the estimated path is true. Generally, the decision rule of thresholds may be based on the minimum error probability, which is defined as the sum of false alarm probability and miss probability. To mitigate the effects from noise and dense multipath interference, and to reduce the computational complexity of the algorithm, a method of threshold settings based on the minimum root mean square error (RMSE) criteria is discussed. In this scheme, the RMSE value for each candidate threshold pair in an appropriate region is computed. Constructing an accurate RMSE table and performing a full-scale grid search of adequate threshold settings can be very time-consuming. A 2-D simulated annealing process is adopted for finding the best pair of thresholds for use in the modified GML algorithm. The simulated annealing, different from the gradient descent, can avoid trapping into a local minimum in finding the best threshold pair. The resulting threshold pair makes the modified GML algorithm become more efficient in estimating the signal arrival time with an automatic search manner. Simulation results show that the proposed scheme can achieve better performance than the grid search approaches in UWB environments.
    Advisory Committee
  • Jiann-Der Lee - chair
  • Hsin-Hsyong Yang - co-chair
  • Shiunn-Jang Chern - co-chair
  • Chin-Der Wann - advisor
  • Files
  • etd-0729108-230746.pdf
  • indicate in-campus access in a year and off_campus not accessible
    Date of Submission 2008-07-29

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