Abstract
Applications of finding location for the subscribers using wireless services continue to expand. Therefore, many wireless location algorithms were devel-oped. Most of the wireless location algorithms were based on principles of Time of Arrival (TOA), Time Difference of Arrival (TDOA), Signal Strength or Angle of Arrival (AOA) to estimate the position of the mobile phone. There are two major error sources in wireless location systems. One is the error due to the clock asynchronization between the base station and the mobile phone. However, the problem could be solved by the location algorithms based on TDOA. The other major location estimation error source is non-line-of sight (NLOS) error which is very common in the signal propagation environment. So that the wireless location system should put more effort to overcome the inac-curacy due to the NLOS errors. To mitigate the estimation error due to NLOS, many wireless location sys-tems use methods that apply least square approach on mobile position to esti-mate the mobile phone position. In this thesis, we apply an alternative least square approach on delays and set up several appropriate constraints on delays to reduce the solution space.