Exact client localization has been an obstacle in the use of WLAN in factories and offices for providing location based service. With respect to a novel localization scheme in WLAN based on wireless clock synchronization, preamble detection for hardware timestamping in the presence of frequency selective fading channels has been discussed in this study. Simulation based approach using adaptive equalizers is studied and the results suggest that preamble detection is possible in frequency selective channels. In practice, some other issues like slow settling of automatic gain controller have to be taken care of to ensure proper preamble detection and hence exact localization.