GPS signals are weak in indoor environment, therefore, wireless positioning system for indoor is being required. Recently, WLAN access points (AP) have been deployed in most of the large buildings at urban area to communicate with smart phones or notebook PCs. Thus WLAN is a suitable system for constructing indoor positioning system. Many indoor positioning solutions using WLAN technology have been developed using received signal strength (RSS) method or time of arrival (TOA) method. TOA method is capable of precise positioning, however, multiple numbers of AP need to be deployed without interference, and time synchronization is need at all station. Positioning method based on RSS is only applicable in line of sight, and has poor positioning performance. This paper show a direction of arrival (DOA) positioning method using dual-antenna access points, which time synchronization between APs are not required and is fairly accurate in line of sight condition. Fast Fourier Transform (FFT) technique, and ambiguity elimination technique is used for DOA estimation. At the end of the paper, the performance of DOA is presented.

Keywords: WLAN, DOA, indoor positioning