“…In addition, satellite signals received in the indoor environment are weak and therefore GPS is unlikely to be able to be used indoor [2], [3]. To overcome these difficulties, various wireless technologies have been experimented with including infrared, bluetooth, IEEE 802.11 wireless LAN, ultrasonic, video camera, and Radio Frequency IDentification (RFID) [1], [4], [5]. RFID seems to be the most suitable candidate for tracking and localization in SH systems because of its robustness, low price, and flexibility [5].…”