Nowadays, several systems are available for outdoor location (i.e GPS, cellular networks based…). However, there is no proper location system for indoor scenarios. The technique presented in this paper proposes the use of the existing wireless LAN infrastructure with minor changes to provide an accurate estimation of the location of mobile devices in indoor environments. This technique is based on round-trip time (RTT) measurements, which are used to estimate TOA and distances between the device to be located and WLAN access points. To avoid the cumbersome modification of the physical layer, each RTT is estimated between the transmission of an IEEE 802.11 link layer data frame and the reception of the associated acknowledgement (ACK). By applying trilateration algorithms, an accurate estimation of the mobile position is calculated.

Peer Reviewed