Location tracking with directional antennas in wireless sensor networks

In this paper, we investigate the use of multiple directional antennas on sensor motes for location determination and mobile node monitoring. One key aspect that distinguishes wireless sensor networks is inexpensive transmitters and receivers that still maintain acceptable connectivity. Therefore, complex RF solutions are often not applicable. We propose and demonstrate a location estimation algorithm on a single sensor node equipped with inexpensive directional antennas by measuring the received signal strength of the transmission peers. This algorithm is further applied to the dynamic tracking of a wandering mote. The location tracking error can be reduced from 30% to 16% by using moving average schemes and merging estimates from different sets of antennas. The mean error of tracking estimates can be obtained to provide the certainty of location tracking. Therefore, only a single mote with angular diverse multiple antennas is needed to determine the location of a mote without triangulation.