Novel Time-Sharing Scheme for Virtual Elimination of Locata-WiFi Interference Effects

Solution accuracy of global navigation satellite systems (GNSS) is often compromised by the satellite-user geometry, weak signal levels and system outages. Locata Corporation’s positioning technology potentially bridges such gaps in availability, providing cm-level accuracy in challenging positioning environments. A Locata network consists of timesynchronized terrestrial transceivers (called LocataLites) operating in the 2.4 GHz Industrial, Scientific and Medical (ISM) band, transmitting signals appropriate for positioning. However, operation in a license-free band suffers from RF interference from various other communications and radio systems using the same portion of frequency spectrum. Among various other systems, WiFi devices are of special concern. Although there has been a significant improvement in Locata’s immunity to WiFi jamming in the latest hardware release, interference from WiFi may still hamper Locata's performance. This paper proposes a novel scheme to virtually eliminate WiFi interference to Locata. This scheme exploits the underlying Time Division Multiple Access (TDMA)-based functionality of both systems to force them to operate in a pseudo-synchronized manner, without any direct connectivity between systems. A new signal is proposed to be added to the Locata system, which will dictate the level of inter-system interference. Controlling this inter-system interference will not only offer control over the levels of solution accuracy from Locata but also over achieved data message throughput for the WiFi network. The advantage of this scheme is that it can be implemented for avoiding interference issues between WiFi and any other Software Defined Radio (SDR)/FPGA based communications system operating in the same band.