Patent ID: 7126951

Claim:
A system for monitoring movement in a three-dimensional multi-level structure, comprising: a plurality of mobile wireless remote terminals, adapted to communicate in a wireless multi-hopping communication network; and a plurality of wireless routers, deployable in the three-dimensional area, and adapted to communicate in the wireless multi-hopping communication network; each of the mobile wireless remote terminals being adapted to exchange signals with any of the routers within its broadcast range and, based on those signals, being adapted to determine its respective closest router and a respective floor identifier that identifies a respective floor on which the mobile wireless remote terminal is present in the three-dimensional structure; wherein said each mobile wireless remote terminal uses time of flight (TOF) data and received signal strength indicator (RSSI) data pertaining to the signals received from said any of the routers within its broadcast range to determine the floor on which it is present in the three-dimensional structure; wherein the three-dimensional structure is a building, and the routers are deployed on respective floors of the building; and said each mobile wireless remote terminal assigns respective scores to each floor based on the TOF data and RSSI data pertaining to the signals, and determines the floor on which it is present based on the scores.