Methods and apparatus are provided to locate a terminal within a
workspace. Radio frequency identification (RFID) tags are provided in
known locations, preferably in, on or adjacent the light fixtures or
other workspace infrastructure. The terminal comprises an RFID tag
interrogation transceiver, processor and memory. The transceiver
interrogates the tags which respond with information correlatable with
their unique locations. The terminal determines its locations relative to
the known locations of responding tags by, for example, varying its
transmit power and/or receiver sensitivity and/or by trilateration using,
for example, phase or time difference of arrival measurements on the tag
response signals. Once it has determined its own location it may transmit
or otherwise announce its location as desired by the user. In a preferred
embodiment, the natural electromagnetic radiation and/or RADAR cross
section backscatter from fluorescent type fixtures, modulated with their
position information, acts as the RFID infrastructure beacon.