Patent ID: 8228205

Claim:
A vehicle position determination system for determining a position of a moving vehicle having a transponder in a multi-lane roadway, the vehicle determination system comprising: roadway antennas to receive a probable lane response signal from the transponder, the roadway antennas having partially overlapped coverage zones, each of the roadway antennas having a unique identifier associated therewith, the probable lane response signal being based on a plurality of counts corresponding to numbers of times the transponder has received a transmission from respective ones of the roadway antennas; a controller to cause each of the roadway antennas to periodically transmit its unique identifier; and a lane determination module to determine the counts corresponding to the numbers of times that the transponder received a transmission from each of the roadway antennas based on the probable lane response signal, and to determine a position of the moving vehicle by comparing ratios of the numbers of times each unique identifier was received by the transponder during a sampling period to values associated with different possible transponder locations, wherein all of the coverage zones have similar elliptical shapes with major axes extending in a direction orthogonal to a travel path of the vehicle.