Enhanced transponder programming in an open road toll system

摘要

A transponder communication system and method for communicating with a transponder in an electronic toll collection system. A roadside reader attempts to program the transponder in a normal mode in which a programming signal is transmitted to a first coverage area. If the programming attempt in the normal mode is unsuccessful, the reader attempts to program the transponder in an enhanced mode in which a programming signal is transmitted to a second coverage area. The coverage area is adjusted after the programming attempt in the normal mode by using an adjacent antenna to the antenna used to transmit in the normal mode or by increasing the power of the programming signal to a level that is greater than the level used to transmit the programming signal in the normal mode.

主权项

1. A method of directing communications with transponders in moving vehicles in a roadway, the roadway having a plurality of antennas having a combined coverage area that includes at least a portion of the roadway, the antennas to operate in a time division multiplexed sequence, the time division multiplexed sequence being comprised of successive superframes, each superframe being comprised of a series of frames, each frame corresponding to communications on one of the antennas, each superframe having a fixed number of frames available for reading data from a memory of the transponder and a fixed number of frames available for writing data to the memory of the transponder, the method comprising:
determining which of the transponders need to be programmed; selecting for immediate programming at least some of the transponders that need to be programmed based on the fixed number of frames available for writing data; determining which of the antennas to use for communicating with the transponders that need to be programmed; determining which frames correspond to the antennas to be used; allocating the frames of a first superframe which have been determined to correspond to the antennas to be used as writing slots, for writing data to the memory of the transponder; and allocating a number of the unallocated frames of the superframe as reading slots, the frames allocated as reading slots not being used as writing slots.