Avoidance method of interference between RFID systems including interference-zone change according to the distance between channels

In a long-range RFID system, the communication range is far longer than that in a conventional short-range RFID system. However, the long-range RFID system tends to suffer interfering problem between systems. In this report, we evaluate the interference avoidance method of assigning the frequency channels and time slots to reader with using the information of the reader position. From the computer simulation, we show that the number of required time slots for avoiding the interference can be reduced and the frequency utilization efficiency can be increased when the dependence between the interference geometrical distance between readers and the frequency distance between channels is taken into account.