RFID system with time slot interleaving

摘要

A method for interleaving time slots in a multi-antenna system for communication with RFID tags is disclosed. An example is shown for an eight antenna system. A first four antennas arranged side-by-side are sequentially energized to interrogate RFID transponders. A second set of four antennas arranged side-by-side, the first of which is adjacent to the last of the first set of antennas. A four-antenna sequence is performed for the first four antennas and a second four antenna sequence is performed for the second set of antennas. The first and second four antenna sequences are offset by only a marginal amount, sufficient to ensure that a transponder signal received four antennas away from an active antenna is not acknowledged because the receive window for the non-active antenna is delayed.

主权项

1. A method of communicating with an active RFID transponder in a system having a plurality transponder reader antennas arranged as a first set of adjacent reader antennas and a second set of adjacent reader antennas and two sets of time slots for sequentially transmitting to the first set of adjacent reader antennas during a first multi-position time slot and to the second set of adjacent reader antennas during a second multi-position time slot comprising:
sequentially transmitting a first interrogation signal to each of the first set of adjacent reader antennas during the first multi-position time slot; opening a first receiving window a predetermined time after each of said first interrogation signals, said first receiving window allowing reception of signals only from the one of said first set of reader antennas that just transmitted; sequentially transmitting a second interrogation signal to each of the second set of adjacent reader antennas during the second multi-position time slot; opening a second receiving window a predetermined time after each of said second interrogation signals, said second receiving window allowing reception of signals only from the one of said second set of reader antennas that just transmitted; and delaying the sequential transmission of said second interrogation signal to said second set of reader antennas from the sequential transmission of said first interrogation signal to said first set of said reader antennas, such that said second receive windows of said second set of reader antennas are not aligned in time with said first receive windows of said first set of reader antennas and said first and second multi-position time slots substantially overlap.