Antenna Isolation, Wideband Multipath Propagation Measurements, and Interference Mitigation for On-frequency Repeaters

On-frequency repeaters provide network operators with a cost-effective means of extending coverage to areas of low signal strength. Their ability to transmit and receive on the same channel essentially renders their operation transparent to the rest of the network. The maximum gain of an on-frequency repeater is, however, limited by the amount of isolation that exists between the transmitter and receiver antennas. Adaptive cancellation techniques may be used to mitigate a lack of isolation, but their performance is limited by their ability to track the time-varying multipath in the channel which exists between the two antennas. This paper presents antenna isolation and wideband power delay profile measurement results for typical repeater installations. In addition, simulation results are presented from a novel adaptive filtering approach that allows repeaters to operate with gains equal to or greater than the existing isolation.