Repeaters for wireless communication systems
View Patent ↗A repeater and associated method of use includes at least one antenna element for communicating in one direction and at least one antenna element for communicating in another direction. A radio frequency uplink path and a radio frequency downlink path are coupled between the antennas. At least one of the radio frequency uplink path or the radio frequency downlink path includes an adaptive cancellation circuit. The adaptive cancellation circuit is configured to generate a cancellation signal without requiring an injected signal. The cancellation signal, when added to a radio frequency signal in the respective uplink and downlink paths, substantially reduces feedback signals present in the radio frequency signal.
1. A repeater comprising:
at least one antenna element for communicating in one direction and at least one antenna element for communicating in another direction;
circuitry establishing a radio frequency uplink path and a radio frequency downlink path coupled between said antennas; and
an adaptive cancellation circuit in at least one of said radio frequency uplink path and said radio frequency downlink path, the adaptive cancellation circuit operable to use a radio frequency input signal and a radio frequency output signal from the at least one uplink path or downlink path to generate a cancellation signal for reducing feedback signals present in a radio frequency signal in one of the uplink path or the downlink path;
the adaptive cancellation circuit including a digital signal processing circuit that samples and digitally processes a radio frequency input signal from the at least one uplink path or downlink path to generate the cancellation signal.
2. The repeater of claim 1 wherein the digital signal processing circuit generates an intermediate signal and further including:
a modulator circuit which receives said intermediate signal and a sample of a radio frequency output signal from said one of said radio frequency uplink and downlink paths and generates said cancellation signal.
3. The repeater of claim 2 wherein said digital signal processing circuit comprises a radio frequency downconverter which converts said incoming radio frequency signal to a lower frequency signal for digital sampling, an analog-to-digital converter coupled to the radio frequency downconverter, which digitizes said lower frequency signal, and a processor coupled to the analog-to-digital converter which computes a desired intermediate signal for the modulator.
4. The repeater of claim 2 further comprising a summing junction which receives and sums said cancellation signal and said radio frequency input signal.
5. The repeater of claim 4 wherein said digital signal processing circuit receives an output of said summing junction.
6. The repeater of claim 2 wherein said modulator circuit comprises a controllable attenuator which receives and attenuates the radio frequency output signal and an I/Q modulator coupled to said attenuator and to said digital signal processing circuit.
7. The repeater of claim 1 wherein said repeater comprises:
a housing having a pair of oppositely facing surfaces;
at least one antenna element mounted with respect to each of said surfaces for radiating energy in a direction opposite to that of the antenna element mounted to the other of said surfaces; and
the circuitry for establishing the uplink path and downlink path mounted to said housing and operatively coupling signals between at least one antenna element on each of said pair of surfaces of said housing.
8. The repeater of claim 7 wherein a single antenna element is mounted to each of said oppositely facing surfaces of said housing and wherein said circuitry includes a frequency diplexer operatively coupled with each of said antennas and signal transmission circuits coupled between said frequency diplexers.
9. The repeater of claim 7 wherein two antenna elements are mounted to each side of said housing, one for transmitting communications signals and one for receiving communications signals.
10. The repeater of claim 1 further comprising beamforming circuitry coupled with at least one of the antennas for creating a desired antenna pattern for the antenna.
11. The repeater of claim 10 wherein the at least one antenna comprises an antenna array having a plurality of antenna elements.
12. The repeater of claim 10 wherein said antennas each comprise an antenna array having a plurality of antenna elements and the beamforming circuitry is coupled with each antenna.
13. The repeater of claim 10 further including a memory for storing angle and elevation information for use by the beamforming circuitry.
14. The repeater of claim 10 wherein said antennas each comprise an antenna array having a plurality of antenna elements and wherein said beamforming circuitry includes a plurality of phase shifting elements respectively coupled with the antenna elements and each of said antenna arrays, and a controller for controlling operation of said phase shifting elements.
15. The repeater of claim 1 wherein said antennas are mounted on a printed circuit board.
16. The repeater of claim 1 further comprising at least one of a modem and a transceiver.