Intelligent backhaul radio with co-band zero division duplexing utilizing transmitter to receiver antenna isolation adaptation

• US 8,948,235 B2
• Filed: 12/16/2013
• Issued: 02/03/2015
• Est. Priority Date: 06/21/2012
• Status: Active Grant

• Current Assignee: COMS IP Holdings LLC
• Original Assignee: CBF Networks, Inc. (COMSovereign Holding Corp.)
• Inventors: Negus, Kevin J., Proctor, James A. Jr.
• Primary Examiner(s): Washburn, Daniel
• Assistant Examiner(s): HUGHES, EBONI N
• Application Number:
  US14/108,200
• Publication Number:
  US 20140106688A1
• Time in Patent Office: 414 Days
• Field of Search: 375/219, 370/310, 370/328, 370/338, 370/342, 370/480, 455/67.11, 455/67.13, 455/452.1, 455/507
• US Class Current: 375/219
• CPC Class Codes: H01Q 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 1/54 using the same frequency for two directions of communication H04B1/44 takes precedence
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04L 5/1423 for simultaneous baseband signals
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A intelligent backhaul radio is disclosed, which can operate by zero division duplexing for use in PTP or PMP topologies, providing for significant spectrum usage benefits among other benefits. Specific system architectures and structures to enable active cancellation of multiple transmit signals at multiple receivers within a MIMO radio are disclosed. Further disclosed aspects include the adaptive optimization of cancellation parameters or coefficients.

Claims

1. An intelligent backhaul radio comprising:

one or more transmit radio frequency (RF) chains to convert from one or more transmit chain input signals to one or more respective RF transmit signals;

a plurality of receive RF chains to convert from a plurality of receive RF signals to a plurality of respective receive chain output signals, wherein each of the plurality of receive RF signals comprises one or more transmitter related signals, each of the one or more transmitter related signals derived from at least one of the one or more RF transmit chain signals;

an antenna array comprising;

a plurality of directive gain antenna elements, wherein each of the plurality of receive RF signals is derived from at least one of a first subset of the plurality of directive gain antenna elements and wherein each of the one or more respective transmit RF signals is coupled to at least one of a second subset of the plurality of directive gain antenna elements; and

one or more element coupling control structures, wherein each of the one or more element coupling control structure accepts an antenna isolation control input signal that affects the RF isolation between at least one of the first subset of the plurality of directive gain antenna elements and at least one of the second subset of the plurality of directive gain antenna elements, and

a cancellation controller to provide at least one of the one or more antenna isolation control input signals to each of the one or more coupling control structures to reduce a level of an interfering signal component within at least one of the receive RF signals, wherein the interfering signal component comprises at least one of said one or more transmitter related signals and,

wherein the cancellation controller utilizes a metric that accounts for at least the interfering signal component.

2. The intelligent backhaul radio of claim 1, further comprising:

one or more demodulator cores, wherein each demodulator core demodulates one or more receive symbol streams to produce a respective receive data interface stream,

a frequency selective receive path channel multiplexer, interposed between the one or more demodulator cores and the plurality of receive RF chains, to produce the one or more receive symbol streams provided to the one or more demodulator cores from the plurality of receive chain output signals.

3. The intelligent backhaul radio of claim 1, wherein said metric comprises one or more of an RF transmit leakage metric, a transmit leakage metric, an RSSI metric, a metric involving a correlation with a reference signal, a metric involving a correlation with a transmit chain input signal, a metric derived from a receive RF chain, a metric associated with a desired receive signal, a metric associated with isolation between certain receive antenna array elements and certain transmit antenna array elements associated with the intelligent backhaul radio, a metric based upon measurements of signals, channel estimates, or cancellation performance, a receiver performance metric such as signal to noise ratio (SNR), bit error rate (BER), or frame error rate (FER), and a metric associated with the forward error correction (FEC) decoder.

4. The intelligent backhaul radio of claim 1, wherein each of the one or more element coupling control structures comprises at least one tuning element that affects an isolation transfer function between at least one of the first subset of the plurality of directive gain antenna elements and at least one of the second subset of the plurality of directive gain antenna elements.

5. The intelligent backhaul radio of claim 1, wherein each of the one or more element coupling control structures receives active control or active adjustment from said cancellation controller based upon a feedback mechanism.

6. The intelligent backhaul radio of claim 2, wherein said frequency selective receive path channel multiplexer comprises a plurality of adaptable baseband filter sets and one or more cancellation combiners.

7. The intelligent backhaul radio of claim 1, wherein said at least one or more antenna isolation control input signals are adjusted based on the metric.

8. The intelligent backhaul radio of claim 1, wherein said plurality of receive RF signals further comprise a plurality of desired receive signals.

9. The intelligent backhaul radio of claim 8, wherein said one or more transmitter related signals are spatially multiplexed with said plurality of desired receive signals.

10. The intelligent backhaul radio of claim 8, wherein a frequency of at least one of the one or more RF transmit chain signals and a frequency of at least one of the plurality of desired receive signals are offset.

11. The intelligent backhaul radio of claim 10, wherein the offset allows at least one of the interfering signal components derived from said one or more transmitter related signals to be further attenuated at the output of a low pass filter such that one or more analog to digital converters comprised within respective ones of the plurality of receive RF chains are not saturated.

12. The intelligent backhaul radio of claim 1, further comprising:

one or more selectable RF connections that selectively couple certain of the first subset of the plurality of directive gain antenna elements to certain of the plurality of receive RF chains, wherein a number of first subset directive gain antenna elements that can be selectively coupled to the plurality of receive RF chains exceeds a number of receive RF chains that can accept receive RF signals from the one or more selectable RF connections.

13. The intelligent backhaul radio of claim 12, further comprising:

a radio resource controller, wherein the radio resource controller sets or causes to be set the specific selective couplings between the certain of the first subset of the plurality of directive gain antenna elements and certain of the plurality of receive RF chains.

14. The intelligent backhaul radio of claim 1, wherein the second subset of the plurality of directive gain antenna elements is utilized only for transmission and wherein the first subset of the plurality of directive gain antenna elements is utilized only for reception.

15. The intelligent backhaul radio of claim 12, wherein at least one of the one or more antenna isolation control input signals is changed in response to a change to the specific selective couplings between the first subset of the plurality of directive gain antenna elements and certain of the plurality of receive RF chains.

16. The intelligent backhaul radio of claim 1, wherein a plurality of said transmit radio frequency (RF) chains are utilized.

17. The intelligent backhaul radio of claim 1, wherein at least one of the one or more RF transmit chain signals is transmitted at all times while receiving at least one of said plurality of receive RF signals.

18. The intelligent backhaul radio of claim 1, wherein the plurality of receive RF chains consists of four receive RF chains and wherein the one or more transmit RF chains consists of two transmit RF chains.

19. The intelligent backhaul radio of claim 1, further comprising:

one or more modulator cores, wherein each modulator core modulates a respective transmit data interface stream to produce one or more transmit symbol streams;

a transmit path channel multiplexer coupled to the one or more modulator cores and to the one or more transmit RF chains, the transmit path channel multiplexer to produce the one or more transmit chain input signals provided to the one or more transmit RF chains.

20. The intelligent backhaul radio of claim 19, wherein the transmit path channel multiplexer comprises a frequency selective transmit equalizer.

21. The intelligent backhaul radio of claim 20, wherein the frequency selective transmit equalizer allows for an increase of an isolation aspect between at least one of the first subset of the plurality of directive gain antenna elements and at least one of the second subset of the plurality of directive gain antenna elements.

22. The intelligent backhaul radio of claim 20, wherein said frequency selective transmit equalizer is configured to perform transmit beam forming from the second subset of the plurality of directive gain antenna elements.

23. The intelligent backhaul radio of claim 20, wherein said frequency selective transmit equalizer is optimized utilizing metrics associated with a target intelligent backhaul radio receiver and the level of the interfering signal component.

24. The intelligent backhaul radio of claim 1, wherein the one or more antenna isolation control input signals are determined by an analysis of one or more predetermined transmitter signals.

25. The intelligent backhaul radio of claim 24, wherein said one or more predetermined transmitter signals include inserted transmit chain preambles.

26. The intelligent backhaul radio of claim 1, wherein each of the plurality of directive gain antenna elements has higher elevation gain than azimuthal gain.

27. The intelligent backhaul radio of claim 12, wherein the first subset of the plurality of directive gain antenna elements consists of eight directive gain antenna elements and wherein the plurality of receive RF chains consists of four receive RF chains.

28. The intelligent backhaul radio of claim 19, wherein the second subset of the plurality of directive gain antenna elements consists of two directive gain antenna elements, the one or more transmit RF chains consists of two transmit RF chains, and one or more transmit symbol streams consists of two transmit symbol streams.

29. The intelligent backhaul radio of claim 1, further comprising:

a plurality of receive baseband cancellation combiners to combine a plurality of baseband transmit leakage cancellation signals with a respective one of said plurality of receive chain output signals to provide a plurality of baseband cancelled receive signals;

a plurality of adaptable baseband transversal filter sets to receive a plurality of signals respectively derived from the plurality of transmit chain input signals and provide a plurality of baseband transmit leakage cancellation signals respectively to each of the plurality of receive baseband cancellation combiners,

wherein each adaptable baseband transversal filter set comprises a plurality of adaptable baseband transversal filters, wherein each of the plurality of adaptable baseband transversal filters is configured to filter a respective one of said plurality of signals respectively derived from the plurality of transmit chain input signals to provide a respective adaptable baseband transversal filtered signal, and wherein each adaptable baseband transversal filter set further comprises a filtered signal combiner to combine the plurality of adaptable baseband transversal filtered signals of the same adaptable baseband transverse filter set and to provide one of said plurality of baseband transmit leakage cancellation signals to a respective one of said plurality of receive baseband cancellation combiners,

wherein said cancellation controller is further configured to adapt each of said plurality of adaptable baseband transversal filters, wherein the cancellation controller is configured to utilize a plurality of baseband cancellation adaptation input signals derived from each of said plurality of receive RF chains or from the receive baseband cancellation combiner of said plurality of receive baseband cancellation combiners that is associated with said one or more adaptable baseband transversal filter sets configured to be adapted by said cancellation controller.

30. The intelligent backhaul radio of claim 29, wherein the plurality of baseband cancellation adaptation signals are derived indirectly.

31. The intelligent backhaul radio of claim 1, wherein the cancellation controller is further configured to set the one or more antenna isolation control input signals based upon maximizing the product of i) the metric as a function of coefficient sets applicable to the one or more of the respective antenna isolation control input signals and ii) a function of isolation between each of the one or more RF transmit chain and each of the plurality of receive chains.

32. The intelligent backhaul radio of claim 31, wherein said coefficient sets comprise predetermined sets of isolation control inputs signals.