Backhaul radio with extreme interference protection

• US 9,313,674 B2
• Filed: 04/16/2015
• Issued: 04/12/2016
• Est. Priority Date: 08/17/2011
• Status: Active Grant

• Current Assignee: COMS IP Holdings LLC
• Original Assignee: CBF Networks, Inc. (COMSovereign Holding Corp.)
• Inventors: Negus, Kevin J., Ghosh, Sagnik, Varadarajan, Badri
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): Sharma, Gautam
• Application Number:
  US14/688,550
• Publication Number:
  US 20150223082A1
• Time in Patent Office: 362 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H01Q 21/0018 Space- fed arrays
• CPC Class Codes: H01Q 21/0075 Stripline fed arrays H01Q21/065 takes precedence
• CPC Class Codes: H01Q 21/065 Patch antenna array
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• 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 21/26 Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 25/005 providing two patterns of opposite direction; back to back antennas H01Q25/004 takes precedence
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0485 Dielectric resonator antennas
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states

Abstract

A backhaul radio is disclosed that operates in multipath propagation environments such as obstructed LOS conditions with uncoordinated interference sources in the same operating band. Such a backhaul radio may use a combination of interference mitigation procedures across multiple of the frequency, time, spatial and cancellation domains. Such backhaul radios may communicate with each other to coordinate radio resource allocations such that accurate interference assessment and channel propagation characteristics assessment may be determined during normal operation.

Claims

1. A backhaul radio for exchanging one or more data interface streams with one or more other backhaul radios, said backhaul radio comprising:

a plurality of receive radio frequency (RF) chains, wherein each receive RF chain is configured to convert from a respective one of a plurality of receive RF signals within a receive frequency band to a respective one of a plurality of receive chain output signals, and wherein each said respective one of a plurality of receive RF signals is characterized by at least a receive channel center frequency and a receive channel bandwidth amongst either of a multitude of possible receive channel center frequencies or a multitude of possible receive channel bandwidths, respectively;

a plurality of transmit radio frequency (RF) chains, wherein each transmit RF chain is configured to convert from a respective one of a plurality of transmit chain input signals to a respective one of a plurality of transmit RF signals within a transmit frequency band, and wherein each said respective one of a plurality of transmit RF signals is characterized by at least a transmit channel center frequency and a transmit channel bandwidth amongst either of a multitude of possible transmit channel center frequencies or a multitude of possible transmit channel bandwidths, respectively;

a plurality of directive gain antenna elements, wherein each directive gain antenna element is configured to operate over at least both of the transmit frequency band and the receive frequency band; and

a plurality of duplexer filters, wherein each duplexer filter comprises at least a receive band-select filter configured to selectively pass RF signals within the receive frequency band and a transmit band-select filter configured to selectively pass RF signals within the transmit frequency band, wherein each duplexer filter is couplable or coupled to at least one of the plurality of directive gain antenna elements, wherein the receive band-select filter of each duplexer filter is couplable or coupled to at least one of the plurality of receive RF chains, and wherein the transmit band-select filter of each duplexer filter is couplable or coupled to at least one of the plurality of transmit RF chains;

wherein the backhaul radio is configured to determine a measure of interference associated with each one of a plurality of combinations of at least receive channel center frequency and receive channel bandwidth;

wherein the backhaul radio is further configured to determine the measure of interference associated with each respective one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth during a respective blanking interval in which the one or more other backhaul radios substantially inhibit transmissions within a respective frequency channel corresponding to the respective one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth;

wherein the backhaul radio is configured to determine or estimate one or more performance metrics associated with each one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth, said determining or estimating of the one or more performance metrics being based at least upon the measure of interference; and

wherein the backhaul radio is configured to change at least one or more of the plurality of receive RF signals from being characterized by a first combination of at least receive channel center frequency and receive channel bandwidth to being characterized by a second combination of at least receive channel center frequency and receive channel bandwidth, said changing being based at least upon an opportunity to improve at least one of the one or more performance metrics.

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

one or more selectable RF connections for selectively coupling certain of the plurality of directive gain antenna elements to certain of the plurality of receive RF chains according to a set of selective receive coupling settings;

wherein at least one of the plurality of combinations further includes at least one of a plurality of possible sets of selective receive coupling settings.

3. The backhaul radio claim 2, further comprising:

a radio resource controller, wherein the radio resource controller is configured to set or cause to be set specific selective receive couplings between the certain of the plurality of directive gain antenna elements and the certain of the plurality of receive RF chains according to the set of selective receive coupling settings.

4. The backhaul radio of claim 3, further comprising:

a backhaul management system agent that is configured to set or cause to be set certain policies relevant to the radio resource controller, wherein the backhaul management system agent is configured to exchange information with other backhaul management system agents within other backhaul radios or with one or more backhaul management system servers.

5. The backhaul radio of claim 4 wherein the information that can be exchanged with said backhaul management system agent can be used at least to set or cause to be set at least one of a receive channel center frequency, a specific selective receive coupling between at least one of the certain of the plurality of directive gain antenna elements and at least one of the certain of the plurality of receive RF chains, or a receive channel bandwidth.

6. The backhaul radio of claim 1, further comprising:

one or more demodulator cores, wherein each demodulator core is configured to demodulate one or more of a plurality of receive symbol streams to produce one or more receive data interface streams;

a frequency selective receive path channel multiplexer, interposed between the one or more demodulator cores and at least two of the plurality of receive RF chains, wherein the frequency selective receive path channel multiplexer is configured to generate the plurality of receive symbol streams from at least two of the plurality of receive chain output signals, and wherein frequency selective receive path channel multiplexer is further configured to determine the measure of interference associated with each of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth.

7. The backhaul radio of claim 1 wherein each one of the plurality of receive RF chains comprises at least a vector demodulator and two analog to digital converters that are configured to produce the respective one of the plurality of receive chain output signals, each said respective one of the plurality of receive chain output signals comprised of digital baseband quadrature signals.

8. The backhaul radio of claim 1 wherein at least one of the plurality of receive RF chains comprises at least one downconverter capable of producing an intermediate frequency (IF) signal.

9. The backhaul radio of claim 6 wherein the frequency selective receive path channel multiplexer comprises at least one of a Space Division Multiple Access (SDMA) combiner or equalizer, a maximal ratio combining (MRC) combiner or equalizer, a minimum mean squared error (MMSE) combiner or equalizer, an Eigen Beam Forming (EBF) combiner or equalizer, a receive beam forming (BF) combiner or equalizer, a Zero Forcing (ZF) combiner or equalizer, a channel estimator, a Maximal Likelihood (DL) detector, an Interference Canceller (IC), a VBLAST combiner or equalizer, a Discrete Fourier Transformer (DFT), a Fast Fourier Transformer (FFT), or an Inverse Fast Fourier Transformer (IFFT).

10. The backhaul radio of claim 2 wherein at least one of the one or more selectable RF connections comprises at least one RF switch, and wherein at least one mapping of ports in the RF switch can be changed according to the set of selective receive coupling settings.

11. The backhaul radio of claim 2 wherein at least one of the one or more selectable RF connections comprises at least one RF or IF combiner or splitter with at least one adjustable path, and wherein at least one of a phase or amplitude for said at least one adjustable path can be changed according to the set of selective receive coupling settings.

12. The backhaul radio of claim 2 wherein the certain of the plurality of directive gain antenna elements that can be selectively coupled to the certain of the plurality of receive RF chains includes at least a first subset with a first polarization and a second subset with a second polarization.

13. The backhaul radio of claim 2 wherein the certain of the plurality of directive gain antenna elements that can be selectively coupled to the certain of the plurality of receive RF chains are arranged on a plurality of facets with one or more directive gain antenna elements per facet, and wherein each facet is oriented at a different azimuthal angle relative to at least one other facet.

14. The backhaul radio of claim 2 wherein the number of directive gain antenna elements that can be selectively coupled to receive RF chains exceeds the number of receive RF chains that can accept receive RF signals from the one or more selectable RF connections.

15. The backhaul radio of claim 6 wherein the number of directive gain antenna elements that can be selectively coupled to receive RF chains exceeds the number of the plurality of receive symbol streams.

16. The backhaul radio of claim 1 wherein the measure of interference associated with each of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth includes a determination of an energy in each of a plurality of frequency bins using a Discrete Fourier Transform or a Fast Fourier Transform.

17. The backhaul radio of claim 1 wherein the blanking interval corresponds to a time duration for a number of transmit blocks within a superframe.

18. The backhaul radio of claim 1, further comprising:

an arbiter control entity, wherein the arbiter control entity is capable of sending and receiving one or more control signals or frames to and from the one or more other backhaul radios in order to mutually arrange the blanking interval.

19. The backhaul radio of claim 1 wherein the one or more performance metrics associated with each one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth includes at least one of or a weighted combination of a plurality of a signal to interference plus noise ratio (SINR), a link throughput, a latency, a jitter or a frame loss rate.

20. The backhaul radio of claim 1 wherein the changing from the first combination to the second combination occurs at a superframe boundary mutually agreed upon by the backhaul radio and the one or more other backhaul radios.

21. The backhaul radio of claim 1 wherein the backhaul radio is configured to determine a channel propagation characteristics assessment for a wireless link between the backhaul radio and at least one of the one or more other backhaul radios, said channel propagation characteristics assessment associated with at least one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth.

22. The backhaul radio of claim 21 wherein the determining or estimating the one or more performance metrics associated with each one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth is also based at least upon the channel propagation characteristics assessment.

23. The backhaul radio of claim 22 wherein the one or more performance metrics associated with each one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth includes at least one of a signal to interference plus noise ratio (SINR) or a link throughput, or a weighted combination of a signal to interference plus noise ratio (SINR) and a link throughput, or a weighted combination at least one of a signal to interference plus noise ratio (SINR) or a link throughput plus at least one of a latency, a jitter or a frame loss rate.

24. The backhaul radio of claim 1, further comprising:

one or more adjunct antenna elements, wherein at least one of the one or more adjunct antenna elements has a larger azimuthal coverage pattern than any of the plurality of directive gain antenna elements.

25. The backhaul radio of claim 24 wherein the backhaul radio is configured to at least partially cancel an interfering signal received at at least one of the one or more adjunct antenna elements within at least one of a plurality of receive symbol streams, and wherein the determining or estimating the one or more performance metrics associated with each one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth is also based on an estimated improvement due to said at least partially cancelling.

26. The backhaul radio of claim 1 wherein at least one of the plurality of combinations of at least receive channel center frequency and receive channel bandwidth includes a channel center frequency within the 5 GHz UNII band.

27. The backhaul radio of claim 24 wherein the backhaul radio is configured to utilize at least one of the one or more adjunct antenna elements for Dynamic Frequency Selection (DFS).

28. The backhaul radio of claim 27 wherein the backhaul radio is configured to schedule successive ones of the respective blanking interval so as to appear non-uniform or pseudo-random to a DFS radar detector.

29. The backhaul radio of claim 1 wherein the backhaul radio is configured to substantially inhibit transmissions within a transmit frequency channel corresponding to the transmit channel center frequency and the transmit channel bandwidth during a transmit blanking interval in response to one or more control signals or frames from the one or more other backhaul radios.

30. The backhaul radio of claim 29 wherein the transmit blanking interval corresponds to a time duration for a number of transmit blocks within a superframe.