Full duplex backhaul radio with MIMO antenna array

• US 9,350,411 B2
• Filed: 08/27/2015
• Issued: 05/24/2016
• Est. Priority Date: 08/17/2011
• Status: Active Grant

• Current Assignee: COMS IP Holdings LLC
• Original Assignee: CBF Networks, Inc. (COMSovereign Holding Corp.)
• Inventors: Lea, David Andrew G., Negus, Kevin J.
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): Sharma, Gautam
• Application Number:
  US14/837,797
• Publication Number:
  US 20160013831A1
• Time in Patent Office: 271 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 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 21/064 using horn or slot aerials slotted waveguides arrays H01Q21/005
• CPC Class Codes: H01Q 21/065 Patch antenna array
• 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 21/29 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 25/001 Crossed polarisation dual antennas orthomode horns H01Q13/0258; cross-polarised rear feeds H01Q19/136; orthomode transducers H01P1/161
• CPC Class Codes: H01Q 25/005 providing two patterns of opposite direction; back to back antennas H01Q25/004 takes precedence
• CPC Class Codes: H04B 1/401 for selecting or indicating operating mode
• CPC Class Codes: H04B 1/50 using different frequencies for the two directions of communication
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04B 7/088 using beam selection
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/18 : Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 25/03828 : Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties partial response systems H04L25/497
• CPC Class Codes: H04L 27/01 : Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005
• CPC Class Codes: H04L 27/2601 : Multicarrier modulation systems
• CPC Class Codes: H04L 27/2636 : with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04W 88/08 : Access point devices

Abstract

A intelligent backhaul radio have an advanced antenna system for use in PTP or PMP topologies. The antenna system provides a significant diversity benefit. Antenna configurations are disclosed that provide for increased transmitter to receiver isolation, adaptive polarization and MIMO transmission equalization. Adaptive optimization of transmission parameters based upon side information provided in the form of metric feedback from a far end receiver utilizing the antenna system is also disclosed.

Claims

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

a frequency selective receive path channel multiplexer, interposed between the one or more demodulator cores and at least 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 the plurality of receive chain output signals;

one or more modulator cores, wherein each modulator core is configured to modulate one or more transmit data interface streams to produce one or more of a plurality of transmit symbol streams;

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;

a transmit path channel multiplexer, interposed between the one or more modulator cores and at least the plurality of transmit RF chains, wherein the transmit path channel multiplexer is configured to generate the plurality of transmit chain input signals from at least the plurality of transmit symbol streams;

a plurality of directional antenna arrays, wherein each directional antenna array comprises a plurality of directional antenna sub-arrays, and wherein each directional antenna sub-array comprises a plurality of directional antenna elements; 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 directional antenna sub-arrays, 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 each of the plurality of directional antenna arrays is configured to operate over at least both of the transmit frequency band and the receive frequency band; and

wherein each of the plurality of directional antenna arrays is horizontally offset relative to at least one other of the plurality of directional antenna arrays.

2. The backhaul radio of claim 1, wherein each one of the one or more demodulator cores comprises at least a decoder and a soft decision symbol demapper;

and 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.

3. The backhaul radio of claim 2, wherein each one of the one or more modulator cores comprises at least an encoder and a symbol mapper;

and wherein each one of the plurality of transmit RF chains comprises at least a vector modulator and two digital to analog converters that are configured to produce the respective one of the plurality of transmit RF signals, each said respective one of the plurality of transmit chain input signals comprised of digital baseband quadrature signals.

4. The backhaul radio of claim 3, wherein each one of the one or more demodulator cores comprises at least one of a descrambler or a deinterleaver;

and wherein each one of the one or more modulator cores comprises at least one of a scrambler or an interleaver.

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

one or more selectable RF connections that are configured to selectively couple certain of the plurality of directional antenna sub-arrays to either or both of certain of the plurality of receive RF chains or certain of the plurality of transmit RF chains;

wherein the number of directional antenna sub-arrays that are configured to be selectively coupled to receive RF chains exceeds the number of receive RF chains that are configured to accept receive RF signals from the one or more selectable RF connections;

or

wherein the number of directional antenna sub-arrays that are configured to be selectively coupled to transmit RF chains exceeds the number of transmit RF chains that are configured to provide transmit RF signals to the one or more selectable RF connections.

6. The backhaul radio of claim 5 wherein at least one of the one or more selectable RF connections comprises at least one RF switch.

7. The backhaul radio of claim 5, wherein the set of receive RF chains that is configured to accept receive RF signals from the one or more selectable RF connections is divided between a first subset that is configured to accept receive RF signals from directional antenna sub-arrays with a first polarization and a second subset that is configured to accept receive RF signals from directional antenna sub-arrays with a second polarization;

or wherein the set of transmit RF chains that is configured to provide transmit RF signals to the one or more selectable RF connections is divided between a third subset that is configured to provide transmit RF signals to directional antenna sub-arrays with a first polarization and a fourth subset that is configured to provide transmit RF signals to directional antenna sub-arrays with a second polarization.

8. The backhaul radio of claim 1, wherein the plurality of directional antenna arrays are arranged on a plurality of facets with one or more directional antenna arrays per facet, and wherein each facet is oriented at a different azimuth angle relative to at least one other facet.

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

a plurality of power amplifiers, wherein each power amplifier is configured to amplify at least one of the transmit RF signals, and wherein each power amplifier is couplable or coupled to at least one of the plurality of transmit RF chains and to at least one transmit band-select filter of the plurality of duplexer filters; and

a plurality of low noise amplifiers, wherein each low noise amplifier is configured to amplify at least one of the receive RF signals, and wherein each low noise amplifier is couplable or coupled to at least one of the plurality of receive RF chains and to at least one receive band-select filter of the plurality of duplexer filters.

10. The backhaul radio of claim 1, wherein both of the transmit frequency band and the receive frequency band are within a frequency range of between 2 GHz and 6 GHz.

11. The backhaul radio of claim 1, wherein both of the transmit frequency band and the receive frequency band are within a frequency range of above 10 GHz.

12. The backhaul radio of claim 1, 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).

13. The backhaul radio of claim 1, wherein the frequency selective receive path channel multiplexer comprises:

a plurality of cyclic prefix removers, wherein each cyclic prefix remover is configured to discard a fraction of an overall number of samples within one or more blocks of a plurality of blocks of samples from a respective one of the plurality of receive chain output signals to produce a respective cyclic prefix removed one or more blocks of samples, said fraction corresponding to a known cyclic prefix length for a plurality of second transmit symbol streams expected to be comprised within the plurality of receive chain output signals;

a plurality of respective complex Discrete Fourier Transformers coupled to each respective cyclic prefix remover, wherein each complex Discrete Fourier Transformer is configured to decompose the respective cyclic prefix removed one or more blocks of samples into a respective set of receive chain frequency domain subchannel samples; and

a plurality of receive channel equalizers coupled to the plurality of respective complex Discrete Fourier Transformers, wherein each receive channel equalizer is configured to produce a set of channel-equalized frequency domain estimates representative of a respective one of the plurality of second transmit symbol streams by applying respective stream-specific and chain-specific receive weights to the respective sets of receive chain frequency domain subchannel samples;

wherein said respective stream-specific and chain-specific receive weights applied to the respective sets of receive chain frequency domain subchannel samples vary with relative frequency domain subchannel position within such sets.

14. The backhaul radio of claim 13, further comprising:

a channel equalizer coefficients generator, wherein the channel equalizer coefficients generator is configured to determine the respective stream-specific and chain-specific receive weights based at least upon comparison of certain sets of receive chain frequency domain subchannel samples with certain expected blocks of known frequency domain subchannel samples expected to be present at certain times within the plurality of receive chain output signals.

15. The backhaul radio of claim 13, further comprising:

a plurality of complex Inverse Discrete Fourier Transformers, wherein each complex Inverse Discrete Fourier Transformer is configured to compose a respective one of the plurality of receive symbol streams from respective sets of channel-equalized frequency domain estimates representative of the respective one of the plurality of second transmit symbol streams.

16. The backhaul radio of claim 15, wherein each of the plurality of complex Inverse Discrete Fourier Transformers is implemented by a structure executing a complex Inverse Fast Fourier Transform (IFFT), and wherein each of the plurality of complex Discrete Fourier Transformers is implemented by a structure executing a complex Fast Fourier Transform (FFT).

17. The backhaul radio of claim 13, wherein each of the plurality of receive channel equalizers comprises a number of complex multipliers corresponding to a number of the plurality of receive chain output signals, and a combiner.

18. The backhaul radio of claim 1, wherein each of the plurality of transmit symbol streams comprises at least a plurality of blocks of symbols and wherein the transmit path channel multiplexer is a non-frequency selective transmit path channel multiplexer comprising:

a plurality of cyclic prefix adders, wherein each cyclic prefix adder is configured to add a fraction of an overall number of samples within one or more blocks of a plurality of blocks of samples corresponding to a respective one of the plurality of transmit chain input signals, said fraction corresponding to a pre-determined cyclic prefix length; and

a plurality of transmit channel equalizers, wherein each transmit channel equalizer is configured to produce one or more blocks of non-frequency selective, channel-equalized samples corresponding to a respective one of the plurality of transmit chain input signals by applying respective sets of the stream-specific and chain-specific transmit beamforming weights to corresponding blocks of symbols from the plurality of transmit symbol streams;

wherein a particular one of said stream-specific and chain-specific transmit beamforming weights is invariant with respect to a relative symbol position within said blocks of symbols;

wherein a first number of the plurality of transmit chain input signals exceeds a second number of the plurality of transmit symbol streams; and

wherein a number of the plurality of cyclic prefix adders and of the plurality of transmit channel equalizers corresponds to the first number.

19. The backhaul radio of claim 18, wherein each respective one of the plurality of transmit channel equalizers is coupled to an input of a respective one of the plurality of cyclic prefix adders.

20. The backhaul radio of claim 18, wherein each of the plurality of transmit channel equalizers comprises a number of complex multipliers corresponding to the second number, and a combiner.

21. The backhaul radio of claim 18, wherein the stream-specific and chain-specific transmit beamforming weights are determined at a receiver comprised within at least one of the backhaul radio or the one or more other backhaul radios.

22. The backhaul radio of claim 21, wherein the receiver that determines the stream-specific and chain-specific transmit beamforming weights further comprises:

a channel equalizer coefficients generator, wherein the channel equalizer coefficients generator is configured to determine the respective stream-specific and chain-specific transmit beamforming weights based at least upon comparison of certain signals at the receiver with certain expected signals expected to be present at certain times.

23. The backhaul radio of claim 18 wherein the stream-specific and chain-specific transmit beamforming weights are determined in order to improve either a signal to interference and noise ratio (SINR) or a signal to noise ratio (SNR).

24. The backhaul radio of claim 20 wherein each of the stream-specific and chain-specific transmit beamforming weights comprises at least a real branch component and an imaginary branch component.

25. The backhaul radio of claim 18 wherein each of the stream-specific and chain-specific transmit beamforming weights comprises at least one of an amplitude component or a phase component.

26. The backhaul radio of claim 1, wherein the exchanging of one or more data interface streams with one or more other backhaul radios is via at least a Single-Carrier Frequency Domain Equalization (SC-FDE) modulation format.

27. The backhaul radio of claim 1, wherein the exchanging of one or more data interface streams with one or more other backhaul radios is via at least an Orthogonal Frequency Division Multiplexing (OFDM) modulation format.

28. The backhaul radio of claim 1, wherein each of the plurality of transmit symbol streams comprises at least a plurality of blocks of symbols and wherein the transmit path channel multiplexer is a non-frequency selective transmit path channel multiplexer comprising:

a plurality of cyclic prefix adders, wherein each cyclic prefix adder is configured to add a fraction of an overall number of samples within one or more of a plurality of blocks of samples corresponding to a respective one of the plurality of transmit chain input signals, said fraction corresponding to a pre-determined cyclic prefix length;

wherein the non-frequency selective transmit path channel multiplexer maps the plurality of blocks of symbols for each respective one of the plurality of transmit symbol streams to the plurality of blocks of samples corresponding to each respective one of the plurality of transmit chain input signals.

29. The backhaul radio of claim 1, wherein a total number of directional antenna sub-arrays comprised within the plurality of directional antenna arrays exceeds either or both of a number of the plurality of receive symbol streams or a number of the plurality of transmit symbol streams.

30. The backhaul radio of claim 1, wherein a total number of directional antenna sub-arrays comprised within the plurality of directional antenna arrays exceeds either or both of a number of the plurality of receive chain output signals or a number of the plurality of transmit chain input signals.

31. The backhaul radio of claim 1, wherein the plurality of directional antenna arrays are arranged on a plurality of facets with one or more directional antenna arrays per facet, and wherein each facet is horizontally offset relative to at least one other facet.

32. The backhaul radio of claim 1, wherein the plurality of directional antenna arrays are arranged on a plurality of facets with one or more directional antenna arrays per facet, and wherein each facet is vertically offset relative to at least one other facet.

33. The backhaul radio of claim 1, wherein an antenna pattern beamwidth of each of the directional antenna sub-arrays is narrower in elevation than an antenna pattern beamwidth of each of the directional antenna sub-arrays in azimuth.

34. The backhaul radio of claim 1, wherein each of the plurality of directional antenna arrays comprises two directional antenna sub-arrays.

35. The backhaul radio of claim 34, wherein a first one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays has a first polarization, and wherein a second one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays has a second polarization that is substantially orthogonal to the first polarization.

36. The backhaul radio of claim 35, wherein each of the plurality of directional antenna elements is one of a patch antenna element or a printed dipole antenna element.

37. The backhaul radio of claim 36, wherein said first one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays comprises a plurality of patch antenna elements with each said patch antenna element excited in the first polarization, and wherein said second one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays comprises the same said plurality of patch antenna elements with each said patch antenna element excited in the second polarization.

38. The backhaul radio of claim 37, wherein each of said plurality of patch antenna elements further comprises a first orthogonal probe feed for excitation in the first polarization for said first one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays, a second orthogonal probe feed for excitation in the second polarization for said second one of the two directional antenna sub-arrays in each of the plurality of directional antenna arrays, and a shorting pin at the center of each said patch antenna element.

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

one or more probe-in-space antenna elements, wherein at least one of the one or more probe-in-space antenna elements has a wider antenna pattern beamwidth in azimuth than an antenna pattern beamwidth in azimuth for any of the directional antenna sub-arrays;

wherein at least one of the one or more probe-in-space antenna elements can be utilized for Dynamic Frequency Selection (DFS) that includes detection of radar systems.

40. The backhaul radio of claim 1, wherein each of the plurality of directional antenna sub-arrays is comprised of one or more columns of a plurality of patch antenna elements.

41. The backhaul radio of claim 40, wherein a number of columns for the one or more columns of a plurality of patch antenna elements is less than a number of patch elements within each of the one or more columns of a plurality of patch antenna elements.

42. The backhaul radio of claim 1, wherein each of the directional antenna sub-arrays comprised within each of the plurality of directional antenna arrays is oriented with respect to an azimuthal antenna pattern at a same azimuthal direction relative to at least one other of the directional antenna sub-arrays within its respective one of the plurality of directional antenna arrays and is oriented with respect to an azimuthal antenna pattern at a different azimuthal direction relative to at least one directional antenna sub-array within at least one other of the plurality of directional antenna arrays.