Intelligent backhaul radio

• US 8,238,318 B1
• Filed: 08/17/2011
• Issued: 08/07/2012
• 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.
• Primary Examiner(s): Moore, Jr., Michael J
• Assistant Examiner(s): Sharma, Gautam
• Application Number:
  US13/212,036
• Time in Patent Office: 356 Days
• Field of Search: None
• US Class Current: 370/338
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• 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 25/005 providing two patterns of opposite direction; back to back antennas H01Q25/004 takes precedence
• CPC Class Codes: H01Q 5/50 Feeding or matching arrangements for broad-band or multi-band operation
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 2001/0408 with power amplifiers
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• 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 27/2636 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 27/2678 using cyclostationarities, e.g. cyclic prefix or postfix
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 24/02 : Arrangements for optimising operational condition
• CPC Class Codes: H04W 52/52 : using AGC [Automatic Gain Control] circuits or amplifiers
• CPC Class Codes: H04W 72/04 : Wireless resource allocation
• CPC Class Codes: H04W 72/0453 : Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 76/27 : Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]

Abstract

A intelligent backhaul radio is disclosed that is compact, light and low power for street level mounting, operates at 100 Mb/s or higher at ranges of 300 m or longer in obstructed LOS conditions with low latencies of 5 ms or less, can support PTP and PMP topologies, uses radio spectrum resources efficiently and does not require precise physical antenna alignment.

Claims

1. An intelligent backhaul radio 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, wherein each of the one or more demodulator cores comprises;

at least one decoder; and

at least one soft decision symbol demapper;

a plurality of receive RF chains to convert from a plurality of receive RF signals to a plurality of respective receive chain output signals;

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 wherein the frequency selective receive path channel multiplexer operates on one or more successive blocks of samples from the plurality of receive chain output signals and the frequency selective receive path channel multiplexer comprises;

a plurality of respective cyclic prefix removers that discard a fraction of the samples within the one or more successive blocks of samples from the plurality of respective receive chain output signals corresponding to a known cyclic prefix length for a set of one or more transmit symbol streams expected to be present within the plurality of receive chain output signals;

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

one or more receive channel equalizers coupled to the plurality of complex Discrete Fourier Transformers, wherein each respective receive channel equalizer produces a set of channel-equalized frequency domain estimates representative of a respective one of the one or more transmit symbol streams expected to be present within the plurality of receive chain output signals by applying respective stream-specific and chain-specific receive weights to the respective sets of receive chain frequency domain subchannel samples, and wherein said 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;

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

at least one encoder;

at least one symbol grouper; and

at least one symbol mapper;

a plurality of transmit RF chains to convert from a plurality of transmit chain input signals to a plurality of respective transmit RF signals;

a transmit path channel multiplexer, interposed between the one or more modulator cores and the plurality of transmit RF chains, to produce the plurality of transmit chain input signals provided to the plurality of transmit RF chains from the one or more transmit symbol streams wherein the transmit path channel multiplexer operates on one or more successive blocks of symbols from the one or more transmit symbol streams and the transmit path channel multiplexer comprises;

at least one cyclic prefix adder that prepends a fraction of the block of transmit chain time domain samples to be transmitted sequentially last in time to such block to produce a cyclically-extended block of transmit chain time domain samples;

an antenna array comprising;

a plurality of directive gain antenna elements;

one or more selectable RF connections that selectively couple certain of the plurality of directive gain antenna elements to certain of the plurality of receive RF chains, 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; and

a plurality of RF connections to couple at least certain of the plurality of directive gain antenna elements to the plurality of transmit RF chains;

wherein at least two or more of the directive gain antenna elements that can be selectively coupled to receive RF chains are oriented in different directions to provide directional diversity, wherein the set of directive gain antenna elements that can be selectively coupled to receive RF chains include directive gain antenna elements of at least two different orthogonal polarizations, wherein the set of the directive gain antenna elements that can be selectively coupled to receive RF chains is divided between one subset with a first polarization and a second subset with a second polarization, and wherein the first polarization is vertical and the second polarization is horizontal;

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

an interface bridge configured to couple the intelligent backhaul radio to a data network, the interface bridge comprising one or more Ethernet interfaces to couple the interface bridge to the data network, the interface bridge multiplexing and buffering the one or more Ethernet interfaces;

a media access controller to exchange data to and from the data network via coupling to at least the interface bridge and to and from at least one other intelligent backhaul radio via coupling to at least the one or more modulator cores and the one or more demodulator cores, wherein the media access controller outputs transmit data to a transmit path and inputs receive data from a receive path; and

a radio link controller, wherein the radio link controller sets or causes to be set certain modulation mapping or forward error correction encoding parameters for the one or more modulator cores.

2. The intelligent backhaul radio of claim 1, wherein the set of receive RF chains that can accept receive RF signals from the one or more selectable RF connections is divided between one subset that accepts receive RF signals from directive gain antenna elements with the first polarization and a second subset that accepts receive RF signals from directive gain antenna elements with a second polarization.

3. The intelligent backhaul radio of claim 1, wherein the directive gain antenna elements that can be selectively coupled to 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 angle in the azimuth relative to at least one other facet.

4. The intelligent backhaul radio of claim 3, wherein the one or more selectable RF connections are arranged such that any receive RF chains that can accept receive RF signals from the one or more selectable RF connections can be selectively coupled to directive gain antenna elements from more than one facet.

5. The intelligent backhaul radio of claim 4, wherein the one or more selectable RF connections are arranged such the set of receive RF chains that can accept receive RF signals from the one or more selectable RF connections can be selectively coupled to directive gain antenna elements from any two facets closest to each other in azimuthal angle amongst all facets comprising directive gain antenna elements that can be selectively coupled to receive RF chains.

6. The intelligent backhaul radio of claim 1, wherein the number of transmit RF chains equals the number of transmit symbol streams.

7. The intelligent backhaul radio of claim 6, wherein the transmit path channel multiplexer couples the plurality of transmit RF chains to respective transmit symbol streams such that each respective transmit chain input signal comprises information from only one respective transmit symbol stream.

8. The intelligent backhaul radio of claim 1, wherein the set of the plurality of directive gain antenna elements that can be coupled to the plurality of transmit RF chains is different than the set of the plurality of directive gain antenna elements that can be coupled to the plurality of receive RF chains.

9. The intelligent backhaul radio of claim 1, wherein the number of directive gain antenna elements that can be coupled to the plurality of transmit RF chains equals the number of transmit RF chains.

10. The intelligent backhaul radio of claim 1, wherein at least two or more of the directive gain antenna elements that can be coupled to transmit RF chains are oriented in different directions to provide directional diversity.

11. The intelligent backhaul radio of claim 1, wherein the set of the directive gain antenna elements that can be coupled to transmit RF chains is divided between one subset with a first transmit polarization and a second subset with a second transmit polarization.

12. The intelligent backhaul radio of claim 11, wherein the first transmit polarization is vertical and the second transmit polarization is horizontal.

13. The intelligent backhaul radio of claim 11, wherein the set of transmit RF chains that can provide transmit RF signals to the one or more RF connections is divided between one subset that provides transmit RF signals to directive gain antenna elements with the first transmit polarization and a second subset that provides transmit RF signals to directive gain antenna elements with the second transmit polarization.

14. The intelligent backhaul radio of claim 1, wherein at least two of the directive gain antenna elements that can be coupled to transmit RF chains are each arranged on separate respective facets amongst a plurality of facets with one or more directive gain antenna elements per facet, and wherein each facet is oriented at a different angle in the azimuth relative to at least one other facet.

15. The intelligent backhaul radio of claim 1, wherein at least one of the directive gain antenna elements that can be coupled to transmit RF chains is arranged on a facet with no directive gain antenna element that can be coupled to any receive RF chain.

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

a channel equalizer coefficients generator, wherein the channel equalizer coefficients generator determines stream-specific and chain-specific receive weights that vary with relative frequency domain subchannel position based on comparison of sets of receive chain frequency domain subchannel samples with the expected samples corresponding to known blocks of training pilots associated with each of the one or more transmit symbol streams expected to be present within the plurality of receive chain output signals.

17. The intelligent backhaul radio of claim 1, wherein the radio link controller sets or causes to be set certain parameters within the plurality of transmit RF chains or a plurality of transmit power amplifiers each coupled to a respective transmit RF chain related to the transmitted signal power from the intelligent backhaul radio.

18. The intelligent backhaul radio of claim 1, wherein the radio link controller composes or causes to be composed a control frame to be sent via the media access controller to another radio link controller in another intelligent backhaul radio.

19. The intelligent backhaul radio of claim 1, wherein the radio resource controller composes or causes to be composed a control frame to be sent via the media access controller to another radio resource controller in another intelligent backhaul radio.

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

an intelligent backhaul management system agent that sets or causes to be set certain policies relevant to the radio resource controller, wherein the intelligent backhaul management system agent exchanges information with other intelligent backhaul management system agents within other intelligent backhaul radios or with one or more intelligent backhaul management system servers.