Non-line of sight wireless communication system and method
A non-line of sight backhaul system and method are described that provides self-alignment of the antennas beams of the wireless radios of the system, that provides robust operation in licensed and unlicensed frequency bands, that facilitates the use of a reduced number of frequency channels from M to 1 and that enables operation in a non-line of sight (NLOS) propagation environment.
1. A method for wireless communication for a backhaul application, a wireless Ethernet replacement application and a broadband wireless drop application, the method comprising:
providing a central broadcast radio having an adaptive antenna array;
providing one or more terminal broadcast radios that communicate wirelessly with the central broadcast radio, each terminal broadcast radio having an adaptive antenna array;
communicating between the central broadcast radio and the one or more terminal broadcast radios using one or more links formed by the adaptive antenna arrays that are capable of using a non-line of sight propagation channel; and
using extreme interference cancellation to invert each link of each adaptive antenna and eliminate interference between the links by directing spatial nulls in the adaptive antenna array of the central broadcast radio in a direction of interfering terminal broadcast radios and forming a beam peak in the direction of a desired terminal broadcast radio.
2. The method of claim 1 further comprising performing self-alignment of each adaptive antenna array.
3. The method of claim 1 further comprising rapidly realigning each adaptive antenna array.
4. The method of claim 1 further comprising aggregating, at the central broadcast radio, a communications link from each of the one or more terminal broadcast radios into a composite link.
5. The method of claim 1 further comprising using one of multiuser space-time adaptive processing and multiuser space-frequency adaptive processing to process the one or more links.
6. The method of claim 1 further comprising generating, at the central broadcast radio, a predetermined number of beams for each of a predetermined number of terminal broadcast radios, wherein each beam uses one of a separate frequency channel and a separate subchannel in a frequency channel.
7. The method of claim 1 further comprising generating, at the central broadcast radio a predetermined number of beams for each of a predetermined number of terminal broadcast radios, wherein each beam uses a single frequency channel and the adaptive antenna arrays eliminates interference between the predetermined number of beams using spatial nulling.
8. The method of claim 1 further comprising managing, by the central broadcast radio, the one or more links.
9. The method of claim 1 , further comprising using, at the central broadcast terminal one of a time division duplexing protocol and a frequency division duplexing protocol.
10. The method of claim 9 , further comprising transmitting, by the central broadcast terminal, a reference signal to train a processor in each of the terminal broadcast radios when the central broadcast terminal uses frequency division protocol.
11. The method of claim 1 further comprising using, by the central broadcast radio, a single radio frequency channel to support the wireless backhaul requirements of a carrier.
12. The method of claim 1 further comprising minimizing a power level of a link adaptively.
13. The method of claim 1 further comprising determining, using a weigh processor in each broadcast radio, a weight for each variable used to generate the link.
14. The method of claim 13 , wherein determining the weight further comprises generating a scaled conjugate of each weight.
15. The method of claim 14 further comprising performing extreme interference cancellation.
16. The method of claim 1 further comprising partitioning a capacity of the central broadcast radio among the one or more terminal broadcast radios using one of frequency division multiple access and time division multiple access.
17. The method of claim 1 further comprising performing, at each terminal broadcast radio, demand downshifting of the link associated with the terminal broadcast radio based on traffic conditions at the terminal broadcast radio.
18. The method of claim 1 further comprising performing, at each terminal broadcast radio, demand upshifting of the link associated with the terminal broadcast radio based on traffic conditions at the terminal broadcast radio.