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 wireless broadcast radio for backhaul applications, wireless Ethernet replacement applications and broadband wireless drop applications, the radio comprising:
an adaptive antenna array including at least two adaptive antennas;
a beamforming network connected to the adaptive antenna array;
a weigh processor connected to the beamforming network; and
one or more baseband radios connected to the beamforming network that deliver a stream of data to an external output of the wireless broadcast radio;
wherein the adaptive antenna array permits non-line of sight communications with another wireless broadcast radio; and
a channel from each adaptive antenna in the adaptive antenna array, wherein the beamforming network uses an extreme interference cancellation having a space-time filter with a quarter bandwidth resolution that inverts the channel from each adaptive antenna in the adaptive antenna array and eliminates interference between the channels from each adaptive antenna in the adaptive antenna array, by directing spatial nulls in the array antenna pattern in the directions of all interfering terminating backhaul radio (TBR) while forming a beam peak in the direction of the desired TBR.
2. The radio of claim 1 , wherein the weight processor computes space-time weights using a fast fourier transform and a fast correlation process.
3. The radio of claim 1 , wherein the weight processor computes space-time weights wherein the signal is transformed into a frequency domain.
4. The radio of claim 1 , wherein the beamforming network performs space-time adaptive processing and extreme interference cancellation that a time-bandwidth required for a predetermine signal to noise ratio and adaptive processing loss.
5. The radio of claim 1 , wherein the beamforming network performs one of space-time adaptive processing and space-frequency adaptive processing and performs low order receiver equalization of an output from one of the space-time adaptive processing and space-frequency adaptive processing.
6. The radio of claim 1 , wherein the adaptive antenna array is adjustable in one or more of azimuth, polarization, time and frequency.
7. The radio of claim 1 , wherein the adaptive antenna array has adaptive down-tilt by adapting an elevation pattern of the adaptive antenna array in an outer adaptive loop independent of a faster inner loop for polarization and azimuth control.
8. The radio of claim 1 , wherein the beamforming network receives a reference signal for link adaption, wherein the reference signal is one of a set of special training symbols, an embedded pilot, a preamble, a statistical significant data replication, a baseband signal replication, a known constellation of a signal and a data directed feedback.
9. The radio of claim 8 , wherein the reference signal is CAZAC code.
10. The radio of claim 8 , wherein the data directed feedback uses a payload to derive the reference signals.
11. The radio of claim 1 , wherein the beamforming network calculates a signal covariance matrix using a voltage domain representation.
12. The radio of claim 1 , wherein the weight processor generates a unique weight for each subcarrier in the baseband radios in one of an orthogonal frequency division multiple access baseband signal and an orthogonal frequency-division multiplexing baseband signal.
13. The radio of claim 1 , wherein the beamforming network performs dynamic multiuser power allocation.
14. The radio of claim 1 , wherein the beamforming network performs modulation and coding downshifting to enhance network capacity.
15. A wireless broadcast radio for backhaul applications, wireless Ethernet replacement applications and broadband wireless drop applications, the radio comprising:
an adaptive antenna array including at least two adaptive antennas;
a beamforming network connected to the adaptive antenna array;
a weigh processor connected to the beamforming network; and
one or more baseband radios connected to the beamforming network that deliver a stream of data to an external output of the wireless broadcast radio;
wherein the adaptive antenna array permits non-line of sight communications with another wireless broadcast radio; and
a channel from each adaptive antenna in the adaptive antenna array, wherein each channel has at least two polarizations and each channel carries a stream of independent data,
wherein the beamforming network performs processing of the two polarizations by doubling a degree of freedom in one of space-time adaptive processing and space-frequency adaptive processing and performs extreme interference cancellation having a space-time filter with a quarter bandwidth resolution that inverts the channel from each adaptive antenna in the adaptive antenna array and eliminates interference between the channels from each adaptive antenna in the adaptive antenna array, by directing spatial nulls in the array antenna pattern in the directions of all interfering terminating backhaul radio (TBR) while forming a beam peak in the direction of the desired TBR.