Zero division duplexing MIMO backhaul radio with adaptable RF and/or baseband cancellation
A intelligent backhaul radio is disclosed, which can operate by zero division duplexing for use in PTP or PMP topologies, providing for significant spectrum usage benefits among other benefits. Specific system architectures and structures to enable active cancellation of multiple transmit signals at multiple receivers within a MIMO radio are disclosed. Further disclosed aspects include the adaptive optimization of cancellation parameters or coefficients.
1. A backhaul radio with adaptable radio frequency (RF) cancellation for reduction of one or more transmit signals at a receiver within the backhaul radio, said backhaul radio comprising:
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;
a plurality of adaptable RF transversal filter sets configured to convert one or more RF cancellation input signals derived from one or more of the plurality of transmit RF signals to a plurality of RF transmit cancellation signals, wherein each one of the plurality of adaptable RF transversal filter sets comprises:
one or more adaptable RF transversal filters, wherein each adaptable RF transversal filter is configured to filter a respective one of the one or more RF cancellation input signals to provide a respective one of one or more adaptable RF transversal filtered signals; and
an RF filtered signal combiner configured to combine the one or more adaptable RF transversal filtered signals within each one of the plurality of adaptable RF transversal filter sets to produce one of the plurality of RF transmit cancellation signals;
a plurality of directive gain antenna elements, wherein each of a plurality of receive RF signals is derived from signals received from at least one of the plurality of directive gain antenna elements, wherein each of the plurality of receive RF signals comprises at least one or more transmitter related signals, and wherein each of the one or more transmitter related signals is derived from at least one of the plurality of transmit RF signals;
a plurality of RF cancellation combiners, wherein each RF cancellation combiner is configured to combine a respective one of at least one of the plurality of RF transmit cancellation signals with at least one of the plurality of RF receive signals to provide a respective one of a plurality of receive chain input signals;
a plurality of receive radio frequency (RF) chains, wherein each receive RF chain is configured to convert from a respective one of the plurality of receive chain input signals to a respective one of a plurality of receive chain output signals; and
a cancellation controller configured to adapt at least one of the one or more adaptable RF transversal filters to reduce a level of an interfering signal component within at least one of the plurality of receive chain output signals, wherein the interfering signal component is derived from at least one of the one or more transmitter related signals, and wherein the cancellation controller utilizes a metric that accounts for at least the interfering signal component.
2. The backhaul radio of claim 1 , further 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; and
a frequency selective receive path channel multiplexer to produce at least two receive symbol streams from at least two of the plurality of receive chain output signals.
3. The backhaul radio of claim 1 , further comprising:
one or more modulator cores, wherein each modulator core modulates a respective transmit data interface stream to produce one or more of a plurality of transmit symbol streams; and
a transmit path channel multiplexer to produce the plurality of transmit chain input signals provided to the plurality of transmit RF chains from the plurality of transmit symbol streams.
4. The backhaul radio of claim 3 , wherein the transmit path channel multiplexer is a frequency selective transmit path channel multiplexer.
5. The backhaul radio of claim 3 , wherein the transmit path channel multiplexer utilizes transmit beam forming.
6. The backhaul radio of claim 1 , wherein the backhaul radio is configured to insert transmit preambles that can be utilized at least to obtain an estimate of the level of the interfering signal component.
7. The backhaul radio of claim 1 , wherein the backhaul radio is configured to estimate of the level of the interfering signal component by using at least a Fast Fourier Transform (FFT).
8. The backhaul radio of claim 1 , wherein the backhaul radio is configured to determine the metric from at least one of a least squares or an MMSE calculation.
9. The backhaul radio of claim 1 , wherein the metric comprises one or more of an RF transmit leakage metric, a transmit leakage metric, an RSSI metric, a metric involving a correlation with a reference signal, a metric involving a correlation with a transmit chain input signal, a metric derived from a receive RF chain, a metric associated with a desired receive signal, a metric associated with isolation between certain receive antenna array elements and certain transmit antenna array elements associated with the intelligent backhaul radio, a metric based upon measurements of signals, channel estimates, or cancellation performance, a receiver performance metric including, but not limited to signal to noise ratio (SNR), bit error rate (BER), or frame error rate (FER), or a metric associated with the forward error correction (FEC) decoder.
10. The backhaul radio of claim 1 , further comprising:
one or more selectable RF connections, wherein each selectable RF connection is configured to selectively couple to at least one of certain of the plurality of directive gain antenna elements to derive at least one of certain of the plurality of receive RF signals.
11. The backhaul radio of claim 10 , wherein at least one of the one or more selectable RF connections comprises circuitry to combine signals received from at least two of the certain of the plurality of directive gain antenna elements.
12. The backhaul radio of claim 11 , wherein the circuitry to combine signals comprises at least an RF switch.
13. The backhaul radio of claim 1 , wherein no channel bandwidth associated with any of the plurality of transmit RF signals at a time of transmission overlaps with any channel bandwidth associated with any of the plurality of receive RF signals at a time of reception, wherein the time of transmission and the time of reception can be coincident.
14. The backhaul radio of claim 1 , wherein at least one channel bandwidth associated with any of the plurality of transmit RF signals at a time of transmission overlaps at least partially with at least one channel bandwidth associated with any of the plurality of receive RF signals at a time of reception, wherein the time of transmission and the time of reception can be coincident.
15. A backhaul radio with adaptable baseband cancellation for reduction of one or more transmit signals at a receiver within the backhaul radio, said backhaul radio comprising:
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;
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 to a respective one of a plurality of receive baseband sampled signals;
a plurality of directive gain antenna elements, wherein each of the plurality of receive RF signals is derived from signals received from at least one of the plurality of directive gain antenna elements, wherein each of the plurality of receive RF signals comprises at least one or more transmitter related signals, and wherein each of the one or more transmitter related signals is derived from at least one of the plurality of transmit RF signals;
a plurality of receive baseband cancellation combiners, wherein each receive baseband cancellation combiner is configured to combine a respective one of the plurality of baseband transmit cancellation signals with a respective one of the plurality of receive baseband sampled signals to provide a respective one of a plurality of receive chain output signals;
a plurality of adaptable baseband transversal filter sets, wherein each respective one of the adaptable baseband transversal filter sets is configured to receive one or more baseband cancellation input signals derived from the plurality of transmit chain input signals and is configured to provide a respective one of a plurality of baseband transmit cancellation signals to a respective one of the plurality of receive baseband cancellation combiners,
wherein each adaptable baseband transversal filter set comprises one or more adaptable baseband transversal filters, wherein each of the one or more adaptable baseband transversal filters is configured to filter at least one of the one or more baseband cancellation input signals and to provide one of one or more adaptable baseband transversal filtered signals, and
wherein each adaptable baseband transversal filter set further comprises a baseband filtered signal combiner configured to combine the one or more adaptable baseband transversal filtered signals associated with each adaptable baseband transverse filter set to provide one of the plurality of baseband transmit cancellation signals; and
a cancellation controller configured to adapt at least one of the one or more adaptable baseband transversal filters comprised within at least one of the plurality of adaptable baseband transversal filter sets to reduce a level of an interfering signal component within at least one of the plurality of receive chain output signals, wherein the interfering signal component is derived from at least one of the one or more transmitter related signals, and wherein the cancellation controller utilizes a metric that accounts for at least the interfering signal component.
16. The backhaul radio of claim 15 , further 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; and
a frequency selective receive path channel multiplexer to produce at least two receive symbol streams from at least two of the plurality of receive chain output signals.
17. The backhaul radio of claim 15 , wherein the backhaul radio is configured to insert transmit preambles that can be utilized at least to obtain an estimate of the level of the interfering signal component.
18. The backhaul radio of claim 15 , wherein the backhaul radio is configured to estimate of the level of the interfering signal component by using at least a Fast Fourier Transform (FFT).
19. The backhaul radio of claim 15 , wherein the backhaul radio is configured to determine the metric from at least one of a least squares or an MMSE calculation.
20. The backhaul radio of claim 15 , wherein the metric comprises one or more of an RF transmit leakage metric, a transmit leakage metric, an RSSI metric, a metric involving a correlation with a reference signal, a metric involving a correlation with a transmit chain input signal, a metric derived from a receive RF chain, a metric associated with a desired receive signal, a metric associated with isolation between certain receive antenna array elements and certain transmit antenna array elements associated with the intelligent backhaul radio, a metric based upon measurements of signals, channel estimates, or cancellation performance, a receiver performance metric including, but not limited to signal to noise ratio (SNR), bit error rate (BER), or frame error rate (FER), or a metric associated with the forward error correction (FEC) decoder.
21. The backhaul radio of claim 15 , wherein at least one channel bandwidth associated with any of the plurality of transmit RF signals at a time of transmission overlaps at least partially with at least one channel bandwidth associated with any of the plurality of receive RF signals at a time of reception, wherein the time of transmission and the time of reception can be coincident.