Method and apparatus for determining a receiver beam in a co-existence cognitive radio
In some embodiments, a method for mitigating interference in a channel having multiple users can include: determining a starting angle based on a direction of a signal of interest (SOI); iteratively steering a beam away from the starting angle in opposite directions and calculating a grade of the beam; choosing the beam at a current angle as a receive beam based on the beam grade; receiving a signal using the receive beam; and decoding the SOI from one or more interfering signals using successive interference cancellation multi-user detection (SIC MUD) on the received signal.
1. A method for mitigating interference in a channel having multiple users, the method comprising:
determining a starting angle based on a direction of a signal of interest (SOI);
iteratively steering a beam away from the starting angle in opposite directions and calculating a grade of the beam, whereby, at each iteration, the beam is steered away from the starting angle in a first direction by an offset angle, steered away from the starting angle in a second direction by the offset angle, and the offset angle is increased;
choosing the beam at a current angle as a receive beam based on the beam grade;
receiving a signal using the receive beam; and
decoding the SOI from one or more interfering signals using successive interference cancellation multi-user detection (SIC MUD) on the received signal.
2. The method of claim 1 , wherein determining the starting angle comprises determining the starting angle as an estimated direction of arrival (DOA) of the SOI.
3. The method of claim 1 , wherein determining the starting angle comprises:
estimating a DOA of the SOI;
estimating a DOA of an interfering channel; and
determining the starting angle as an angle halfway between the estimated DOA of the SOI and the estimating DOA of the interfering channel.
4. The method of claim 1 , wherein determining the starting angle comprises using an adaptive interference nulling technique.
5. The method of claim 1 , wherein choosing the beam at the current angle as the receive beam comprises:
determining that the beam grade exceeds a predetermined beam grade threshold.
6. The method of claim 1 , comprising:
determining a grade of the receive beam based on a detection score for the SOI.
7. The method of claim 6 , wherein determining the grade of the receive beam comprises:
estimating an interference to signal-plus-noise-power ratio (ISNR) of the received signal; and
determining if the ISNR of the received signal is outside of a predetermined ISNR range.
8. The method of claim 6 , comprising:
determining grades of multiple beams in parallel.
9. The method of claim 1 , wherein receiving the signal using the receive beam comprises receiving the signal using a digital beamformer.
10. The method of claim 1 , wherein receiving the signal using the receive beam comprises receiving the signal using an analog beamformer.
11. A method for mitigating interference in a channel having multiple users, the method comprising:
determining a starting angle based on a direction of a signal of interest (SOI) by:
estimating a direction of arrival (DOA) of the SOI,
estimating a DOA of an interfering channel, and
determining the starting angle as an angle halfway between the estimated DOA of the SOI and the estimating DOA of the interfering channel;
iteratively steering a beam away from the starting angle in opposite directions and calculating a grade of the beam;
choosing the beam at a current angle as a receive beam based on the beam grade;
receiving a signal using the receive beam; and
decoding the SOI from one or more interfering signals using successive interference cancellation multi-user detection (SIC MUD) on the received signal.
12. The method of claim 11 , wherein determining the starting angle comprises using an adaptive interference nulling technique.
13. The method of claim 11 , wherein choosing the beam at the current angle as the receive beam comprises:
determining that the beam grade exceeds a predetermined beam grade threshold.
14. The method of claim 11 , comprising:
determining a grade of the receive beam based on a detection score for the SOI.
15. The method of claim 14 , wherein determining the grade of the receive beam comprises:
estimating an interference to signal-plus-noise-power ratio (ISNR) of the received signal; and
determining if the ISNR of the received signal is outside of a predetermined ISNR range.
16. The method of claim 14 , comprising:
determining grades of multiple beams in parallel.
17. The method of claim 11 , wherein receiving the signal using the receive beam comprises receiving the signal using a digital beamformer.
18. The method of claim 11 , wherein receiving the signal using the receive beam comprises receiving the signal using an analog beamformer.