Phase combining diversity
View Patent ↗Embodiments of methods of receiving transmitted signals are disclosed. The methods include a first antenna receiving a second signal, a second antenna receiving a second signal, adjusting a phase relationship between the first signal and the second signal, combining the phase adjusted first signal and second signal, and processing the phase adjusted first signal and second signal to determine the phase adjustment for optimizing at least one of signal to noise ratio and signal to interference ratio of the combined signals.
1. A method of receiving transmitted signals comprising:
a first antenna receiving a first signal, the first signal comprising multiple sub-carrier signals;
a second antenna receiving a second signal, the second signal comprising multiple sub-carrier signals;
adjusting a phase relationship between the first signal and the second signal;
combining the phase adjusted first signal and second signal;
processing the combined phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing a joint optimization of SNR and SIR over a combination of sub-carriers.
2. The method of claim 1 , wherein the first signal and the second signal comprise a desired signal and at least one interference signal.
3. The method of claim 1 , wherein a finite number of phase adjustments exist, and the processing determines a selection of one of the phase adjustments.
4. The method of claim 1 , wherein the processing comprises estimating a channel response associated with the first antenna, and estimating a channel response associated with the second antenna.
5. The method of claim 4 , wherein the channel responses are between a desired signal source and the first antenna, and the second antenna.
6. The method of claim 4 , wherein the processing further comprises adjusting the phase until the energy of combined channel responses is maximized.
7. The method of claim 4 , further comprising windowing channel responses based on knowledge of the channel responses.
8. The method of claim 1 , further comprising adjusting an amplitude of at least one of the first signal and second signal.
9. The method of claim 8 , wherein the adjustment of the amplitude reduces the effect of gain variations of receiver chains associated with the first antenna and the second antenna.
10. The method of claim 1 , wherein if a power level of the first signal is a threshold amount greater than a power level of the second signal, then only the second signal is selected for reception/processing.
11. The method of claim 1 , further comprising determining a signal to noise ratio (SNR) and signal to interference ratio (SIR) of the first signal and the second signal.
12. The method of claim 11 , wherein if the SIR is a threshold less than the SNR, then the phase is adjusted to minimize an energy of interfering signals resulting from a summation of channel responses of interference signals over a plurality of time samples.
13. The method of claim 12 , wherein the minimization is based on response of tones of multi-carrier signals.
14. The method of claim 12 , wherein SNR or SIR dominance is determined during a scanning mode of the receiver.
15. The method of claim 11 , wherein if the SIR is a threshold less than the SNR, then the phase is adjusted to maximize the SIR.
16. The method of claim 15 , wherein if signal energy of a summation of a combination of interference signal channel responses of the first signal and the second signal is greater than signal energy of an interference signal channel response of first signal energy, and signal energy of interference signal channel response of the second signal, then using both the first signal and the second signal for reception.
17. The method of claim 15 , wherein if signal energy of interference signal channel response of the first signal is greater than signal energy of a summation of a combination of interference signal channel responses of the first signal and the second signal, and signal energy of interference channel response of the second signal, then using the first signal for reception.
18. The method of claim 11 , wherein if the SIR is a threshold greater than the SNR, then the phase is adjusted to maximize an energy of desired signals resulting from a summation of desired signal channel responses over a plurality of time samples.
19. The method of claim 18 , wherein the maximization is based on response of tones of multi-carrier signals.
20. The method of claim 11 , wherein if the SIR is a threshold greater than the SNR, then the phase is adjusted to maximize the SNR.
21. The method of claim 20 , wherein if signal energy of a summation of a combination of interference signal channel responses of the first signal and the second signal is greater than signal energy of interference signal channel response of the first signal, and signal energy of the interference signal channel response of the second signal, then using the first signal and the second signal for reception.
22. The method of claim 20 , wherein if signal energy of interference signal channel response of the first signal is greater than signal energy of a summation of a combination of interference signal channel responses of the first signal and the second signal, and signal energy of interference signal channel response of the second signal, then using the first signal for reception.
23. The method of claim 1 , further comprising determining whether the first signal and the second signal are uncorrelated;
selecting reception of only the first signal or only the second signal if the first signal and the second signal are determined to be uncorrelated.
24. The method of claim 1 , wherein the weighted summation of a plurality of the sub-carrier signals comprises a weighted summation of a plurality of sub-carrier channels of the sub-carrier signals.
25. The method of claim 1 , wherein the weighted summation of a plurality of the sub-carrier signals comprises a weighted summation of all the sub-carrier signals.
26. The method of claim 1 , wherein the weighted summation of a plurality of the sub-carrier signals comprises a weighted summation of a plurality of the sub-carrier signals of the first signal and a plurality of the sub-carrier signals of the second signal.
27. The method of claim 1 , wherein the selected single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, provides a joint optimization over a combination of sub-carriers, and is sub-optimal for SNR and SIR for at least one individual sub-carrier.
28. A multi-chain receiver comprising;
a first receiver chain connected to a first receiver antenna;
a second receiver chain connected to a second receiver antenna;
an adjustable phase adjustor for adjusting a first phase of a first signal received by the first receiver chain with respect to a second phase of a second signal received by the second receiver chain, the first signal comprising multiple sub-carrier signals, the second signal comprising multiple sub-carrier signals; and
a processor for processing the combined phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing a joint optimization of SNR and SIR over a combination of sub-carriers.
29. The receiver of claim 28 , wherein the first signal and the second signal comprise a desired signal and at least one interference signal.
30. The receiver of claim 28 , wherein the processing comprises estimating a channel response associated with the first antenna, and estimating a channel response associated with the second antenna.
31. The receiver of claim 30 , wherein the channel responses are between a desired signal source and the first antenna, and the second antenna.
32. The receiver of claim 30 , wherein the processing further comprises adjusting the phase until the channel responses are maximized.
33. The receiver of claim 28 , further comprising determining a signal to noise ratio (SNR) and signal to interference ratio (SIR) of the first signal and the second signal.
34. The receiver of claim 33 , wherein if the SIR is threshold less than the SNR, then the phase is adjusted to minimize a summation of interference signal channel responses over a plurality of time samples.
35. The receiver of claim 34 , wherein the minimization is based on response of tones of multi-carrier signals.
36. The method of claim 33 , wherein if the SIR is a threshold less than the SNR, then the phase is adjusted to maximize the SIR.
37. The receiver of claim 33 , wherein if the SIR is a threshold greater than the SNR, then the phase is adjusted to maximize a summation desired signal channel responses over a plurality of time samples.
38. The receiver of claim 37 , wherein the maximization is based on response of tones of multi-carrier signals.
39. The receiver of claim 37 , if the summation is less than a summation of second signal channel responses, then the second signal of the second antenna is processed.
40. The receiver of claim 37 , if the summation is less than a summation of second signal channel responses, then the second signal of the second antenna is processed.
41. The method of claim 33 , wherein if the SIR is a threshold greater than the SNR, then the phase is adjusted to maximize the SNR.
42. A transceiver comprising:
a receiver, the receiver including;
a first receiver chain connected to a first antenna
a second receiver chain connected to a second antenna
an adjustable phase adjustor for adjusting a first phase of a first signal received by the first receiver chain with respect to a second phase of a second signal received by the second receiver chain, the first signal comprising multiple sub-carrier signals, the second signal comprising multiple sub-carrier signals; and
a processor for processing the combined phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing a joint optimization of SNR and SIR over a combination of sub-carriers;
a transmitter, the transmitter including;
a first transmitter chain connected to the first antenna;
a second transmitter chain connected to the second antenna; wherein
the adjustable phase adjustor also adjusts a first phase of a first transmit signal of the first transmitter chain with respect to a second phase of a second transmit signal of the second transmitter chain.
43. The transceiver of claim 42 , wherein the signal to noise ratio is optimized at the transmitter.
44. The transceiver of claim 43 , wherein the signal to noise ratio is optimized by phase combining at the transmitter.
45. The transceiver of claim 42 , wherein the signal to interference ratio is optimized at the receiver.
46. The transceiver of claim 45 , wherein the signal to interference ratio is optimized by phase combining at the receiver.
47. The transceiver of claim 42 , wherein transmit signals are phase adjusted to optimize SNR, and receive signals are phase adjusted to optimize SIR.
48. A multi-chain transmitter comprising:
a first transmitter chain connected to a first antenna;
a second transmitter chain connected to a second antenna; wherein
an adjustable phase adjustor adjusts a first phase of a first transmit signal of the first transmitter chain with respect to a second phase of a second transmit signal of the second transmitter chain, the first signal comprising multiple sub-carrier signals, the second signal comprising multiple sub-carrier signals;
a phase adjust controller receiving feedback from a receiver of the first and second transmit signals; wherein
the feedback is generated by processing at the receiver, and includes processing the combined phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing a joint optimization of SNR and SIR over a combination of sub-carriers.
49. A method of receiving transmitted signals comprising:
a first antenna receiving a first signal, the first signal comprising multiple sub-carrier signals;
a second antenna receiving a second signal, the second signal comprising multiple sub-carrier signals;
adjusting a phase relationship between the first signal and the second signal;
combining the phase adjusted first signal and second signal;
processing the phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing an optimization of SNR over a combination of sub-carriers.
50. A method of receiving transmitted signals comprising:
a first antenna receiving a first signal, the first signal comprising multiple sub-carrier signals;
a second antenna receiving a second signal, the second signal comprising multiple sub-carrier signals;
adjusting a phase relationship between the first signal and the second signal;
combining the phase adjusted first signal and second signal;
processing the phase adjusted first signal and second signal, the processing including selecting a single phase setting for the phase relationship between the first and second signals based on a weighted summation of a plurality of the sub-carrier signals, providing an optimization of SIR over a combination of sub-carriers.