SYSTEM AND METHOD FOR CONTROLLING COMBINED RADIO SIGNALS

• US 20100329401A1
• Filed: 06/28/2010
• Published: 12/30/2010
• Est. Priority Date: 06/26/2009
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Hypres, Inc.
• Inventors: Terry, John David
• Granted Patent: US 8,582,687 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2615 Reduction thereof using coding
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

A method for controlling a combined waveform, representing a combination of at least two signals having orthogonal frequency multiplexed signal components, comprising: receiving information defining the at least two signals; transforming the information defining each signal to a representation having orthogonal frequency multiplexed signal components, such that at least one signal has at least two alternate representations of the same information, and combining the transformed information using the at least two alternate representations, in at least two different ways, to define respectively different combinations; analyzing the respectively different combinations with respect to at least one criterion; and outputting a respective combined waveform or information defining the waveform, representing a selected combination of the transformed information from each of the at least two signals selected based on the analysis.

Claims

1. A method for controlling a combined waveform, representing a combination of at least two signals having orthogonal frequency multiplexed signal components, comprising:

receiving information defining the at least two signals;

transforming the information defining each signal to a representation having orthogonal frequency multiplexed signal components, such that at least one signal has at least two alternate representations of the same information, and combining the transformed information using the at least two alternate representations, in at least two different ways to define respectively different combinations;

analyzing the respectively different combinations with respect to at least one criterion; and

outputting information representing a respective combined waveform comprising a selected combination of the transformed information from each of the at least two signals selected based on said analyzing.

2. The method according to claim 1, wherein a first combination and a second combination of the transformed information differ with respect to at least one of (a) a relative timing of a modulation of the frequency components of a first signal with respect to a second signal and (b) a relative phase of the frequency components of a signal.

3. The method according to claim 1, wherein the at least one criterion comprises a peak to average power ratio (PAPR).

4. The method according to claim 1, wherein the signals comprise orthogonal frequency division multiplexed signals.

5. The method according to claim 1, wherein at least one signal is an orthogonal frequency division multiplexed stream which is compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate the at least two respectively different combinations without requiring additional information to be transmitted outside of said protocol.

6. The method according to claim 1, wherein the at least two alternate representations differ respectively in a cyclic time shift in a modulation sequence.

7. The method according to claim 1, wherein the at least two alternate representations differ respectively in a cyclic time shift in a modulation sequence, and the at least one criterion comprises a peak to average power ratio (PAPR), wherein an alternate representation which results in a lowest peak to average power ratio is selected for combination.

8. The method according to claim 1, wherein at least said analyzing is performed using superconducting digital circuit logic.

9. The method according to claim 1, wherein said analyzing step comprises analyzing with respect to dynamic range of a respective combination.

10. The method according to claim 1, wherein said analyzing step comprises analyzing with respect to a predicted error rate of a reference receiver design for one of the signals.

11. The method according to claim 1, wherein said analyzing step comprises analyzing with respect to a peak to average power ratio of the combined waveform and a predicted error rate of a receiver for one of the signals.

12. The method according to claim 1, wherein said analyzing step comprises analyzing a clipping distortion of the combined waveform.

13. The method according to claim 1, wherein said outputting comprises outputting the selected combined signal as a direct conversion from a digital representation of the combined signal to a radio frequency analog signal adapted for transmission without frequency modification.

14. The method according to claim 1, wherein said outputting comprises outputting an intermediate frequency representation of the combined signal.

15. The method according to claim 1, wherein said outputting comprises outputting a set of parameters for converting a digital baseband signal into the selected combined signal.

16. The method according to claim 1, further comprising predistorting at least one of an intermediate frequency and a radio frequency representation of the selected combined signal.

17. The method according to claim 16, wherein the predistorting compensates for at least a portion of one or more of an analog non-linearity, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combined signal.

18. The method according to claim 16, wherein the predistorting compensates for a non-linear distortion of a power amplifier which amplifies the selected combined signal.

19. The method according to claim 1, wherein each of the at least two signals comprises an orthogonal frequency domain multiplexed signal having a cyclic prefix, and wherein the two alternate representations differ in a respective cyclic time shift.

20. The method according to claim 1, wherein each of the at least two signals is received as an orthogonal frequency division multiplexed signal conforming to a communications protocol, at least one of the signals is modified to generate the at least two alternate representations, and the at least one criterion comprises a peak to average power ratio of the combined signal, wherein the selected combined signal is a combined signal representing a lowest peak to average power ratio.

21. A method for combining a plurality of signals in a respective plurality of channels, each signal comprising a set of phase and/or amplitude modulated orthogonal frequency components within a channel, comprising:

receiving information defining each of the plurality of signals;

representing the plurality of signals as a plurality of orthogonal frequency multiplexed signal components;

transforming a representation of at least one signal in at least two different ways, each transformed representation representing the same information;

analyzing with respect to at least one fitness criterion a plurality of different combinations of the plurality of signals, each of the plurality of representations including alternate representations of at least one signal subject to at least two different transformations;

selecting a combination based on said analyzing; and

outputting at least one of an identification of the selected combination, the selected combination, and information defining the selected combination.

22. The method according to claim 21, wherein

the signals comprise orthogonal frequency division multiplexed signals;

a first combination and a second combination of the transformed information differ with respect to at least one of (a) a relative timing of a modulation of the frequency components of a first signal with respect to a second signal and (b) a relative phase of the frequency components of a signal;

the at least one criterion comprises a peak to average power ratio (PAPR); and

the selected combination comprises a combination with a lowest peak to average power ratio.

23. The method according to claim 22, wherein each transformed representation differs respectively in a cyclic time shift in a modulation sequence, and wherein the orthogonal frequency division multiplexed signals are compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol, and wherein a receiver compliant with the at least one protocol can demodulate the at least two respectively different combinations without requiring additional information to be transmitted outside of said protocol.

24. The method according to claim 21, wherein each transformed representation differs respectively in a cyclic time shift in a modulation sequence, and the at least one criterion comprises a peak to average power ratio (PAPR), wherein an alternate representation which results in a lowest peak to average power ratio is selected for combination.

25. The method according to claim 21, wherein at least said analyzing is performed using superconducting digital circuit logic.

26. The method according to claim 21, wherein said analyzing step comprises analyzing a clipping distortion of the combined waveform in a model of an amplifier.

27. The method according to claim 21, wherein said outputting comprises outputting the selected combined signal as a direct conversion from a digital representation of the selected combination to a radio frequency analog signal adapted for transmission without frequency modification.

28. The method according to claim 21, further comprising predistorting at least one of an intermediate frequency and a radio frequency representation of the selected combination.

29. The method according to claim 28, wherein the predistorting compensates for at least a portion of one or more of an analog non-linearity, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combined signal.

30. An apparatus for controlling a combined waveform, representing a combination of at least two signals having orthogonal frequency multiplexed signal components, comprising:

an input port configured to receive information defining the at least two signals;

a processor configured to;

transform the information defining each signal to a representation having orthogonal frequency multiplexed signal components, such that at least one signal has at least two alternate representations of the same information, and combining the transformed information using the at least two alternate representations, in at least two different ways to define respectively different combinations; and

analyze the respectively different combinations with respect to at least one criterion; and

an output port configured to output information representing a respective combined waveform comprising a selected combination of the transformed information from each of the at least two signals selected based on said analyzing.

31. The apparatus according to claim 30, wherein a first combination and a second combination of the transformed information differ with respect to at least one of (a) a relative timing of a modulation of the frequency components of a first signal with respect to a second signal and (b) a relative phase of the frequency components of a signal, and the at least one criterion comprises a peak to average power ratio (PAPR).

32. The apparatus according to claim 30, wherein at least one signal is an orthogonal frequency division multiplexed stream which is compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate the at least two respectively different combinations of without requiring additional information to be transmitted outside of said protocol.

33. The apparatus according to claim 30, wherein the at least two alternate representations differ respectively in a cyclic time shift in a modulation sequence, and the at least one criterion comprises a peak to average power ratio (PAPR), wherein an alternate representation which results in a lowest peak to average power ratio is selected for combination.

34. The apparatus according to claim 30, wherein said processor comprises at least one of superconducting digital circuit logic and a complex programmable logic device (CPLD).

35. The apparatus according to claim 30, wherein said output port is configured to output the selected combined signal as a direct conversion from a digital representation of the combined signal to a radio frequency analog signal adapted for transmission without frequency modification.

36. The apparatus according to claim 30, wherein said processor is further configured to predistorting at least one of an intermediate frequency and a radio frequency representation of the selected combined signal.

37. The apparatus according to claim 36, wherein the predistorting compensates for at least a portion of one or more of an analog non-linearity, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combined signal.

38. The apparatus according to claim 30, wherein each of the at least two signals is received as an orthogonal frequency division multiplexed signal conforming to a communications protocol, at least one of the signals is modified to generate the at least two alternate representations, each of which can be demodulated by a receiver compatible with the protocol without requiring receipt of additional information outside of the communications protocol, and the at least one criterion comprises a peak to average power ratio of the combined signal, wherein the selected combined signal is a combined signal representing a lowest peak to average power ratio.

39. An apparatus for combining a plurality of signals in a respective plurality of channels, each signal comprising a set of phase and/or amplitude modulated orthogonal frequency components within a channel, comprising:

a processor configured to receive information defining each of the plurality of signals, being represented as a plurality of orthogonal frequency multiplexed signal components, transforming a representation of at least one signal in at least two different ways, each transformed representation representing the same information, analyzing with respect to at least one fitness criterion a plurality of different combinations of the plurality of signals, each of the plurality of representations including alternate representations of at least one signal subject to at least two different transformations, and selecting a combination based on said analyzing; and

an output port configured to present at least one of an identification of the selected combination, the selected combination, and information defining the selected combination.

40. The apparatus according to claim 39, wherein

the signals comprise orthogonal frequency division multiplexed signals;

a first combination and a second combination of the transformed information differ with respect to at least one of (a) a relative timing of a modulation of the frequency components of a first signal with respect to a second signal and (b) a relative phase of the frequency components of a signal;

the at least one criterion comprises a peak to average power ratio (PAPR); and

the selected combination comprises a combination with a lowest peak to average power ratio.

41. The apparatus according to claim 39, wherein each transformed representation differs respectively in a cyclic time shift in a modulation sequence, and wherein the orthogonal frequency division multiplexed signals are compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate the at least two respectively different combinations of without requiring additional information to be transmitted outside of said protocol, each transformed representation differing respectively in a cyclic time shift in a modulation sequence, and the at least one criterion comprises a peak to average power ratio (PAPR), wherein an alternate representation which results in a lowest peak to average power ratio is selected for combination.

42. The apparatus according to claim 39, wherein the processor comprises at least one of superconducting digital circuit logic and a complex programmable logic device (CPLD).

43. The apparatus according to claim 39, wherein the processor analyzes a nonlinear distortion of the combined waveform in a model of an amplifier, and further predistorts at least one component of the selected combination.