System and method for controlling combined radio signals

• US 9,641,372 B2
• Filed: 10/09/2015
• Issued: 05/02/2017
• Est. Priority Date: 06/26/2009
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: PlusN LLC
• Inventors: Terry, John David
• Primary Examiner(s): Vlahos, Sophia
• Application Number:
  US14/879,557
• Publication Number:
  US 20160036612A1
• Time in Patent Office: 571 Days
• 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 orthogonal frequency division multiplexed signals having orthogonal frequency signal components which occupy different frequency bands, comprising:

receiving information defining the at least two orthogonal frequency division multiplexed signals which occupy different frequency bands;

transforming the information defining each respective orthogonal frequency division multiplexed signal to at least one representation having orthogonal frequency signal components, the information defining at least one of the respective orthogonal frequency division multiplexed signals being transformed into at least two alternate representations, each representation being a orthogonal frequency division multiplexed having different orthogonal frequency signal components representing the same information;

combining the transformed representation of the information of the at least two orthogonal frequency division multiplexed signals each having orthogonal frequency signal components, using the at least two alternate representations, in at least two different ways, to define respectively different combined waveforms of the at least two orthogonal frequency division multiplexed signals which occupy different frequency bands and are not mutually orthogonal with respect to each other, each of the at least two alternate representations representing the same information;

analyzing the respectively different combined waveforms representing the same information with respect to at least one criterion dependent on the combination;

selecting a respective one of the at least two alternate respectively different combined waveforms for inclusion in a combination based on said analyzing and

outputting at least one of;

(a) information identifying a respective combined waveform,

(b) information defining the respective combined waveform, and

(c) information representing a respective combined waveform, based on said selecting.

2. The method according to claim 1, wherein a first respective combined waveform and a second respective combined waveform differ with respect to one of:

(a) a relative timing of a modulation of the orthogonal frequency signal components of a first signal with respect to a second signal, and

(b) a relative phase of the orthogonal frequency signal components of a orthogonal frequency division multiplexed signal.

3. The method according claim 1, wherein the at least one criterion comprises a peak to average power ratio (PAPR), and wherein at least one orthogonal frequency division multiplexed 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 DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate the at least two respectively different respective combined waveforms without requiring additional information to be transmitted outside of said protocol.

4. The method according to claim 1, wherein the at least two alternate respectively different combined waveforms differ respectively in a cyclic time shift in a modulation sequence comprising the entirety of the information defining a respective orthogonal frequency division multiplexed signal representation having orthogonal frequency signal components, and the at least one criterion comprises a peak to average power ratio (PAPR), wherein an alternate respective combined waveform which results in a lowest peak to average power ratio is selected for combination.

5. The method according to claim 1, wherein said analyzing comprises analyzing a clipping distortion of the respective combined waveform in a model of an amplifier.

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

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

8. The method according to claim 7, wherein the predistorting compensates for at least a portion of one or more of an analog non-linearity, a non-linear distortion of a power amplifier which amplifies the selected respective combined waveform, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected respective combined waveform.

9. The method according to claim 1, wherein each representation of the at least two orthogonal frequency division multiplexed signals having orthogonal frequency signal components of the same information comprises an orthogonal frequency domain multiplexed signal having a cyclic prefix, and wherein the two alternate respective combined waveforms differ in a respective cyclic time shift of the entire orthogonal frequency domain multiplexed signal having a cyclic prefix.

10. The method according to claim 1, wherein each of the at least two orthogonal frequency division multiplexed signals is received as an orthogonal frequency division multiplexed signal having a cyclic prefix, at least one of the signals is modified to generate the at least two alternate respective combined waveforms which differ with respect to at least one of:

(a) a relative timing of a modulation of all of the frequency components of a first orthogonal frequency division multiplexed signal with respect to a second orthogonal frequency division multiplexed signal, and

(b) a relative phase of all of the orthogonal frequency signal components, and

the at least one criterion comprises a peak to average power ratio of the combined signal,

wherein the selected respective combined waveform is a respective combined waveform representing a lowest peak to average power ratio.

11. An apparatus for combining a plurality of orthogonal frequency division multiplexed signals, each orthogonal frequency division multiplexed signal comprising a set of phase and/or amplitude modulated orthogonal frequency components within a respective different frequency band communication channel which are not mutually orthogonal with respect to each other, comprising:

at least one automated processor configured to;

receive information defining each of the plurality of orthogonal frequency division multiplexed signals,

represent the received information defining each of the plurality of orthogonal frequency division multiplexed signals as a respective plurality of orthogonal frequency signal components which are not mutually orthogonal with respect to each other, wherein the information defining at least one of the plurality of orthogonal frequency division multiplexed signals is represented as a plurality of alternate sets of orthogonal frequency signal components together defining the same received information,

analyze with respect to at least one fitness criterion a plurality of different combinations of the respective plurality of orthogonal frequency signals, each respective different combination representing the plurality of orthogonal frequency division multiplexed signals in the respective different frequency band communication channels which are not mutually orthogonal with respect to each other, and each comprising one of the plurality of respectively alternate sets of orthogonal frequency signal components, and

select a respective one of the different combinations based on the analysis; and

an output port configured to present the selected combination.

12. The apparatus according to claim 11, wherein a first combination and a second combination of the transformed information differ with respect to one of (a) a relative timing of a modulation of all of the orthogonal frequency components of a first orthogonal frequency division multiplexed signal with respect to a second orthogonal frequency division multiplexed signal and (b) a relative phase of all of the orthogonal frequency components of a orthogonal frequency division multiplexed signal, and the at least one criterion comprises a peak to average power ratio (PAPR).

13. The apparatus according to claim 11, wherein at least one of the plurality of orthogonal frequency division multiplexed signals is compatible with at least one protocol selected from the group of an IEEE 802.11 protocol, an IEEE 802.16 protocol, a DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate each of the plurality of alternate sets of orthogonal frequency signal components of the at least one of the plurality of orthogonal frequency division multiplexed signals without requiring additional information to be transmitted outside of said protocol.

14. The apparatus according to claim 11, wherein the plurality of alternate sets of orthogonal frequency signal components of the at least one of the plurality of orthogonal frequency division multiplexed signals 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.

15. The apparatus according to claim 11, wherein the output port is configured to output a direct conversion from a digital representation of the combined signal to a radio frequency analog signal adapted for transmission without frequency modification.

16. The apparatus according to claim 11, wherein the at least one automated processor is further configured to predistort at least one of an intermediate frequency and a radio frequency representation of the selected combination.

17. The apparatus according to claim 16, wherein the predistortion compensates for at least a portion of one or more of an analog non-linearity, a non-linear distortion of a power amplifier which is configured to amplify the selected combination, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combination.

18. The apparatus according to claim 11, wherein each of the plurality of orthogonal frequency division multiplexed signals conforms to a communications protocol, the plurality of alternate sets of orthogonal frequency signal components of the at least one of the plurality of orthogonal frequency division multiplexed signals are each adapted to 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 respective combination, wherein the selected respective combination is a combined signal representing a lowest peak to average power ratio.

19. The apparatus according to claim 11, wherein the at least one automated processor is further configured to analyze a nonlinear distortion of each respective combination in a model of an amplifier, and further to predistort at least one component of the selected combination.

20. An apparatus for combining a plurality of orthogonal frequency division multiplexed signals occupying different frequency channels and which are not mutually orthogonal, comprising:

an input port configured to receive information defining the plurality of orthogonal frequency division multiplexed signals;

a processor configured to;

represent the received information defining at least one of the plurality of orthogonal frequency division multiplexed signals as at least two alternate sets of respective plurality of orthogonal frequency signal components together defining the same received information,

analyze a plurality of respective different combinations of the plurality of orthogonal frequency division multiplexed signals occupying different frequency channels and which are not mutually orthogonal, each respective different combination comprising one of the at least two alternate sets of respective plurality of orthogonal frequency signal components, with respect to at least one fitness criterion, and

select a respective one of the plurality of respective different combinations of the plurality of orthogonal frequency division multiplexed signals occupying different frequency channels and which are not mutually orthogonal, based on the analysis; and

an output port configured to present the selected respective one of the plurality of respective different combinations of the plurality of orthogonal frequency division multiplexed signals occupying different frequency channels and which are not mutually orthogonal.