System and method for controlling combined radio signals

• US 9,565,045 B2
• Filed: 11/30/2015
• Issued: 02/07/2017
• Est. Priority Date: 06/26/2009
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: PlusN LLC
• Inventors: Terry, John David
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US14/954,326
• Publication Number:
  US 20160080189A1
• Time in Patent Office: 435 Days
• Field of Search: 375/260, 375/295, 375/296, 375/297, 370/203, 370/210
• US Class Current: 1/1
• CPC Class Codes: H04J 11/00 Orthogonal multiplex systems, e.g. using WALSH codesH04J13/00 takes precedence
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2618 Reduction thereof using auxiliary subcarriers
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 27/2624 by soft clipping
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2649 Demodulators
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/367 using predistortion
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]

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, comprising:

receiving information defining the at least two signals;

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 combinations of the at least two orthogonal frequency division multiplexed signals representing the same information which are each compatible with a radio frequency communication of the same information to a receiver according to a model of the receiver, within a radio frequency carrier modulated by a respective orthogonal frequency division multiplexed signal;

analyzing the respectively different combinations 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 representations 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 defined waveform, and (c) information representing a respective combined waveform comprising a selected combination of the transformed information from each of the at least two orthogonal frequency division multiplexed signals, based on said selecting.

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 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 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.

4. The method according to claim 1, wherein the at least two alternate representations 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 representation 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 combined waveform in a model of an amplifier.

6. 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.

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 combined signal.

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 combined signal, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combined signal.

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 representations 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 representations 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 combined signal is a combined signal representing a lowest peak to average power ratio.

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

a 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, 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 signal components representing the plurality of signals, each of the plurality of representations including respectively alternate sets of orthogonal frequency signal components of the at least one of the plurality of orthogonal frequency division multiplexed signals, and the respectively alternate sets of orthogonal frequency signal components each being compatible, according to a model of a receiver, with a communication of the received information to the modelled receiver via a radio frequency carrier modulated with each respective set 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 at least one of an identification of the selected combination, the selected combination, and information defining 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 at least 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 3GPP-LTE downlink protocol, a DAB protocol and a DVB protocol, wherein a receiver compliant with the at least one protocol can demodulate each of the respectively 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 respectively 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 processor is further configured to predistort at least one of an intermediate frequency and a radio frequency representation of the selected combined signal.

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 amplifies the selected combined signal, a transmission channel impairment, and a receiver characteristic of an analog radio communication system communicating using the selected combined signal.

18. The apparatus according to claim 11, wherein each of the at least two orthogonal frequency division multiplexed signals conforms to a communications protocol, the respectively 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 combined signal, wherein the selected combined signal is a combined signal representing a lowest peak to average power ratio.

19. The apparatus according to claim 11, 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.

20. An apparatus for combining a plurality of orthogonal frequency division multiplexed signals in different frequency channels, 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 with respect to at least one fitness criterion selectively dependent on a respective combination of a plurality of different combinations of the respective plurality of orthogonal frequency division multiplexed signals, which are each determined to be compatible, according to a model of a receiver, with a communication of a radio frequency carrier modulated with the respective orthogonal frequency division multiplexed signal to the modelled receiver; and

select a respective one of the different combinations of the respective plurality of orthogonal frequency division multiplexed signals based on the analysis; 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.