Managing spectra of modulated signals in a communication network

• US 20070064788A1
• Filed: 07/26/2006
• Published: 03/22/2007
• Est. Priority Date: 07/27/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yonge, Lawrence
• Granted Patent: US 8,175,190 B2
• Time in Patent Office: Days
• US Class Current: 375/239
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
• CPC Class Codes: H04L 25/03847 Shaping by selective switching of amplifying elements
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/2053 using more than one carrier, e.g. carriers with different phases
• CPC Class Codes: H04L 27/2623 Reduction thereof by clipping
• CPC Class Codes: H04L 27/3411 reducing the peak to average power ratio or the mean power of the constellation; Arrangements for increasing the shape gain of a signal set
• CPC Class Codes: H04L 27/3472 by switching between alternative constellations
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided

Abstract

Information is modulated onto frequency components of a signal. The resulting modulated signal includes at least some redundancy in frequency enabling a portion of the information modulated onto selected frequency components to be recovered from fewer than all of the selected frequency components. Controlling the spectrum of the modulated signal includes enabling the amplitude of at least some frequency components of the modulated signal to be set below a predetermined amplitude used for modulating the information.

Claims

1. A method, comprising:

modulating information onto frequency components of a signal, the resulting modulated signal including at least some redundancy in frequency enabling a portion of the information modulated onto selected frequency components to be recovered from fewer than all of the selected frequency components; and

controlling the spectrum of the modulated signal, including enabling the amplitude of at least some frequency components of the modulated signal to be set below a predetermined amplitude used for modulating the information.

2. The method of claim 1, wherein modulating the portion of the information onto selected frequency components comprises modulating redundant data from which the portion of the information can be decoded onto respective frequency components having different center frequencies.

3. The method of claim 2, wherein the signal comprises a plurality of symbols, and at least some of the respective frequency components are in different symbols.

4. The method of claim 2, wherein the redundant data comprises one or more encoded bits associated with the information.

5. The method of claim 4, wherein the one or more encoded bits comprise data bits representing the information.

6. The method of claim 4, wherein the one or more encoded bits comprise parity bits used for decoding the information.

7. The method of claim 2, wherein the center frequencies are spread approximately uniformly over most of a set of frequency components available for modulating the information.

8. The method of claim 1, further comprising transmitting the modulated signal from a first node to a second node.

9. The method of claim 8, wherein the first node and the second node each stores information identifying a set of frequency components available for modulating the information.

10. The method of claim 8, wherein the second node is able to recover the portion of the information without needing to receive information from the first station indicating whether any of the selected frequency components have been set below the predetermined amplitude used for modulating the information.

11. The method of claim 1, further comprising demodulating each of the selected frequency components, and using resulting demodulated information to recover the portion of the information.

12. The method of claim 11, wherein recovering the portion of the information comprises decoding the demodulated information.

13. The method of claim 11, wherein the amplitude of at least one of the selected frequency components has been set below the predetermined amplitude used for modulating the information.

14. The method of claim 1, wherein the predetermined amplitude used for modulating the information comprises an amplitude corresponding to a phase shift keying modulation constellation.

15. The method of claim 1, wherein the predetermined amplitude used for modulating the information comprises one of a plurality of amplitudes corresponding to a quadrature amplitude modulation constellation.

16. The method of claim 1, wherein setting the amplitude of one of the frequency components below the predetermined amplitude used for modulating the information comprises setting the amplitude of the frequency component below a limit based on a constraint on power that can be radiated in a portion of the spectrum of the modulated signal in which the frequency component is located.

17. The method of claim 16, wherein the constraint on the power is based on a prohibition from interfering with a licensed entity.

18. The method of claim 17, further comprising setting the amplitude of the frequency component below the limit in response to detecting a transmission from the licensed entity.

19. The method of claim 1, wherein setting the amplitude of one of the frequency components below the predetermined amplitude used for modulating the information comprises turning off the frequency component.

20. The method of claim 1, further comprising selecting the frequency components of the signal according to a set of available frequencies that excludes at least some frequencies in a range of frequencies.

21. The method of claim 20, wherein the excluded frequencies correspond to frequencies that are likely to interfere with licensed entities in a region.

22. A transmitter, comprising:

an encoder module including circuitry to redundantly encode information to be modulated onto frequency components of a signal, the resulting modulated signal including at least some redundancy in frequency enabling a portion of the information modulated onto selected frequency components to be recovered from fewer than all of the selected frequency components; and

a spectral shaping module including circuitry to control the spectrum of the modulated signal, including enabling the amplitude of at least some frequency components of the modulated signal to be set below a predetermined amplitude used for modulating the information.