CHANNEL REUSE WITH COGNITIVE LOW INTERFERENCE SIGNALS

• US 20100124940A1
• Filed: 11/14/2008
• Published: 05/20/2010
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: de Vries, Pierre, Hassan, Amer A.
• Granted Patent: US 8,805,427 B2
• Time in Patent Office: Days
• US Class Current: 455/509
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A computing system in which devices communicate wirelessly as secondary users in a band assigned to primary users. The computers communicate using new signals developed to reduce disruption to primary users of the band. The new signals may be produced by sensing, or otherwise determining, signals used by primary users and developing signals using a modulation scheme or other signal parameters that provides little disruption to primary users. These techniques make available to users unused and/or underused portions of the radio spectrum, such as whitespaces between television channels. The new signals may be generated by software defined radios within the computing devices or by switching between modulation schemes supported by conventional wireless network interface card.

Claims

1. A method of operating a communication device to communicate as a secondary user in a portion of a frequency spectrum that may be used by a primary user to transmit at least one primary signal to convey data to one or more primary recipients, the method comprising:

in response to a detected primary signal, selecting a modulation scheme for a secondary signal for communicating in a channel within the portion of the frequency spectrum without disrupting decoding of the at least one primary signal, to obtain the data, by the one or more primary recipients.

2. The method of claim 1, wherein selecting the modulation scheme comprises:

defining a derived modulation scheme, the derived modulation scheme comprising symbols selected from at least two of a plurality of modulation schemes.

3. The method of claim 2, further comprising:

producing the secondary signal by encoding data according to the derived modulation scheme; and

transmitting the secondary signal comprising the encoded data.

4. The method of claim 2, wherein defining the derived modulation scheme comprises:

defining the derived modulation scheme such that the secondary signal will be disregarded by a receipt procedure of a destination of the at least one primary signal.

5. The method of claim 2, wherein defining the derived modulation scheme comprises:

selecting, for the derived modulation scheme, a set of symbols included in the at least two modulation schemes, the set of symbols comprising symbols having a low correlation to a primary set of symbols used for the at least one primary signal.

6. The method of claim 1, further comprising:

detecting the primary user using the portion of the frequency spectrum.

7. The method of claim 6, wherein detecting the primary user using the portion comprises detecting the primary user based on predefined information on the communication device regarding the primary signals.

8. The method of claim 6, wherein detecting the primary user using the portion of the frequency spectrum by the primary comprises detecting use of a second channel adjacent to the channel by the primary user.

9. The method of claim 1, wherein the primary user is a television broadcaster broadcasting television signals over a second channel adjacent to the channel, and the channel is whitespace between the channel and a third channel.

10. An apparatus comprising:

a radio comprising a modulator, the modulator configurable to transmit in a channel of the licensed spectrum in accordance with a configurable modulation scheme;

a controller for the radio, the controller adapted to;

sense communication of primary signals in the channel, the primary signals being transmitted by a licensee of a portion of the licensed spectrum;

select a modulation scheme for non-disruption with the primary signals; and

configure the radio to communicate secondary signals with the selected modulation scheme.

11. The apparatus of claim 10, wherein selecting the modulation scheme comprises:

defining a derived modulation scheme, the derived modulation scheme comprising symbols selected from at least two of a plurality of modulation schemes.

12. The apparatus of claim 10, wherein defining the derived modulation scheme comprises:

selecting a primary code sequence by which to transmit data in the secondary signal, the secondary code sequence having a low correlation to a primary code sequence used to transmit data in the primary signal.

13. The apparatus of claim 10, wherein the radio is adapted to communicate according to at least a first predesigned signal and a second predesigned signal, and

wherein configuring the radio to communicate a secondary signal with the selected modulation scheme comprises configuring the radio to transmit a first symbol of the secondary signal according to the first predesigned signal and a second symbol of the secondary signal according to the second predesigned signal.

14. The apparatus of claim 10, wherein sensing communication of primary signals in the channel comprises sensing communication of primary signals in a second channel adjacent to the channel.

15. The apparatus of claim 10, wherein the primary signals are television signals being broadcast over a second channel adjacent to the channel, and the channel is whitespace between the second channel and a third channel.

16. At least one computer-readable medium having encoded thereon computer-executable instructions that, when executed by a computer, cause the computer to carry out a method of operating a radio, the radio being adapted to be configured to operate in accordance with each of a plurality of modulation schemes, each modulation scheme comprising a constellation mapping a plurality of symbols to signal parameters, the method comprising:

defining a derived encoding scheme, the derived encoding scheme comprising symbols selected from at least two of the plurality of encoding schemes; and

communicating information encoded with the derived encoding scheme by changing the configuration of the radio to operate in accordance with the at least two of the plurality of encoding schemes as the information is being communicated.

17. The at least one computer-readable medium of claim 16, wherein the communicating the encoded information comprises selecting, on a symbol-by-symbol basis, an encoding scheme of the plurality of encoding schemes for use in communicating the information.

18. The at least one computer-readable medium of claim 16, wherein defining the derived modulation scheme comprises:

defining the derived encoding scheme such that a secondary signal transmitted in accordance with the derived encoding scheme will be disregarded by a receipt procedure of a destination of primary signals such that the secondary signal does not disrupt the primary signals.

19. The at least one computer-readable medium of claim 16, wherein changing the configuration of the radio to operate in accordance with the at least two of the plurality of encoding schemes as the information is being communicated comprises changing the configuration of the radio to transmit a first symbol from a first encoding scheme and changing the configuration of the radio to transmit a second symbol from a second encoding scheme.

20. The at least one computer-readable medium of claim 20, wherein each of the first and second symbols comprises a phase-power pair defining a phase angle and a power with which a signal corresponding to the symbol will be generated.