GENERALIZED DIVISION FREE DUPLEXING TECHNIQUES FOR DECREASING RENDEVOUS TIME

• US 20110255448A1
• Filed: 04/15/2010
• Published: 10/20/2011
• Est. Priority Date: 04/15/2010
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Zinser, Richard Louis, Ross, John Anderson Fergus, Hershey, John Erik, Hartman, Michael James, Dell'Anno, Michael J.
• Granted Patent: US 8,379,584 B2
• Time in Patent Office: Days
• US Class Current: 370/277
• 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: H04L 5/1423 for simultaneous baseband signals
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

Provided are methods and systems of using division-free duplexing (DFD) to reduce rendezvous time between two or more cognitive radio devices. The cognitive radio devices may opportunistically use available frequency spectra by communicating over available channels. To communicate, a first device may rendezvous with a second device by transmitting a beaconing signal over a frequency on which the second device is listening. DFD techniques may enable each of the devices to listen to a channel while concurrently transmitting beacon signals over the same channel. As periods of listening and periods of transmitting over the same channel need not be separated due to the transmitter cancelling approach used in DFD techniques, rendezvous time may be significantly reduced. Further, embodiments include a generalized DFD (GDFD) approach wherein devices listen to a broad band of frequencies, thus further reducing rendezvous time.

Claims

1. A method of managing a communication between devices in a network, the method comprising:

analyzing spectral use using cognitive radio protocols to determine available spectra;

continuously receiving over a band of frequencies; and

transmitting a beacon signal over a beacon frequency within the band of frequencies while receiving over the band of frequencies.

2. The method of claim 1, comprising:

establishing a rendezvous when a first device transmits a first beacon signal over a first frequency while a second device receives the first beacon signal; and

maintaining the rendezvous according to the cognitive radio protocols.

3. The method of claim 2, wherein maintaining the rendezvous comprises transmitting a second beacon signal from the first device over a second beacon frequency within the band of frequencies while receiving over the band of frequencies at the first device.

4. The method of claim 2, wherein maintaining the rendezvous comprises monitoring spectral use of the first frequency and transmitting the beacon signal over a second frequency within the band of frequencies when a third device transmits over the first frequency, wherein the third device has a higher priority than one or both of the first device and the second device.

5. The method of claim 1, wherein continuously receiving over the band of frequencies and transmitting the beacon signal over the beacon frequency within the band of frequencies while receiving over the band of frequencies is enabled by implementing a division-free duplexing (DFD) technique in one or more of the devices.

6. The method of claim 5, comprising implementing a division duplexing technique when the division duplexing technique is more reliable than the DFD technique.

7. The method of claim 5, wherein the DFD technique comprises:

receiving an analog primary signal from a receiver front end, an antenna, or a receiver input port;

receiving an analog reference signal from a transmitter;

converting the analog primary signal into a digital primary signal;

converting the analog reference signal into a digital reference signal;

processing the digital reference signal with a digital adaptive filter, wherein the digital adaptive filter uses the digital reference signal and digital primary signal as inputs for determining filter weights of the digital adaptive filter to provide an output; and

subtracting the output of the digital adaptive filter from the digital primary signal to generate a digital cancelled signal.

8. The method of claim 1, wherein the available spectra comprises spectra that is not used by primary user devices of the spectra, and wherein the beacon frequency is in the available spectra.

9. The method of claim 1, wherein the band of frequencies comprises substantially all the available spectra.

10. The method of claim 1, wherein transmitting the beacon signal comprises:

transmitting a first beacon signal from a first device according to a first beaconing sequence; and

transmitting a second beacon signal from a second device according to a second beaconing sequence, wherein the first beaconing sequence has randomized periods of transmitting the first beaconing sequence with respect to periods of transmitting the second beaconing sequence in the second beacon signal.

11. The method of claim 1, wherein transmitting the beacon signal comprises transmitting a beacon signal over a plurality of beacon frequencies within the band of frequencies, wherein the plurality of beacon frequencies is transmitted individually according to a randomized order to form the beacon signal.

12. The method of claim 1, wherein transmitting the beacon signal comprises transmitting a beacon signal over a plurality of beacon frequencies within the band of frequencies, wherein the plurality of beacon frequencies is transmitted individually according to a randomized order and for randomized periods of time to form the beacon signal.

13. A communication system, comprising:

a plurality of communication devices, each configured to;

analyze spectral use of a radio frequency spectrum;

select one or more frequencies for communication based on the analysis of the spectral use; and

use division free duplexing (DFD) to concurrently receive incoming transmissions from others of the plurality of communication devices in the system and transmit an outgoing beacon signal over the selected one or more frequencies.

14. The communication system of claim 13, wherein each of the plurality of communication devices is configured to receive incoming transmissions over substantially all of an available spectrum band in the radio frequency spectrum.

15. The communication system of claim 13, wherein a secondary device of the plurality of communication devices is configured to analyze spectral use to avoid interferences with a primary device of the plurality of communication devices, wherein the primary device has superior rights to the one or more frequencies in the radio frequency spectrum.

16. The communication system of claim 13, wherein a first device of the plurality of communication devices is configured to communicate with a second device of the plurality of communication devices when a first beacon signal is transmitted over a first frequency from the first device and received at the second device.

17. The communication system of claim 16, wherein the first device is configured to select a second frequency for communication with the second device with the first device determines that the first frequency is unavailable based on the analysis of spectral use.

18. The communication system of claim 13, comprising a DFD enabled communication facilitator device configured to:

continuously transmit a facilitating beacon signal;

receive a request signal from a requesting device of the plurality of communication devices while continuously transmitting the facilitating beacon signal;

identify a requested device of the plurality of communication devices based on the request signal; and

enable a communication between the requesting device and the requested device.

19. The communication system of claim 13, wherein the outgoing beacon signal comprises one or more of randomized transmission periods and randomized transmission frequencies.

20. The communication system of claim 13, wherein each of the plurality of communication devices comprises a DFD enabled transceiver comprises instructions for:

receiving a primary signal from a receiver front end, an antenna, or a receiver input port;

receiving a reference signal from a transmitter;

processing the reference signal with an adaptive filter, wherein the adaptive filter uses the reference signal and primary signal as inputs for determining filter weights of the adaptive filter to provide an output; and

subtracting the output of the adaptive filter from the primary signal to generate a cancelled signal.

22. The method of claim 20, wherein the cognitive radio techniques comprises one or more of monitoring spectral use, avoiding channels in use by primary devices, and using statistical analysis to predict available channels.

23. The method of claim 20, wherein the cognitive radio techniques comprises:

identifying an interference or a potential interference from a secondary device on a channel occupied by a primary device;

transmitting a silencer signal to the secondary device; and

ceasing a transmission from the secondary device on the occupied channel based on the silencer signal.

24. The method of claim 23, wherein the secondary device is a DFD enabled device.

21. A method, comprising:

identifying available channels for communication using cognitive radio techniques;

listening to a frequency spectrum for an incoming beacon;

transmitting an outgoing beacon based on the identified available channels while listening to the frequency spectrum; and

cancelling interferences between the incoming beacon and the outgoing beacon using a division-free duplexing (DFD) technique.