Cognitive multi-user OFDM

• US 20080137634A1
• Filed: 12/12/2006
• Published: 06/12/2008
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Huitema, Christian, Hassan, Amer A.
• Granted Patent: US 8,144,793 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30
• CPC Class Codes: H04J 1/16 Monitoring arrangements for transmission in general H04B17/00; for amplifiers H03F1/52, H03F1/523
• CPC Class Codes: H04J 11/003 at the transmitter transmission to multiple receive units in multiple input multiple output [MIMO] H04B7/0452; transmit antenna weighting H04B7/0615
• CPC Class Codes: H04J 11/0066 of narrowband interference narrowband interference reduction H04B1/1036
• 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 27/16 Frequency regulation arrangements
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning

Abstract

A computing device operating according to a frequency division multiplexed protocol in which communication occurs over a signal formed from a plurality of sub-channels selected from anywhere in a frequency spectrum. A computing device may select sub-channels cognitively by using information about sub-channels previously deemed suitable or unsuitable by that computing device or other computing devices. A described technique for determining sub-channel suitability includes analyzing radio frequency energy in the sub-channel to detect signals generated by another computing device or high noise levels. Information may also be used to cognitively select sub-channels to be analyzed, such as by first selecting for analysis previously-used sub-channels.

Claims

1. A method of operating a computing device for communication using a frequency-division multiplexing protocol, the method comprising:

selecting a first plurality of selected sub-channels to carry a signal having a first bandwidth, the first plurality being selected from a second plurality of sub-channels, the second plurality collectively having a second bandwidth, the second bandwidth greater than the first bandwidth; and

communicating the signal using the first plurality of selected sub-channels.

2. The method of claim 1, wherein the act of selecting the first plurality of sub-channels comprises acts of:

(A) determining a number of sub-channels based on a desired data rate;

(B) examining a sub-channel of the second plurality of sub-channels to determine whether the sub-channel has conditions unsuitable to data transmission;

(C) identifying the sub-channel as suitable for communication or identifying the sub-channel as unsuitable for communication according to a determination of act (B), and selecting the sub-channel for communication if it has been identified as suitable;

(D) repeating acts (B) and (C) for different sub-channels of the second plurality of sub-channels until at least the number of sub-channels is selected.

3. The method of claim 2, wherein

the act (D) further comprises storing an indication of the sub-channels selected;

and

the act (B) further comprises examining a previously-selected sub-channel before a previously-unselected sub-channel if the computing device attempts to create a new signal within a predetermined period of time.

4. The method of claim 2, wherein

the act (D) further comprises storing sub-channels identified as unsuitable for communication;

and

the act (B) further comprises examining a sub-channel previously identified as unsuitable after other sub-channels not previously identified as unsuitable if the computing device attempts to create a new signal within a predetermined period of time.

5. The method of claim 2, wherein the act (B) further comprises choosing a sub-channel to examine by one of a random selection process or a linear sequential selection process.

6. The method of claim 1, wherein the act of communicating wirelessly further comprises:

transmitting a selection notice to at least one other computing device, the selection notice comprising a notification that the computing device has selected a set of sub-channels; and

not choosing sub-channels listed in a selection notice received from an other computing device for a predetermined period of time.

7. The method of claim 2, wherein the act (B) further comprises examining the sub-channel for a predetermined period of time before making the determination.

8. The method of claim 1, wherein the act of selecting is performed once at the beginning of a communication session and the method further comprises releasing the selected sub-channels at the end of the communication session.

9. The method of claim 8, wherein a communication session is a discrete data transmission.

10. A computer apparatus comprising at least one computer readable medium encoded with instructions for execution on a computer, wherein the instructions, when executed, perform a method comprising:

determining a set of usable sub-channels in a first plurality of sub-channels;

selecting a second plurality of selected sub-channels, the selected sub-channels being selected from the set of usable sub-channels, the second plurality being less than the first plurality; and

communicating the signal over the second plurality of selected sub-channels.

11. The computer apparatus of claim 10, wherein the computer-readable medium is further encoded with a list of previously-selected sub-channels, and wherein the act of determining further comprises determining whether the previously-selected sub-channels in the list are usable.

12. The computer apparatus of claim 10, wherein the computer-readable medium is further encoded with a list of sub-channels previously determined to be unusable, and wherein the act of determining further comprises determining whether the sub-channels previously determined to be unusable are usable after determining whether other sub-channels are usable.

13. The computer apparatus of claim 10, further comprising a network interface, wherein the computer-executable instructions control the network interface.

14. The computer apparatus of claim 10, wherein the computer-readable medium is further encoded with computer-executable instructions that, when executed, perform a method of operation in a low power mode, the method comprising:

determining a second set of usable sub-channels in a third plurality of sub-channels, the third plurality of sub-channels being a subset of the first plurality of sub-channels; and

selecting a fourth plurality of sub-channels from the second set of usable sub-channels, the fourth plurality being less than the third plurality.

15. The computer apparatus of claim 10, further comprising a battery.

16. A method of communicating between a first computing device and a second computing device, the method comprising:

with the first computing device, selecting a plurality of selected sub-channels to carry a signal having a first bandwidth, the selected sub-channels being selected from a plurality of sub-channels, the plurality of sub-channels collectively having a second bandwidth, the second bandwidth greater than the first bandwidth; and

transmitting at least one message over the plurality of selected sub-channels.

17. The method of claim 16, wherein transmitting at least one message over the plurality of selected sub-channels comprises transmitting a message from the second computing device to the first computing device.

18. The method of claim 16, further comprising an act of transmitting from the first computing device to the second computing device an identification of the selected sub-channels prior to the act of transmitting the at least one message.

19. The method of claim 16, further comprising an act of analyzing by the second computing device signals received by the second computing device to determine the sub-channels selected by the first computing device.

20. The method of claim 19, wherein the act of analyzing further comprises examining a store of sub-channels previously used for communication between the first computing device and the second computing device, and analyzing signals received on those sub-channels prior to examining signals received on other sub-channels.