Media Access Control (MAC) Protocol for Cognitive Wireless Networks

• US 20080130519A1
• Filed: 08/29/2007
• Published: 06/05/2008
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bahl, Paramvir, Moscibroda, Thomas, Wu, Yunnan, Chandra, Ranveer, Narlanka, Gopala Sri Hari, Yuan, Yuan
• Granted Patent: US 8,879,573 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/0882 Utilisation of link capacity
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A new media access control (MAC) protocol for cognitive wireless networks is described. The new MAC protocol allows each of multiple nodes, such as cell phones and computers with wireless, to determine utilization of a communication spectrum, such as the television broadcast band. The nodes collaborate to achieve a combined view of spectrum utilization in their local vicinity, in which scheduled users and empty time segments are mapped across a wide range of frequencies. Nodes negotiate with each other to reserve idle segments of the spectrum for packet exchange on negotiated frequencies. Control packet structure allows nodes to become prescient of the local spectrum utilization during handshaking. A cognitive device operating under the new MAC has a first radio that both scans the spectrum and monitors a control channel; and a second reconfigurable radio with adjustable parameters, including frequency and bandwidth, for packet transmission.

Claims

1. A method, comprising:

determining a utilization of a communication spectrum at each of multiple nodes;

aggregating the utilizations from at least some of the nodes into a combined view of the spectrum utilization; and

reserving a part of the communication spectrum based on the combined view.

2. The method as recited in claim 1, wherein reserving a part of the communication spectrum includes negotiating a resource block in the communication spectrum, between two of the nodes.

3. The method as recited in claim 2, wherein negotiating the resource block includes determining an available frequency in the communication spectrum, determining a bandwidth around the frequency, determining a starting time, and determining a duration to exchange information using the frequency and the bandwidth.

4. The method as recited in claim 2, wherein the negotiating includes sending a request-to-send (RTS) packet, wherein the RTS packet structure contains a view of the spectrum utilization at a node sending the RTS packet.

5. The method as recited in claim 2, wherein the negotiating includes sending a request-to-send (RTS) packet from a sender, wherein the RTS packet structure designates candidate idle segments of the spectrum.

6. The method as recited in claim 2, wherein the negotiating includes sending a clear-to-send (CTS) packet from a receiver, wherein the CTS packet structure contains a view of the spectrum utilization at a node sending the CTS packet and the CTS packet structure designates candidate idle segments of the spectrum.

7. The method as recited in claim 2, wherein the negotiating includes sending a data transmission reservation (DTS) packet from a sender, wherein the DTS packet structure contains a reservation defining a segment of the spectrum to reserve, wherein the reservation includes a frequency, a bandwidth around the frequency, a starting time, and a duration.

8. The method as recited in claim 1, wherein determining a utilization comprises determining a utilization of the television broadcast spectrum.

9. The method as recited in claim 1, wherein the collaborating and the reserving use a control channel common to the nodes, wherein data exchanged on the control channel inform the multiple nodes of the spectrum utilization viewed at particular nodes.

10. The method as recited in claim 1, further comprising:

storing the spectrum utilization in a matrix at each node; and

wherein the collaborating includes sharing at least part of one of the matrices with other nodes.

11. The method as recited in claim 1, wherein determining a utilization includes scanning the communication spectrum to determine current users and their associated frequencies.

12. The method as recited in claim 1, wherein determining a utilization includes monitoring a control channel to update the combined view of the spectrum utilization.

13. A cognitive wireless network system, comprising:

a cognitive media access control (MAC) protocol that provisions collaborative sensing of communication spectrum utilization; and

nodes of the wireless network, wherein the MAC provisions the nodes to negotiate and reserve idle blocks of the communication spectrum.

14. The cognitive wireless network system as recited in claim 13, further comprising a communication channel common to the nodes for the collaborative sensing, the negotiating, and the reserving.

15. The cognitive wireless network system as recited in claim 14, wherein the nodes negotiate adaptive spectrum allocation such that the nodes self-organize into a network without coordination from a central controller.

16. The cognitive wireless network system as recited in claim 14, wherein each node includes a first radio for scanning the communication spectrum for the idle blocks and a second radio tunable to idle blocks of various frequencies for data communication.

17. The cognitive wireless network system as recited in claim 15, wherein the first radio also monitors the control channel.

18. The cognitive wireless network system as recited in claim 17, wherein a node reserves a part of the communication spectrum via the control channel before scanning the part of the communication spectrum.

19. The cognitive wireless network system as recited in claim 14, wherein the control channel uses a higher frequency than frequencies reserved for data exchange and wherein the control channel has a shorter wireless range than the wireless range of the frequencies reserved for data exchange.

20. A media access control protocol, comprising:

a first set of conventions for achieving collaborative sensing of a communication spectrum via combining scanning results; and

a second set of conventions for reserving idle parts of the communication spectrum.