Method for performing handoff in wireless network

• US 20050143073A1
• Filed: 12/03/2004
• Published: 06/30/2005
• Est. Priority Date: 11/08/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd., University of Maryland, College Park
• Original Assignee: Samsung Electronics Co. Ltd., University of Maryland, College Park
• Inventors: Jang, Kyung-Hun, Mishra, Arunesh, Shin, Min-Ho, Arbaugh, William Albert, Lee, In-Sun
• Granted Patent: US 8,977,265 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 12/06 Authentication
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/0038 of security context information
• CPC Class Codes: H04W 40/00 Communication routing or communication path finding
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: H04W 92/20 between access points

Abstract

A method for minimizing handoff latencies when a handoff is performed in a wireless network. An access point (AP) or base station associated to a current wireless station (STA) allows information required for a reassociation to the STA to be propagated to handoff-capable neighboring APs or base stations. When the STA moves, a neighboring AP or base station performs the reassociation to the STA on the basis of context. When a handoff procedure is performed, the time taken to receive context of a corresponding STA is reduced, such that a fast handoff can be implemented.

Claims

1. A method of propagating information including context of a station from an access point to another access point in a wireless network, the method comprising propagating the information including the context to one or more access points of the wireless network that are fit for handoff of the station thereto from the access point, where the context is present in the access point, in response to association or re-association of the station to the access point.

2. The method according to claim 1, wherein each of the one or more access points is an access point to which the station in handoff is directly associable from the access point without going through another access point of the wireless network.

3. The method according to claim 1, wherein the propagating of the information including the context comprises:

accessing a neighborhood graph comprising information on the one or more access points; and

propagating the information including the context based on the information accessed from the neighborhood graph.

4. The method according to claim 3, wherein the information on one or more access points comprises connection relationship information between the access point and the one or more access points.

5. The method according to claim 3, wherein the neighborhood graph is provided in one of the access point and a server of the wireless network.

6. The method according to claim 1, wherein, in response to the context of the station not being present in the access point, the method further comprises:

forming a channel with a prior access point of the station; and

receiving the information including the context from the prior access point.

7. The method according to claim 6, wherein the information including the context from the prior access point is received through an inter access point protocol procedure.

8. A computer-readable medium comprising computer-executable instructions for performing the operation recited in claim 1.

9. An access point through which a station accesses a wireless network, the access point comprising:

a neighborhood graph for containing information on one or more access points of the wireless network that are fit for handoff of the station thereto from the access point; and

a storage for storing information including context of the station, wherein the access point propagates information including the context to the one or more access points in response to association or re-association of the station to the access point.

10. The apparatus according to claim 9, wherein the information on one or more access points comprises connection relationship information between the access point and the one or more access points.

11. The apparatus according to claim 9, wherein each of the one or more access points is an access point to which the station in handoff is directly associable from the access point without going through another access point of the wireless network.

12. The apparatus according to claim 9, wherein, in response to the storage not containing the context corresponding to the station, the access point forms a channel with a prior access point of the station and receives the information including the context from the prior access point.

13. The apparatus according to claim 9, wherein the access point and one or more access points are base stations of a telecommunication system.

14. The apparatus according to claim 9, wherein the station is a mobile terminal.

15. An access point through which a station accesses a wireless network, the access point comprising a storage for storing information including context of the station, wherein the access point accesses a neighborhood graph, for containing information on one or more access points of the wireless network that are fit for handoff of the station thereto from the access point, and propagates information including the context of the station to the one or more access points in response to association or re-association of the station to the access point.

16. The apparatus according to claim 15, wherein the access point accesses the neighborhood graph from one of the access point and a server of the wireless network.

17. The apparatus according to claim 16, wherein the wireless network includes at least one access point, and the neighborhood graph comprises a data structure containing information on one or more access points of the wireless network that are fit for handoff of the station thereto from a corresponding one of the at least one access point, for each of the at least one access point.

18. The apparatus according to claim 15, wherein the storage is a cache for temporarily storing the information including the context.

19. The apparatus according to claim 15, wherein the access point deletes the oldest context to store newly received context in response to insufficient storage capacity.

20. A server for a wireless network having at least one access point through which a station accesses the wireless network, the server comprising a storage for storing a neighborhood graph containing information on one or more access points of the wireless network that are fit for handoff of the station thereto from a corresponding one of the at least one access point, for each of the at least one access point, wherein:

the neighborhood graph is accessible by each of the at least one access point, and

the corresponding one of the at least one access point propagates information including context of the station to the corresponding one or more access points that are fit for handoff in response to association or re-association of the station to the corresponding one of the at least one access point.

21. The apparatus according to claim 20, wherein for each of the at least one access point, each of the corresponding one or more access points is an access point to which the station in handoff is directly associable without going through another access point of the wireless network.