Load Balancing Apparatus And Method In Wireless Network Hotspots

• US 20080085723A1
• Filed: 12/20/2006
• Published: 04/10/2008
• Est. Priority Date: 10/05/2006
• Status: Active Grant

• Current Assignee: National Chiao Tung University (Government of The Republic of China), Industrial Technology Research Institute
• Original Assignee: National Chiao Tung University (Government of The Republic of China), Industrial Technology Research Institute
• Inventors: Hsu, Chih-Chien, Yu, Tai-Xing, Tsao, Shiao-Li
• Granted Patent: US 8,000,716 B2
• Time in Patent Office: Days
• US Class Current: 455/452.2
• CPC Class Codes: H04W 16/08 Load shedding arrangements
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Disclosed is a load balancing apparatus and method in wireless network hotspots, which comprises a resource allocation module and a load balancer. The resources reallocation module establishes the resources module and the relationship between access points (APs) and STAs in the wireless network hotspots, and seeks possible load balance shift paths (LBSPs). From these possible LBSPs, an LBSP is selected. Based on the selected LBSP, the load balancer reallocates network resources and dynamically arranges the load among the APs in the wireless network hotspots. This invention can be applicable to a centralized or a decentralized wireless communication system.

Claims

1. A load balancing apparatus for wireless network hotspot, said wireless network hotspot having a plurality of access points (APs) and a plurality of STAs, applicable when any said AP unable to admit a quality of service (QoS) request of any said STA, said apparatus comprising:

a resources allocation module, for establishing a resources model and relation between said APs and said STAs, and finding a load balancing shift path (LBSP); and

a load balancer, for re-allocating network resources and dynamically adjusting the loads of said APs based on said LBSP.

2. The apparatus as claimed in claim 1, wherein said apparatus is applicable to a centralized wireless communication system.

3. The apparatus as claimed in claim 1, wherein said apparatus is applicable to a decentralized wireless communication system.

4. The apparatus as claimed in claim 2, wherein said resources allocation module further includes a directed resource allocation graph to describe the resource model and the relation between said APs and said STAs of said wireless network hotspot.

5. The apparatus as claimed in claim 4, wherein said directed resource allocation graph further includes:

a plurality of nodes, representing said plurality of APs and said plurality of STAs; and

a plurality of edges, consisting of a plurality of assignment edges and a plurality of claim edges, said assignment edge indicating an AP serving an STA, and said claim edge indicating an AP being in a scan list of an STA, but said AP not serving said STA, or an STA is requesting service from its serving AP.

6. A load balancing method for wireless network hotspot, said wireless network hotspot having a plurality of access points (APs) and a plurality of STAs, said method being activated when any said AP unable to admit a quality of service (QoS) request of one of said plurality of STAs, said method comprising the steps of:

establishing a resource model and relation between said plurality of APs and said plurality of STAs, and finding a load balancing shift path (LBSP); and

reallocating network resources and dynamically adjusting the load of said plurality of APs according to said LBSP.

7. The method as claimed in claim 6, wherein said method is applicable to a centralized wireless communication system.

8. The method as claimed in claim 6, wherein said method is applicable to a decentralized wireless communication system.

9. The method as claimed in claim 6, wherein said method uses a fast handoff technique to dynamically adjust the loads of said plurality of APs.

10. The method as claimed in claim 6, wherein said method finds possible LBSPs before deciding said LBSP.

11. The method as claimed in claim 6, wherein said relation between said APs and said STAs comprises a coverage area relation between said plurality of APs and said plurality of STAs, and a service relation between said plurality of APs and said plurality of STAs.

12. The method as claimed in claim 6, wherein said method uses two techniques to find said LBSP, first being path that spends the minimal resources, and second being shortest path, that is the path that minimizes migration overhead.

13. The method as claimed in claim 6, further including the following steps before said establishing resource model and relation between said plurality of APs and said plurality of STAs:

receiving said QoS request from said STA;

determining whether the serving AP of said STA able to admit said QoS request; and

responding a success message to said STA, if able to admit said QoS request.

14. The method as claimed in claim 7, wherein said method owns information of said plurality of APs and said plurality of STAs through a central server, finds said LBSP and dynamically adjusts said load balancing among said plurality of APs through said central server.

15. The method as claimed in claim 8, wherein said method floods a find LBSP request to neighbor APs to find said LBSP.

16. The method as claimed in claim 8, wherein after said QoS request being received, the serving AP of said STA, when unable to admit said QoS request, performs the following steps of:

setting a threshold for the limited overhead parameter, and finding the STAs in said serving AP meeting the two conditions of releasing the bandwidth and said serving AP able to admit said request, and having neighbor APs for association;

transferring said find LBSP request to said neighbor APs;

waiting for a response of said LBSP within a period of T; and

rejecting said QoS request if no said response of said LBSP being responded.

17. The method as claimed in claim 15, wherein said find LBSP request further includes the information of a traced path, a limited overhead parameter, a threshold for said limited overhead parameter, and a plurality of corresponding STA QoS parameters.

18. The method as claimed in claim 17, wherein said method performs the following steps after receiving said find LBSP request:

if said neighbor APs are able to admit said QoS request, and said limited overhead parameter are within a range of said threshold, responding to source AP of said find LBSP request;

finding the STAs of said neighbor APs, and once said STA releasing its bandwidth, said serving AP able to accommodate all the services of STAs going to be added to the traced path; and

adjusting all the parameters in said find LBSP request and transferring said find LBSP request to all neighbor APs corresponding to said STA.