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For IEEE 802.11 Wireless LAN. Dynamic Load Balancing. Outline. Problem Description AP-station association Dynamic Load Balancing Channel Auto-selection Association Migration Practical Concern. Problem Description.
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For IEEE 802.11 Wireless LAN Dynamic Load Balancing
Outline • Problem Description • AP-station association • Dynamic Load Balancing • Channel Auto-selection • Association • Migration • Practical Concern
Problem Description • Given a set of access points and some mobile stations. How to distribute these stations to get maximal bandwidth utilization. • It is just a matching problem if the topology is fixed and bandwidth usage is predictable.
AP-station association • Stations always select the AP with highest received signal strength indicator (RSSI). • This make many stations associate with a few APs which implies poor bandwidth utilization.
Dynamic Load Balancing • Balanced load can be archived through three levels. • Channel auto-selection • Let AP choose a channel with smallest interference automatically when it is booting up. • Association • Migration • The AP may force some stations to move to other APs when necessary.
Association • First a station sends out probe request. • Then APs send back probe response with addition information such as the number of stations associated with the AP or channel utilization estimate (CUE). • The station choose the AP based on received information in hopes of getting a well balanced network.
Practical Concern • It is hard to change standards. • Load balanced among APs does not imply that all stations get the best quality. • But one only care how to get as much resource as possible. • So it is reasonable to implement the whole algorithm in APs only.
References • S. Sheu and C. Wu, “Dynamic Load Balance Algorithm (DLBA) for IEEE 802.11 Wireless LAN”, Tamkang Journal of Science and Engineering, vol. 2, No 1, pp.45-52 (1999). • I. Papanikos and M. Logothetis, A Study on Dynamic Load Balance for IEEE 802.11b Wireless LAN,COMCON, 2001. • G. Sawma, I. Aib, K. Barbar, and G. Pujolle, A Recursive Load Balancing Technique for VoIP-dedicated WLANs, AICCSA 2008: 830-833