Adaptive Access Points Selection for 802.11 Wireless Networks

I-P. Hsieh, F.-M. Chang, and S.-J. Kao (Taiwan)


Signal Strength Strategy (SSS), Throughput-only, AP selection, Eligibility of Access Point (EoAP)


Network access of a mobile node is usually accomplished by connecting to a nearby access point (AP), which is currently determined only by the signal strength, so called the Signal Strength Strategy (SSS). Even though signal strength is a simple and efficient indicator for AP connection, it does not guarantee to the best performance of data transmission. Recently, several throughput-only AP selection mechanisms have been proposed to replace signaling strategy. However, throughput-only selection could suffer from unstable connection and cause re-association frequently. In this paper, an adaptive access point selection scheme by taking into account the signal strength, throughput, and AP’s load is proposed. We choose a desired AP by calculating Eligibility of Access Point (EoAP), which is a function of signal strength, throughput, and channel speed. For each nearby AP, both signal strength and channel speed are collected once the association having been established, while throughput is estimated by actually transmitting TCP/IP packets. Eventually, the AP with the largest EoAP is selected. Two experiments are presented. The first one demonstrates that the loading factor of AP could be accurately calculated, while the second experiment shows that our method provides a better performance than those of signal strength strategy or throughput-only.

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