Bandwidth based vertical handoff for tightly coupled wimax/wlan overlay networks

Abstract

<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-GB">Deployment of WLAN increases globally due to its low cost implementation and high speed connectivity. The maximum data rate of 600Mbps provided by 802.11n makes it a popular standard for deploying WLANs. The primary disadvantage in WLAN is its short coverage, which is not suitable for devices with high velocity. The alternate network technology for WLAN with almost equal bandwidth with wider coverage area is WiMAX, which is the growing technology throughout the world. Hence the integration of WLAN and WiMAX is considered to be a good approach in 4G. This paper presents handoff related issues in WiMAX/WLAN overlay networks, numerical methods for estimating network conditions of both WiMAX and WLAN networks and impact on 802.1ln clients by legacy 802.11a/b/g clients. Also, we propose throughput based proactive handoff algorithm for WiMAX/WLAN overlay networks which considers network condition, bandwidth requirements and client type. Simulation results show that the proposed handoff algorithm improves overall throughput considerably.</span>