A Fast MAC Mechanism for Handoff Process in Heterogeneous Wireless Networks Pavan Kumar Tummala, Ramesh Babu Battula, Srikanth Vemuru, Rajasekhara Rao Kurra {pavankumar_ist, rameshbabu_ist, vsrikanth, rajasekharrao.kurra}@kluniversity.in Department of Computer Science and Engineering,K L University ABSTRACT-Next generation wireless communications will likely rely on integrated networks consisting of multiple wireless technologies. Hybrid networks based, for instance, on systems such as WMAN and WLAN can combine their respective advantages on coverage and data rates. WLAN is provided in hotspots, places like coffee bars, airports, shopping centers etc. where the hotspots are covered by access points. As the mobile node moves, it may leave the current wireless network and enter another wireless network; vertical handoff should be taken to the new network so as to maintain the current connection. Existing methods require more time for the vertical handoff process, which causes serious problems for multimedia applications. Vertical handoff delay should be minimum to have seamless vertical handoff communication. To achieve seamless handoff communication a Layer2 handoff method is proposed. In this method, a mobile with two radios of dual- mode capability, and WLAN having the extended region capability is used. The second interface is switched between 802.16 and 802.11 to know ahead to which network it is about to enter. Mobile node comes to know about its nearby network before actually entering the network, thereby reducing vertical handoff delay, making it suitable to seamless vertical handoff Communication. Keywords-Horizontal handoff, Vertical handoff, IEEE 802.11, WiMax. 1. INTRODUCTION During the past decade both telecommunication and Internet technologies have been in a phase of rapid development. The mobile Internet evolution has taken many important steps towards providing better quality wireless data services to a wide audience. In cellular networks, evolution for the first three generations contributed to growing data rates and enhanced communication capabilities, achieving its current peak only recently in the third generation (3G) mobile networks and handsets. At the same time wireless local area networks have achieved enormous popularity in providing wireless broadband connection in public, enterprise and residential environments. Combining these two wireless technologies has attracted researchers now for about a decade. The next evolutionary steps after the third generation aim to provide extended mobility with optimized data rates and services. Nomadic users have more flexibility when using multiservice networks that provide services such as seamless connection to the Internet via heterogeneous networks, advanced spatial location and navigation services and true IP based real- time multimedia. During the last years, IEEE802.11 Wireless Local Area Networks have been deployed widely and 802.11 access points (APs) can cover areas of a few thousand square meters, making them suitable for enterprise networks and public hot spot scenarios such as airports and hotel. Recently, WMAN using IEEE802.16 standard has been receiving much attention because of the high data rate support, the intrinsic QoS capabilities and the much wider area of coverage that enables ubiquitous connectivity. An interworking between those two technologies has been considered as a viable option towards realizing the 4G scenario. However, this interoperation raises several challenges especially when seamless session continuity is required for e.g. media calls like VoIP or video stream. The deployment of an architecture that allows users to seamlessly switch between these two types of networks would present several advantages to both users and service providers. By offering integrated 802.11/802.16 services, users would benefit from the enhanced performance and high data rate of such combined service. For the providers, this could capitalize on their investment, attract a wider user base and ultimately facilitate the ubiquitous introduction of high speed wireless data. The design of a network architecture that efficiently integrates WLAN and WMAN is a challenging task. The objective is to make the interoperation between both technologies as seamless and as efficient as possible, both from the end users and from operator’s perspectives. A common usage scenario is when a WLAN user is admitted into a WMAN environment and then obtains IP connectivity. Other scenarios are more challenging, for example when a WLAN subscriber initiates a VoIP call along with video streaming and data transfer in its WLAN zone and subsequently hands off to a WMAN environment while both video and audio sessions as well as data transfer continue seamlessly without having much vertical handoff delay. The 802.16 based WMAN were designed from the beginning to support QoS [2]. Finally, the decision when to switch between those different networks is also not an easy task. Ongoing efforts are on the way in IEEE802.21 WG in order to integrate different type of networks by introducing MIH (media independent handover) which aims to achieve a seamless handoff among different wireless networks regardless the type of technology [3]. Handover decision criteria used by existing mobility management technologies can be classified according to Pavan Kumar Tummala et al IJCSET |December 2011 | Vol 1, Issue 11, 684-689 684