A New Resource Distribution Model for Improved QoS in an Integrated WiMAX/WiFi Architecture Md. Golam Rabbani * , Joarder Kamruzzaman * , Iqbal Gondal * and Iftekhar Ahmad † * Faculty of IT, Monash University, VIC, Australia † School of Engineering, Edith Cowan University, WA, Australia Email: {golam.rabbani, joarder.kamruzzaman, iqbal.gondal}@monash.edu, i.ahmad@ecu.edu.au Abstract—Wireless access technology has come a long way in its relatively short but remarkable lifetime, which has so far been led by the WiFi technology. While WiFi enjoys a high penetration in the market, its hotspots are connected to the internet through wired connections, making its deploy- ment cost very high. WiMAX has emerged as an existing new wireless technology, which provides larger coverage and higher bandwidth. Deployment of WiMAX only infrastructure, however, is highly expensive, which has motivated researchers to search for a low cost integrated WiMAX/WiFi architecture (using WiMAX as the backhaul and WiFi as the last mile technology) that supports 4G applications and provides high speed broadband services. WiMAX technology is equipped with mechanisms capable of delivering guaranteed quality of service (QoS). WiFi, on the other hand, has very limited capacity for providing QoS to the end applications. Delivering improved QoS in an integrated WiMAX/WiFi architecture poses a serious technological challenge. In this paper, we depict a converged architecture of WiMAX and WiFi, and then propose an adaptive resource distribution model for the access points. The new model is designed as an optimization problem that maximizes the QoS utility of the network. A new QoS utility function is proposed that takes the connection priority and continuity into account. Our simulation results show that our proposed scheme maintains QoS in different scenarios whereas existing other resource sharing schemes experience violation of QoS (minimum rate requirement) in 66% cases. Keywords—Integration; QoS; Scheduling; WiMAX; WiFi I. I NTRODUCTION WiFi has contributed to a tremendous growth in high-speed Internet access through its efficient wireless access technology. WiFi has become the defacto standard for the ”last feet” broadband connectivity in homes, offices, convention centres, and public hotspot locations, such as hotels, cafes, and airports. Over 97% of laptops today come with WiFi as a standard feature, and an increasing number of handhelds and Consumer Electronics (CE) devices are adding WiFi capabilities [1]. Despite being a highly popular technology, WiFi is not free from drawbacks. Small range and inability to provide strict QoS for different classes of services are the biggest drawbacks in WiFi, which also suffers from limited mobility. WiMAX, the Worldwide Interoperability for Microwave Access, is the much-anticipated technology targeting to pro- vide business and consumer wireless broadband access on the scale of Metropolitan Area Network. The distinct features of WiMAX include very high peak data rate, scalable bandwidth and data rate, adaptive modulation and coding, flexible and dynamic per user resource allocation and support for advanced antenna techniques. All these features enable WiMAX to support better QoS for connections and higher mobility, and offer robust security. With its large coverage area and high transmission rate, WiMAX can serve as a backbone for WiFi hotspots for connecting to the internet. Alternatively, users can connect mobile devices such as laptops and handsets directly to WiMAX base stations (BSs) without using WiFi. The technology is capable of providing fast and cheap broad- band access to markets that lack infrastructure, such as rural areas and developing countries suffering from low penetration of wireline telephone system. As WiMAX supports higher bandwidth, it is also suitable to provide internet connection in densely populated area. Supporting mobility has made WiMAX a key technology for the internet users to use high speed internet in bus, express train [2], ships, etc. As for example, mobile WiMAX technology now offers wireless broadband service in the main harbor and coastal areas in southern Singapore which enables the crew and passengers on ships to enjoy various services, such as Internet browsing, email, video conferencing, video on demand and to receive updated information on navigation, port calls and departures in real time wirelessly while onboard. Despite offering some clear benefits over WiFi technolo- gies, WiMAX faces some key challenges for its widespread deployment: i) WiMAX service will cost end users 50-100% more compared to WiFi services, which makes it even more difficult to bridge the so called digital divide between the rich and the poor citizens, ii) widespread consumer adoption of WiMAX devices is far lower than WiFi devices, iii) WiMAX communication using licensed spectrum heavily depends on the service of the local spectrum monopoly owner, and iv) supporting all clients across a big coverage area with a single WiMAX BS requires enormous frequency spectrum. Considering the widespread penetration of WiFi into the consumer markets and long range capability of WiMAX, the convergence of WiMAX and WiFi using WiMAX as back- bone for WiFi offers an excellent opportunity for the service providers to provide wireless broadband internet service in the rural, regional as well as urban areas. This offers the advantage of low cost connections to the access points (AP) using WiFi and a low cost backhaul/backbone deployment for the ISP provider using WiMAX technology. It is not far- 978-1-4577-9538-2/11/$26.00 ©2011 IEEE 266