PROVISION OF QUALITY OF SERVICE IN OPEN WIRELESS ARCHITECTURES Faouzi Zarai, Noureddine Boudriga CN&S Research Lab., University of Carthage, Tunisia Email: nab@supcom.mu.tn ABSTRACT The open wireless architecture networks are targeted for the support of various applications such as voice, data, video conferencing, and video streaming. Providing Quality of Service guarantees for these systems is an important objective in the design of the fourth generation (4G). In this paper, we propose a Medium Access Control protocol that maximizes the bandwidth utilization while successfully integrating different classes of traffic. In addition, we propose a generic scheduling scheme, named Channel State-EDF. 1. INTRODUCTION Open Wireless Architecture (OWA) networks are integrating heterogeneous access networks and IP-based transport technologies. In these networks, user-to-user communication can be provided with high quality multimedia and access to information and services on public networks with enhanced QoS (Quality of Service) guarantees and security services. The delivery of multimedia services to mobile users is a major goal in open wireless architectures because the use of several services simultaneously raises the demands for the support of QoS for each application. Consequently, the Medium Access Control (MAC) and network layer scheduling algorithms must select and transmit packets in accordance with the QoS requirements. Among all MAC protocols, random medium access control protocols have been widely studied for wireless networks due to their low cost and easy implementation. IEEE 802.11 MAC minimizes the collision level and resolves the hidden terminal problem, [7] [8]. However, there are still many problems that IEEE 802.11 MAC has not adequately addressed. A well designed MAC protocol makes full use of multi-user diversity in terms of multiple transmitters to maximize bandwidth utilization and minimize collision while successfully supporting different classes of traffic. There have been many schemes that deterministically guarantee the meeting of deadline of arriving packets [5], [6]. The main limitation of these schemes is that they do not take into consideration the variable nature of the wireless channel quality. In fact, to handle packet errors and time varying we consider the problem of scheduling packet transmissions depending on the channel state. Our contribution in this paper is two fold. First, we propose a novel protocol to address MAC layer problems for OWA. Second, we propose a generic scheduling scheme, named CS-EDF (Channel State-Earliest Deadline First. The rest of the paper is organized as follows: Section 2 give the OWA configuration. Section 3 details the MAC protocol design. In Section 4, we present the proposed scheduling algorithm. We present the simulation results in Section 5. Finally, Section 6 gives the conclusion and perspectives of this paper. 2. CONFIGURATION OF OWA OWA networks utilize multiple radio access technologies including cellular networks (such as GSM, GPRS, UMTS ... ), satellite-based networks, and Wireless LANs are seamlessly integrated to form a heterogeneous wIreless network. The integration is typically based on Mobile IP and cellular IP. OWA will emerge as the convergence of the next generation wireless systems and with the objectives of providing anywhere, anytIme seamless service to mobile users. The major challenge for the OWA systems remains in the fact that the architecture will have to be very flexible and open, capable of supporting various types of networks, terminals and applications. The proposed network architecture for wireless 4G network is illustrated in Figure 1. In this architecture the hierarchical cell structure of UMTS offers a global'radio coverage and each of the wireless access networks has its own ability to handle IP networking among its own operation some have a master (Bluetooth), Access POInt (WLAN), Cellular Access Point (GSM, GPRS, and UMTS), Cluster Head (Ad-hoc network). The proposed architectural consists of three major layers: 1. Core Network (CN): It is based on the IP protocol. All WLAN Access Point and Cellular Access Point are connected to this network. 2. Radio Access Networks (RAN): These networks are connected to the core nodes (BS) via heterogeneous units (HU). 3. Mobile Terminals (MT): The user terminal is equipped with a multi-radio interface.