راه حل جدید برای مدیریت میکرو تحرک در شبکه های نسل آینده

One main feature of next generation networks should be its heterogeneous communication environment, where different systems coexist and various wireless access networks and corresponding services are used. Despite the large number of current protocols, we believe that no efficient solution is available for automatic handoff between different wireless technologies. In order to develop an efficient technology agnostic solution, we propose to manage the problem just above the link layer. In this paper, we propose a novel architecture for the vertical handoff problem that operate at the layer 2.5. Our proposal is mainly based on an MPLS switching process and a Virtual Network Interface (VI) concept.

Mobility management has widely been recognized as one of the most important and challenging problems for a seamless access to wireless networks and mobile services. Future mobile communication systems evolve with the trend of global connectivity through the Internet working of heterogeneous wireless networks: towards an ubiquitous Wireless Internet. A major challenge in building ‘ALL-IP’ wireless access networks, besides the use of IP as the unifying layer, relates to transparency of the IP handoff process. In fact, the IP address plays the dual role of both end-point identification and location identification. Routing of packets in the Internet is based on IP addresses. Routers check the destination address of incoming packets and forward them to the port assigned to the so-called best prefix. Today, as nodes move, this static association represents an important constraint and cause service interruption. Introducing mobile nodes requires several changes or enhancements of the current protocol suite. As mobility should be transparent to most applications, changing the IP address of a node according to its current location is not possible. Neither would most applications continue to work after the address has been changed on-the-fly, nor could any communication partner find the node with the new, unknown address. By separating location from identity we will be able to manage transparent mobility. Different approaches have been developed to address this problem and to manage transparent mobility to application layers. Some of the most relevant schemes that have been reported in the literature are Mobile IP [1] and its multiple variants [2], Cellular IP [3] and Hawaii [4]. These standards solve some of the inherent IP mobility problems, but as they are operating at higher layers (3 and 4), an additional important delay is introduced to the handover problem. In this paper, we present a new scheme for supporting micro-mobility in wireless IP networks, namely a layer two mobility aware architecture for fast handover and an MPLS network based mobility solution (W-MPLS). The architecture requires very few changes to existing protocol stacks. In particular, no changes to non-mobile hosts is required. It provides efficient micro-mobility with continuous QoS support by combining the advantages of MPLS, such as IP QoS support, with these of a host-based link layer solution (Virtual Interface), such as low-latency handoffs. The rest of the paper is organized as follows. Section 2 describes the virtual interface architecture. Section 3 presents VIP, a Linux prototype for the virtual interface. Section 4 describes the principles of wireless MPLS “W-MPLS”. Section 5 considers location update optimization scheme. In Section 6, our simulations results are presented. Finally, Section 7 concludes this paper.

In this paper we have presented a new architecture for fast handover and micro-mobility management. The proposed scheme is a promising candidate for the next generation wireless networks. It addresses the key problems of transparent vertical and horizontal handoff. In order to reduce the handoff delay and consequently packets loss, we proposed to manage the problem at the layer 2.5. By combining the advantage of the virtual interface and the MPLS forwarding mechanism, we propose a simple solution that covers intranet and Internet connectivity. We also described our implementation for the virtual interface and results of a performance evaluation of the prototype system. We have shown using simulation that using W-MPLS can lead to substantial reductions in handover delays.