OPTIMIZING HANDOFF TIME FOR MAINTAINING QoS IN W-ATM NETWORKS

Abstract

The extension of. ATM Networks to the Wireless domain presents a challenging set of problems for both network designers and managers. One of the key problems within this set is mobility management. Wireless ATM networks require efficient mobility management to cope with frequent handoff and rerouting of connections. This work simulates and studies one such mobility management protocol (W-ATM signaling protocol) and possible improvements in it for quick handoff. This report discusses two novel schemes for optimizing handoff delays. In the first approach, mobile motion prediction (MMP) algorithm is used to predict the "future" location of a mobile user according to user's movement history i.e. previous movement patterns. Knowing this, the system does advance optimal route establishment and resource reservation in the route to maintain desired QoS. So, when the user enters a new zone, it will receive service or data with the same efficiency as the previous location. In the second scheme, during handoff, rather than establishing a new path with the end point, only a partial path is established. This partial path set up is handled by special switches called Cross-Over-Switches (COS). The COS behaves as a virtual end point and performs all the signaling that is required for performing handoff. The prediction scheme makes some changes in the existing W-ATM signaling protocol by adding a set of new signals, while the latter scheme keeps the existing protocol intact, but requires upgrading of some of ATM switches in the network: Ii The performance of these schemes have been compared against some other schemes like VCT (Virtual Connection Tree) and it is shown that these schemes provide better resource (bandwidth) utilization. The program is implemented in JAVA (JDK 1.1.4) and has been built on Windows 98 environment. in