ATM networks

Handoff algorithms in terrestrial wireless networks focus on the connection rerouting problem. Basically, there are three connection rerouting approaches: full connection establishment, partial connection reestablishment, and multicast connection reestablishment. Full connection establishment algorithms calculate a new optimum route for the call as for a new call request. The resulting route is always optimal; however, the call rerouting delay and the signaling overheads are high. To alleviate these problems, a partial connection reestablishment algorithm reestablishes certain parts of the connection route while preserving the remaining route. This way the route update process involves only local changes in the route and can be performed faster. However, the resulting route may not be optimal. In the multicast connection reestablishment algorithm, a Virtual Connection Tree (VCT) is created during the initial call admission process. The root of the tree is a fixed switching node, while the leaves are the switching centers to serve the user terminal in the future. By using the multicast connection reestablishment method, when a call moves to a cell with a new switching center, connection rerouting is done immediately owing to the already established routes. The disadvantage of this algorithm is that network resources can be underutilized as a result of resources allocated in the connection tree.

We define the Chain Routing Algorithm and implement it as a partial connection reestablishment in the handoff scheme. This process is done during chain elongation. This handoff scheme can be used in the Wireless ATM (WATM) model.

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