Handover Mechanisms in ATM-Based Mobile Systems

This paper presents two handover mechanisms that can he used in the access part of an ATM-based mobile system. The first handover mechanism, which is called "handover synchronised switching" is relatively simple and does not use any ATM multicasting or resynchrnnisation in the network. It assumes that there is sufficient time available such that all data and history information of the old path can be transferred to the Mobile Terminal (MT) before the actual handnver to the new path takes place. It is possible that the time between a handnver decision and the actual handover is too short to end the transmission on the old path gracefully (e.g., ending the interleaving matrix, ending transcoder functions, emptying intermediate buffers). A possible solution to this problem is given by the second handover mechanism, where multicast connections to all possible target Radio Systems ( U S ) are used in the core network. This mechanism is called "handover with multicast support".