UMTS will build on the success of GSM and is likely to become even more widespread. In addition, the continued growth of international travel for business and leisure means that the number of roaming UMTS and GSM subscribers is set to increase significantly. Every time a subscriber moves to a location area served by a different MSC/VLR or SGSN, the subscriber data must be downloaded from the HLR in the home PLMN to the new entity serving the user and deleted in the old MSC/VLR or SGSN. If the location areas associated with these entities are small or the subscriber frequently moves between location areas the subscriber will represent a large signalling load. This is equally applicable to subscribers moving within their home network and roaming subscribers except in the latter case international signalling costs are incurred. The Super-Charger uses spare capacity in the MSC/VLR or SGSN and modifies subscriber data handling to reduce the signalling load associated with roaming. The reduction in signalling load is achieved without introducing a new node but does require new functionality within the network.

The present document describes the use of Super-Charger mechanism within UMTS to reduce the signalling traffic associated with mobility. This document provides a technical proposal and example uses of the Super-Charger concept but also identifies issues that require further study. Finally, this document highlights the advantages and disadvantages, and identifies the UMTS Technical Specifications that would require enhancing to support this functionality.