1 Mobility

Personal mobility means, that the user is able to use services independent of the network access point he/she is connected to and independent of the user equipment. This contains outgoing and incoming services. The usage of services of course is limited by the features of the user equipment and the network in use. The user gets a unique identity (e.g. IMSI, International Mobil Subscriber Identity), valid independent of the network and the connection. Billing is registered with that number. The mobility is discrete.

Personal mobility is a logical assignment and is built on top of the (physical) terminal mobility. For an incoming call, first it has to be checked which user equipment the user is working with at the moment and where that user equipment is located (in which network, with which network access point). Personal mobility is based upon the information of the actual association of user to user equipment and localization based on the user’s identity. With worldwide personal mobility this causes very large amounts of data that cannot be stored in a centralized database. It is possible to store the data locally in an always-on device. This device is contacted in case of an incoming call and sends back the information about the currently used user equipment.

If users are allowed to register with different user equipment (as in UMTS) then it has also to be decided about the order in which the different user equipment shall be contacted.
Personal mobility in principle allows the personalization of each terminal worldwide. Constraints are given by the compatibility of networks and user equipment. If we restrain to GSM networks, personal mobility only needs agreements of all operators. The personalization of the user equipment is based on a smart card (SIM, Subscriber Identification Module) that is plugged into the user equipment. The UPT-concept (Universal Personal Telecommunication) shall enable personal mobility between different networks. Therefore, the networks need a minimum intelligence, e.g. to register correct billing data. User equipment, which cannot handle smart cards, can be personalized via calling a number of an UPT-contractor and getting the identity from there.