Network impacts of privacy and authentication protocols for PCS

This paper describes the message flow due to authentication, voice privacy, and signaling message encryption of two schemes that are expected to be incorporated in the EIA/TIA´s cellular industry Interim Standard IS 41 Revision C. We compare the two schemes with the use of a simple mobility model for users and study their impact on the traffic to network databases. Defining user mobility rate as the number of registrations per hour per user, we show that as the user mobility rate increases from roughly 0.5 to 15, the effectiveness of one of the schemes (the one that shares the shared secret data or SSD with the visited system) as compared to the other (the one that does not share it with the visited system) varies from about 66% improvement to about 30% degradation, clearly implying that the mobility characteristics of the user population dictate the choice of the authentication scheme