Communicating while we are moving has been a desire for a long time. With mobile communication systems, mobile users can make and receive calls while they are moving independent of time, location and network access. One of the most attractive features that came with the Global System for Mobile communication (GSM) is roaming. Wireless systems are more vulnerable to fraudulent access and eavesdropping. As a remedy for that, GSM gives more importance to the user's privacy and authentication process. Although the process gives a reasonable security level, it overloads the network with significant signaling traffic and increases the call set-up time. The signaling load and the authentication delay are of particular importance and have become the subject of widespread research interest. In this paper, we study and analyze the GSM authentication protocols for roaming users, and propose a new scheme with less signaling traffic and better call set-up time.

LogGP is a simple parallel machine model that reflects the important parameters required to measure the real performance of parallel computers (Alexandrov et al., 1995). The message passing interface (MPI) standard provides new opportunities for developing high performance parallel and distributed applications. We use LogGP as a conceptual framework for evaluating the performance of MPI communications on three platforms: Cray-research T3D, Convex Exemplar 1600, and a network of workstations (NOW). Each machine is viewed as a "black box" that supports the same MPI implementation.

Mobile communication is one of the fastest growing sectors of the telecommunication industry. Mobile users can make and receive calls while they are moving independent of time, location and network access. The Global System for Mobile communication (GSM) is a pan-European digital cellular mobile system supporting widespread roaming and personal communication services (PCS) in a worldwide wireless communication network. However, wireless mobile systems are more vulnerable to fraudulent access and eavesdropping. Although the authentication process in GSM provides a reasonable security level it overloads the network with significant signaling traffic and increases the call set up time. The signaling load and the authentication delays are of particular importance and are becoming the subject of widespread research interest. We study and analyze the GSM privacy and authentication protocols, and propose a new authentication protocol with less signaling traffic and better call set up time, that can be used in GSM networks.