The growth of telecommunications has been largely based on mobile and data services in the past 10 years and this growth will continue. For instance, it is forecasted that after 2005 the mobile traffic turnover in Europe will exceed that of fixed telephone traffic, and the penetration of Internet access through mobile will exceed that of fixed access. It is expected that new value-added services will be Internet-based and that IP traffic will outweigh the amount of traditional ISDN based telephone traffic. The transition from existing telecommunications services to mobile and Internet-based services will change the service infrastructure as well as the customer and service management structures. This volume comprises the proceedings of the Working Conference on Personal Wireless Communications (PWC'2001), which was sponsored by the International Federation for Information Processing (IFIP) and organized by IFIP Working Group 6.8. It was held in Lappeenranta, Finland in August 2001. The PWC'2001 conference is a forum for tutorials, discussions and presentations of new developments in mobile and wireless research. The contributions to this volume have been divided into six categories that vary from voice over IP implementations to quality of service issues; from service aspects to performance and modelling issues; from modern cellular networks to future wireless systems. This volume will be essential reading for IT students and researchers as well as for theoreticians interested in the current state of the telecommunication systems.