Advances in future mobile/wireless networks and services

With over one billion mobile phone users (plus millions of PDA users) projected by the end of 2003, it is anticipated that mobile handheld devices will become the predominant user terminal of choice in near future. Several technologies and frameworks have either been developed or are under progress to provide seamless wireless connectivity ‘anytime anywhere’. Towards meeting this goal, third-generation (3G) standards within IMT2000 framework is being deployed. At the same time, major efforts are underway to deliver applications and services to the mobile user over a packet-switched IP network with the ultimate goal of eliminating circuit switching and the cellular infrastructure, as it exists today. So the current trends in network evolution are directed towards an all-IP core network, with a vision of providing an all-IP networking platform up to the terminal in the next generation. Work has already begun on such an all-IP end-to-end solution, commonly referred to as the fourth-generation (4G) systems that will combine mobility with multimedia-rich content, high bit rate, and IP transport. New network architectures based on 802.11 wireless local area network (WLAN) standards are also being proposed to build Hot-Spot networks as well as metropolitan area network (MAN). This issue of Computer Communications is devoted to addressing some of the challenges and recent advances in mobile/wireless communication networks. After careful review by the guest-editors and several external reviewers, eight papers were selected for inclusion in this special issue. The chosen papers cover a range topics including mobility management, handover support, crosslayer issues in protocol stack design, case study of providing multimedia over wireless network, authentication issues, as well as location management and work load characterization of wireless MAN. The special issue opens with a paper “Analysis of SIP-based Mobility Management in 4G Wireless Networks” by Banerjee et al. They have analyzed the handoff performance of SIP in a IP based 4G network with Universal Mobile Telecommunication System (UMTS) and Wireless LAN (WLAN) access networks and suitability of these schemes for multimedia communications. Pervasive Computing in future wireless networks will allow users to roam freely between heterogeneous networks while maintaining the continuity of their applications. Balasubramaniam and Indulska propose a vertical handover mechanism suitable for multimedia applications in such environment in the second paper titled “Vertical Handover Supporting Pervasive Computing in Future Wireless Networks”. Their work focuses on the handover decisionmaking process that uses context information regarding user devices, user location, network environment and requested Quality of Service (QoS). The next paper by Raisinghani and Iyer investigates the issue of cross-layer design optimisations in wireless protocol stacks. Current layered protocol stacks do not function efficiently in mobile wireless environments. The authors propose a cross-layer feedback in the protocol stack that would be useful to improve the efficiency of protocol stacks. This paper discusses the benefits of cross-layer feedback on the mobile device and presents a representative survey. Experimental evaluation of protocols and systems is an extremely challenging issue. Authors of paper titled “Realizing Mobile Wireless Internet Telephony and Streaming Multimedia Test bed” have shared their results and experiences from experimental work carried out in their indoor and outdoor test bed laboratory. This paper captures the incorporation and inter-relation of a wide catalog of IETF protocols—such as SIP, SAP, RTP/RTCP/RTSP, MGCP, variants of Mobile-IP to name a few. The paper also provides insight into hands on deployment issues that will be helpful in understanding of the important deployment issues for a Mobile Wireless Internet. Lin et al. present authentication and auto-configuration issues in GPRS-based WLAN. They propose an authentication and auto-configuration mechanism for WLAN based on short message service that does not require user intervention. The next two papers focus on new type of 802.11 based network solutions. Hassan and Jha propose a novel lightweight mobile communication network architecture called Cell-Hopping which consists of base stations interconnected by wireless inter base station links (WIBLs) as the network infrastructure. WIBLs support all routing and switching in cell-hopping networks, obviating the need for costly core networks. Rest of the paper is dedicated to location management issues in such network. The other paper by Hollick et al. proposes a novel approach to mobility modeling and workload characterization for a wireless metropolitan area network. Their model is a hybrid of empirical mobility model and synthetic traffic model. Application of their model to Darmstadt city in Germany gives some interesting insight into designing a wireless WAN.