We are happy to introduce this special issue of Performance Evaluation dedicated to Modeling and Analysis of Wireless Networks. Wireless networks play an increasingly important role at the edge of the Internet where they provide access to users on the move. Cellular networks are providing increasing data services to users, wireless LANs and mesh networks provide broadband network access to mobile users, and ad hoc and sensor networks allow a collection of wireless devices to self configure and communicate among each other. In all of these areas, we are experiencing a period of innovation and rapid progress: new ideas and improvements drive these fields towards ever more ambitious systems and solutions. The multitude of research and system ideas places special importance on high quality modeling and analysis, in order to enable effective performance evaluation and foster a deep understanding of the issues and trade-offs that make up the design space, which is the motivation for this special issue.
We have restricted the scope of the special issue to networking protocols and services in non-cellular networks, to improve its focus. We invited extended versions of the best papers on these topics presented at the Tenth ACM/IEEE International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems (MSWiM 2007). We ended up with nine excellent papers that were selected through this process.
The first group of three papers derives new analytical results for problems in ad hoc and sensor networks. The first paper in this group is titled ''Energy Optimization for Proactive Unicast Route Maintenance in MANETs under End-to-End Reliability Requirements'', by Tridib Mukherjee, Sandeep K. S. Gupta and Georgios Varsamopoulos. In this paper, the authors analyze proactive routing protocols-an important class of routing protocols used in Mobile Ad hoc Networks (MANETs). They construct a model of these protocols and use it to estimate the optimal timer periods that control when information is exchanged by these protocols. They use the analysis to develop an optimal version of the DSDV protocol, which minimizes the overhead required for the routing packets. The model results are validated against simulation.
Esa HyytiΓ€ and Jorma Virtamo contributed the paper ''On the Optimality of Field-line Routing in Massively Dense Wireless Multi-hop Networks''. The paper considers the question of finding the optimal routes in a multi-hop wireless network under the asymptotic assumption of infinite node density. Interestingly, they discover that single-path routing is optimal from a load balancing perspective under these assumptions; this is a result that is quite useful if it holds in more conventional networks. The paper illustrates the results with a number of numerical examples.
The final paper in this group is titled ''Trend Forecasting based on Singular Spectrum Analysis of Traffic Workload in a Large-Scale Wireless LAN'', by George Tzagkarakis, Maria Papadopouli and Panagiotis Tsakalides. The paper carries out a statistical analysis of traffic measured in a campus wide WLAN network. They discover that the time-series of the traffic load at each AP can be accurately modeled using a small number of principal components. The residual information captures the small irregular variations that are not part of the stable network traffic pattern. The paper then develops a traffic predictor by projecting the original time-series obtained from the traffic analysis.
The next group of papers explores new ideas in services and protocols for emerging wireless networks. In the paper ''Quality-of-Service Tradeoff Analysis for Wireless Sensor Networks'', by Rob Hoes, Twan Basten, Chen-Khong Tham, Marc * Corresponding editor.