Welcome to this special issue of the ACM/Springer Mobile Networks and Applications (MONET). This special issue is devoted to the topic of the latest research and development on wireless Internet. Wireless Internet is quickly emerging as a reality, thanks to the fast evolution of many wireless access technologies. Convergence of heterogeneous wireless networks and the next generation Internet further brings wireless Internet into a variety of application scenarios which provide mobile users with a wide range of highly demanding services, such as high speed data and real-time multimedia delivery. On the other hand, it is of critical importance to obtain a fundamental understanding of wireless Internet architectures and explore new services and solutions in order to achieve the ultimate goal of wireless Internet access anytime anywhere

The aim of this special issue is to present a collection of high-quality research papers that report the latest research advances in wireless Internet communications, networks, systems, services, and applications. The whole special issue includes the extended papers in the 5th Annual International Wireless Internet Conference (WICON 2010), which was held in March 2010 (http://www.wicon.org/2010/). In this special issue, we selected 6 papers. The selected papers covered the following important topics in the field of wireless Internet: cognitive radio, wireless sensor networks, multimedia communications, and vehicular networks. A detailed overview of the selected works is given below.

The first paper, Joint Spectrum Allocation and Relay Selection in Cellular Cognitive Radio Networks, presents a cross-layer framework that jointly considers spectrum allocation and relay selection with the objective of maximizing the minimum traffic demand of secondary users in a cognitive radio network cell. This cross-layer design problem is formulated as a Mixed Integer Linear Programming (MILP) and a low complexity heuristic algorithm is proposed to solve the problem. In addition, a spectrum allocation is studied among several cells with the objective of maximizing the overall minimum throughput of all cells while ensuring each individual cell’s minimum throughput requirement.

The second paper, Joint Optimization of Power, Packet Forwarding and Reliability in MIMO Wireless Sensor Networks, investigates the reliable packet forwarding in Wireless Sensor Networks (WSNs) with the multiple-input multiple-output (MIMO) and orthogonal space time block codes (OSTBC) techniques. The objective is to propose a cross-layer optimized forwarding scheme to maximize the Successful Transmission Rate (STR) while satisfying the given end-to-end power consumption constraint. The channel coding, power allocation, and route planning are jointly considered to significantly improve the transmission quality in terms of STR. The joint optimization design is formulated as a global deterministic optimization and also a local stochastic optimization issues. Results have shown that the distributed scheme is able to provide sufficiently accurate prediction of the global optimization. In addition, the proposed scheme can clearly reduce the Symbol Error Rate (SER) and achieve higher STR compared with two existing energy-efficient routing protocols, in which joint design is not considered.

The third paper, Enhanced Active Queue Management for Multi-hop Networks, provides valuable new insights into the queuing mechanisms in wireless mesh networks and studies the QMMN algorithm (Queue Management for Multi-hop Networks), which tends to improve throughput, fairness and reduce global synchronization problems. An Enhanced QMMN (EQMMN) algorithm is also proposed to solve the problem of fairness between flows and eventually improve TCP throughput at wireless access points. Results show that EQMMN algorithm has higher performance with respect to throughput (TCP) and fairness index compared to QMMN algorithms.

The fourth paper, A Genetic Algorithm Approach to Multi-Agent Itinerary Planning in Wireless Sensor Networks, shows that using Mobile Agents (MAs) in wireless sensor networks (WSNs) can help to achieve the flexibility of over-the-air software deployment on demand. In MA-based WSNs, it is crucial to find out an optimal itinerary for an MA to perform data collection from multiple distributed sensors. However, using a single MA brings up the shortcomings such as large latency, inefficient route, and unbalanced resource (e.g. energy) consumption. Then a novel genetic algorithm based multi-agent itinerary planning (GA-MIP) scheme is proposed to address these drawbacks. The extensive simulation experiments show that GA-MIP performs better than the prior single agent algorithms in terms of the product of delay and energy consumption.

The fifth paper, A Resource Allocation Framework for Scalable Video Broadcast in Cellular Networks, provides an analysis of video broadcast streaming services for different combinations of layered coding and AL-FEC, using a realistic LTE PHY layer. Results show that the scalable content adaptation given by Scalable Video Coding (SVC) and the scheduling flexibility offered by the 3G-LTE MAC-layer provide a good match for enhanced video broadcast services for next generation cellular networks. The proposed solution is compared to baseline algorithms and broadcast systems based on H.264/AVC streaming solutions. The authors emphasize the system quality improvement brought by the solution and discuss implications for a wide-scale practical deployment.

The sixth paper, The Impact of Infostation Density on Vehicular Data Dissemination, investigates the role of Infostations in vehicle networks by acting as gateways to the Internet and by extending network connectivity. In this context, the paper studies an important issue “What is the minimum number of infostations that need to be deployed in an area in order to support vehicular applications”. Optimizing infostation density is vital to understanding and reducing the cost of deployment and management. In particular, the authors examine the required infostation density in a highway scenario using different data dissemination models. Efficient techniques are proposed to improve dissemination performance and reduce the required infostation density.

In conclusion, this issue of MONET offers a groundbreaking view into the recent advances in wireless Internet. We believe that this issue offers both academic and industry appeal- the former as a basis toward future research directions, and the latter toward viable commercial applications.

Finally, we would like to express our gratitude to the Editor-in-Chief of MONET, Dr. Imrich Chlamtac for his advice and encouragement from the beginning until the final stage. We thank Sara Fruner for the hard working and patience during the production of the special issue. We thank all anonymous reviewers who spent much of their precious time reviewing all the papers. Their timely reviews and comments greatly helped us select the best papers in this special issue.

We hope you will enjoy reading the great selection of papers in this issue.