Wireless Heterogeneous Networks and Next Generation Internet

The recent advances in wireless access technologies as well as the increasing number of mobile applications have made Wireless Internet a reality. A wide variety of bandwidth demanding services including high speed data delivery and multimedia communication have been materialized through the convergence of the next generation Internet and heterogeneous wireless networks. However, providing even higher bandwidth and richer applications necessitates a fundamental understanding of wireless Internet architecture and the interactions between heterogeneous users. Consequently, fundamental advances in many concepts of the wireless Internet are required for the ultimate goal of communication anytime anywhere. This special issue of the ACM Mobile Networks and Applications Journal is dedicated to the recent advances in the area of Wireless Internet. We accepted 10 papers out of 59 submissions from all over the world with a 17% acceptance rate. Papers describing management schemes, protocols, models, evaluation methods, and experimental studies of Wireless Internet are included in this special issue to provide a broad view of recent advances in this field. In the first paper, R. Yu, Y. Zhang, M. Huang, and S. Xie address the call admission control (CAC) problem in cognitive radio networks in their work titled “Cross-Layer Optimized Call Admission Control in Cognitive Radio Networks.” In addition to traditional CAC challenges, they also consider the presence of sensing errors that may mislead the CAC strategy to make an inefficient or even incorrect decision. To this end, the parameters of CAC strategy and spectrum sensing scheme are simultaneously tuned to minimize the dropping rate while satisfying the requirements of both blocking rate and interference threshold by the developed optimization framework. The crosslayer optimization is modeled as a non-linear programming problem after introducing a multiple-stair Markov model to approximate the non-memoryless state transitions. Accordingly, the dropping rate is shown to be reduced while still meeting the blocking rate and the interference probability constraints. In their paper titled “Joint Dynamic Resource Allocation for QoS Provisioning in Multi-Access and Multi-Service Wireless Systems,” D. Calabuig, J. F. Monserrat, D. Martin-Sacristan and N. Cardona analyze the resource allocation problem in multi-access wireless systems. The joint dynamic resource allocation (JDRA) algorithm simultaneously allocates the best-suited Radio Access Technology (RAT) and the amount of resources to all the users active in a multi-access wireless system. The Quality of Service (QoS) requirements of different users in terms of delay and bit rate are guaranteed through an optimization formalization based on a Hopfield Neural Network (HNN) formulation. The analysis and simulations highlight the advantages of joint decision approach compared to a twostep procedure and show that JDRA can address different levels of congestion and load distribution among RATs compared to the state-of-the-art. In the paper titled “LAMA/CA: A Load-Adaptive MAC Protocol for Short Packets”, Z. Noar develops a load adaptive medium access control protocol with collision avoidance. The protocol design is based on the fact that very often the Internet access messages, such as HTTP E. Ekici Ohio State University, Columbus, OH, USA e-mail: ekici@ece.osu.edu