Special issue: Research in ad hoc networking, smart sensing, and pervasive computing

Abstract

Wireless communications have added a new dimension to the networking field. One recent development is the wireless ad hoc network, which is characterized by many mobile computers interconnected by wireless transceivers without the support of fixed infrastructure, making it attractive for use in emergency relief and battlefield communication. The network can be formed quickly and dynamically. However, efficiency of ad hoc networks needs to be addressed carefully. For example, power saving is a critical issue to extend the lifetime of an ad hoc network. The medium access control (MAC) is also a very challenging issue since interference would be intensive in an ad hoc network. Mobility management and QoS are important to support high-level applications. Sensor networks, which are created by tiny smart sensors combined with computation and communication capabilities, are being proposed recently for applications such as military combat, environment surveillance, and pollution detection. Common features of sensor networks and ad hoc networks include multi-hop communication and dynamically changing network topology. These two new network architectures, together with the development of lightweight, small computing devices, have made pervasive computing possible. Many issues, such as routing, medium access, energy management, fault tolerance, and scalability, need to be addressed. This special issue is targeted at addressing the development of these issues. Nine papers are selected for publication in this special issue from over thirty submissions. The first paper ‘Spatial Agents: integrating of user mobility and program mobility in ubiquitous computing environments’ by I. Satoh presents a framework for the building of context-aware applications in ubiquitous and mobile computing settings. The framework provides people, places, and things with computational functionalities to support and annotate them. Using location-tracking systems, the framework provides a way for mobile agents to follow their users as they move around. A prototype implementation of the framework has been built on a Java-based mobile agent system and tested with several practical applications, including follow-me applications and a user navigational assistance system. The second paper ‘Power-aware broadcasting and activity scheduling in ad hoc wireless networks using connected dominating sets’ by J. Wu and B. Wu and I. Stojmenovic addresses the broadcasting issue in an ad hoc network. A straightforward broadcasting by flooding is usually very costly and will result in substantial redundancy and more energy consumption. A new broadcasting based on connected dominating sets is proposed. The authors propose to apply the notion of power-aware connected dominating set to broadcasting and activity scheduling. The effectiveness of the proposed method in prolonging the life span of the network is confirmed. The third paper ‘Reliable MAC layer multicast in IEEE 802.11 wireless networks’ by M. Sun, L. Huang, S. Wang, A. Arora and T.-H. Lai addresses the multicast/broadcast support in an IEEE 802.11 wireless network. The IEEE 802.11 multicast/broadcast protocol is designed based on CSMA/CA and does not provide any MAC layer recovery on multicast/broadcast frames, thus suffering from the reliability problem. To redress the problems of reliability and efficiency, the authors propose a reliable Batch Mode Multicast MAC protocol, which considerably reduces the time required for a multicast/broadcast. Then the authors further propose a Location Aware Multicast MAC protocol that uses station location information to further improve the performance. One of the most important applications for mobile commerce is location-based application and location determination technology. In the fourth paper entitled