Advances in parallel, distributed, embedded, and ubiquitous systems

Computing systems are now invading in every aspect of our daily life and promise to revolutionize our life. The emergence of the related technology is a natural outcome of research and technological advances in a variety of areas including parallel computing, distributed computing, embedded systems, pervasive computing and communications, wireless networks, mobile computing, and agent technologies. These new and exciting paradigms provide computing and communication services to the end users all the time and everywhere. This special issue focuses on the recent advances in the new generation computing systems such as parallel, distributed, embedded, and ubiquitous systems. We are pleased to present to you nine technical papers dealing with cutting-edge research and technology related to this topic. These papers were selected out of the significantly extended versions of the 85 submissions from 33 countries in the 11th International Conference on Algorithms and Architectures for Parallel Processing (ICA3PP 2011) and a large number of open submissions. The selection has been very rigorous, and only the best papers were selected. In the first paper, ‘Power-Aware Scheduling with Effective Task Migration for Real-Time Multicore Embedded Systems’ [1], March et al. propose a power-aware scheduling allowing task migration scheme to reduce energy consumption in multicore embedded systems. Two algorithms are proposed working under real-time constraints. As power consumption is a significant problem in real-time embedded systems, this paper presents substantial research results in the area. In the second paper, ‘Optimal tracking agent: A new framework of reinforcement learning for multiagent systems’ [2], Chen et al. propose a new framework to deal with the exponentially growing learning and storage problem with the increased number of agents in the distributed agent systems. This framework views the other agents as a part of the environment and uses a reduced form to learn the optimal decision. Aggregate queries are useful tools in the context of sensor network-based systems, as they retrieve knowledge from huge amounts of summarized readings to be exploited for knowledge discovery purposes. In the third paper, ‘Exploiting Compression and Approximation Paradigms for Effective and Efficient OLAP over Sensor Network Readings in Data Grid Environments’ [3], Cuzzocrea and Sacca propose a grid framework to provide approximate answers to aggregate queries on summarized sensor network data to address this interesting problem. With the development of Wireless Mesh Networks, fault diagnosis in Wireless Mesh Networks is becoming a challenging task. In the fourth paper, ‘An Efficient Self-Diagnosis Protocol for Hierarchical Wireless Mesh Networks’ [4], Xu et al. propose a new protocol that has a comparison approach to diagnose two-level topology architecture. The authors provide the analysis of correctness, communication complexity, and time complexity of the protocol, and compare this protocol with others by both theoretical proof and practical simulation. The analysis shows that this protocol has significant advantages over other existing work. In recent years, a new type of peer-to-peer communications protocol for worldwide file sharing is rapidly evolving towards Private BitTorrent (PT). In the fifth paper, ‘A Measurement-based Study on User Management in Private BitTorrent Communities’ [5], Jiang et al. study the effects on user behavior, download performance, content availability, and system scalability in PT networks. The measurement results presented in this paper are based on large-scale experiments conducted over six representative PT sites for over a year. Their analysis poses a direction for the design of new incentive mechanisms that take the difficulty of enrollment into the consideration. Delay tolerant networks are resource-constrained dynamic networks where a continuous end-to-end connectivity is not always available. In the sixth paper, ‘Practical Distributed Secret Key Generation for Delay Tolerant Networks’ [6], Xie and Wang propose a distributed secret key generation system