Editorial:

This special issue features eight selected papers with high quality.

The first article, “A Cost-Effective Methodology Applied to Videoconference Services on Hybrid Clouds” by Javier Cerviño, Pedro Rodriguez, Irena Trajkovska, Fernando Escribano and Joaquín Salvachúa, tackles the optimization of applications in multi-provider hybrid cloud scenarios from an economic point of view. However the approach was intended to introduce a novel solution by making maximum use of divide and rule. Also this article describes a methodology to create cost aware cloud applications that can be broken down into the three most important components in cloud infrastructures: computation, network and storage. A real videoconference system has been modified in order to evaluate this idea with both theoretical and empirical experiments. The proposed system has become a widely used as a tool in several national and European projects for e-learning and collaboration purposes.

The second article, “An Efficient Dynamic Integration Middleware for Cyber-Physical Systems in Mobile Environments” by Young-Sik Jeong, Sang Oh Park and Jong Hyuk Park, proposes a cyber-physical system (CPS) middleware framework that ensures interoperability and communication between heterogeneous components in a global CPS network. A CPS is a tight integration of the system’s computational and physical elements. The CPS technology builds on the older discipline of embedded systems, and CPS applications can be found in diverse industry sectors, such as smart home, health care, and transportation. The article assume that a global CPS network that integrates different CPS networks appears in the near future. Through local and global communications, the proposed middleware makes mobile devices in different networks interoperable.

The third article, “Particle Swarm Optimization with Skyline Operator for Fast Cloud-based Web Service Composition” by Shangguang Wang, Qibo Sun, Hua Zou, Fangchun Yang, proposed a fast Cloud-based web service (CWSs) composition approach based on the notion of Skyline. Such an approach adopts Skyline operator to prune rebundunt CWS candidates then employs Particle Swarm Optimization to select CWS from amount of candidates for composing single service into a more powerful composite service. In order to show the proposed approach, an experiment based on real dataset is conducted. Experimental results show that the approach is effective and efficient for CWS composition.

The fourth article, “A Novel Approach to detect Network Malicious Activity based on Cloud Computing Testbed” by Junwon Lee, Jaeik Cho, Jungtaek Seo, Taeshik Shon, Dongho Won, analyzed typical example of network testbeds, which have been used for malicious activity data collection and its subsequent analysis. Furthermore an effective malicious network application testbeds, which is based on a cloud system is proposed. Also the new testbed was compared with real malicious activity with the cloud-based testbeds results in order to verify the performance.

The next article, “A Survey of Computation Offloading for Mobile Systems” from Karthik Kumar, Jibang Liu and Yung-Hsiang Lu, is a survey paper that provides an overview of the background, techniques, systems, and research areas for offloading computation. This article takes on as it describes brief history of enabling technologies, two objectives for offloading, and why offloading will become increasingly important in the future.

The sixth article, “Accurate and Efficient Node Localization for Mobile Sensor Networks” by Hongyang Chen, consider a range-free cooperative localization algorithm for mobile sensor networks by combining hop-distance measurements with particle filtering. In the article a differential-error correction scheme was designed in hop-distance measurement step in order to backoff-based broadcast mechanism in the proposed localization algorithm. The proposed localization method has fast convergence with small location estimation error.

The seventh, “A Survey of Energy Efficient Mobile Cloud Computing” by Yong Cui, Xiao Ma, Hongyi Wang and Jiangchuan Liu, discuss the trade-off and then present a survey of related works. Based on the significance of wireless network interface in the power use of mobile devices, considerable researches have been de-voted to a low-power design of the usage style/protocol. This effort towards enhancing energy efficiency has allowed providing a comprehensive summary of recent work on transmission energy savings. Additionally, as one increasingly prevalent type of application in mobile cloud environments, location based applications also present some inherent limitations surrounding energy. For example, the GPS (Global Positioning System) based positioning mechanism is well-known to be extremely power-hungry. Moreover this article present an overview of energy-efficient positioning mechanism which have emerged in the last 2 or 3 years and discuss the future research directions of energy efficiency issues.

The last article, “Window-based Rate Adaptation in 802.11n Wireless Networks” the authors (Ioannis Pefkianakis, Yun Hu, Suk-Bok Lee, Chunyi Peng, Sofia Sakellaridi, Songwu Lu) used real experiments to study MIMO 802.11n Rate Adaptation (RA) on a programmable AP platform. The result revealed nontrivial inter-, intra-mode opportunistic gains with respect to transient channel variations in both MIMO operation mode of Diversity and Spatial Multiplexing. To exploit these short-term gains, a new Window-based Rate Adaptation (WRA) algorithm was designed and implemented. WRA differently from existing MIMO 802.11n proposals, runs an independent RA in each MIMO mode in parallel, to address the unique characteristics of each MIMO mode. To Window for each individual mode, and opportunistically selects the best-goodput rate among the candidates on a per-transmission basis. WRA also applied novel techniques to limit probing overhead and to improve responsiveness to mobility. The experiments show that WRA gives 52.8 % goodput gains over Atheros MIMO RA algorithm, and 72.5 % gains over practical legacy 802.11a/b/g designs in field trials.