Ensuring clean water availability is critical for sustainability and health. Conventional water quality assessments are limited by manual sampling, poor temporal resolution, and centralized data processing. This study proposes HydroFedNet, a multisource water quality monitoring framework that uses Federated Learning (FL) to integrate diverse data sources, including LANDSAT satellite imagery, RGB pond images, and Internet of Things (IoT) sensor streams. The spatio-spectral transfer learning network (Spatio-Spectral TLNet), the color transfer learning network (Color TLNet) and the sensor convolutional neural network - temporal convolutional network (Sensor CNN - TCN) are fundamental models for HydroFedNet. Spatio-Spectral TLNet and Color TLNet leverage EfficientNetB3 for optimized, low-cost training, while Sensor CNN–TCN exploits improved temporal modeling. Models are trained locally and share weight updates with a central server, which builds a global model using the chosen FL strategy. FL strategies such as Federated Averaging (FedAvg), FL with Temporally Aware aggregation (FedLTA), and Federated Optimization (FedOpt) are evaluated with six objectives, including energy efficiency, fault tolerance, and handling of non-independent and identically distributed (non-IID) data. FedLTA surpasses the 90% accuracy across all three models with less communication overhead, whereas FedOpt effectively handles non-IID data. HydroFedNet allows an optimal selection of an intent-aware FL strategy, allowing robust, scalable, and efficient water quality monitoring across heterogeneous environments.

With the widespread adoption of mobile devices, an increasing number of users are engaging in social interactions through these devices. Mobile social networks have thus emerged in response. Existing research has shown that utilizing mobile social relations can effectively enhance the performance of recommendation systems. However, most studies only exploit single social relations such as pairwise relations, overlooking the effect of high-order complexity of user relations which contain some potentially beneficial information. What's more, they ignore the impact of the trusters who provide some potential feedbacks in the mobile social network. Therefore, this paper proposes our framework H2TRec using hypergraph convolution in the pretraining stage to learn high-order neighbor information in the mobile social network and utilizing the metapath-based GAT to model users' bidirectional trust relations. First, mobile social communities are partitioned by random walk based on the fusion graph which consolidates all different nodes and relations. Second, each mobile social community is represented as a hyperedge to construct the hypergraph and the high-order neighbor prior knowledge is learned using hypergraph convolution. Third, implicit relations are mined and the metapath-based GAT is utilized to model the preferences of users and items. Notably, unlike previous work, we consider mobile users' out-degree and in-degree features, which enhance the user embeddings. Additionally, a loss term aiming to improve centrality is added to make the preference features of mobile social communities more prominent. Extensive experiments on five popular real-world datasets demonstrate that our H2TRec can improve precision compared with state-of-the-art methods. We release the source code athttps://github.com/kangkang-yun/H2TRec.

Wireless Sensor Network (WSN) reliability evaluation is essential for ensuring the stable operation of network. Traditional methods usually focus on the network topology structure, and calculate the normal operation probability of WSNs. However, these methods usually ignore the energy consumption and network lifetime. In this paper, a novel reliability evaluation algorithm TLR is proposed, which calculates the network lifetime under dynamic network environment according to the pre-set network topology structure reliability threshold, and realizes the comprehensive reliability analysis of network topology and lifetime. In addition, as the basis for reliability evaluation, this paper proposes a new deep reinforcement learning network framework GNN-AC combining graph neural network and actor-critic network, which solves the challenge of constructing Virtual Backbone Network (VBN) in dynamically operating networks. Based on the self-defined fitness matrix and fitness value, the objective function is set to optimize the VBN construction scheme to accurately calculate the network lifetime, and the relationship between the reliability of network topology and network lifetime is discussed. Simulations are carried out for various sizes of WSNs to show the advantages and effectiveness of the proposed approach in estimating network lifetime and reliability evaluation.

ABSTRACT A total of 12 papers were accepted for the special issue on the topic of ‘New Technologies of Artificial Intelligence in Convergence ICT’. Recently, as the convergence of artificial intelligence continues to occur in various fields, various technologies are emerging. In this paper, 12 papers introduce AI utilisation technologies in various fields such as smart city, security, medical, economy, healthcare and electricity.

The Cloud-Fog Automation is a newly proposed digital industrial automation architecture aimed at accelerating the integration and collaboration of communication, computing, and control towards next-generation cyber-physical systems (CPSs). Data reliability is one of the key considerations for achieving Cloud-Fog Automation. Sensor nodes serve as infrastructures for data collection within industrial CPSs and are essential for maintaining ultra-high data reliability. However, the underlying sensor nodes communicate frequently, are damage-prone and difficult to identify, which dramatically shortens the network lifetime and poses great challenges to data reliability. Motivated by this fact, this paper co-designs communication architecture, algorithms, and computing models for next-generation industrial CPSs with Cloud-Fog Automation to ensure data reliability and functional security. First, a four-layer energy-efficient communication architecture is proposed and a cluster head computing algorithm based on double deep Q-learning (CH-DDQ) is designed inside the architecture. Besides, a 2-stage hyBrid fault detection scheme (2-Brain) is proposed for underlying sensor nodes. 2-Brain first incorporates the Obstacle Triple Jump Protocol (OTP) and OTP packets to improve hard fault detection performance. Then, an unsupervised sensor reading soft fault detection model (SR-SFD) based on contrastive learning, momentum, and tensor is adopted to learn discriminative representations of sensor readings and identify soft faults. Simulations and a case study in the nuclear power industry manifest CH-DDQ improves the network lifetime by 5.4%~484.3% compared to three peer methods, and OTP performs better than baselines by 33.1% on average. Additionally, SR-SFD exhibits high efficiency in sensor soft fault detection and other application scenarios.

The large-scale applications of wireless sensor networks (WSNs) place higher demands on their reliability. WSNs deployed in the intelligent tunnel are often affected by environmental interference or malicious intrusions, which lead to untrusted paths and affect the reliability of transmission. A trusted path ensures that the collected information can be successfully and reliably transmitted to the sink node. To solve the transmission reliability problem of wireless sensor networks, a trusted multi-source shortest path-based transmission reliability (TMSPR) algorithm is proposed in this paper. A lightweight trust management model with a node relation matrix (RM) is applied to identify and exclude untrusted nodes, thereby establishing secure transmission links. Meanwhile, the shortest transmission path is selected based on the minimum path to save the energy of the nodes. The information transmitted through trusted multi-source shortest paths (TMSPs) can successfully reach the sink node, which significantly improves the transmission reliability of the network. Furthermore, a transmission reliability indexTRelis defined as a probabilistic measure to assess reliability. Simulation results demonstrate that the proposed algorithm exponentially reduces both computation time and memory usage, while enhancing transmission reliability by approximately 5%.

AI-empowered edge computing has given rise to a new paradigm and effectively facilitated the promotion and development of multimedia applications. The speech assistant is one of the significant services provided by multimedia applications, which aims to offer intelligent interactive experiences between humans and machines. However, malicious attackers may exploit spoofed speeches to deceive speech assistants, posing great challenges to the security of multimedia applications. The limited resources of multimedia terminal devices hinder their ability to effectively load speech spoofing detection models. Furthermore, processing and analyzing speech in the cloud can result in poor real-time performance and potential privacy risks. Existing speech spoofing detection methods rely heavily on annotated data and exhibit poor generalization capabilities for unseen spoofed speeches. To address these challenges, this article first proposes the Coordinate Attention Network (CA2Net) that consists of coordinate attention blocks and Res2Net blocks. CA2Net can simultaneously extract temporal and spectral speech feature information and represent multi-scale speech features at a granularity level. Besides, a contrastive learning-based speech spoofing detection framework named GEMINI is proposed. GEMINI can be effectively deployed on edge nodes and autonomously learn speech features with strong generalization capabilities. GEMINI first performs data augmentation on speech signals and extracts conventional acoustic features to enhance the feature robustness. Subsequently, GEMINI utilizes the proposed CA2Net to further explore the discriminative speech features. Then, a tensor-based multi-attention comparison model is employed to maximize the consistency between speech contexts. GEMINI continuously updates CA2Net with contrastive learning, which enables CA2Net to effectively represent speech signals and accurately detect spoofed speeches. Extensive experiments on the ASVspoof2019 dataset show that GEMINI reduces the Equal Error Rate and tandem Detection Cost Function by up to 96.75% and 96.35% in the physical access scenario, and by up to 86.62% and 87.71% in the logical access scenario compared to peer methods.

Internet of Things (IoT) reliability evaluation contributes to the sustainable computing and enhanced stability of the network. Previous algorithms usually evaluate the reliability of IoT by enumenating the states of nodes and networks, which are difficult to handle IoT with hundreds of nodes because the computational cost. In this paper, a novel algorithm, TMCRA, is proposed to evaluate the reliability of IoT in complex network environment, which consider both coverage and connectivity. For coverage, TMCRA employs the Confident Information Coverage (CIC) model to divide the target area into independent grids and calculates the coverage rate. In terms of connectivity, TMCRA forming the Virtual Backbone Network (VBN) based on two proposed methods: TMA and MGIN, and evaluate connectivity by analyzing the VBN rather than the whole network. The TMA and MGIN are two algorithms for constructing Minimum Connected Dominant Sets (MCDS), which are suitable for different scale networks. Finally, based on the data of coverage and connectivity, TMCRA utilizes tensors for the unified modeling and representation of network structure, and calculates IoT reliability based on the tensors. Simulations are carried out for various sizes of IoT to show the advantages and effectiveness of the proposed approach in reliability evaluation.

\beginabstract Social network has obtained extensive attention in recommender system. Existing social recommendation models mostly leverage social relations to capture potential interactions between users and items, thereby enhancing recommendation performance. However, these methods ignore the fine-grained bidirectional trust weight and the constraint on the relative positions of entities in social network and user-item interaction network. To this end, in this paper, we propose a social recommendation framework with Trust mining and multi-semantic reGularization (TrustGo). Specifically, we firstly construct a trust network based on the observed social network and establish a high-quality item implicit network. Then, we integrate the trust network, item implicit network, and user-item interaction network into a heterogeneous network. We introduce a meta-path based aggregation in this heterogeneous network to map the users and items into a latent space. And then, by using an ensemble method, we can obtain the final prediction ratings. Considering the users' different behaviors in social network and user-item interaction network, we define two semantic spaces, i.e., the social semantic space and user-item interactional semantic space. And a multi-semantic regularization module is designed to adjust the relative positions of entities in the two kinds of semantic spaces, respectively. Extensive experiments on three real-world datasets demonstrate that our TrustGo model is superior to other state-of-the-art recommendation models. \endabstract

Remote Patient Monitoring (RPM) using Electronic Healthcare (E-health) is a growing phenomenon enabling doctors predict patient health such as possible cardiac arrests from identified abnormal arrythmia. Remote Patient Monitoring enables healthcare staff to notify patients with preventive measures to avoid a medical emergency reducing patient stress. However weak authentication security protocols in IoT wearables such as pacemakers, enable cyberattacks to transmit corrupt data, preventing patients from receiving medical care. In this paper we focus on the security of wearable devices for reliable healthcare services and propose a Lightweight Key Agreement (LKA) based authentication scheme for securing Device-to-Device (D2D) communication. A Network Key Manager on the edge builds keys for each device for device validation. Device authentication requests are verified using certificates, reducing network communication costs. E-health empowered mobile devices are store authentication certificates for future seamless device validation. The LKA scheme is evaluated and compared with existing studies and exhibits reduced operation time for key generation operation costs and lower communication costs incurred during the execution of the device authentication protocol compared with other studies. The LKA scheme further exhibits reduced latency when compared with the three existing schemes due to reduced communication costs.

Discrimination against different user groups has received growing attention in the recommendation field. To address this problem, existing works typically remove sensitive attributes that may cause discrimination through adversary learning to achieve fair recommendations. However, these approaches leverage all available interactions for learning user representations and overlook the fact that different interactions have varying relevance to users’ sensitive attributes. Ignoring this issue may weaken the effectiveness of adversary learning in removing sensitive attributes. To tackle this challenge, we propose a novel model called GS-FairRec, which distinguishes between user interactions to achieve better removal of sensitive attributes. The model consists of three modules: graph sampling-based representation learning, pseudo-user representation learning, and adversarial learning. Firstly, the graph sampling-based representation learning module removes some irrelevant neighbors from a user-item bipartite graph and employs a graph convolutional network (GCN) to learn user/item representations. Next, items that are relevant to a user’s sensitive information but do not match their preferences are defined as the user’s pseudo-interest items, which are leveraged to learn the pseudo-user representation. In the adversarial learning module, the user’s two kinds of representations are fused for adversarial learning to remove sensitive information. Additionally, we design a new metric to measure the model’s ability to remove sensitive attributes based on how a generated recommendation list discloses the user’s sensitive attributes. Finally, we conduct experiments on two real-world datasets, and our results demonstrate the superiority of our proposed model in fairness tasks.

In recent years, the Internet of Things (IoT) and enterprise management systems (EMS) have been rapidly growing and applied in advanced Industries. It provides better big data analytics and the most promising computing platforms. Moreover, IoT is transforming into the augmented intelligence of things (AIoT), developing a human-oriented paradigm for enterprises with AI. Still, smart enterprises and industries have additional requirements, such as device and data trust, robust decision-making, communication latency, and secure data storage. However, previous emerging paradigms and approaches did not fully address all of the aforementioned requirements. Therefore, this article proposes a blockchain-based trust management scheme for smart enterprises with augmented intelligence. The blockchain-based device trust authentication mechanism is used at the device connection layer for device authentication in clusters of IoT devices (smart enterprises branch-SEB). Furthermore, the blockchain-based augmented intelligence enabled approach is leveraged for data authentication at the authentication layer. Finally, smart enterprise data are stored in the distributed hash table (DHTs) and decentralized cloud layer with distributed hash table. We evaluated the proposed scheme using qualitative and quantitative analysis and compared it to the existing studies, showing better performance as 40.887-ms computational cost and 1872-bits transactional cost.

Medical Cyber-Physical Systems support the mobility of electronic health records data for clinical research to accelerate new scientific discoveries. Artificial Intelligence improves medical informatics, but current centralized data training and insecure data storage management techniques expose private medical data to unauthorized foreign entities. In this paper, a Federated Learning-based Electronic Health Record sharing scheme is proposed for Medical Informatics to preserve patient data privacy. A decentralized Federated Learning-based Convolutional Neural Network model trains data locally in the hospital and stores results in a private InterPlanetary File System. A secondary global model is trained at the research center using the local models. Private IPFS secures all medical data stored locally in the hospital. The novelty of this study resides in securing valuable hospital biomedical data useful for clinical research organizations. Blockchain and smart contracts enable patients to negotiate with external entities for rewards in exchange for their data. Evaluation results demonstrate that the decentralized CNN model performs better in accuracy, sensitivity, and specificity, similar to the traditional centralized model. The performance of the Private IPFS exceeds the Blockchain-based IPFS based on file upload and download time. The scheme is suitable for promoting a secure and privacy-friendly environment for sharing data with clinical research centers for biomedical research.

The growing congruence of gadgets today resulted in a numerous type of cyber attacks. A similar trend occurs with the industrial Internet of Things (IIoT), wherein increasing data created by connected equipment offers up new opportunities for enhancing service quality for new applications. But, security has become a major design priority for smart devices since the introduction of the IIoT. However, data providers have significant challenges in exchanging their data between different cyber physical systems due to privacy and security concerns (e.g., data imbalance and leakage). In this article, we developed a safe data sharing architecture for various IIoT devices using federated learning (FL). The proposed architecture incorporates FL into the edge computing consensus process, allowing the consensus computing activity to be used for federated training as well. The proposed framework achieves high efficiency, and better security, according to numerical findings generated by experimenting deep learning models. More precisely, the proposed framework named as SecureIIoT, is able to achieve 99.79% accuracy by detecting attacks as a binary classification problem.

With the recent development of Internet of Things (IoT) in the next generation cyber-physical system (CPS) such as autonomous driving, there is a significant requirement of big data analysis with high accuracy and low latency. For efficient big data analysis, deep learning (DL) supports strong analytic capability; it has been applied at the cloud and edge layers by extensive research to provide accurate data analysis at low latency. However, existing researches failed to address certain challenges, such as centralized control, adversarial attacks, security, and privacy. To this end, we propose DeepBlockIoTNet, a secure DL approach with blockchain for the IoT network wherein the DL operation is carried out among the edge nodes at the edge layer in a decentralized, secure manner. The blockchain provides a secure DL operation and removes the control from a centralized authority. The experimental evaluation demonstrates that the proposed approach supports higher accuracy.

Conventional centralized architectures are sufficiently educated to provide high scalability, availability, and low latency and bandwidth usages for the Internet of Things (IoT) network. The exponential increase in volume and number of IoT devices in Intelligent Transportation Systems (ITS) turns our physical world into the cyber world. Security and privacy in the ITS network have become the main concern. To address these issues and challenges, a secure distributed mist computing network architecture for ITS is proposed by leveraging the features of blockchain technology. In this model, we present IoT user/device registration and authentication algorithms and enable the computing resources at the extreme edge of the network by deploying a smart contract. The proposed model uses an aggregate signature scheme to generate a signature for multiple IoT devices. To evaluate the proposed model, we performed an experimental analysis based on various performance measures. The proposed model gains 81% of lower median latency at local nodes compared to the core model. The result shows that the model performed effectively and a suitable solution for various ITS applications.

Summary Recently, low‐power wide area network (LPWAN) has attracted attention as a wireless network for long‐range Internet of Things (IoT) services. IoT devices in an LPWAN are managed by a network server in the cloud. Various data are delivered from the IoT devices to the network server, and the role of the centralized network server in the cloud has become important for efficient data transfer over an LPWAN. However, control by the network server concentrates the control load on the network server and is vulnerable in terms of response time and bandwidth utilization. Therefore, this paper takes the approach of moving the control of the LPWAN to the edge cloud, which provides computing and storage environments at base stations. An LPWAN gateway is then integrated with the edge cloud, and LPWAN data are cached at the edge cloud in the gateway for LPWAN control. LPWAN control such as report interval control for data, transmission power control, and data aggregation is applied to improve the efficiency of data transmission. Network control is performed by learning using cached data in the edge cloud. Compared with the existing LPWAN control approach, the proposed approach exhibits improved performance for IoT data transmission. The simulation results show the proposed approach's efficiency.

With the increasing number of electric vehicles (EVs), temporary charging demands grow rapidly. Unlike charging at home or workplace, temporary charging requires less waiting time. In this article, a mobile edge computing (MEC)-enabled charging and discharging networking system algorithm (CDNSA) is proposed to minimize the waiting time for EVs in charging stations (CSs). A software-defined network (SDN) paradigm is adopted to enhance the data transmission efficiency for MEC servers. In CDNSA, the optimization problem is formulated as a mixed-integer nonlinear programming (MINLP). A heuristic algorithm is proposed to solve the optimal CS selection variables for EVs that needs to be charged (EVCs) and EVs that can be discharged (EVDs), and then a remaining problem nonlinear programming (NLP) is obtained. By verifying the convexity of each continuous variable, the NLP is solved by adopting the block coordinate descent (BCD) method. In simulation, the optimality of CDNSA is verified by comparing with the exhaustive algorithm in terms of minimizing maximal waiting time (MMWT) of CSs. We also compare CDNSA with other benchmarks to illustrate its advantage.

Nowadays, for different purposes and contexts, we interact with a lot of different smart devices in our daily lives. Most of these devices are connected to the Internet and are therefore commonly referred to as the Internet of Things (IoT). Mobile edge computing (MEC) has recently evolved as an emerging technique by moving the computing and storage resources from the cloud to the edge of the network. The MEC supports IoT devices to improve their efficiency and scalability; helps to reduce latency delay for real-time applications, bandwidth bottlenecks, and energy consumption; and delivers contextual information processing. MEC offers many features and capabilities, such as access to a multitude of network interface (from 4G and 5G to Wi-Fi), support for device mobility, device context, geo-location awareness, and geographical distribution. Such attributes can support the real-time processing requirements of the Internet of Everything application, such as patient care, disaster management and detection (e.g., earthquakes), and flood monitoring. However, to fully exploit the potential of MEC in the IoT applications, many challenges need to be addressed, such as issues related to IoT Big Data, effective management of data storage and computing, privacy and security concerns, and innovative and emerging communication paradigm (e.g., 5G), require new architectures, applications, and methods.

The digitalization and massive adoption of advanced technologies in the automotive industry not only transform the equipment manufacturer's operating mode, but also change the current business models. The increased adoption of autonomous cars is expected to disrupt government regulations, manufacturing, insurance, and maintenance services. Moreover, providing integrated, personalized, and on-demand services have shared, connected, and autonomous cars in the smart city for a sustainable ecosystem. To address these issues in this paper, we propose a blockchain-based distributed framework for the automotive industry in the smart city. The proposed framework includes a novel miner node selection algorithm for the blockchain-based distributed network architecture. To evaluate the feasibility of the proposed framework, we simulated the proposed model on a private Ethereum blockchain platform using captured dataset of mined blocks from litecoinpool.org. The simulation results show the proof-of-concept of the proposed model that can be used for wide range of future smart applications.

With the revolution in smart infrastructure in the recent past, the smart healthcare system has been paid more considerable attention. The continuous upgradation of electricity meters to smart electricity devices has probed into a new market of intelligent data analysis services, providing aid to the health care systems. This paper presents a unified framework for extracting user behaviour patterns from home-based smart electricity meter data. The structure allows exploration and integration of frequent pattern growth algorithm for pattern mining and application of a variety of machine learning algorithms for categorizing the activities into manually labelled classes along with the implementation of Local Outlier Factor method for detection of an abnormal pattern of the inhabitant of smart homes. To evaluate the proposed framework, the work is implemented on the smart electricity dataset from the United Kingdom by separating the data into four distinct data files meant for the morning, afternoon, evening, and night energy utilization records. The results show a remarkable performance of Support Vector Machine (SVM) and Multilayer Perceptron (MLP) classifiers with kappa statics greater than 0.95 for all time slots data. The resultant frequent device utilization patterns with anomaly score more than the threshold value, reflecting abnormal activity patterns, are found more in evening time data in comparison to other time slots, requiring the immediate attention of concerned healthcare authorities.

Technological advances over the last decade in the field of wireless communications have resulted in the improvement of small and low cost sensor nodes outfitted with wireless communication abilities capable of establishing wireless sensor network (WSN). Due to the expansion of Internet of Things (IoT), there are many areas in IoT application where WSN applications are found. These applications generally impose severe constraints on the lifetime of the WSN, which is expected to last several years. It is necessary to diminish the overall energy consumption of the sensor node and to find an additional source of energy for achieving this objective. On the other hand, due to the imminent crisis of the radio frequency spectrum, light fidelity (LiFi) offers many key benefits and effective solutions for these issues that have been postured in the most recent decade. In this paper, we propose a novel EH-HL model for future smart homes and industries based on the integration of energy harvesting WSN (EH-WSN) and hybrid LiFi/WiFi communication techniques. The proposed model is capable of efficiently transmitting data at high speed for bidirectional multidevice and by harvesting energy, we provide the power to the sensor nodes. To synchronize multidevice transmissions, transmit data and provide low-cost wireless communication, we used the color beams of the red, green, and blue LEDs. The result of the evaluation shows that the hybrid communication scheme is proposed in the EH-HL model. It also offers superior performance and achieves a data rate of 25 Mb/s for multiaccess/multiusers.

Industrial Internet of Things (IIoT) is an emerging trend, including in nontraditional technological sector (e.g., oil and gas industry). There are, however, a number of research challenges such using cryptography and other techniques to ensure security and privacy in IIoT applications and services. In this special issue, we present existing state-of-the-art advances reported by the 21 accepted papers. We then conclude the special issue with a number of potential research agenda.

The next generation of cyberspace online world of the future should be open, interoperable, reliable, and secure. Through next-generation cyberspace, individuals and communities are able to connect, socialize, and organize together. The goal of next-generation cyberspace is to deliver breakthrough innovation results for enterprises, enabling new products/services/markets, providing better quality for the digital economy and building better governments. However, there is existing challenges (such as growing demands, threats, constrained resources, and heterogeneous environments exist) in establishing next-generation cyberspace. It also calls for security and personal privacy considerations. The starting point for building a next-generation cyberspace can be found in a multitude of wired and wireless communication environments and a new technology or concept to support differentiated human-centric operations. The research efforts should provide innovative solutions in order to deliver resilient, cost-effective capabilities to the next-generation cyberspace and to meet the operational requirements in terms of security and privacy. The main motivation for this special issue is to bring together researchers from academic and industry laboratories to discuss current research issues and advances, which cover diverse aspects of next-generation cyberspace. The aim of our special issue is to provide a platform for discussing relevant research questions and engagement in the growing area of next-generation cyberspace. We have received many manuscripts. However, only 12 manuscripts in high quality were finally selected for this special issue. Each manuscript selected was blind reviewed by at least three reviewers consisting of guest editors and external reviewers. The first paper entitled “Server-based Code Obfuscation Scheme for APK Tamper Detection” by Yuxue Piao et al. analyzes the DexGuard tool from both a static and dynamic points of view. Their analysis reveals that DexGuard has some weaknesses. In this paper, they proposed an obfuscation technique based on a client/server model with one-time secret key delivery using SMS or network protocol. The main concept is to store the core execute class file through obfuscation on the server. When a program needs to execute core routines, it must request these routines from the server. In this way, they can protect Android apps from reverse engineering. The second paper entitled “An Authentication, Authorization, and Accounting Mechanism for 3G/WLAN Networks” by Wei-Chen Wu and Horng-Twu Liaw proposes a practical, efficient, and secure authentication, authorization, and accounting mechanism within the interworking architecture proposed by 3GPP. The next paper entitled “Identifying an OpenID Anti-Phishing Scheme for Cyberspace” by Haider Abbas et al. presents a user authentication scheme. This paper aims at identifying and discussing a solution to OpenID phishing by proposing a user authentication scheme that allows OpenID providers to identify a user using publicly known entities. The research will help in next-generation cyber security innovations by reducing the authentication dependency on user credentials. The authentication scheme is also validated through detailed descriptions of use cases and prototype implementation. “A Histogram-based Method for Efficient Detection of Rewriting Attacks in SOAP Messages” by Aziz Nasridinov et al. presents an efficient method for detecting XML rewriting attacks on SOAP messages using a histogram. With the proposed method, once the source of attacks is identified, it saves in the form of a histogram, which enables us to maintain a statistical information about the location of the attack in the SOAP message. This information can be used to detect attacks in the future and thus avoid unnecessary check of all elements in the SOAP message. Experiments show that the methods outperform those existing methods by several times in many cases. “Implementation of Vessel Traffic System's Mobile Middleware Platform for Secure IVEF Service” by Namje Park and Hyo-Chan Bang presents a vessel traffic service platform for securing inter-VTS data exchange format (IVEF). In this paper, they developed a system enabling IVEF service simulation under a wireless environment made possible by improving IVEF SDK, which is an open source. For this, a mobile phone loaded with Android platform and desktop PC has been used for emulation of a ship on voyage and VTS center. “Optimisation Based Collaborative Determination of Component Trustworthiness in Service Compositions” by Hisain Elshaafi and Dmitri Botvich describes a collaborative trustworthiness determination approach using optimization that can provide a solution to select trustworthy component service constructs based on monitoring and consumer quality of experience reporting of existing composite services from peer providers. “An Enhanced Security Framework for Reliable Android OS” by J. H. Park et al. proposes an enhanced security framework for reliable Android OS. The framework provides means to prevent influx of malware by examining the Android OS and file system. In addition, it recovers data once deleted by security breaches. “A Study on SW-Blackbox to Ensure the Reliability of Content Distribution Using File System Event Monitoring of OSPs” by Sang-Ho Seo et al. presents an SW-Blackbox technical method using file system event monitoring to verify the reliability of online service providers (OSPs) that operate file hosting web hard services. This method prevents the bypassing of filtering solutions and the omission, fabrication, and altering of transaction-related logs for the intentional distribution of illegal content. “Introducing Touchstroke: Keystroke-based Authentication System for Smartphones” by Georgios Kambourakis et al. presents a touchstroke system. They implemented a touchstroke system in the Android platform and executed different scenarios under disparate methodologies to estimate its effectiveness in authenticating the end user. Apart from typical classification features used in legacy keystroke systems, they introduce two novel ones, namely, speed and distance. From the experiments, it can be argued that touchstroke dynamics can be quite competitive, at least when compared with similar results obtained from keystroke evaluation studies. As far as they are aware of, this is the first time this newly arisen behavioral trait is put into focus. “Small Target Detection using Morphology and modified Gaussian Distance Function” by Jong-Ho Kim et al. proposes a new small target detection system that detects small target candidates based on morphology operations and detects actual targets using a modified Gaussian distance function. To reduce clutter on the edges of clouds, a median filter is applied as preprocessing. Two kinds of images are calculated with closing and opening morphological operators, respectively. In the morphology operations, various sizes of structure elements are used to consider the sizes of targets, and candidate targets are extracted from difference images between the two images in the closing and opening operations. With a modified Gaussian distance function, small targets are detected from the candidate targets. The proposed method is less sensitive to clutters than the existing methods and has a detection rate of 98%. “Single Authentication Through (SAT) in Convergence Space using Collaborative Smart Cameras” by Geon Woo Kim et al. suggests a scheme to access any ubiquitous service with single authentication at initial stage for efficiently identifying an object moving multiple convergence spaces by relaying the identifiable information along the movement. This is carried out by enabling distributed smart cameras to deliver identifiable information of the identified moving object. The last paper entitled “Time Synchronization: Pivotal Element in Cloud Forensics” by Nikolaos Marangos et al. investigates the impact that the cloud computing (CC) model has on the trustworthiness of one of the main cloud forensics (CF) sources of information, the log files. More precisely, they bring forth a crucial but rather underestimated problem, the problem of accurate log records timestamping. The synchronization of time (stamps) is of major importance for the investigation logs to be used as source of evidence. They show that this requirement is not easy in the cloud context. They demonstrate that the main features of CC render existing time synchronization techniques inadequate, and they provide a list of guidelines towards a CF aware timekeeping system. Our special thanks go to Professor Hsiao-Hwa Chen and Professor Hamid R. Sharif who are Editors-in-Chief of Security and Communication Networks and all editorial staffs for their valuable supports throughout the preparation and publication of this special issue. We would like to thank all authors for their contributions to this special issue. We also extend our thanks to the external reviewers for their excellent help in reviewing the manuscripts.

Abstract The number of applications loaded with malware is rapidly increasing in Android operating system (OS). These malwares spread through the official Android market “Play Store”, unofficial “black market”, and private web pages. Once the malware activates, personal information can be extracted and some data can be deleted, causing tremendous damage to users. In order to provide reliability on Android OS, there is a need to analyze and address these malwares and recover the modified data. In this paper, we propose an enhanced security framework for a reliable Android OS. The framework provides means to prevent influx of malware by examining the Android OS and file system. In addition, it recovers data once deleted by security breaches. Copyright © 2013 John Wiley & Sons, Ltd.

Recently wireless sensor networks have been used as the technology that is actively grafted onto industries and daily living. Sensors should have built-in routing functions and basic sensing functions for the self-configuration of topologies. The number of sensors necessary for using them in an actual observation ranges from tens to hundreds or thousands. When theses sensors are wrongly placed in an observation region, they can quickly run out of batteries or be disconnected. These incidents may result in huge losses in terms of sensing data from numerous sensors and their costs. Therefore a number of simulators have been developed as tools for effective design and verification before the actual arrangement of sensors. While a number of simulators have been developed, simulation results can be fairly limited and the execution speed can be markedly slow depending on the function of each simulator. To improve the performance of existing simulators, this paper aimed to develop a parallel processing simulator for separate sensor (P2S3) that enables users to selectively use the GPU mode. It enables parallel and independent operations by matching GPU with many cores in order to resolve the slowdown of the execution speed when numerous sensor nodes are used for simulations. Also, P2S3 include the analyzed of sensor nodes with log data and visualization. The P2S3 supports the GPU mode in an environment that allows the operation of compute unified device architecture (CUDA), and performs the parallel simulation processing of multiple sensors using the mode within a short period of time.

With ever-rising popularity of social media, some sort of on-the-fly experiences are being learned and obtained by daily users. Despite a wide spectrum of research development efforts, how to facilitate knowledge discovery from an open environment and provide corresponding services remains an open challenge. In this special issue, we aim to foster the dissemination of high-quality research in methods, theories and techniques concerning the knowledge discovery from the next generation social media. Original and research articles include all aspects of theoretical studies, practical applications and experimental prototypes.

One of the challenges of the binary translation on virtual machine(VM) is to make a mapping from registers in emulated architecture to registers in the target architecture. The efficiency on the emulated architecture is best translated into efficiency on the target machine if target instructions also operated on register operands. However, conventional binary translators of popular VMs do not take into account instruction dependency among two or more basic blocks. This results in performance degradation due to inter-translation block dependency. Because binary translation makes use of 1 or 2 registers repeatedly for the majority of translation blocks. The translation block corresponds to a guest(emulated) instruction, which in turn the amount of work is not large. Even though there are no dependencies between translation blocks, false dependencies are generated by the repeated use of the same register usage order. In order to resolve the problem, we propose a novel approach maintaining two different register allocation orders, applying them alternatively. We call this as alternative register allocation in this paper. The experimental results show up to 26.3% better performance to conventional method.

ABSTRACT The ever growing storage device capacity poses a severe limit to the standard digital forensics collection procedures based on duplicating the original storage device by creating a bit‐by‐bit copy. Such a traditional procedure is followed, even if the goal of the investigation is to find a limited quantity of digital objects to support or refute an investigative hypothesis related to a precise case category. Therefore, in this paper, we propose a new methodology to deal with data leak cases, by applying an intelligent collection paradigm, a fast analysis approach that reduces investigation time. Copyright © 2012 John Wiley & Sons, Ltd.

The objectives of this special issue are advanced security technologies and services for future computing environments, including, but not limited to, security primitives, protocols and security applications and services. Recent advances in security technologies and services for future computing environments have created a new class of the following: (i) Wireless sensor networks and radio-frequency identification security and privacy; (ii) security architectures for distributed network systems, P2P systems, cloud and grid systems; and (iii) security in e-commerce, mobile and wireless networks, and finally, security standards and assurance methods. All papers are expected to focus on novel approaches for advanced security technologies and services for future computing environments and to present high-quality results for tackling problems arising from the ever-growing advanced security technologies and services for future computing environments.

This study proposes an efficient localization scheme in wireless sensor networks. The proposed scheme utilizes mobile anchors and is based on ring overlapping. In a wireless sensor network, the nodes that know their locations are called reference nodes, and the other nodes that are without the knowledge of their locations are called blind nodes. To localize a certain blind node, by comparing the relative RSSI (Received Signal Strength Indicator) values among nodes, mobile beacons are utilized to find out the rings that are centered at a reference node and contain the blind node. These rings are called B-Rings. Since the mobile anchors and the reference nodes know their own locations, the B-Rings can be precisely derived. Moreover, by using multiple mobile beacons, the widths of the B-Rings can be further minimized; and then by overlapping them, the location of the blind nodes can be efficiently estimated. Most existing localization schemes that utilize mobile anchors let the mobile anchors move randomly. In contrast, the proposed scheme provides regular and simple movement mechanisms for the mobile anchors. Thus, the mobile anchors consume less energy than the other schemes, in which the mobile anchors move randomly. Analytical analysis and simulation results show that the proposed localization mechanism can achieve better location accuracy as well as less movement length of the mobile anchor than the other existing related approaches.

With the increase in commercial electronic equipment and its complicated control interfaces, how to design an effective and user-friendly control interface has become a topic for many researchers. This research introduces two-directional communication of an interactive graphical user interface on a universal remote control (URC). It is different from current URCs where users must often spend huge amounts of time setting the command codes and encoding each device. With the increase in the number of appliances that the controller needs to manage and the complicated and numerous control buttons, using such controllers often causes difficulties for users. This research employs a cross-platform with integration theories, so when a user wants to connect an appliance, both the appliance end and the controller end will build a two-directional connection through pairing over Radio Frequency for Consumer Electronics (RF4CE). After connection, the system will automatically set the communication protocol between the controller and the device. The appliance will automatically transmit its current state and service in the form of bundles to the controller, then the controller will project it onto an LCD screen. The controller can also show the number of appliances connected to the current position of the user, allowing the user to use one controller to control all home appliances with ease, achieving a simplified and instinctive control interface to build the integrated control environment for commercial appliances.

SUMMARY On the basis of CSC (Cluster Supply Chain) networks with two four‐echelon single supply chains, chain‐to‐chain inventory transshipment between two retailers is taken into account in the context of the two single chains cooperation. The uncertain robust switched control system model is built. Meanwhile, the methodology of robust optimization is introduced to minimize the bullwhip effect, and the solution of optimal decision serials is explored utilizing H‐infinity switched control algorithm. The online decision‐making simulation framework structure is developed to demonstrate the switching procedure. The simulation example proves that chain‐to‐chain inventory transshipment in CSC networks and robust switch control method can effectively weaken the bullwhip effect, reduce stock, dwindle fluctuation of order, and improve response to cluster market. Copyright © 2011 John Wiley & Sons, Ltd.

Recently, methods that combine the concepts of dynamic voltage scaling (DVS) and dynamic power management (DPM) approaches have been proposed for a single task. This study proposes adaptive power management system (APMS), which utilises useful features of both DPM and DVS and an existing pattern analysis algorithm, and new break even time-based task partition scheduling (BET-BTPS). APMS splits tasks based on BET to reduce the total power consumption of multiple multimedia applications in a mobile embedded system environment and analyses their usage patterns of peripheral devices and apply the results to their scheduling for further reduction of power consumption. It also takes into account the additional time delay that may occur while invoking and executing a timeslot scheduler to guarantee real-time services for multimedia data streams when the scheduling of APMS is in effect. In order to determine the optimal processor speed that minimises power consumption, the extra consumption required by the scheduler is compared with that reduced by BTPS. The proposed approach demonstrates better performance compared to existing power management schemes not only for single task but multiple tasks.

ABSTRACT The essence of this paper is to illustrate live data acquisition within the random access memory of a notebook trying to utilize the collected digital evidences in order to partially reconstruct previous Gmail session, which could be probative digital evidence in a court of law. The proposed framework is essentially crucial for the investigation of certain related cybercrimes on the basis of the digital breadcrumb trails being professionally disclosed and appropriately handled. Without loss of generality, the volatile data would vanish forever when the power of the computing devices is no longer sustainable. This research pinpoints the imminent threat of IT savvy cyber criminals and the corresponding counter procedures used to crack criminal cases if web‐based e‐mail utilities are essentially involved. This paper is focused on the prevalent e‐mail utility, Gmail, as the research subject. At last, live digital evidence acquisition must be accurately fulfilled before the seizure of the computing devices in the crime scene to avoid irreversible investigation procedures which mean the digital evidences could be deleted, resulting in the loss of probative evidence. Copyright © 2012 John Wiley & Sons, Ltd.

ABSTRACT Voice over internet protocol (VoIP) provided voice service using Internet. It receives footlights when it escapes an initial curiosity. Interest to VoIP increased, because it can transfer existing phone service and deliver voice data through Internet technology. Communication service providers introduce Next Generation Network and Broadband convergence Network with VoIP as an added service to the consumer. In addition, session initiation protocol (SIP) service can be applied even outside the Internet phone service. However, it is needed to ensure secrecy of VoIP call in a special situation. It is relatively difficult to eavesdrop in the commonly used Public Switched Telephone Network (PSTN) as it is connected with 1:1 circuit. In this paper, we propose a new model of Internet telephone for eavesdrop prevention enabling VoIP (using SIP protocol) to use the virtual private network (VPN) protocol and establish the probability of practical use comparing it with Internet telephone. Copyright © 2010 John Wiley & Sons, Ltd.

Recent advances in pervasive computers, networks, telecommunication, and information technology, along with the proliferation of multimedia-capable mobile devices, such as laptops, portable media players, personal digital assistants, and cellular telephones, have stimulated the development of intelligent and pervasive multimedia applications in a ubiquitous environment.Due to constant changing environments, Mobile multimedia implies considerable challenges to operators, infrastructure builders in terms of ensuring fast, reliable services and accommodating the quick growing global customer needs.This special issue aims to foster the dissemination of high quality research in any new theory and technique and to present future directions regarding multimedia and mobile computing.This special issue welcomes papers focused on all topics ranging in the wide spectrum of multimedia and mobile computing with emphasis on theoretical aspects as well as practical frameworks and implementations.Overall, the special issue will outline the recent trends, major challenges, and perspectives related to multimedia and mobile computing.We have received many manuscripts.Only 10 manuscripts with high quality were finally selected for this special issue.Each manuscript selected was blindly reviewed by at least three reviewers consisting of guest editors and external reviewers.We present a brief overview of each manuscript in the following.The first paper entitled "Fine-grained user access control in ciphertext-policy attribute-based encryption" by Junbeom Hur et al. propose a fine-grained user revocation scheme without affecting any non-revoked users who share the same attributes in ciphertext-policy ABE; it does not require the users to access the key authority and to update keys periodically.The proposed scheme improves the efficiency compared with previous revocable schemes and enhances the security in terms of the backward/forward secrecy on any membership changes in the ciphertext-policy ABE system.The second paper entitled "Privacy Preserving Frequent Itemsets Mining via Secure Collaborative Framework" by Kok Seng Wong et al. present the problem of privacypreserving frequent itemsets mining under distributed environment.This solution reduces the risk for central data mining and improves the efficiency of the current generic SMC solutions.Furthermore, this solution is more reliable and flexible regardless of the number of parties involved.

ABSTRACT This paper presents a robust and secure hybrid connectivity framework for ubiquitous convergence in a home environment. The proposed hybrid connectivity framework is based on various consumer electronics and mobile devices with wireless interfaces such as IEEE 802.15.4 (e.g., radio frequency for consumer electronics (RF4CE) or ZigBee) and IEEE 802.11. In particular, this framework involves an RF4CE‐based WiFi zero‐configuration scheme. It simplifies connectivity by means of secure key distribution and a simple WiFi configuration involving WiFi‐capable devices. To validate our framework, we analyzed the system and security performance using real hardware prototypes. Copyright © 2011 John Wiley & Sons, Ltd.

Abstract In this paper we focus on the mobile GIS management system based on multi‐agents, and wider range of client devices with J2ME‐MIDP kernel are supported in it. A kit (Map Database Manager) is developed and described in detail. The kit can convert GIS data of commercial formats such as ArcGIS and Mapinfo into Geospatial data in GML, and provide Geospatial data for handheld devices freely without commercial plug‐in software. A peer to peer multi‐agents mechanism on mobile GIS services is the main subject of this paper. According to user's requirement and known buffer area radius on map, agent can define the factors to calculate the optimal path from one node to target node in a map, which considers not only the length of the road but also traffic flow, road cost, and other factors. We use the integrated cost to re‐define the road path weights, and select the optimal path among the road based on the minimum weight. The actual experimental results shown that in the quantified traffic flow and road condition, from node to other target nodes, we can get an optimal path on map, which satisfies the condition mostly. The results can greatly assist the searching of the optimal path in GIS services. Copyright © 2010 John Wiley & Sons, Ltd.

Topology control is one of the most fundamental problems in wireless sensor networks (WSNs). It is of great importance for prolonging network lifetime, reducing radio interference and energy consumption, increasing the efficiency of media access control (MAC) protocols and routing protocols, among other things. In this paper, the problem is transformed into a model of multi-criteria degree constrained minimum spanning tree (mcd-MST), and a non-dominated discrete particle swarm optimization (NDPSO) is designed to deal with this problem. To obtain a better approximation of true Pareto front, the phenotype sharing function of the objective space is applied in the definition of fitness function in NDPSO. Furthermore, a topology control scheme based on NDPSO is proposed in this paper. Simulation results show that the topology derived under the proposed scheme has low total power consumption, high robust structure and low contention among nodes, and it also can effectively prolong the lifetime of network.

Geographical information systems (GIS) and applications assist us in commuting, traveling and locating our points of interests. The efficient implementation and support of spatial queries in those systems is of particular interest and importance. The use of a Voronoi diagram has traditionally been applied to computational geometry. In this paper, we will show how a Voronoi diagram can be applied to support spatial queries in GIS systems, and in particular to reverse nearest neighbor (RNN) queries. An RNN query retrieves the set of interest objects having the query object as the nearest neighbor among other objects. Two cases of RNN queries are: monochromatic (MRNN) and bichromatic (BRNN). In the MRNN, the interest objects and the query object are of the same type, whereas in the BRNN they are of two different types. Due to the shortcomings of solutions for BRNN in the literature, we develop a new approach and algorithm, named the ‘2Vor BRNN algorithm’, for processing this query type in the context of the spatial network database (SNDB). Our novel approach extends the previous work and uses the ‘order-2 network Voronoi diagram’ to provide a more efficient solution for the BRNN. In addition, we experimentally confirm that the proposed algorithm outperforms the previous one in terms of memory used and response time.

The advent of converged environment merged with wireless sensor networks (WSNs) and mobile networks can have the possibility on enabling us to experience variety of ubiquitous applications based on multi-sensor attached smartphones. However, most of current researches are failed to recognise the fact that there are many drawbacks to break through between the heterogeneous networks such as a WSN and mobile network. In this study, the authors propose the authentication and key agreement protocol that efficiently reduces the overall computational and communication costs in the next generation converged network. The enhanced security procedures are operated through the mobile network in order to maximise the lifetime of the sensor networks and to apply the combined capabilities of both networks. The authors show the presented novel design can show the feasibility to minimise the usage of the sensor networks with the battery-powered sensors in comparison with the existing authentication models, and can be deployed under the standard architectures.

Traditionally, the authors could establish secure computation protocols using variants of public key cryptology whose security is based on hard mathematics problems. However, classical protocols will become insecure owing to the emergence of quantum algorithms like Shors. In this paper, the authors demonstrate that nanoscale phenomenon can be applied not only in device level but also in high layer applications, such as secure computation. The authors study the possibility of performing secure computation by building non-local machines based on quantum entanglement and non-locality, which are phenomena available only at the nanometre scale. Comparing with classical secure computation algorithms, the security of this protocol is based on physical laws, instead of any unproven mathematic conjecture.

Social Networking Service (SNS) emerges to be one of the most promising directions of web applications regarding the next generation of Internet technology evolutions. Substantively, innumerable global on-line community members share common interests with each other via the User Generated Content (UGC) platforms. Facebook is one of them and it facilitates the social networking participants to deliver the digital contents to authorized consumers or specific groups. As cybercrimes mushroom in recent years, more and more digital crime investigations have strong relations to Facebook. Unarguably, Facebook has been exploited via global perpetrators. Consequently, we spotlight on live data acquisition within the RAM of the desktop PC with emphasis on some distinct strings that could be found in order to reconstruct the previous Facebook session, which plays an extremely precious role for the associate digital forensics investigators to incubate additional thoughtful decisions concerning the discovery of breadcrumb digital evidences in this unparalleled cybercrime incidents era.

Abstract Wireless body area networks (WBANs) are receiving a significant interest as an emerging technology in next generation wireless networks. Security challenges as well as this interest are also beginning to rise to the surface. We derived specific security requirements from WBANs, and proposed a new hybrid security protocol for WBANs which satisfies these requirements. This proposed protocol dealt with the overall security including up to the in‐ on‐, and out‐body, and utilized two heterogeneous cryptosystems (the symmetric and asymmetric) for diverse environments of WBANs. Our protocol shows that it satisfies more security requirements than existing security protocols including the overall coverage of WBANs. Copyright © 2010 John Wiley & Sons, Ltd.

Next Generation Communications (NGC) represent advanced communication environments featuring objects that are focused on users. NGC has rapidly emerged as an exciting new paradigm that includes ubiquitous, grid, and P2P computing. It provides computing and communication services in a much more convenient and pleasurable way, anytime, and anywhere. That is, a user will be able to remotely access and control all information and appliances used in the workplace, as well as at home and office, utilizing in an easy and convenient way various services without any limitations on space and time. In order to tackle the more sophisticated and powerful attack mechanisms that nowadays exist, it is crucial to build active and smart defence systems. Finding effective and efficient ways to protect information and digital forensics for NGC are very challenging research topics. This special issue aims to address network security and digital forensics for NGC and to encourage researchers to publish their results in WCMC journal. It will accept both original research papers and review articles that enhance the state-of-the-art in NGC security issues, including topics like security and digital forensics theory, services, business models, and novel applications that are associated with NGC utilization. The papers will be peer reviewed and will be selected on the basis of their quality and relevance to the theme of this special issue. This special issue brings together 12 contributions, with both theoretical and practical results of significance on aspects of network security and digital forensics in next generation communications. The contributions vary from themes like secure network middleware interactions to privacy and authentication schemes for next generation communications. Misra et al. present a Mobile Ad hoc Key Revocation Server (MAKeRS) scheme for key revocation in Mobile Ad Hoc Networks (MANETs). The scheme proposes to improve the performance and reliability of the existing system. Simulations show that the concept presented in the paper is more reliable, faster, and scalable than the existing usage of PKI over ad hoc networks. The various scenarios of mobility of nodes and servers are considered and the scheme is designed to suit such scenarios in an optimum way. The paper “Security analysis and improvements of IEEE standard 802.16 in next generation wireless metropolitan access network” is authored by Xiong Naixue. The paper “Secure handover for Proxy Mobile IPv6 in next-generation communications: scenarios and performance” by Jong-Hyouk Lee and Tai-Myoung Chung introduces two fast handover authentication scenarios for Proxy Mobile IPv6: namely, handover re-authentication (HORA) and handover early-authentication (HOEA). The introduced scenarios are based on the Handover Keying (HOKEY) working group in the IETF. In HORA, a mobile node utilizes the previously obtained root key for its handover so that the number of round trips for exchanging of authentication data and keying materials is reduced during its handover. In HOEA, the proactive signaling supported by link layer technologies is used to fast discover a candidate access network where a mobile node potentially attaches to so that the mobile node could perform authentication procedures before the mobile node attaches to the candidate access network. The paper “A secure and efficient RSU-aided bundle forwarding protocol for vehicular delay tolerant networks” by Xiaodong Lin and Hsiao-Hwa Chen studies data forwarding in vehicular delay tolerant networks. By using unique characteristics of vehicular delay tolerant networks, particularly, hybrid communication between the vehicles (V2V communications) and the roadside infrastructure (V2I communications), the authors propose a secure and efficient roadside unit (RSU) aided bundle forwarding protocol for vehicular delay tolerant networks. The paper “Security mechanism for voice over multipath mobile ad hoc networks” by Binod Vaidya, Meiso K. Denko, and Joel J.P.C Rodrigues not only presents a framework for secure voice transmission over multipath MANET but also proposes an efficient traffic allocation approach for it, then the proposed security mechanism was evaluated and its correctness was proved using formal verification. Hai-Cheng Chu, Der-Jiunn Deng, and Han-Chieh Chao present the paper whose scope encompasses the live data collection and analysis trying to disclose the digital trails that might be accidentally left behind with respect to the internal memory and the registry based on the IM session of Skype. A case review was conducted to illustrate the hidden digital trails within the PDA from the Registry of the Windows Mobile and volatile data in the RAM to discover the possible network security leakage scenarios that resulted in the vandalism of intangible digital assets of the organization. The paper “Authenticated key exchange protocol with selectable identities” by Hua Guo, Yi Mu, Xiyong Zhang, and Zhoujun Li deals with a key agreement protocol which allows a single private key to map multiple public keys (identities) that are selectable by the user. In the new protocol, the established session key is associated with an arbitrary subset of identities held by the user, while the unselected identities remain secret to other participants. The paper “Development of digital forensics practice and research in Japan” by Liu J., Uehara T., and Sasaki R. provide a nutshell of the Japanese political structures, legal systems, and law enforcement practice, and then present an overview of updated and new laws, awareness programs, and the research activities in digital forensics. The paper entitled “A lightweight block cipher based on a multiple recursive generator for wireless sensor networks and RFID” by Alina Olteanu, Yang Xiao, Fei Hu, Bo Sun, and Hongmei Deng use a Multiple Recursive Generator (MRG) to generate sequences of numbers with very long periods. The proposed cipher is a light weight cipher, which is very useful for resource limited resources such as sensor nodes in sensor networks and RFID tags. The paper “A cross-layer approach for integrating security mechanisms in sensor networks architectures” by Rodrigo Roman, Pablo Najera, and Javier Lopez analyzes how the security mechanisms used by sensor network applications should be integrated with existing architecture paradigms. The paper considers that a transversal layer is the optimal component forstoring the security mechanisms. Such layer retains the benefits of layered architectures, and adequately controls the disadvantages of cross-layer approaches. The paper “Hybrid security protocol for wireless body area networks” by dealt with the overall security including up to the in/on and out-body, and utilized two heterogeneous cryptosystems (the symmetric and asymmetric) for diverse environments of WBANs. Our protocol shows that it satisfies more security requirements than existing security protocols including the overall coverage of WBANs. The paper “Privacy preserving context transfer schemes for 4G networks” by Iosif Terzis, Georgios Kambourakis, Giorgos Karopoulos, and Costas Lambrinoudakis focuses on user's roaming between different administrative domains location privacy and proposes a number of privacy enhanced context transfer schemes. All the proposed schemes are analyzed in terms of message exchange, evaluated through simulations and compared with the ones been proposed by the Seamoby work group in CXTP RFC 4067. The results show that the proposed schemes are very efficient in terms of application handover times, while at the same time guarantee the privacy of the end-user. We wish to thank all the authors for their great work and for considering Wireless Communications & Mobile Computing journal for submitting their papers. Special thanks go to the anonymous reviewers for their help and dedication in reviewing the papers and providing useful comments to the authors for their papers improvement. Special thanks to the EiC Professor Mohsen Guizani for hosting this special issue in the prestigious John Wiley & Sons' Wireless Communications and Mobile Computing journal, and for their excellent support. We hope that this special issue will represent a timely and significant reference for future researches.

Abstract Next generation communications (NGC) represents advanced communication environments featuring objects that are focused on users. It is crucial to protect information and digital forensics for NGC. In this paper, we aim to address network security for NGC, including IEEE standard 802.16 that are associated with NGC utilization. The IEEE standard 802.16 is a wireless air interface technology in Wireless Metropolitan Access Network (WMAN). Now in the new era of wireless networking, it is the solution for ‘last mile’ problem. Point‐to‐MultiPoint (PMP) network architecture network mode and mesh network mode are two optional networking modes proposed in this standard. However, the security problems in its original protocol may be becoming the most serious obstacle in its marketable producing process. In this paper, explanation and analysis of the security mechanism are based on PMP and mesh networking modes, respectively. This paper focuses on authentication & authorization, which is the most important part but not explicitly defined in original security design of IEEE standard 802.16. Two improved schemes focused on authentication & authorization based on the two modes are proposed to strengthen 802.16 WMAN security, respectively. The relevant analysis and simulation results prove that our schemes are effective. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract The rapid development of wireless technology plays extremely important roles in monitoring, control, and collaboration related applications. This paper aims at state‐of‐the‐art self‐stabilizing flocking control of wireless mobile robots with memory corruption. Flocking of a group of wireless mobile robots has gained a lot of attention due to its wide applications in recent years. While there are few works addressed on fault tolerance issue of flocking, especially for transient failure of robots. However, in the practical applications of robots, for the weak robots, some of their parts, like sensor, moving actuator, or memory etc., are prone to be crashed due to the complex environment. So, it is interesting to explore such kind of component crash or corruption (partly crash), especially for transient failure. The transient failure means the failure is temporary and after a while the robots will not be influenced by outside environment. Specially, in this paper, we mainly focus on how one kind of transient failure—memory corruption affects robot flocking, especially for the existed fault tolerant flocking. Copyright © 2009 John Wiley & Sons, Ltd.

Spatial Audio Coding (SAC) is an emerging technology with a distinguishing feature of delivering good even excellent audio quality at monotonic or stereo bitrate of conventional perceptual transform coders. By a systematic exploitation of spatial hearing, Binaural Cue Coding illustrates the power and potentials of SAC in the future for intelligent multimedia services. MPEG Surround, receiving cumulative efforts from industry and academy, strives to build a SAC system with great versatility and high quality. The initial test results of MPEG Surround show its performance advantage over conventional state-of-the-art coders in a wide range of coding configurations.

A next generation network (NGN) exploits advanced multiple broadband, quality of service (QoS)-enabled service technologies. The NGN is aimed at users and service-related functions, including web services. Recently, web service composition (WSC) has become a new approach for overcoming many difficult problems confronted by B2B e-commerce, inter-organization workflow management, enterprise application integration etc. Due to the uncertainty of the NGNs and various web services, the performance of the WSC cannot be ensured. How to model it and predict its performance becomes a difficult problem for WSC. In this paper, we propose a novel performance simulation model for WSC, called STPM+. The STPM+ model can support modeling and simulating the time and non-time QoS metrics. Based on the stochastic timed colored Petri net, the STPM+ model can simulate and predict multiple QoS metrics, such as cost, reliability, reputation and so on. To examine the validation of our STPM+ model, we have designed and realized a visual performance simulation tool, called VisualWSCPE. Based on VisualWSCPE, we have fulfilled some simulation experiments. The experiment results demonstrate the feasibility and efficiency of the STPM+ model.

With the rapid development of vehicular sensor networks (VSNs) technology, the potential use of networked real-time control and automation is enormous and appealing. However, closed-loop control VSNs via the Internet are very difficult to implement practically because of their stochastic nature. One of the biggest challenges in VSNs is how to deal with sensor networks time delay and data loss. The authors investigate the potential of using the predictive control scheme for VSNs based on round-trip time (RTT) delay prediction to overcome the VSNs transmission delay and data loss. The predicted RTT delay is taken as the sampling interval reference for variable-period sampling approach. Modelling the time delay of networked control systems as a non-linear time series, the least mean square (LMS) filter algorithm is adopted to predict online the time delay induced in VSNs. The simulation results show that the LMS algorithm can achieve ideal efficacy if time delay has no variety abnormally. The predictive compensation strategy is proposed to reduce the detrimental effect of stochastic time delays induced by communication networks on control performance. The results of offline simulations via the Internet illustrate that the predictive control scheme based on RTT delay prediction has the potential to overcome the VSNs time delay and data loss.

Free-riding is a grave threat against the existence and efficient operation of peer-to-peer networks. This study proposes a rank-based fair incentive mechanism to restrain free-riding and solve the problem of the tragedy of the commons. In this mechanism, each user has a rank according to its utility value and it can just visit the corresponding rating files with its rank in the system. The utility function in this study takes the absolute contribution value and the physical performance into account for fairness and their values are calculated by the analytic hierarchy process. Besides, a pyramidal rank structure is constructed in this mechanism, and the computation formula for the node's transfer in each layer is established. In addition, the four defects in other restrain mechanisms are resolved in this incentive mechanism. The simulations in three aspects have verified that this mechanism is effective and practical.

These days, a wide variety of wireless interfaces are available to connect to Internet. When coverage area of these different technologies overlap, receiver equipped with multiple interfaces can use them simultaneously to improve the performance of its applications in terms of bandwidth rely on bandwidth aggregation. However, specific conditions such as bottleneck bandwidth and end-to-end delay need to be accounted for before using such techniques. If this problem of end-to-end delay and bottleneck bandwidth are not properly addressed, there may be many packets along multiple paths which can arrive late and can lead to a large number of out-of-order packets at the receiver, which can eventually cause serious degradation of video quality at the receiver. For this reason, in this study, the authors propose a multi-path transmission control scheme (MTCS) combining bandwidth aggregation and packet scheduling for real-time streaming in a multi-path environment. In a bandwidth aggregation scheme, the authors propose a mathematical model to find the transmission rate over each path in order to obtain the optimal total throughput. However, the end-to-end delay of each path is not the same. The out-of-order packets problem will become serious in a multi-path environment. Therefore the authors propose a packet scheduling scheme to arrange the transmission sequence in order to effectively minimise the impact of packet reordering at the receiver. Our proposed control scheme not only aggregates the available bandwidth of multiple paths, but also reduces the time of packet reordering at the receiver. Experimental results show with our proposed scheme, the authors not only obtain the optimal transmission throughput but also reduce packet reordering delays under varying drop and delay conditions caused by the underlying network.

Among the research community, on-going efforts are being continued to efficiently interconnect MANETs to fixed infrastructure in order to expand the reach of the Internet to Wireless access networks. Such scenario gives raise to a number of challenges that require solutions involving Internet gateway selection scheme, extensions to ad hoc routing technique. In this paper, we depict a network architecture framework that integrates Mobile IP and to achieve the interconnection between a multipath MANET and the Internet. We propose multipath routing protocol and also depict a gateway selection scheme. We conduct simulation for such an approach and evaluate its performance with various metrics.

Recently, control and coordination of a set of autonomous mobile robots has been paid a lot of attentions, because the cooperation of simple robots offers several advantages, such as redundancy and flexibility, and allows performing hard tasks that could be impossible for one single robot. There are a lot of interesting applications of multiple robots, such as satellite exploration and surveillance missions. So far, there are many papers working on the coordination of mobile robots. The characteristic of simplicity of mobile robots brings potential wide applications; however this characteristic also lead to crash with higher probability during cooperation, especially in harsh environment. Surprisingly, only few researches consider the fault tolerance of mobile robots, especially for dynamic coordination application - robot flocking. In this paper, we summarize the existed flocking algorithms and discuss their characteristics. Then we briefly described our fault tolerant flocking algorithms in different models. Finally we proposed the potential future research directions for dynamic flocking of a group of mobile robots. In all, this work can provide a good reference for the researchers working on dynamic cooperation of agents in distributed system.

Due to advantages in enough number of channels and favorable bandwidth, 2.4 GHz ISM band is used as the most prevalent band for the IEEE802.15.4 LR-WPAN. However, there are an increasing number of other devices and systems which may interfere with the IEEE 802.15.4 communication. Therefore, the coexistence issue is one of the most critical challenges for the IEEE 802.15.4. In this paper, we propose an Adaptive Multi-Channel Utilization scheme (AMCU), to enable a WPAN to coexist with other interfering systems. By utilizing multiple channels dynamically, it is possible that an interfered device or coordinator is recovered quickly, avoiding interference during run time as well as during association stage. In addition, in normal state, each device maintains very low duty cycle as in the standard.

The requirements for access control have been increased significantly in smart home systems. Many factors such as user ID, user location, service usage conditions and so on, regarded as authorization attributes, are important in making authorization decision in smart home systems. We investigate into the dynamic characteristics of the authorization in smart home systems and propose a new access-control model, SH-CRBAC, which aims to combine the advantages of attribute-based authorization mechanism and role-based access-control mechanism, and imposes attribute and status constraints on the RBAC model and enhances the generality and flexibility of authorization significantly in smart home systems. The status consistency of SH-CRBAC is analysed, and we also analyse the characteristics of SH-CRBAC through comparison with other popular existing authorization models in smart home systems.

Adapting wireless devices to communicate within grid networks empower users. This makes deployment of a wide range of applications possible within appropriate limits, including intermittent network connectivity and non-dedicated heterogeneous system capacity. The performance prediction model is used to improve the performance of the mobile grid job scheduling algorithm (MG-JSA). The proposed algorithm predicts the response time for processing the distributed application in each mobile node, although considering wireless network environments and inherent non-dedicated heterogeneous system capacity. Using this prediction model, the algorithm partitions and allocates the distributed jobs to available mobile nodes for rapid job processing. The efficiency of the MG-JSA model is demonstrated by evaluating its performance.

The control and coordination of mobile robots in groups that can freely cooperate and move on a plane is a widely studied topic in distributed robotics. In this paper, we focus on the flocking problem: there are two kinds of robots: the leader robot and the follower robots. The follower robots are required to follow the leader robot wherever it goes (following), while keeping a formation they are given in input (flocking). A novel scheme is proposed based on the relative motion theory. Extensive theoretical analysis and simulation results demonstrate that this scheme provides the follower robots an efficient method to follow the leader as soon as possible with the shortest path. Furthermore, this scheme is scalable, and the processing load for every robot is not increased with the addition of more robots.

As the Internet and networks advance, the combination of wired/wireless technologies is spreading rapidly, since it enables the creation of new services, and provides new features to both users and service providers. In such wired/wireless integrated services, network integration is very important,

Electronic documents made by some application (e.g. Microsoft PowerPoint application) have traces of work like editing, and these traces exist in the format of electronic documents. In digital forensic investigation, examiners have failed to notice traces of past work. It is because of that the traces of the past work cannot be identified by its application easily. However, identifying traces of the past work is important for digital forensic investigation because this data can be essential information which is created by culprit's intention not appeared in electronic document. This paper focuses on analyzing the Microsoft PowerPoint application (version 97 ~ 2003) which has the feature that it has traces of past work. In case of Microsoft PowerPoint file, it is possible to identify traces of past work by analyzing saving algorithm of application. To detect the traces automatically, PRIX (PPT residual information extractor) tool is developed.

Group communication is an important technique for many network computing applications. In group communication, a member in a group sends a message to others normally by multicast. Group signature guarantees the integrity of the exchanged data and provides source authentication. In a virtual machine (VMs) based computing system, a virtual machine monitor (VMM) allows applications to run in different VMs strongly isolated from each other. A trusted VMM (TVMM) based platform can provide stronger security protection for group signature systems than traditional computing platforms can. The authors first introduce a TVMM-based group signature architecture and a TVMM security protection mechanism for group signature components. Then, the authors propose a group signature scheme using the function of message checking based on the discrete logarithm problem. Finally, the authors prove the correctness of the group signature scheme and analyse its security in virtual computing environments.

With the rapid progress in information technology and an enormous amount of media appearing over Internet, e.g., text, audio, speech, music, image, and video, guaranteeing information security is becoming increasingly important. Several pivotal challenges include copyright protection, integrity verification, authentication, and access control etc. As a consequence, the subject of security protection in multimedia communication has attracted intensive research activities in academia, industry, and also government. Nowadays, multimedia data are used more and more widely in human's daily life. The typical applications include audio broadcasting, Digital TV, Mobile TV, etc., which are constructed on multimedia communication techniques. Associated with these applications, there are some security issues, e.g., multimedia content security, payment security and user privacy. To solve these issues, some means are required. During the past decades, various techniques have been reported for secure multimedia communication, including key management, multimedia encryption, authentication, digital watermarking, digital fingerprinting, access control, and digital rights management. Among them, multimedia encryption, authentication, digital watermarking, and digital fingerprinting aim to protect multimedia content's confidentiality, integrity, ownership, and traitor traceability. For example, digital fingerprinting embeds a unique customer code into multimedia content in order to produce a unique copy for the certain customer. Thus, the illegal redistribution of the media copy can be traced by detecting and comparing the embedded customer code. Some other techniques, e.g., key management, access control, and digital rights management, are able to protect payment security and user privacy. Taking access control for example, it permits only the authorized customer to access the multimedia content, while some other customers without payment often have limited access right. Additionally, in different networks such as Internet, 3G wireless, DVB-H, and p2p, different secure protocols and algorithms are required to provide the system security. For example, in DVB-H, the broad cast mode is used for data transmission, while in Internet-based services, the unicast or multicast mode is often used. Different from them, in p2p, the multi-hop transmission without the server is often used. When different networks are converged, the secure system with interactivity and interoperability is expected. All these topics are in active development. Furthermore, devices like digital cameras, mobile/video phones, graphics processing units, DVD player, etc. are expected to be equipped with such security mechanisms. In these situations, software solutions may not be adequate to provide high real-time performance. On the other hand, hardware assisted solutions are much better for easy integration with multimedia hardware, which has low power consumption, higher reliability/availability, and low cost. The aim of this special issue is to present a collection of high-quality research papers that report the latest research advances in secure transmission or distribution of multimedia content than on multimedia content protection. In this special issue, we selected 7 papers, which can demonstrate advanced works in this field. A detailed overview of the selected works is given below. The first paper, A Secure Virtual Point of Service for Purchasing Digital Media Content over 3G Wireless Networks, presents the secure virtual point of service (SVPOS) for secure multimedia content transactions and payments. The proposed solutions based on 3rd generation partnership project (3GPP) generic authentication architecture (GAA) and standard charging and billing protocols (e.g., Parlay-X) guarantees some desirable privacy and security properties, including privacy of subscribers, protection of 3G operator and merchant, and interaction security. The scheme is suitable for cell phone based merchant purchase in 3G networks. The second paper, Realising Time-limitation for Cryptographic Keys in Secure Multimedia Distribution, reports a promising transmission infrastructure and key construction scheme for future multimedia delivery. In particular, the scheme is transmitting the encoded layers on separate streams which will be secured using SRTP. This allows fast adaptation by just dropping layers if necessary. The session keys used for SRTP are time-limited and hierarchically dependent such that only one key is necessary for the client to decrypt all desired layers. Although the prerequisites for choosing the initial values of the time-limited keys are fairly high, this structure implies less administration effort. The third paper, Integrating Fingerprint with Cryptosystem Internet-Based Live Pay-TV System, proposes a new architecture to protect contents from unauthorized viewing and illegal redistribution for an internet-based live pay-TV system. Code embedding is considered in order to enhance the resistance against collusion of fingerprinted video. The paper has demonstrated that the proposed scheme can provide higher security and better trade-off between image and video encryption and fingerprinting imperceptibility than existing works. The paper also indicates the ongoing implementation of the pay broadcasting system based on the proposed architecture. The fourth paper, User Plane Security Alternatives in the 3G Evolved Multimedia Broadcast Multicast Service (e-MBMS), proposes a secure multicast overlay (SMO) approach and describe how to implement based on a proof-of-concept test-bed over public domain Linux routers. The paper demonstrates that SMO is able to achieve a low risk of denial of service attacks, significant advantages in terms of impact on the architecture and on device requirements, and high security association management and key management. The fifth paper, Step-wise Inter-frame Correlation-based Steganalysis System for Video Streams, reports a collusion scheme among video frames to find out whether secret data is hidden in frames or not. The effect of local motion interfering detection precision is studied. The local motion and message embedded in video frame is treated as a bimodal noise. To reliably detect the existence of the embedded message, block-wise correlation-based steganalysis scheme is proposed to reduce the local motion interfering effect. The video steganalysis process is divided into two stages. In the first stage, suspicious video frames will be recognized by decision module employing features extracted with a light-weight collusion scheme. In the second stage, suspicious frames will be analyzed critically by the present powerful image steganalysis schemes. In addition, the determine principle is also studied to reduce the false positive rate in first stage. Experimental results have been presented to show the performance of the proposed strategy. The sixth paper, AuthoCast - a Mobility-compliant Protocol Framework for Multicast Sender Authentication, introduces a protocol framework for authenticating multicast sources and securing their mobility handovers. Using a self-consistent, one-way authentication based on cryptographically generated addresses, a common design is derived to jointly comply with the mobile any source and source specific multicast protocols that are currently proposed. This light-weight scheme smoothly extends the unicast enhanced route optimization for mobile IPv6 and adds only little overhead to multicast packets and protocol operations. The seventh paper, Early Security Key Exchange for Encryption in Mobile IPv6 Handoff, proposes an early security key exchange for encryption in Mobile IPv6 handoff in order to reduce the security latency. In the approach, two issues are addressed in dealing with the latency within the encryption technology during the handover. First, the study extends the early binding update method to deal with the long security exchange negotiation time for the Mobile IPv6 handoff. Secondly, the study adopts the security access gateway (SAG) to solve the limited computing and memory in the mobile node. In conclusion, this issue of Security and Communications Networks offers a ground-breaking view into the recent advances in secure multimedia communications. 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, Dr. Hsiao-Hwa Chen for his advice, patience, and encouragements since the beginning until the final stage. Special thanks go to Michelle in Wiley during the production. 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 also thank all authors who have submitted their papers for consideration for this issue. We hope you will enjoy reading the great selection of papers in this issue.

Abstract Multimedia transmissions are delay‐sensitive Internet applications. Because mobile stations are in continual motion, handoff processes are necessary and unavoidable in wireless network environments. Because handoff processes tend to break the communication link, the research has been conducted on reducing the break time and arrival delay during Internet multimedia applications. In this paper, we propose an approach based on Fuzzy Logic to evaluate the average variation in signal strength received by a mobile station and produce a FitAP factor. This factor indicates the possible handoff access point that is suitable for the mobile station. According to the FitAP factor, a mobile station needs only to execute an active scan process once. Therefore, smaller handoff latency is expected. We compare the results from the current cell search scheme with that of the Fuzzy Logic approach. The statistical results show that the proposed method outperforms the current cell search scheme with an improved handoff latency performance. Copyright © 2007 John Wiley & Sons, Ltd.

In this paper, we propose UsMSS (User-centric secure Multimedia Service System) which provides interoperability of multimedia contents among incompatible devices in intelligent home. In addition, an authentication method suitable for the intelligent home is suggested. Furthermore, the proposed system provides intelligent services by reflecting context information (user preference, user location, device status information, etc.) through a sensor network module and home server, providing transparent and secure service.

This paper presents a fault-tolerant object group (FTOG) framework that provides both group management service and load scheduling service for consistency maintenance as well as state transparency. The group management service manages the overall FTOG framework while providing a couple of schemes to overcome unexpected faults. The load scheduling service effectively distributes the client requests to improve the quality of service by considering the load of service objects. We develop an intelligent home network simulator (IHNS) as a simulation program for using the FTOG framework on distributed environments. Through certain simulations, we validate that the FTOG framework supports both of reliability and stability of the distributed home-networking systems