Various collaboration technologies and Internet services have successfully and continually improved enterprise work efficiency, and have influenced and changed the quality of our lives over the past decade. Mobile collaboration technologies and Internet services, however, still lack robust functionality and content representation support. Meanwhile, the explosive growth of data traffic for user services threatens the current mobile systems. Especially, mobility models, architectures, and application services have posed various challenges to those in academia, industry, and governmental research labs. In particular, the key challenges for improving efficiency, scalability, and reliability are the development of mobile collaboration technologies and Internet services and the measurement of precise performance of mobile collaboration technologies and Internet services. These challenges allow us to design and develop new models, architectures, and services for future mobile systems. New research results in theory, simulation, and experimental approaches on mobile collaboration technologies and Internet services are welcome.

This special issue covers the following main topics:

- Security and data management

- Cloud architecture

- Hospital wireless sensor network

- Internet of things service interface

- Perspective security techniques for public Internet services

- Mobile devices and wireless communication technologies

- Protocols and algorithms for cooperative wireless relay networks

- Security and dependable applications

- Secure machine-to-machine communication

- Network architecture of big data

- Trust and privacy in wireless sensor networks

- Innovative cooperative communication technologies

- Social networking services

- Innovative intelligent algorithms and network security.

These subjects, as well as some others, are the focus of this special issue of “Mobile Collaboration Technologies and Internet Services”. The special issue is organized as follows:

The first paper by Yi-Li Huang, Fang-Yie Leu, Jian-Hong Chen and William Cheng-Chung Chu, propose a true random-number encryption method employing block cipher and pseudo random number generator. They present a more secure one, called the True Random Number Encryption Method (TRNEM for short), which employs the current time, true random numbers and system security codes as the parameters of the encryption process to increase the security level of a system. The same plaintext file encrypted by the TRNEM at different time points generates different ciphertext files. So the ciphertext files are difficult to be cracked. They also analyze the security of the Data Encryption Standard (DES), Advanced Encryption Standard (AES) and TRNEM, and explain why the TRNEM can effectively defend some specific attacks, and why it is safer than the DES and AES.

The second paper by Chin-Ling Chen, Woei-Jiunn Tsaur, Yu-Yi Chen and Yao-Chung Chang, presents a secure mobile digital rights management (DRM) system based on cloud architecture. They show that information security can be achieved efficiently via cloud server architecture and a cryptography mechanism. The proposed scheme focuses on using a mobile device to access the cloud service. The DRM mechanisms can protect digital content; once the mobile users pass the authentication they can access the cloud services, with authenticated users able to easily use mobile devices to read digital content.

The third paper by Mohammadreza Sahebi Shahamabadi, Borhanuddin M Ali, Nor Kamariah Bt. Noordin, Mohd Fadlee B. A. Rasid, Pooria Varahram and Antonio J. Jara, describes a Network Mobility - Hospital Wireless Sensor Network (NEMO-HWSN) solution to support IPv6 Low-power Personal Area Networks (6LoWPAN) network mobility in hospital wireless sensor network. They survey IPv6 mobility protocols and later propose a suitable solution for a hospital architecture based on 6LoWPAN technology. Moreover, they discuss an important metric like signaling overload to optimize the power consumption and how it can be optimized through the mobility management. This metric is more effective on the mobile router as a coordinator in NEMO since a mobile router normally constitutes a bottleneck in such a system. Finally, they present their initial results on a reduction of the mobility signaling cost and the tunneling traffic on the mobile personal area network.

The fourth paper by Hae-Min Moon and Sung Bum Pan, suggests long distance face recognition for enhanced performance of Internet of things service interface. While the existing face recognition algorithm uses single distance image as training images, the proposed algorithm uses face images at distance extracted from 1 to 5m as training images. In the proposed Linear Discriminant Analysis (LDA)-based long distance face recognition algorithm, the bilinear interpolation is used to normalize the size of the face image and a Euclidean distance measure is used for the similarity measure. As a result, the proposed face recognition algorithm is improved in its performance by 6.1% at short distance and 31.0% at long distance, so it is expected to be applicable for Ubiquitous Sensor Network (USN)’s robot and surveillance security systems.

The fifth paper by Tianhan Gao, Nan Guo, Kangbin Yim and Qianyi Wang, proposes a Privacy-Preserving Security (PPS) scheme for multi-operator wireless mesh networks with enhanced user experience. By hybrid utilization of the tri-lateral variable pseudonym approach and different kinds of tickets under identity-based proxy signature and proxy blind signature (PBS), anonymity, untraceability, as well as sophisticated unlinkability are satisfied during Mesh Client (MC)’s roaming. User accountability is also achieved through PBS-based e-cash system that is incorporated into their mutual authentication protocols together with key agreement features. Their analysis shows that PPS is able to implement desired security objectives and high efficiency.

The sixth paper by Hae-Duck Joshua Jeong, Sang-Kug Ye, Jiyoung Lim, Ilsun You and Woo-Seok Hyun, describes a computer remote control system using speech recognition technologies of mobile devices and wireless communication technologies for the blind and physically disabled population as assistive technology. These people experience difficulty and inconvenience using computers through a keyboard and/or mouse. The purpose of this system is to provide a way that the blind and physically disabled population can easily control many functions of a computer via speech. The configuration of the system consists of a mobile device such as a smartphone, a Personal Computer (PC) server, and a Google server that are connected to each other. Users can command a mobile device to do something via speech; such as directly controlling computers, writing emails and documents, calculating numbers, checking the weather forecast, or managing a schedule. These commands are then immediately executed. The proposed system also provides blind people with a function via text to speech of the Google server if they want to receive contents of a document stored in a computer.

The seventh paper by Young-Long Chen, Mu-Yen Chen, Fu-Kai Cheung and Yung-Chi Chang, proposes a hybrid architecture based on power-efficient gathering in sensor information system (PEGASIS) and low-energy adaptive clustering hierarchy (LEACH). This architecture can achieve an average distribution of energy loads, and reduced energy consumption in transmission. To further extend the system lifetime, they combine the intersection-based coverage algorithm (IBCA) with LEACH architecture and the hybrid architecture to prolong the system lifetime that introducing sensor nodes to enter sleep mode when inactive. This step can save more energy consumption. Simulation results show that the performance of their proposed LEACH architecture with IBCA and the hybrid architecture with IBCA perform better than LEACH architecture with PBCA in terms of energy efficiency, surviving nodes and sensing areas.

The eighth paper by Taerim Lee, Hyejoo Lee, Kyung-Hyune Rhee and Sang Uk Shin, introduces a Distributed Text Processing System based on Hadoop, called DTPS, and explains about the distinctions between DTPS and other related researches to emphasize the necessity of it. In addition, this paper describes various experimental results in order to find the best implementation strategy in using Hadoop MapReduce for the distributed indexing and to analyze the worth for practical use of DTPS by comparative evaluation of its performance with similar tools. To be short, the ultimate purpose of this study is the development of useful search engine specially aimed at big data indexing as a major part for the future e-Discovery cloud service.

In the ninth paper by Yongman Han, Jongcheon Choi, Seong-Je Cho, Haeyoung Yoo, Jinwoon Woo, Yunmook Nah and Minkyu Park, to detect block and remove pirated software (illegal programs) on Online Service Provider (OSP) and Peer-To-Peer (P2P) networks, they study a new filtering approach using software birthmark, which is unique characteristics of program and can be used to identify each program. Software birthmark typically includes constant values, library information, sequence of function calls, and call graphs, etc. They target Microsoft Windows applications and utilize the numbers and names of Dynamic-Link Libraries (DLLs) and Application Programming Interfaces (APIs) stored in a Windows executable file. Using that information and each cryptographic hash value of the API sequence of programs, they construct software birthmark database. Whenever a program is uploaded or downloaded on OSP and P2P networks, they can identify the program by comparing software birthmark of the program with birthmarks in the database. It is possible to grasp to some extent whether software is an illegally copied one. The experiments show that the proposed software birthmark can effectively identify Windows applications. That is, their proposed technique can be employed to efficiently detect and block pirated programs on OSP and P2P networks.

The tenth paper by Inshil Doh, Jiyoung Lim, Shi Li and Kijoon Chae, proposes key establishment mechanisms for secure communication among entities in the cellular Machine-to-Machine (M2M) network. Considering the characteristics of cellular M2M networks, traditional security solutions are not proper to be applied to cellular M2M networks because the M2M network itself is vulnerable to various attacks. Their mechanism includes pairwise keys for the M2M communication and the group communication among the M2M Equipments (M2MEs). Their key agreement proposal can provide security and reliability for the cellular M2M communication.

The eleventh paper by Hsing-Chung Chen, Cheng-Ying Yang, Hui-Kai Su, Ching-Chuan Wei and Chao-Ching Lee, describes a new e-mail delivery mechanism using secure multicast key protocol with ID-based factorial number structure (ID-based FNS) in an encryption multicast system. In the e-mail delivery mechanism, the message of e-mail is required to encrypt first before sending out in order to safeguard the secrecy of the message on a public channel, such as wire-lined public switching communication links and wireless communication systems. Without loss generality, the public-key system is usually adopted in the multicast environment for the convenience at the easy key management need. As a manner of fact, the mechanism is having analyzed the space occupation; their scheme outperforms the existed methods in the way of magnitude order of reconstructing secure command key. In addition, the extraction of direct secure command key associated each intended receiver is fast operated to succeed the subsequent e-mail message recovery.

The twelfth paper by Hyoung Woo Park, Il Yeon Yeo, Jongsuk Ruth Lee and Haengjin Jang, presents the important paradigm shifts of network architecture caused by big data traffic. They show the new network architecture which resulted from their experience of the European Organization for Nuclear Research (CERN) Large Hadron Collider (LHC) data service. They also illustrate the effect of the throughput improvements of the proposed network architecture using Network Simulator (NS)-2. An interesting feature of their new approach for network architecture is a kind of recycling-friendly architecture because the proposed architecture requires a plentiful number of legacy network cables and legacy low-end network devices instead of buying expensive and cutting-edge network devices. According to their investigation, the future network architecture of the big data center will be a dual matrix architecture in which the big data part will be located at the front and the center of the architecture in order to reduce the number of interactions between the big data traffic and the legacy traffic.

The thirteenth paper by Guowei Wu, Xiaojie Chen, Lin Yao, Youngjun Lee and Kangbin Yim, proposes wormhole attack detection based on transmission range that exploits the local neighborhood information check without using extra hardware or clock synchronizations. Extensive simulations are conducted under different mobility models. Simulation results indicate that the proposed method can detect wormhole attacks effectively and efficiently in wireless senor networks.

The fourteenth paper by Chien-Erh Weng, Jyh-Horng Wen, Hsing-Chung Chen and Lie Yang, describes the backoff procedure characteristics of the Markov chain model with direct/cooperative transmission strategies with Request to Send / Clear to Send (RTS/CTS) mechanism. There is no guarantee that the earlier strategy adopting cooperative transmission presents better performance. With the population of multimedia applications in Wireless Local Area Networks (WLANs), they extend the Markov chain model to support the Quality of Service (QoS) requirements. Differentiating the contention window size is better than differentiating the arbitration interframe space in terms of throughput and delay. Nevertheless, differentiating the arbitration interframe space is a fast way to access the channel. This can be explained by the fact that the different contention window durations can differentiate the probability of collision and provide priority, whereas the arbitration interframe space only provides the priority by differentiating the duration that the station accesses channel.

The fifteenth paper by Guangzhi Zhang, Yunchuan Sun, Mengling Xu and Rongfang Bie, proposes a new approach to cluster the Weibo data by analyzing the users’ reposting behavior data besides the text contents. To verify the proposed approach, a data set of users’ real behaviors from the actual Social Networking Service (SNS) platform is utilized. Experimental results show that the proposed method works better than previous works which depend on the text analysis only.

Finally, in the last paper by Neng-Yih Shih and Hsing-Chung Chen, they study decision approach for selecting candidates in soft-handover procedure in 4th generation mobile communication via grey relational analysis of the series similarity and approximation. The multi-generating and second grey relational analysis procedure is proposed in this paper. It could be applied to the kind of application for selecting candidates in soft-handover procedure; during to the properties of the multi-generating data series are similar to the velocity and acceleration series. With several simulations are validated, the approach could be used to deal with the candidates selecting in soft-handover, and output the best results of feasibility and effectiveness for user equipment in 4th generation mobile communications.

We strongly believe that the papers presented in this special issue make significant contributions to the work and studies conducted by academic researchers, industry professionals, students, and everyone in the areas of mobile collaboration technologies and Internet services.

We would like to thank all the authors for their valuable contributions. Our special thanks go to prof. Mirjana Ivanović, Editor in Chief of the Computer Science and Information Systems (ComSIS) Journal, for inviting us to prepare this special issue and for his productive comments and great support throughout the entire publication process.

Editors of the special issue
Hae-Duck Joshua Jeong (Korean Bible University, Seoul, South Korea)
Fatos Xhafa (Technical University of Catalonia, Barcelona, Spain)
Makoto Takizawa (Hosei University, Tokyo, Japan)