Search

Opportunity networks provide a chance to offload the tremendous cellular traffic generated by sharing popular content on mobile networks. Analyzing the content spread characteristics in real opportunity environments can discover important clues for traffic offloading decision making. However, relevant published work is very limited since it is not easy to collect data from real environments. In this study, we elaborate the analysis on the dataset collected from a real opportunity environment formed by the users of Xender, which is one of the leading mobile applications for content sharing. To discover content transmission characteristics, scale, speed, and type analyses are implemented on the dataset. The analysis results show that file transmission has obvious periodicity, that only a very small fraction of files spread widely, and that application files have much higher probability to be popular than other files. We also propose a solution to maximize file spread scales, which is very helpful for forecasting popular files. The experimental results verify the effectiveness and usefulness of our solution.

Wireless Ad Hoc Network is a distributed self-organizing networking with no infrastructure and central control. To probe the unknown environment and obtain the associated data, this paper offers a Multi-Strategy Data Transmission Scheme (MSDTS) for Ad-hoc network based on link queue, alternate node and ferry transmission. This kind of scheme has good performance on building link Ad-hoc network, data drop rate, average throughput of network.

At present, many enterprises have expressed interests in private clouds and have an optimistic attitude about the future prospects of private clouds. And more and more enterprises want to have their own private cloud computing center or the data center to optimize operation and save money. But there are many technical problems that need to be considered in the framework of the enterprise private cloud platform, such as protecting sensitive data, which has become the focus of the enterprise. Based on the eCryptfs (enterprise file encryption system) and carried on a deep research to the main file encryption system. And Implemented a secure private cloud encryption system combined with the overall architecture of the private cloud system within the operating system environment of ubuntu10.04 of the enterprise private cloud file storage server. This solution achieved the security of storage resource by using eCryptfs file system non-interactively and solved the main security problems that private cloud system face in large scale application environment.

The rapid growth in demand for cloud services has led to the establishment of huge virtual machines. Online virtual machine (VM) migration techniques offer cloud providers means to reduce power consumption while keeping quality of service. However, the efficiency of online migration is suboptimal since it is degraded by the execution of redundant migrations. To alleviate this problem, we introduce a load-aware VM migration technique. The key idea is to defer these migrations and perform a quick analysis of the loads on target servers before launching any migration. This consolidation is applied in two steps: first all migrations are tested and a set of candidates that are suspected to be redundant are formed and postponed for a short time. Then, the servers are analysed and only a subset of the migration candidates is activated. Our selection mechanism is conservative in the sense that it avoids selecting and activating VM migrations that are unlikely to cause a harmful overloading on the target servers. Taking this conservative migration policy leads to an overall effective execution of virtual machines. Our experiment results demonstrate the usefulness and effectiveness of our method.

Network security research is an important aspect of CSCW (computer supported cooperative work). It helps to make work environment essential and reliable. Access control security technology mainly includes firewall technology, intrusion detection technology, and security auditing technology. These technologies still have some problems and shortages though they are matured in some degree. The expert system for preventing and auditing intrusion is a series of software and hardware systems for reducing the risk of computer network security. It is an effective closed loop control system that integrates with firewall, intrusion detection, and auditing trail analysis. It uses the learning ability of expert system to add knowledge and rules. Also it combines the characteristics of real-time and unreal-time to form an access control security system and enhance the security of the network.