ISSN 1000-1239 CN 11-1777/TP

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    Journal of Computer Research and Development    2015, 52 (12): 2657-2658.  
    Abstract1387)   HTML9)    PDF (425KB)(881)       Save
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    A DRM Scheme Supporting Attribute Revocation and Outsourced Decryption in the Cloud Computing Environment
    Zhang Weiwei, Feng Gui, Liu Jianyi, Yang Yixian
    Journal of Computer Research and Development    2015, 52 (12): 2659-2668.   DOI: 10.7544/issn1000-1239.2015.20150749
    Abstract1091)   HTML3)    PDF (1638KB)(791)       Save
    DRM (digital rights management) is an important part of the construction of informatization in China. Unfortunately, high investment costs and poor user experience are two issues of DRM for further promotion in practice. Previous studies for DRM focused merely on storage service of cloud computing, lacking of concerning on the advantage of its computing service. This paper proposes a DRM scheme supporting attribute revocation and outsourced decryption in the cloud computing environment. In order to protect the users privacy in the DRM system, we propose that users purchase licenses through anonymous tags. In addition, in order to give full play to the advantages of cloud computing in computing and be flexible, fine-grained revocation of the user’s attributes, a supporting revocation of the outsourcing decryption CP-ABE scheme is proposed. Compared with the existing digital rights management schemes based on cloud computing, the proposed scheme protects content security and user privacy. Besides, it supports flexible access control mechanism and fine-grained user’s attributes revocation, and it is more applicable in the content protection in the cloud computing.
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    A Real-Time Task Availability Improving Fault-Tolerant Scheduling Algorithm on Heterogeneous Platform
    Sun Jian, Zhang Xingjun, Dong Xiaoshe
    Journal of Computer Research and Development    2015, 52 (12): 2669-2683.   DOI: 10.7544/issn1000-1239.2015.20150721
    Abstract1093)   HTML1)    PDF (3172KB)(798)       Save
    With the rapid development of Internet plus, cloud computing, big data and other fields, heterogeneous system has become an important platform for the deployment of scientific computing, industrial control, cloud storage and other key applications. Because of the heterogeneity of processor performance and software/hardware structure, heterogeneous platform shows better scalability and high cost-performance ratio. However, with the scale of platform becoming larger and the system application becoming more complex, system schedulability becomes worse, and availability decreases. To solve this problem, we propose a fault-tolerant scheduling algorithm aiming to improve availability for real-time tasks on heterogeneous platform, namely AIFSAL. The algorithm uses processor utilization and availability cost to design real-time task scheduling model, and combines availability cost and primary/backup copy (PB) method together for fault-tolerant. During task scheduling, no matter task’s primary or backup copy, processors with lower availability cost is chosen preferentially in order to improve system availability, meanwhile tasks’ backup copies are executed as the type of passive backup copy preferentially in order to achieve fault-tolerant and ensure the schedulability of task allocation. Simulation experiments and comparison analysis with other task scheduling algorithms, including availability approached task scheduling algorithm (AATSAL), task partition based fault tolerant rate-monotonic (TPFTRM) and the earliest completion algorithm (MinMin), verify the effectiveness of the proposed algorithm on availability improving and schedulability assuring. Hence, the system comprehensive cost is reduced and comprehensive performance is improved significantly.
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    A Packet Loss Differentiation Algorithm for 4G-LTE Network
    Du Haipeng, Zheng Qinghua, Zhang Weizhan, Yan Jifeng
    Journal of Computer Research and Development    2015, 52 (12): 2684-2694.   DOI: 10.7544/issn1000-1239.2015.20150726
    Abstract1741)   HTML4)    PDF (2952KB)(697)       Save
    On wireless networks, packet losses are usually caused by congestion or wireless fading. Loss differentiation is a fundamental problem of how to identify the cause of packet losses based on the transmission characteristics of wireless network. When moving on to LTE network, this remains an issue worthy of study due to the possible changes in packet loss patterns. In light of this, this paper proposes a loss differentiation algorism LDA-LTE for LTE network. We firstly conduct a detailed measurement study of the transmission characteristics of LTE network in configurable congestion and wireless channel fading scenarios. The test bed is based on an emulated LTE network in the laboratory by adopting a LTE base station emulator. Then, we find that the packet loss patterns that previous works used as the principal basis for loss differentiation do not hold when moving on to LTE network. This makes these works fail to work on LTE network. Finally, we design a loss differentiation algorism LDA-LTE, which collectively uses observed loss patterns to infer the cause of the packet losses on the LTE network in the hybrid scenario where congestion loss and wireless loss occur simultaneously. Evaluations on the test bed show that the accuracy of loss differentiation with LDA-LTE is significantly improved compared with previous work.
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    Preemption Threshold Scheduling for Energy Harvesting Based Cyber-Physical Systems
    Ge Yongqi, Dong Yunwei, Gu Bin
    Journal of Computer Research and Development    2015, 52 (12): 2695-2706.   DOI: 10.7544/issn1000-1239.2015.20150745
    Abstract1043)   HTML3)    PDF (3222KB)(620)       Save
    In energy harvesting based cyber-physical systems (EHCPS), energy management architecture is different from traditional battery powered embedded systems. The task scheduling of EHCPS should take account of the output power of energy harvesting unit, the energy level of battery and the energy consumption of computing tasks. A real-time task may meet time constraint only if its energy constraint is satisfied. Against this background, the schedulability analysis of conventional preemption threshold scheduling doesn’t consider the tasks energy consumption, thus the preemption threshold assignment algorithm is not suitable for EHCPS. An energy related preemption threshold scheduling (ERPT) for EHCPS is proposed in this paper. It integrates tasks energy consumption and energy supply ability into schedulability analysis, and the preemption threshold assignment algorithms are also presented. ERPT presents a solution for applying preemption threshold scheduling in EHCPS. The proposed scheduling strategy is validated compared with other two existing classical algorithms. The experimental results show that the proposed scheduling can reduce the tasks preemption effectively.
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