Software defined networking（SDN） has emerged as an efficient network technology for lowering operating cost through simplified hardware, software and management. Specific research focus has been placed to achieve a successful carrier grade network with SDN, in terms of scalability, reliability, Qo S and service management. In this paper, graph theory and traffic engineering are used to model the network state transitions and path assignment problem at first. Next, we present a quantitative assessment model on path assignment for a centralized controller to assess different kinds of path assignments, considering optimal path utilization, network load balance, network load volatility, and resource utilization simultaneously. In the end, an example forquantitatively assessing existing different path assignments is detailed to illustrate our proposed model.
WANG XiaomaoHUANG ChuanheSHI JiaoliFAN XiyinZHOU Hao
车载自组织网络(VANET)中车辆节点既是网络终端也是路由器,可以实现自组织和自管理,它不需要基础设施的帮助,仅仅通过车辆间的通信就能够在一段时间内把信息存储在一个给定的地理区域内。本文针对城市环境和高速公路环境这两种不同的交通模式来分析估算消息在VANET的局部存储时间。在高速公路环境中,我们研究VANET的参数对该时间的影响;在城市环境中,我们将它的结果与随机路径模型(Random Way Point)的模拟结果进行比较。结果显示在高速公路环境下,节点的传输半径能极大的影响局部信息的存储时间;在城市环境下,我们选取存储信息的地理区域的大小决定了该区域内信息的存储时间。
In cloud,data access control is a crucial way to ensure data security.Functional encryption(FE) is a novel cryptographic primitive supporting fine-grained access control of encrypted data in cloud.In FE,every ciphertext is specified with an access policy,a decryptor can access the data if and only if his secret key matches with the access policy.However,the FE cannot be directly applied to construct access control scheme due to the exposure of the access policy which may contain sensitive information.In this paper,we deal with the policy privacy issue and present a mechanism named multi-authority vector policy(MAVP) which provides hidden and expressive access policy for FE.Firstly,each access policy is encoded as a matrix and decryptors can only obtain the matched result from the matrix in MAVP.Then,we design a novel function encryption scheme based on the multi-authority spatial policy(MAVPFE),which can support privacy-preserving yet non-monotone access policy.Moreover,we greatly improve the efficiency of encryption and decryption in MAVP-FE by shifting the major computation of clients to the outsourced server.Finally,the security and performance analysis show that our MAVP-FE is secure and efficient in practice.
WANG JingHUANG ChuanheYANG KanWANG JinhaiWANG XiaomaoCHEN Xi
车载自组织网络VANET(vehicular ad hoc network)由于车辆高速移动性、分布不均匀、运动行为受交通环境限制等因素的影响,使得VANET具有网络拓扑结构变化频繁、传输信号受干扰大、网络易于断裂等固有特性。路由选择是VANET的重要组成部分。如何选择下一跳节点是实现路由方法的关键,链路稳定度是衡量VANET性能的重要因素。本文通过计算预期路径的链路稳定度来选择下一跳节点,提出一种基于链路稳定度的路由方法。实验结果表明与传统的AODV相比,本文提出的方法在端到端延时,数据包的传递率等方面有较大的提高。
