基于k-匿名的隐私保护计算卸载方法

针对移动边缘计算(MEC)中用户的卸载任务及卸载频率可能使用户被攻击者锁定的问题,该文提出一种基于k-匿名的隐私保护计算卸载方法。首先,该方法基于用户间卸载任务及其卸载频率的差异性,提出隐私约束并建立基于卸载频率的隐私保护计算卸载模型;然后,提出基于模拟退火的隐私保护计算卸载算法(PCOSA)求得最优的k-匿名分组结果和组内各任务的隐私约束频率;最后,在卸载过程中改变用户原始卸载频率满足隐私约束,最小化终端能耗。仿真结果表明,PCOSA算法能找出用户所处MEC节点下与用户卸载表现最相近的k个用户形成匿名集,有效保护了所有用户隐私。     

基于Lyapunov优化的隐私感知计算卸载方法

移动边缘计算(MEC)中计算卸载决策可能暴露用户特征,导致用户被锁定。针对此问题,该文提出一种基于Lyapunov优化的隐私感知计算卸载方法。首先,该方法定义卸载任务中的隐私量,并引入隐私限制使各MEC节点上卸载任务的累积隐私量尽可能小;然后,提出假任务机制权衡终端能耗和隐私保护的关系,当系统因隐私限制无法正常执行计算卸载时,在MEC节点生成虚假的卸载任务以降低累积隐私量;最后,建立隐私感知计算卸载模型,并基于Lyapunov优化原理求解。仿真结果表明,基于Lyapunov优化的隐私感知卸载算法(LPOA)能使用户的累积隐私量稳定在0附近,且总卸载频率与不考虑隐私的决策一致,有效保护了用户隐私,同时保持了较低的平均能耗。     

基于非正交多址接入的移动边缘计算安全节能联合资源分配

为提高基于非正交多址接入(NOMA)的移动边缘计算(MEC)系统中计算任务部分卸载时的安全性,该文在存在窃听者情况下研究MEC网络的物理层安全,采用保密中断概率来衡量计算卸载的保密性能,考虑发射功率约束、本地任务计算约束和保密中断概率约束,同时引入能耗权重因子以平衡传输能耗和计算能耗,最终实现系统能耗加权和最小。在满足两个用户优先级情况下,为降低系统开销,提出一种联合任务卸载和资源分配机制,通过基于二分搜索的迭代优化算法寻求问题变换后的最优解,并获得最优的任务卸载和功率分配。仿真结果表明,所提算法可有效降低系统能耗。     

一种主从MEC服务器协作卸载与资源分配方案

移动边缘计算(Mobile Edge Computing,MEC)通过将云计算能力下沉至用户侧,提高了用户的任务执行能力.但在热点小区中,MEC服务器存在计算资源有限的问题.为了减少热点小区内任务执行总代价,提出了一种基于主从MEC系统的任务联合卸载方案.首先,方案随机生成卸载集,然后将卸载集内的任务分配至目标MEC服...     

超密集网络中基于移动边缘计算的任务卸载和资源优化

移动边缘计算(MEC)通过在无线网络边缘为用户提供计算能力,来提高用户的体验质量。然而,MEC的计算卸载仍面临着许多问题。该文针对超密集组网(UDN)的MEC场景下的计算卸载,考虑系统总能耗,提出卸载决策和资源分配的联合优化问题。首先采用坐标下降法制定了卸载决定的优化方案。同时,在满足用户时延约束下采用基于改进的匈牙利算法和贪婪算法来进行子信道分配。然后,将能耗最小化问题转化为功率最小化问题,并将其转化为一个凸优化问题得到用户最优的发送功率。仿真结果表明,所提出的卸载方案可以在满足用户不同时延的要求下最小化系统能耗,有效地提升了系统性能。     

MEC系统中基于多智能体深度增强学习的协作式任务卸载和资源分配

移动边缘计算(MEC)通过将计算任务卸载到MEC服务器上,在缓解智能移动设备计算负载的同时,可以降低服务时延。然而目前在MEC系统中,关于任务卸载和资源分配仍然存在以下问题：1)边缘节点间缺乏协作;2)计算任务到达与实际环境中动态变化的特征不匹配;3)协作式任务卸载和资源分配动态联合优化问题。为解决上述问题,文章在协作式MEC架构的基础上,提出了一种基于多智能体的深度确定性策略梯度算法(MADDPG)的任务卸载和资源分配算法,最小化系统中所有用户的长期平均成本。仿真结果表明,该算法可以有效降低系统的时延及能耗。     

基于NOMA的移动边缘计算系统公平能效调度算法

将移动边缘计算技术(MEC)与非正交多址技术(NOMA)结合,同时考虑公平性,该文研究了采用NOMA上行部分卸载的MEC系统公平能效问题。首先将基于公平函数的用户速率与功耗比值定义为公平能效函数,随后提出了两种公平能效调度准则下的能效调度算法,即最大化最小速率准则下DK-SCA算法及最大化系统能效准则下DK-SCALE算法,通过算法实现分别得到两种公平能效调度准则下用户最佳本地CPU处理频率及最佳传输功率。最后通过仿真表明,与基准方案相比,所提基于NOMA的部分卸载方案能够有效地将本地计算和基于NOMA的边缘卸载结合,达到最佳的公平能效性能。     

移动边缘计算卸载技术综述

移动边缘计算(Mobile Edge Computing,MEC)将云服务器的计算资源扩展到更靠近用户一侧的网络边缘,使得用户可以将任务卸载到边缘服务器,从而克服原先云计算中将任务卸载到云服务器所带来的高时延问题。首先介绍了移动边缘计算的基本概念、基本框架和应用场景,然后围绕卸载决策、联合资源分配的卸载决策分别从单MEC服务器和多MEC服务器两种场景总结了任务卸载技术的研究现状,最后结合当前MEC卸载技术中存在的不足展望了未来MEC卸载技术的研究。     

超密集网络中基于MEC的动态任务卸载方案

超密集网络(Ultra-dense Network,UDN)中集成移动边缘计算(Mobile Edge Computing,MEC),是5G中为用户提供计算资源的可靠方式,在多种因素影响下进行MEC任务卸载决策一直都是一个研究热点。目前已存在大量任务卸载相关的方案,但是这些方案中很少将重心放在用户在不同条件下的能耗需求差异上,无法有效提升用户体验质量(Quality of Experience,QoE)。在动态MEC系统中提出了一个考虑用户能耗需求的多用户任务卸载问题,通过最大化满意度的方式提升用户QoE,并将现有的深度强化学习算法进行了改进,使其更加适合求解所提优化问题。仿真结果表明,所提算法较现有算法在算法收敛性以及稳定性上具有一定提升。     

车联网中基于NOMA-MEC的卸载策略研究

随着车联网(IoV)的迅猛发展,请求进行任务卸载的汽车终端用户也逐渐增长,而基于移动边缘计算(MEC)的通信网络能够有效地解决任务卸载在上行传输时延较高的挑战,但是该网络模型同时也面临着信道资源不足的问题。该文引入的非正交多址(NOMA)技术相较于正交多址(OMA)能够在相同的信道资源条件下为更多的用户提供任务卸载,同时考虑到任务卸载过程中多方面的影响因子,提出了混合NOMA-MEC卸载策略。该文设计了一种基于深度学习网络(DQN)的博弈算法,帮助车辆用户进行信道选择,并通过神经网络多次迭代学习,为用户提供最优的功率分配策略。仿真结果表明,该文所提出的混合NOMA-MEC卸载策略能够有效地优化多用户卸载的时延以及能耗,最大限度保证用户效益。     

NOMA-MEC系统中基于改进遗传算法的协作式计算卸载与资源管理

为平衡网络负载与充分利用网络资源,针对超密集异构的多用户和多任务边缘计算网络,在用户时延约束下,该文构造了协作式计算任务卸载与无线资源管理的联合优化问题以最小化系统能耗。问题建模时,为应对基站超密集部署导致的严重干扰问题,该文采用了频带划分机制,并引入了非正交多址技术(NOMA)以提升上行频谱利用率。鉴于该目标优化问题具备非线性混合整数的形式,根据多样性引导变异的自适应遗传算法(AGADGM),设计出了协作式计算卸载与资源分配算法。仿真结果表明,在严格满足时延约束条件下,该算法能获取较其他算法更低的系统能耗。     

Privacy self-correlation privacy-preserving scheme in LBS

The prevalence of mobile intelligent terminals gives the location-based service (LBS) more opportunities to enrich mobile users’ lives.However,mobile users enjoy the convenience with the cost of personal privacy.The side information and mobile user’s recent requirement records were considered,which were obtained or stored by the service provider.Based on the existence of recent requirement records,adversary can employ the inference attack to analysis mobile user’s personal information.Therefore,two schemes were proposed,including of basic privacy self-correlation privacy-preserving scheme (Ba-2PS) and enhanced privacy self-correlation privacy-preserving scheme(En-2PS).In En-2PS,the privacy-preserving scheme was designed from two dimensions of aspects of time factor and query region,which increased the uncertainty inferring out the real information.Finally,the privacy analysis was illustrated to proof En-2PS’s privacy degree,then the performance and privacy evaluation results indicate that En-2PS is effective and efficient.     

Joint computation offloading and task caching for multi-user and multi-task MEC systems: reinforcement learning-based algorithms

Computation offloading at mobile edge computing (MEC) servers can mitigate the resource limitation and reduce the communication latency for mobile devices. Thereby, in this study, we proposed an offloading model for a multi-user MEC system with multi-task. In addition, a new caching concept is introduced for the computation tasks, where the application program and related code for the completed tasks are cached at the edge server. Furthermore, an efficient model of task offloading and caching integration is formulated as a nonlinear problem whose goal is to reduce the total overhead of time and energy. However, solving these types of problems is computationally prohibitive, especially for large-scale of mobile users. Thus, an equivalent form of reinforcement learning is created where the state spaces are defined based on all possible solutions and the actions are defined on the basis of movement between the different states. Afterwards, two effective Q-learning and Deep-Q-Network-based algorithms are proposed to derive the near-optimal solution for this problem. Finally, experimental evaluations verify that our proposed model can substantially minimize the mobile devices’ overhead by deploying computation offloading and task caching strategy reasonably.

     

Visual privacy-preserving level evaluation for multilayer compressed sensing model using contrast and salient structural features

Recognition and classification tasks in images or videos are ubiquitous, but they can lead to privacy issues. People increasingly hope that camera systems can record and recognize important events and objects, such as real-time recording of traffic conditions and accident scenes, elderly fall detection, and in-home monitoring. However, people also want to ensure these activities do not violate the privacy of users or others. The sparse representation classification and recognition algorithms based on compressed sensing (CS) are robust at recognizing human faces from frontal views with varying expressions and illuminations, as well as occlusions and disguises. This is a potential way to perform recognition tasks while preserving visual privacy. In this paper, an improved Gaussian random measurement matrix is adopted in the proposed multilayer CS (MCS) model to realize multiple image CS and achieve a balance between visual privacy-preserving and recognition tasks. The visual privacy-preserving level evaluation for MCS images has important guiding significance for image processing and recognition. Therefore, we propose an image visual privacy-preserving level evaluation method for the MCS model (MCS-VPLE) based on contrast and salient structural features. The basic concept is to use the contrast measurement model based on the statistical mean of the asymmetric alpha-trimmed filter and the salient generalized center-symmetric local binary pattern operator to extract contrast and salient structural features, respectively. The features are fed into a support vector regression to obtain the image quality score, and the fuzzy c-means algorithm is used for clustering to obtain the final evaluated image visual privacy-preserving score. Experiments on three constructed databases show that the proposed method has better prediction effectiveness and performance than conventional methods.     

Efficient privacy-preserving group-nearest-neighbor queries with the presence of active adversaries

Location-based services (LBSs) allow users to ask location-dependent queries and receive information based on their location. A group of users can send a group-nearest-neighbor (GNN) query in order to receive a Point Of Interest (POI). This POI in turn shows a point which is the minimum distance from all members of the group. To benefit from these services, it is important to preserve the location privacy of each group user from others in the group (Intragroup location privacy) as well as from anyone outside of the group, including the LBS, (Intergroup location privacy). It may also be necessary to protect the location privacy of the resulting POI from the LBS and other possible attackers. In this paper, we propose two different privacy-preserving protocols for finding the exact answer to a GNN query among a set of returned POIs. The first protocol assumes a semi-honest model while the second one works in a malicious model. The proposed protocols are based on the Anonymous Veto network and Burmester–Desmedt key establishment protocols. The security analysis shows that the proposed protocols provide both Intragroup and Intergroup location privacy; they also protect the location privacy of the resulting POI and are resistant to collusion and multi-point aggregate distance attacks. The performed analyses indicate that they incur a constant computation cost per user and are efficient in terms of computation and communication costs.

     

基于二次规划的任务卸载决策和资源分配方法

主要研究移动用户均有多个独立任务的多用户移动云计算系统,这些移动用户将任务卸载到云端时共享通信资源。如何对所有用户的任务卸载决策和通信资源分配进行联合优化,以便使所有用户的能耗、计算量和延时降到最低是目前研究的难点。将该问题建模为NP难度的非凸的具有二次约束的二次规划(QCQP)问题,提出一种高效的近似算法进行求解,通过单独的半正定松驰(SDR)处理后,确定二元卸载决策和通信资源最优分配。采用代表最小系统成本的性能下界作为性能基准进行仿真实验,结果表明,本文算法在多种参数配置下的性能均接近最优性能。     

多小区蜂窝网络中计算卸载与资源分配联合优化算法

本文在多基站和远端云构成的多层计算卸载场景中,提出了一种多小区蜂窝网络中基站选择、计算卸载与资源分配联合优化算法。该算法考虑多基站重叠覆盖用户的基站选择,在边缘服务器计算资源约束条件下,构建了能耗与时延加权和的最小化问题,这是NP-hard问题。本文首先对单用户多基站计算卸载问题,采用拉格朗日乘子法对其进行求解;然后针对多用户多基站场景,考虑用户的基站选择以及边缘服务器计算资源的竞争,基于定义的选择函数对接入基站进行选择,采用次优的迭代启发式算法对单用户场景下的卸载决策做出动态修正,获得卸载决策和边缘服务器资源分配。仿真结果表明,提出的计算卸载及资源分配算法能有效的降低任务完成的时延与终端的能耗。