路网环境下的语义多样性位置隐私保护方法

针对位置服务中基于K-匿名方法构造的匿名集因未考虑语义信息导致语义推断攻击问题,提出了一种路网环境下的语义多样性位置隐私保护方法。该方法根据不同语义位置用户访问数量,利用欧氏距离选择具有相似特性的语义位置类型,构建最优语义位置类型集合。根据路段上属于该类型集的语义位置所占比例,选择最优路段构建匿名集,使得匿名集不仅满足语义多样性,而且增加了用户语义位置的不确定性。实验结果表明,与LSBASC算法相比,该方法在平均匿名时间上提高了27%,SDA算法的执行效率更好。在相对空间粒度上减小了21%,隐私泄露程度上降低了3%,SDA算法以更小的匿名空间提供更高的服务质量和隐私保护程度,能有效地保护用户语义位置隐私。     

基于网格划分空间的位置匿名算法

现有的位置匿名算法的匿名时间较长,匿名后的空间区域较大,严重影响查询的服务质量。为了解决这些问题,提出了一种基于网格划分空间的位置匿名算法,该算法基于位置k-匿名模型,采用网格结构划分空间后对用户位置进行位置匿名。实验结果表明,该算法在满足用户位置隐私需求的前提下,位置匿名时间更短,用户的平均匿名空间减小,从而大幅度提升用户查询的服务质量。     

PTDC:路网环境中感知隐私的轨迹数据采集技术

针对路网环境中移动对象轨迹隐私泄露以及语义位置同质性攻击等问题,提出了一种路网环境中感知隐私的轨迹数据采集（PTDC）算法。首先,通过兴趣位置（POI）访问人次的信息墒计算路网中POI的敏感性;其次,根据顶点间敏感性和距离的混合差距,定义了θ-边权,并建立路网空间的图模型、定义了k-θ-D匿名模型以抵御语义位置同质性攻击;最后,以无向图的广度优先遍历为基础,设计了满足POI语义差异性的匿名算法,将用户的敏感采样位置用匿名区域取代,并衡量了PTDC算法处理后数据的可用性。通过实验对PTDC算法进行了验证,并和自由空间中的基于语义位置的隐私保护算法——YCWA进行了比对。理论上讲,YCWA算法的隐私保护度低于PTDC算法。实验表明,PTDC算法的信息丢失率平均在15%左右,空间范围查询误差平均在12%左右,略逊于YCWA算法;然而,PTDC算法的运行时间在5 s以内,远远优于YCWA算法,可满足实时在线数据采集的需求。     

面向连续查询的敏感语义位置隐私保护方案

针对连续查询位置服务中构造匿名区域未考虑语义位置信息导致敏感隐私泄露问题，通过设计[(K,θ)]-隐私模型，提出一种路网环境下面向连续查询的敏感语义位置隐私保护方案。该方案利用Voronoi图将城市路网预先划分为独立的Voronoi单元，依据用户的移动路径和移动速度，选择具有相似特性的其他[K-1]个用户，构建匿名用户集；利用匿名用户集用户设定的敏感语义位置类型和语义安全阈值，以及用户所处语义位置的Voronoi单元，构建满足[(K,θ)]-隐私模型的语义安全匿名区域，可以同时防止连续查询追踪攻击和语义推断攻击。实验结果表明，与SCPA算法相比，该方案在隐私保护程度上提升约15%，系统开销上降低约20%。     

基于经纬网格的递增KNN位置隐私保护查询算法

为了在使用基于位置的服务时用户的位置信息不被不可信的位置服务提供商所泄漏,k-匿名位置隐私保护已被广泛研究.然而在集中匿名器被黑客控制时原k-匿名算法会泄漏所有用户的位置隐私,在进行k个最近邻目标查询时对网络的负载较重,而SpaceTwist算法又不能保证k-匿名.提出了一种基于经纬网格的递增KNN位置隐私保护查询算法,将经典的k-匿名算法与SpaceTwist算法相杂交,并引入经纬网格代替原来精确的位置上报给集中匿名器,从而解决了上述问题.实验证明基于经纬网格的递增KNN查询算法比较节省从集中匿名器到位置服务提供商的服务器之间的网络流量.     

基于SpaceTwist的K-匿名增量近邻查询位置隐私保护算法

摘 要：随着移动网络的持续进步,基于位置的服务在日常生活中被广泛应用,同时位置隐私保护也成为广大用户所关注的焦点。基于SpaceTwist算法和K-匿名算法,结合路网环境提出一种新的位置隐私保护方法。该方法摆脱第三方可信匿名器,采用客户-服务器体系结构,根据用户的位置隐私需求结合用户所在路网环境设计出用户端匿名区生成算法,并且保证K-匿名。用户端以该匿名区请求基于位置的服务,服务器根据用户请求返回检索点并满足用户期望的K近临结果。根据不同的路网环境和用户隐私需求进行大量实验,证明该算法在满足用户基于位置服务需求的同时提高了对用户位置隐私的保护。     

位置大数据中一种基于Bloom Filter的匿名保护方法

位置大数据服务应用中存在大量的用户敏感信息,针对服务中海量数据分析的隐私泄露问题,提出一种基于Bloom Filter多哈希散列编码的位置匿名保护方法。采用启发式的隐私度量技术划分匿名区来隐藏真实的位置数据,保持欧氏距离上搜索目标的邻近关系以优化空间匿名框的面积,并在划分策略中引入查询服务相似性因子以减少空间碎片的产生。在移动用户和服务器之间构建可信的第三方位置匿名服务器,能有效地模糊目标节点,从而抵御恶意的隐私攻击。理论分析和仿真实验表明,新算法能有效优化匿名空间区域,提高隐私保护程度,并在海量数据集的构建过程中具有较优的时间复杂度。     

移动对象连续查询位置匿名策略

用户位置隐私保护已经成为基于位置服务领域研究的热点问题之一,现有的方法多是只针对用户单独一次查询的隐私保护,没有考虑移动过程中由于连续查询而造成的位置隐私泄露问题。主要针对连续查询下的移动对象位置隐私保护提出一种基于历史用户的虚假用户生成的位置匿名方法,该方法结合用户历史数据,通过确定合理的假用户生成区域及假用户生成时刻其空间位置,使虚假用户能够实时对真实用户位置进行保护,通过实验验证其可行性和有效性。     

路网环境下兴趣点查询的隐私保护方法

近年来,随着无线通信技术的迅猛发展,推动了基于位置服务（Location-based services,LBS）的发展进程.而其中兴趣点（Point of Interest,POI）查询是基于位置服务最重要的应用之一.针对在路网环境下,用户查询过程中位置隐私泄露的问题,提出了一种新的位置k匿名隐私保护方法.首先,匿名服务器将兴趣点作为种子节点生成网络Voronoi图,将整个路网划分为相互独立且不重叠的网络Voronoi单元（Network Voronoi Cell,NVC）;其次,利用Hilbert曲线遍历路网空间,并按照Hilbert顺序,对路网上所有的兴趣点进行排序.当用户发起查询时,提出的匿名算法通过查找与用户所在NVC的查询频率相同且位置分散的k-1个NVC,并根据用户的相对位置在NVC内生成匿名位置,从而保证了生成的匿名集中位置之间的相互性,克服了传统k-匿名不能抵御推断攻击的缺陷.最后,理论分析和实验结果表明本文提出的隐私保护方案,能有效保护用户位置隐私.     

基于连续位置服务请求的位置匿名方法的研究

随着无线技术和移动定位技术的蓬勃发展,出现了一种新的研究领域——基于位置的服务(location-based service,LBS)。用户在享受此类服务的时候不得不把自己的精确位置发送给服务提供商,使得用户可能面临位置隐私泄露的危险。位置k-匿名是最常见的位置隐私保护技术之一,通过将用户的精确位置泛化为一个具有k-匿名性质的区域来达到隐私保护的目的。但是在移动用户连续不断发出位置服务请求的场景下,攻击者能够根据用户的历史请求之间的关系推测出用户的隐私。此种状况下,传统的孤立查询的k-匿名模型失效。文章提出了一种更加优化的k-匿名模型,在满足用户指定匿名度的前提下,利用活动区域内用户的历史位置分布情况寻找出现次数最多且位置分布最密集的k-1个用户组成共同匿名集。实验结果表明,该方法在保证用户要求匿名度的前提下能够有效降低共同匿名区域的面积。     

An efficient metric-based (EM-B) location management scheme for wireless cellular networks

In the current era, the wireless cellular network is gaining much attention in the network mobility for qualitative service. Towards enhancing the QoS and narrowing the dilemma of network management (location management) an efficient metric-based location management technique is introduced in this paper to capture the current location of mobile subscribers. The attributes of this technique are based on metrics calculation and location management message routing path determination. First, the current mobile switching center will calculate the shortest metric-based path between current and master (previous) location of mobile terminals (user), thereafter it performs the location management procedure through the optimal suggested path by the mobile switching center. This proposed technique will reduce the signaling cost, registration delay, call setup delay, network overheads and total location management cost. The proposed analytical model checks the scalability and effectiveness of proposed system over certain attributes and a comparison is made with the existing available techniques.     

Efficient location area planning for cellular networks with hierarchical location databases

Location area planning (LAP) is an important issue in the design of high-performance PCS networks. It could have a serious impact on the total mobility management cost of mobile terminals. Most of the previous works either explored the LAP problem as a 0–1 linear programming problem or used adopted techniques, such as simulated annealing, taboo search, and genetic algorithms [IEEE Trans. Vehicular Technol. 49 (2000) 1678; Proceedings of 1999 Vehicular Technology Conference, vol. 4, 1999, pp. 2119–2123; IEEE Vehicular Technol. Conf. 3 (1996) 1835; Proceedings of IEEE INFOCOM'01, Anchorage, Alaska, April 2001; IEEE Trans. Vehicular Technol. 47 (1998) 987], to derive a solution to minimize the location update cost. In this paper, we model and resolve the LAP problem as a set-covering problem. The main advantage of this approach is that it can adapt to the changing mobility patterns of the mobile terminals. We propose the set-covering-based location area planning (SCBLP) algorithm to minimize the total number of location updates, in which the cost-benefit functions are defined based on the coupling and cohesive functions among neighboring cells. We then apply SCBLP to the location database system with a hierarchical structure to further improve the overall system performance in searching and updating the location databases. Extensive simulation experiments have been conducted, and the experimental results show that our proposed algorithms can significantly reduce the location management costs, compared to the greedy algorithm and the random algorithm.     

A simple and effective evolutionary algorithm for the capacitated location–routing problem

This paper proposes a hybrid genetic algorithm (GA) to solve the capacitated location–routing problem. The proposed algorithm follows the standard GA framework using local search procedures in the mutation phase. Computational evaluation was carried out on three sets of benchmark instances from the literature. Results show that, although relatively simple, the proposed algorithm is effective, providing competitive results for benchmark instances within reasonable computing time.     

室内定位技术分析

对位置信息的识别是普适计算中的一个重要研究领域,其中大多教的应用都是在室内环境下.介绍位置识别的一般技术与方法,展示目前在室内定位领域兵有代表性的研究性和商业性的定位系统,分析各种技术的长处及其局限性,提出今后的研究方向.     

Cloaking locations for anonymous location based services: a hybrid approach

An important privacy issue in Location Based Services is to hide a user’s identity while still provide quality location based services. Previous work has addressed the problem of locational -anonymity either based on centralized or decentralized schemes. However, a centralized scheme relies on an anonymizing server (AS) for location cloaking, which may become the performance bottleneck when there are large number of clients. More importantly, holding information in a centralized place is more vulnerable to malicious attacks. A decentralized scheme depends on peer communication to cloak locations and is more scalable. However, it may pose too much computation and communication overhead to the clients. The service fulfillment rate may also be unsatisfied especially when there are not enough peers nearby. This paper proposes a new hybrid framework called HiSC that balances the load between the AS and mobile clients. HiSC partitions the space into base cells and a mobile client claims a surrounding area consisting of base cells. The number of mobile clients in the surrounding cells is kept and updated at both client and AS sides. A mobile client can either request cloaking service from the centralized AS or use a peer-to-peer approach for spatial cloaking based on personalized privacy, response time, and service quality requirements. HiSC can elegantly distribute the work load between the AS and the mobile clients by tuning one system parameter base cell size and two client parameters - surrounding cell size and tolerance count. By integrating salient features of two schemes, HiSC successfully preserves query anonymity and provides more scalable and consistent service. Both the AS and the clients can enjoy much less work load. Additionally, we propose a simple yet effective random range shifting algorithm to prevent possible privacy leakage that would exist in the original P2P approach. Our experiments show that HiSC can elegantly balance the work load based on privacy requirements and client distribution. HiSC provides close to optimal service quality. Meanwhile, it reduces the response time by more than an order of magnitude from both the P2P scheme and the centralized scheme when anonymity level(value of ) or number of clients is large. It also reduces the update message cost of the AS by nearly 6 times and the peer searching message cost of the clients by more than an order of magnitude.

基于SUPERMAP的手机监控系统

结合中国移动快捷的通讯网络和SuperMap地理信息系统软件的优点,建立基于LBS的手机监控系统.通过中国移动的基站获得位置信息,以短消息方式传递位置信息,达到对手机终端进行监控的目的.加上地理信息系统丰富的空间信息,实现了手机终端用户在任何时间、任何地点都可以监控到本机和其他授权手机终端的位置信息及其他与位置相关的商务信息,给用户的生活和工作带来了极大的便利.     

网上数据库的选址问题

文章主要分析在一个通信网络中数据库如何分布,分布多少,才能使总费用最低,并建立了相应的数据库选址模型。     

An integrated approach to facility location problems

An integrated analysis approach to facility location problems is described. The approach is based on integrating analytical location models and a multicriteria decision model.     

高效的混合式查找方案*

通过整合基于服务器/客户机模式的集中式查找方案和基于对等计算模式的分散式查找方案,提出了一种混合式查找方案。该方案既有可扩展性、高容错性和自组织性等分散式查找方案的优点,又有利于集中管理和控制,安全性好等集中式查找方案的优势。仿真实验结果表明,该方案的RDP指标优于常规的分散式查找方案,实际查询时间开销更是远远少于常规的分散式查找方案。     

A priori error estimates for wireless local area network positioning systems

Location determination based on wireless local area networks has received considerable attention as an accurate and inexpensive means of indoor positioning. Research on this topic has mainly focused on experimental systems while little has been done to model and analyse the problem. Yet, analytical models are essential for understanding the influence of system parameters and a system’s overall behaviour. This article introduces two analytical models that can provide pessimistic and optimistic estimates for the location error in a given environment. The findings are compared to measurements and simulations of a probabilistic Wireless LAN positioning system.