用EDA和禁忌搜索算法进行文本聚类

基于VSM的文本聚类忽略了文本关键词稀疏带来的相似度漂移问题和关键词之间的语义信息和各维度之间的关系,致使文本的相似度计算不精确,文中对相似度计算方法TF—IDF进行了改进,并提出一种新的聚类方法,利用分布式估计算法和禁忌搜索算法进行聚类,融合分布式估计算法的收敛速度快和禁忌搜索算法能跳出局部搜索的优点,首先对文本进行预处理,然后用分布式估计算法和禁忌搜索算法聚类,既能快速聚类又能防止聚类收敛到局部最优。测试结果表明这种算法行之有效。     

An efficient and fair cooperative approach for resource management in wireless networks

In cellular networks, the implementation of various resource management processes, such as bandwidth reservation and location updates, has been based on the one‐to‐one resource management information exchange paradigm, between the mobile nodes and the base stations. In this paper, we design and demonstrate the use of a distributed cooperative scheme that can be applied in the future wireless networks to improve the energy consumption for the routine management processes of mobile terminals, by adopting the peer‐to‐peer communication concept of wireless ad hoc networks. In our approach, the network is subdivided into one‐hop ad hoc clusters where the members of each cluster cooperate to perform the required management functions, and conventional individual direct report transmissions of the mobile terminals to the base stations are replaced by two‐hop transmissions. The performance evaluation and the corresponding numerical results presented in this paper confirm that our proposed scheme reduces significantly the overall system energy consumption when compared with the conventional one‐to‐one direct information management exchange approach. Furthermore the issue of fairness in dynamically selecting the various cluster heads in successive operational cycles of the proposed scheme is analyzed, and an enhanced algorithm is proposed and evaluated, which improves significantly the cluster head selection fairness, in order to balance the energy consumption among the various mobile terminals. Copyright © 2005 John Wiley & Sons, Ltd.     

基于环境模型的移动机器人路径规划

介绍了一种新的移动机器人路径规划方法。采用链接图法,对工作空间建模。用Dijkstra算法决策出全局最短路径,然后用遗传算法对此路径进行优化,得到全局最优路径。最后提出了一种对路径几何改进的方法。仿真结果表明,该方法方便简单,对所规划的路径质量有所提高。     

当前移动通信网络的规划与优化探讨

保持移动通信网络的持续、高效、高质量的运营,网络的规划和优化是必不可少的内容.本文概述了当前移动通信网络规划和优化的必要性、特点、主要内容和方法,同时对未来移动通信网络的评估体系和优化的一些发展方向做了进一步的探讨.     

适用于无人搜救机组的新型移动中继通信模型

为了提高无人机远程搜救系统的通信效率和整体搜救成功率,提出了无人搜救机组的新型移动中继通信模型。该模型引入移动中继和协同通信技术,实现无人机组之间以及无人机组与地面基站之间的通信连接、数据传输和信息同步。理论分析和仿真测试表明,该模型提高了无人机组的数据采集效率,减少了无人机组的数据采集时间,提高了控制平台的机动性和搜索效率。     

An efficient location cache scheme for three‐level database architecture in PCS networks

Recently, hierarchical architecture for location databases has been proposed in order to accommodate the growing number of personal communication systems users. With the three‐level hierarchical database architecture, which is compatible with the current cellular mobile systems, newly developed additional databases, including the regional location database (RLR), are positioned between the HLR and the VLRs. We propose an efficient cache scheme, the double T‐thresholds location cache scheme, which could reduce the network and database costs to lookup a portable using the three‐level architecture. This scheme extends the existing T‐threshold location cache scheme, which is effective only under the two‐level architecture of location databases currently adopted by IS‐41 and GSM. The idea behind our proposed scheme is to use two pieces of cache information, VLR and RLR, which serve the called portables. These two pieces are required in order to exploit not only the locality of a registration area (RA), but also the locality of a regional registration area (RRA), a wide area covered by the RLR. We also use two threshold values in order to determine whether the two pieces are obsolete. In order to model the RRA residence time, the branching Erlang‐∞ distribution is introduced. The cost analysis presented in this paper shows that the double T‐thresholds location cache scheme significantly reduces the network and database costs for most patterns of portables. Copyright © 2001 John Wiley & Sons, Ltd.     

An efficient MAC protocol for multi‐channel mobile ad hoc networks based on location information

This paper considers the channel assignment problem in a multi‐channel MANET environment. We propose a scheme called GRID, by which a mobile host can easily determine which channel to use based on its current location. In fact, following the GSM style, our GRID spends no communication cost to allocate channels to mobile hosts since channel assignment is purely determined by hosts' physical locations. We show that this can improve the channel reuse ratio. We then propose a multi‐channel MAC protocol, which integrates GRID. Our protocol is characterized by the following features: (i) it follows an ‘on‐demand’ style to access the medium and thus a mobile host will occupy a channel only when necessary, (ii) the number of channels required is independent of the network topology, and (iii) no form of clock synchronization is required. On the other hand, most existing protocols assign channels to a host statically even if it has no intention to transmit [IEEE/ACM Trans. Networks 1995; 3 (4):441–449; 1993; 1 (6): 668–677; IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352], require a number of channels which is a function of the maximum connectivity [IEEE/ACM Trans. Networks 1995; 3 (4):441–449; 1993; 1 (6): 668–677; Proceedings of IEEE MILCOM'97, November 1997; IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352], or necessitate a clock synchronization among all hosts in the MANET [IEEE J. Selected Areas Commun. 1999; 17 (8):1345–1352; Proceedings of IEEE INFOCOM'99, October 1999]. Through simulations, we demonstrate the advantages of our protocol. Copyright © 2005 John Wiley & Sons, Ltd.     

5G NR的小区搜索改进算法

5G NR时代对速率、容量和用户体验都有更高的要求。在5G NR物理层中,小区搜索是不可或缺的过程。小区搜索主要包括主同步信号(primary synchronization signal,PPS)检测算法以及辅同步信号(secondary synchronization signal,SSS)检测算法。传统PSS检测算法和SSS检测算法已无法满足5G NR各项指标的基本需求。为了解决这一问题,在传统M分段互相关检测算法基础上提出了改进PSS检测算法。当信道环境恶劣时,传统SSS检测算法也将失效,提出的改进SSS检测算法可以解决此问题。最后,对传统算法和改进算法进行仿真对比分析。仿真结果表明,改进算法的检测性能明显提升,检测效率和整体性能也提高了。     

A simple and efficient authentication scheme for mobile satellite communication systems

In this article, the authors shall propose a simple and efficient authentication scheme for mobile satellite communication systems. The proposed scheme can achieve the following security requirements: (S1) withstand impersonation attacks; (S2) withstand denial server attacks; (S3) withstand smart card loss attacks; (S4) withstand replay attacks; and (S5) withstand stolen‐verifier attacks, and achieve the following functionality requirements: (F1) freely choose identity; (F2) provide mutual authentication; (F3) provide session key agreement; (F4) provide user anonymity; and (F5) provide perfect forward secrecy. In additional, the proposed scheme does not use the high complex computation, such as public key cryptosystem or secret key cryptosystem, for the mobile users' side. The proposed scheme is only based on hash functions and exclusive‐OR operations. Compared with other schemes, the proposed scheme has a lower computation cost. It is more simple and efficient scheme. Copyright © 2011 John Wiley & Sons, Ltd.     

Estimation‐based cell search method for a mobile relay deployed on a moving network

Mobile relay (MR) can be deployed in many scenarios for a promising solution to extend a capacity in moving networks. The cell search is important for the mobility management. The cell search of the MR may cause two problems. First, all the mobile stations (MSs) connected via the MR experience service interruption during the cell search of the MR. Second, the wireless resources allocated to the MR is wasted during the cell search of the MR. To solve these problems, we propose an estimation‐based cell search method (ECSM) for the MR. The ECSM exploits the signal quality information measured by the MSs to detect the neighbor base stations (BSs) and to estimate the signal quality between the detected neighbor BSs and the MR. We verified the performance of ECSM in terms of estimation error, cell detection probability, and network overhead. Unlike the conventional estimation method, the estimation error of ECSM rapidly converges and attains to less than 1 dB when the number of measurements is 4. The ECSM can improve the cell detection probability at the expense of a relatively small amount of the signaling overhead. Therefore, the proposed method can be applied to a next‐generation relay‐enhanced cellular network. Copyright © 2016 John Wiley & Sons, Ltd.     

基于民用移动通信信号的经典TDOA定位算法分析

基于民用移动通信信号的无源雷达系统具有隐蔽性好、反隐身能力及抗干扰能力强、系统简单可靠等优点，近年来受到各国的重视，得到了较快的发展。针对基于民用移动通信信号的无源定位系统中Chan氏算法和Taylor级数算法的实现过程展开分析研究，并在不同的基站配置下，与其相应的定位精度卡拉美罗下限进行了比较，发现当测量误差的均方差较小时，利用Chan氏算法和Taylor级数算法均可以逼近卡拉美罗下限。     

An efficient algorithm for dynamic task offloading using cloudlets in mobile cloud computing

It is a visible fact that the growth of mobile devices is enormous. More computations are required to be carried out for various applications in these mobile devices. But the drawback of the mobile devices is less computation power and low available energy. The mobile cloud computing helps in resolving these issues by integrating the mobile devices with cloud technology. Again, the issue is increased in the latency as the task and data to be offloaded to the cloud environment uses WAN. Hence, to decrease the latency, this paper proposes cloudlet‐based dynamic task offloading (CDTO) algorithm where the task can be executed in device environment, cloudlet environment, cloud server environment, and integrated environment. The proposed algorithm, CDTO, is tested in terms of energy consumption and completion time.     

卫星与地面移动通信系统综合环境下的一种位置管理策略

提出了一种在卫星与地面移动系统综合环境下的位置管理方案，即把两系统相重叠的小区设置为边界位置区(BLA)，漫游用户在BLA中进行位置更新，呼叫到达时，BLA中的位置寄存器配合系统进行寻呼。通过计算和数值分析证明该方案不仅可以使原有两系统结构不发生变化，并且能有效减小位置更新与寻呼造成的系统开销。     

ATM网络虚通道路由规划的禁忌搜索方法

本文针对ＡＴＭ网络虚通道（ＶＰ）路由规划问题（简称ＶＲＰ）问题进行了分析,提出了使用禁忌搜索求解该问题的新方法,并分析了算法复杂度。仿真表明这种算法是有效的。     

An efficient authentication system of smart device using multi factors in mobile cloud service architecture

Mobile cloud computing environments have overcome the performance limitation of mobile devices and provide use environments not restricted by places. However, user information protection mechanisms are required because of both the security vulnerability of mobile devices and the security vulnerability of cloud computing. In this paper, a multifactor mobile device authentication system is proposed to provide safety, efficiency, and user convenience for mobile device use in cloud service architectures. This system improves security by reinforcing the user authentication required before using cloud computing services. Furthermore, to reinforce user convenience, the system proposed increases the strength of authentication keys by establishing multiple factors for authentication. For efficient entries in mobile device use environments, this system combines mobile device identification number entries, basic ID/password type authentication methods, and the authentication of diverse user bio‐information. This system also enhances authentication efficiency by processing the authentication factors of a user's authentication attempt in a lump instead of one by one in the cloud computing service environment. These authentication factors can be continuously added, and this authentication system provides authentication efficiency even when authentication factors are added. The main contribution is to improve high security level by through authentication of mobile devices with multifactors simultaneously and to use the mobile cloud service architecture for its efficient processing with respect to execution time of it. Copyright © 2013 John Wiley & Sons, Ltd.     

A tabu search heuristic for the routing and wavelength assignment problem in multigranular optical networks

This paper proposes a tabu search heuristic for solving the routing and wavelength assignment problem in multigranular optical networks, considering the wavelength-continuity constraint and a set of connections to satisfy. For a number of fibers per link, a number of wavebands per fiber, and a number of wavelengths per waveband, this algorithm attempts to minimize the total number of ports used in the network by efficiently grouping lightpaths into bands and fibers, and switching the whole bands and fibers. The algorithm has been implemented and tested on the NSFNET network, and comparisons have been made with the Balanced Path Routing and Heavy Traffic First (BPHT) algorithm in terms of number of ports. Generally, the results obtained with our tabu search heuristic are better than those provided by this algorithm.

移动通信中一种新的位置查询方案及其性能仿真

移动用户的剧增和移动通信业务的发展,对位置管理提出了更高的要求,因此,在移动通信的结构中,设计一个有效的位置管理方案是十分必要的。回顾了针对PCS网络的4种已经存在的位置查询方案,并提出了一种新的查询方案。仿真结果表明,这种新的位置查询方案在性能上要优于4种旧方案。     

Similar physical entity matching strategy for mobile edge search

In recent years, a large number of intelligent sensing devices have been deployed in the physical world, which brings great difficulties to the existing entity search. With the increase of the number of intelligent sensing devices, the accuracy of the search system in querying the entities to match the user’s request is reduced, and the delay of entity search is increased. We use the mobile edge technology to alleviate this problem by processing user requests on the edge side and propose a similar physical entity matching strategy for the mobile edge search. First, the raw data collected by the sensor is lightly weighted and expressed to reduce the storage overhead of the observed data. Furthermore, a physical entity matching degree estimation method is proposed, in which the similarity between the sensor and the given sensor in the network is estimated, and the matching search of the user request is performed according to the similarity. Simulation results show that the proposed method can effectively reduce the data storage overhead and improve the precision of the sensor search system.     

PSMECS: A provably secure ID-based communication in mobile edge computing

Human-centered systems play an important role in the modern world, for example, driverless car, autonomous and smart vehicles, drones, and robotics. The internet of things environment demands a faster real-time response depending on the applications processed in a particular duration. Mobile edge computing (MEC) allows a user to get a real-time response as compared with cloud computing (CC), although ensuring a number of security attributes in MEC environment remains challenging. In this article, a protocol is designed to achieve mutual authentication, anonymous communication, and security against traceability, as these are very crucial factors to ensure the security of data and user's privacy. Moreover, the proposed scheme ensures mutual authentication between a mobile user and an edge server along with the user's anonymity and untraceability. The proof of security and evaluation of performance of the scheme validates that it ensures security attributes and improves efficiency in terms of communication and computation overheads.     

An intelligent database proactive cache replacement policy for mobile communication system based on genetic programming

In the mobile environment, the movement of the users, disconnected modes, many data updates, power battery consumption, limited cache size, and limited bandwidth impose significant challenges in information access. Caching is considered one of the most important concepts to deal with these challenges. There are 2 general topics related to the client cache policy: cache invalidation method keeps data in the cache up to date and cache replacement method chooses the cached element(s) that would be removed from the cache once the cache stays full. The aim of this work is to introduce a new technique for cache replacement in a mobile database that takes into consideration the impact of invalidation time for enhancing data availability in the mobile environment by using genetic programming. In this case, each client collects information for every cached item in the cache like access probability, cached document size, and validation time and uses these factors in a fitness function to determine cached items that will be removed from the cache. The experiments were carried by NS2 simulator to assess the efficiency of the proposed method, and the outcomes are judged against existing cache replacement algorithms. It is concluded that the proposed approach performs significantly better than other approaches.