地图发布平台下瓦片金字塔技术研究

瓦片金字塔技术是ArcGIS server地图发布中的关键技术之一,其主要是为客户端用户能快速查询和显示地图数据,服务器端对海量地图数据的存储管理;而地图预生成技术的出现,结合瓦片金字塔技术,进一步提高了B/S开发模式下客户端和服务器系统的响应速度.     

面向5G技术应用的纵向协作缓存技术研究

5G技术的应用,改善了网络尤其是移动网络的使用效果,使活跃于网络中的数据信息以指数级的速度增长,而现有的信息传输网络很难完全满足5G技术应用的信息传输与显示要求,容易出现诸如网络拥塞、时延较大、清晰度不够等问题,影响了用户的网络体验。对此,基于当前5G技术应用的实际,提出一种纵向协作的缓存技术方案,通过将终端、基站、核心网进行纵向位置的部署,来实现纵向协作缓存的目的,从而提高5G技术应用中的网络传输与网络存储能力,改善用户使用网络应用的体验。     

移动位置服务中网络地图服务迁移研究

分析对比了移动位置服务中现有的C/S和B/S两种地图服务模式。针对移动服务的特点,从提高用户的使用体验角度,提出一种基于B/S模式的网络电子地图服务迁移架构——MobileWMS,实现了地图服务、地图服务应用和地图数据等的分离与迁移。构建了系统原型并阐述了主要功能模块的实现。实验测试验证了该架构的可行性,与传统的静态、集中式的B/S地图服务模式相比,服务性能有明显的改善。     

配电线路智能巡检系统web离线地图的技术研究

文中阐述了配电线路智能巡检系统中web离线地图的开发与应用,论述了瓦片地图、Google Map API和系统技术方案,系统web离线地图显示有线路地图显示、巡视轨迹显示、设备地图显示等。     

瓦片地图技术在可视化基站管理系统中的应用研究

对于传统动态地图服务,客户端每进行一次请求,服务器都会根据请求重新读取数据库、渲染图片,导致系统性能低,而采用瓦片地图技术可以预生成不同级别的瓦片地图,采用瓦片地图作为背景地图,能提高系统的地图浏览、查询、空间分析等出图效率。本文对瓦片地图技术的技术实现以及在可视化基站管理系统中的应用进行了阐述。     

A-GPS终端一致性测试

A-GPS(Assisted Global Positioning System)是一种通过移动通信网络辅助的全球定位技术,此技术结合了两类位置信息,一类是移动台通过自身GPS接收机获得的,而另一类则是移动台通过移动通信网络获取的。A-GPS技术可以在2G,3G以及未来4G的通信网络中部署应用,移动终端应用A-GPS定位业务,需要增加A-GPS接收机及相应信号处理模块。A-GPS的终端一致性认证,即对于移动终端的A-GPS功能部分进行一致性验证,目前国际上采用的包含A-GPS一致性测试规范有3GPP51.010,3GPP34.171,3GPP34.123,3GPP2C.S0036,3GPP2C.S0059,OMA-ETS-SUPL等,本文对上述规范做了详细介绍。     

多模移动终端芯片设计

文章分析了B3G技术可能的演进进程,在此基础上,对移动终端基带处理芯片进行了介绍,并探讨了多模移动终端基带处理芯片的关键技术.文章认为B3G终端技术是B3G技术研究的重点,而移动终端基带处理芯片研发是B3G终端技术研究的重点,为此提出了一种统一无线平台,利用该平台可方便地进行多模移动终端基带处理芯片的研发.     

4G技术演进及移动终端芯片设计

文章分析了4G技术可能的演进进程，在此基础上，对移动终端基带处理芯片进行了介绍，并探讨了多模移动终端基带处理芯片的关键技术。作者认为4G终端技术是4G技术研究的重点，而移动终端基带处理芯片研发是4G终端技术研究的重点，为此提出了一种统一无线平台，利用该平台可方便地进行多模移动终端基带处理芯片的研发。     

基于云端的PCB版图在Web上的加速显示

本文提出将地图显示中常用的瓦片技术引入云端EDA工具PCB版图的显示中,从而达到使PCB版图在Web上加速显示的目的。     

5G毫米波移动终端测试关键OTA技术研究

对于5G通信,极高的数据速率和极可靠的低延迟的技术场景中,毫米波的大带宽是非常具有吸引力的关键技术。对于5G毫米波移动终端设备,由于支持系统级动态波束赋形和无法使用天线连接器,使得毫米波性能评估从传统的传导测量转向系统级的OTA测试。首先探讨了5G毫米波测试的背景,对三种用于毫米波移动终端的OTA测试方法,分析了其在5G毫米波终端测试中的适用性和局限性,接下来研究毫米波OTA测试方法面临的挑战及相应的解决方案,最后对毫米波移动终端测试技术进行总结。     

Optimized D-RAN Aware Data Retrieval for 5G Information Centric Networks

The evolution of wireless network services has enabled consumers and intelligent devices to freely exchange information with each other. Mobile users frequently exchange popular contents, resulting in massive increase in the mobile traffic. The redundant mobile traffic can be reduced by archiving the frequently accessed data within a 5G core network or radio access network, and demands for the same content can be readily met without relying on remote servers. In this paper, we propose an eNB/gNB aware data retrieval algorithm along with Liveliness and Size based data Replacement algorithm to refine, rank, and cache the data items efficiently. Data items are selected based on their popularity and cached in D-RAN for efficient data replacement. We have also included a cost-optimized Radar-Based data Retrieval algorithm that helps to find the data nearness in the neighbouring eNBs. In our proposed technique, unique contents are maintained at each end of the cluster to aid in extending content diversity within the cluster. The experimental analysis shows that the proposed model achieves lower latency, lower congestion, and higher cache hit ratio in 5G networks.

     

3G移动用户定位技术研究

探讨了第三代移动通信技术（3G,3rd-Generation）无线网络下的移动用户定位技术。一方面是该技术中的上游技术中的空间数据服务系统的设计,实现了系统数据架构模块、业务层模块、接口模块的功能;另一方面是便携式移动定位终端,将全球定位系统（GPS,Global Positioning System）以模块化的方式进行了嵌入,实现与上游中的数据库支持技术中的接口模块的设计与实现。在设计中考虑将GPS定位功能与3G网络支持下的定位功能进行结合,既可以单独使用也可以综合应用,这进一步提高了该设备的应用范围,这对于设备功能的强化是一种有益的尝试。     

基于模式抵消法的耦合环集成MIMO 天线

针对移动终端设备中MIMO 天线尺寸受限的问题,文中基于模式抵消法提出了一种耦合环结构的集成 MIMO 天线。在传统环天线结构中增加断点以调节共模频率使其与差模频率匹配,从而实现集成环天线的自解耦,无 需任何额外的解耦结构。仿真和测试结果表明,该耦合环集成MIMO 天线的-6dB 阻抗带宽为3.3~5.0GHz,隔离度 大于10 dB,天线的测试效率为52%~74%,包络相关系数(ECC)<0.15。此外,文中还进一步讨论了将该天线应用于实 际的5G 移动终端设备中。相比于已有研究,该设计具有结构简单、无需额外解耦结构、宽带等性能优势,具有较大的 工业应用前景。     

基于缓存窗口和段补丁预取的流媒体动态调度算法

该文提出了一种新的基于缓存窗口和段补丁预取的移动流媒体动态调度算法,采用代理缓存窗口自适应伸缩和分段缓存补丁块方案,实现了移动流媒体对象在代理服务器中缓存的数据量和其流行度成正比的原则。仿真结果表明,对于客户请求到达速率的变化,该算法比传统算法具有更好的适应性,在最大缓存空间相同的情况下,能显著减少通过补丁通道传输的补丁数据,从而降低了服务器和骨干网络带宽的使用,能快速缓存媒体对象到缓存窗口,同时减少了代理服务器的缓存平均占有量。     

A group-based data-driven approach for data synchronization in unstructured mobile P2P systems

This paper addresses the problem of data consistency on mobile peer-to-peer (MP2P) systems (or MP2P networks). The considered MP2P system is based on a mobile ad-hoc network, where the energy and connectivity on the mobile devices are limited. Since different mobile nodes may store copies of shared information, data synchronization on an MP2P system becomes crucial and challenging due to frequent disconnection and change on network topology caused by node mobility. We propose an effective approach to improving the performance of data synchronization with a dynamic inverted data indexing structure and group-based data-driven consistency management. The proposed approach can effectively synchronize the data items without using a central cache node in each group (or cluster) and perform well in terms of the coverage of successfully synchronized nodes and the number of redundant messages. Last, the proposed approach is validated through extensive simulation experiments.     

Mobility-aware caching in energy-harvesting-powered small-cell networks

Wireless Networks - The rapid increase of mobile devices has made user mobility one of the important factors affecting the cache. With the development of energy harvesting technology, the cache...     

一种支持MD无线接入的新型混合式P2P模型

混合式P2P软件是目前互联网上广泛应用的P2P文件共享软件，但混合式P2P协议并没有特别考虑移动设备（Mobile Device）线接入的问题。文章将在混合式P2P模型的基础上，针对MD计算能力、存储能力的限制和无线连接的特点．提出一种支持MD无线接入的新型混合式P2P网络模型。它通过扩展移动支持节点的功能，使用移动代理代表MD接入P2P网络共享资源。并利用客户机缓存技术进行优化，有效的减少了MD自身的开销以及无线通信的开销．同时对MD的移动性和无线连接的断接性提供了很好的支持。     

Dynamic cache invalidation scheme for wireless mobile environments

The caching of frequently accessed data items on the client side is an effective technique to improve performance in a mobile environment. Caching data in a wireless mobile computer can significantly reduce the bandwidth requirement. However, cache content needs to be validated; classical cache invalidation strategies are not suitable for mobile environments due to the disconnection frequency and mobility of the mobile clients. Attractive cache invalidation techniques are based on invalidation reports (IRs). But, IR-based cache invalidation schemes result in considerable consumption of uplink and download bandwidth. In this paper, we address these problems by presenting a new energy-efficient cache invalidation method for the wireless mobile environment. The new cache invalidation scheme is called Adaptive Energy Efficient Cache Invalidation Scheme (AEECIS). The algorithm is adaptive since it changes the data dissemination strategy based on the current conditions. To reduce the bandwidth requirement, the server transmits in one of three modes: slow, fast or super-fast. The mode is selected based on thresholds specified for time and the number of clients requesting updated objects. An efficient implementation of AEECIS is presented and simulations have been carried out to evaluate its caching effectiveness. The results demonstrate that it can substantially improve mobile caching by reducing the communication bandwidth (thus energy consumption) for query processing. Also, the reported results demonstrate that compared to previous IR-based schemes, AEECIS can significantly improve the bandwidth consumption and the number of uplink requests.

Proactive content caching by exploiting transfer learning for mobile edge computing

To address the vast multimedia traffic volume and requirements of user quality of experience in the next‐generation mobile communication system (5G), it is imperative to develop efficient content caching strategy at mobile network edges, which is deemed as a key technique for 5G. Recent advances in edge/cloud computing and machine learning facilitate efficient content caching for 5G, where mobile edge computing can be exploited to reduce service latency by equipping computation and storage capacity at the edge network. In this paper, we propose a proactive caching mechanism named learning‐based cooperative caching (LECC) strategy based on mobile edge computing architecture to reduce transmission cost while improving user quality of experience for future mobile networks. In LECC, we exploit a transfer learning‐based approach for estimating content popularity and then formulate the proactive caching optimization model. As the optimization problem is NP‐hard, we resort to a greedy algorithm for solving the cache content placement problem. Performance evaluation reveals that LECC can apparently improve content cache hit rate and decrease content delivery latency and transmission cost in comparison with known existing caching strategies.     

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.