A mobile virtual-distributed system architecture for supporting wireless mobile computing and communications

This paper describes a novel mobile virtual-distrubuted system architecture for supporting global mobile computing and communications. the principal contribution of this paper is to innovatively apply virtual memory concepts to mobile systems by deploying mobile-floating agents to de-couple services and resources from the underlying network and allow them to move around following their mobile users. The mobile-floating agents maintain data structures associated with a mobile user. By combining the mobile-floating agent functions with a predictive mobility management algorithm and location-aware caching and prefetching, services and user data structure are pre-connected and pre-assigned at the locations to which the user is moving. Thus, the users can maintain their data structures or immediately receive service with virtually the same efficiency as at the previous location.     

3G wireless communications for mobile robotic tele-ultrasonography systems

Mobile healthcare (m-health) is a new paradigm that brings together the evolution of emerging wireless communications and network technologies with the concept of 'connected healthcare' anytime and anywhere. In this article, we present the performance analysis of an end-to-end mobile tele-echography using an ultra-light robot (OTELO), over the third-generation (3G) mobile communications network. The experimental setup of the OTELO system over a 3G connectivity link used to measure the system performance is described. The performance of the relevant medical data and the relevant quality of service (QoS) issues defined in terms of the average throughput, delta-time packet delay, and jitter delay are investigated. The real-time 3G performance results show the successful operation of this bandwidth demanding robotic m-health system.     

第四代移动通信技术初探

目前，第4 代移动通信技术还只是处于业务和技术描述阶段，本文对4G 的框架进行了初步的分析和探讨。     

Satellite constellation design for 5G wireless networks of mobile communications

Satellite constellation design plays an important role in satellite networks. Network constellation system design can affect the effectiveness of current improvements of the communications link and the management of the entire network. The power requirement of the mobile stations and ground stations is very high in a geostationary Earth orbit communication system, which means the terrestrial terminal is hard to be made handheld for fifth generation mobile communications. The emergence of nongeostationary orbit satellites such as low Earth orbit satellites greatly compensates for the disadvantage of geostationary Earth orbit satellites. Based on the classical constellation design method, the orthogonal circular orbit constellation is proposed. The design objectives considered here are the following: global Earth coverage by low Earth orbit satellites, the duration of continuously covering one mobile station by one satellite is more than 9.57 min, the access satellite link duration time of the mobile station is more than 4.79 min, and the number of satellites and orbits is to be minimum.     

浅谈第四代移动通信技术

一、前言当第三代移动通信标准还在激烈地竞争的时候，第四代移动通信(4G)技术已经悄悄问世。目前有不少的国家已经投入了一定的人力，开展4G系统的研究，主要是对其概念与框架的研究，提出了不同于3G的设想。4G的概念可称为宽带(Broadband)接入和分布网络，具有非对称的超过2M     

Cell hopping: a lightweight architecture for wireless communications

We propose a novel lightweight cellular wireless network architecture called cell hopping. Unlike traditional cellular networks, cell hopping has base stations interconnected by wireless inter-base station links, WIBLs. WIBLs support all routing and switching in cell hopping networks, obviating the need for costly core networks (or a costly switching infrastructure). Cell hopping utilizes an unlicensed frequency and presents a low-cost, rapidly deployable solution for mobile communications. We discuss various technical challenges that must be addressed before cell hopping can become a reality. In particular, we concentrate on location management. We propose an on-demand location management technique that completely eliminates the need for location databases and periodic updates by mobile stations. We provide a few variations of the location management scheme, and compare their performance through simulation.     

Tracking mobile users in wireless communications networks

Tracking strategies for mobile wireless networks are studied. A cellular architecture in which base stations that are interconnected by a wired network communicate with mobile units via wireless links is assumed. The cost of utilizing the wireless links for the actual tracking of mobile users is considered. A tracking strategy in which a subset of all base stations is selected and designed as reporting centers is proposed. Mobile users transmit update messages only upon entering cells of reporting centers, while every search for a mobile user is restricted to the vicinity of the reporting center to which the user last reported. It is shown that, for an arbitrary topology of the cellular network (represented by the mobility graph), finding an optimal set of reporting centers is an NP-complete problem. Optimal and near-optimal solutions for important special cases of the mobility graph are presented     

Joint multipath-Doppler diversity in mobile wireless communications

We introduce a new approach for achieving diversity in spread-spectrum communications over fast-fading multipath channels. The RAKE receiver used in existing systems suffers from significant performance degradation due to the rapid channel variations encountered under fast fading. We show that the Doppler spread induced by temporal channel variations in fact provides another means for diversity that can be further exploited to combat fading. We develop the concept of Doppler diversity and propose a framework that exploits joint multipath-Doppler diversity in an optimal fashion. Performance analysis shows that even the relatively small Doppler spreads encountered in practice can be leveraged into significant diversity gains via our approach. The framework is applicable in several mobile wireless multiple access systems and can provide substantial performance improvement over existing systems     

第三代移动通信业务剖析

通信网络的发展已使得信息化的步伐大大加快，表现为：统一网络的趋势日趋明显，信息可以大范围、多形式交换；人们的生活、工作已经与信息的传递、加工、分析越来越密不可分，电子商务正成为一种新的工作、生活方式。正如GSM的标准化吸收了N-ISDN发展成果一样，第三代移动通信系统（简称3G，本文3G特指W-CDMA，2.5G特指GPRS，2G特指GSM）也试图吸收目前通信领域发展的最新成果，并考虑可预见未来技术所能达到的高度，实现一个先进的通信设施。3G网络是指单个运营商管理的电信网络，包括以W-CDMA、TD-CDMA技术实现的UTRAN…     

第三代移动通信技术的发展

移动通信从80年代进入人们的生活后，以每10年换一代的速度，走过了模拟话音系统和窄带数字话音系统两个阶段。在21世纪到来之际，完成了第三代移动通信系统(正式名称为IMT-2000系统)标准的制定工作，为今后十余年移动通信向多媒体数据通信的发展打下了基础。IMT-2000系统标准的发展历程与演进ITU在1996年底确定了第三代移动通信系统的基本框架，包括业务需求、工作频带、网络过渡要求和无线传输技术的评估方法等，并将FPLMTS更名为IMT-2000，其用意在于希望在2000年左右商用、最高速率达2Mb/s、工作在2GHz频段。IMT-2000的目标是…     

Evolution toward 4G wireless networking [Guest Editorial]

This special issue serves as a stimulus to promote and accelerate technological evolution toward 4G networking. The response to the call for papers for this issue is indicative of the great interest with which the community views this topic. Of the many high quality in depth and breadth papers received from both academia and industry around the world, we could only accommodate a selected few in this issue. The research on the next generation wireless networking involves many cutting-edge research topics, which are presented in some articles included in this special issue     

移动通信与无线接入业务趋于融合

过去的几年里,宽带移动通信引起了人们越来越多的兴趣,这主要由于移动用户数量的增加以及大量的移动用户希望能以高速率接入Internet,从而享受移动Internet和电子商务的乐趣。移动通信和无线接入的融合将会引起无线通信领域的新的热点,从而会出现一种新的网络架构,基于这种新的网络架构的无线通信系统在普通的配置下就可以向移动用户提供宽带服务并且支持高增值业务和交互式多媒体通信。目前半导体技术的高速发展也会使这种系统更容易实现。移动Internet是两者业务融合后的宽带无线通信系统的主要应用,通信终端会变得高度智能化,能…     

3G移动通信中的射频元器件

以高速传输数据并能传送图像为特征的第三代(3G)移动通信系统对通信设备提出了新的要求,同时也将毫无疑问地引发新一代移动终端的革命。WCDMA、CDMA2000和TD-SCDMA作为3G通信标准已获得国际电联(ITU)的认可,它们将兼容第二代移动通信系统并在其基础上投入运营。因此,相应的3G移动通信终端必将要求满足多模式和多频段工作的需要。多模、多频段手机研发取决于先进的元器件,而前端射频元器件一直是研发的“瓶颈”所在。本文简要分析和概括3G移动通信中相关射频元器件的现状和研发进展,同时也报道一些最近的研究成果。3G移动通信系统…     

Technology prospect of 6G mobile communications

To achieve a deeper level of intelligent communication for human beings,the sixth generation mobile communication system (6G) will realize the extension from the real world to the virtual world.To this end,the “human-machine-thing-genie” problem introduced by 6G was presented,and an evolved dual-world architecture for 6G was proposed.The architecture includes the fourth elements of 6G,genie,in the virtual world.The potential key theories and technologies to support the design and implementation of 6G were proposed and analyzed.     

移动通信中的开放性

技术创新的层出不穷,使得关于开放体系和专有体系之间的争论愈演愈烈。历史经验证明,开放体系带来长期的令人瞩目的商业价值。如开放标准通过漫游呼叫和不断增长的短信互通流量,大大提高了运营商的收入。汲取早期的成功经验,移动通信产业正在选择开放?体系,以期在多媒体信息及更先进的第三代移动服务方面取得进一步的成功。移动产业中的有关各方均从开放性中获益:消费者在终端、服务方面有更多选择,成本也更低廉;运营商能够以更低廉的成本快速部署新服务;设备制造商可以从更大的规模效益和由此带来的低成本中获益;应用开发商、供应商和转包…     

Technological developments and socio-economic issues of wireless mobile communications

During the last 10 years, wireless communications can be considered as the fastest growing segment of telecommunications. In fact, mobile telephones have become an everyday accessory for hundreds of million people, and they are increasingly being used in the most developed and many developing countries in the world. Current forecasts indicate that demands for wireless access will exceed the number of fixed access lines by year 2010. This paper examines the technological developments, as well as the worldwide social-economic impacts of wireless mobile communications. More specifically, it gives an overview on the technological developments of wireless mobile communications, describes the evolution towards the next-generation systems, analyzes the reasons for the growth rate of subscribers, and the related social development. As a conclusion, it suggests several solutions in response to dangerous behaviour generated by wireless terminals.