Antenna systems for broadband wireless access

Broadband wireless access along with evolving mobile Internet and multimedia services are driving the surge of research and development activities for future wireless communication systems. We provide an overview of antenna systems for broadband wireless communications and introduce some of the important issues surrounding them. The approach we use is to first provide a general framework of how antenna systems may be utilized in wireless communication systems and then describe the antenna systems themselves. In particular, we consider antenna systems for the base station, mobile station, and then finally multiple-input multiple-output antenna systems where antenna systems are utilized at both the base and mobile stations     

On architectures for broadband wireless systems

The growing popularity of portable and mobile computing and communication devices, along with the introduction of wireline broadband networks, is fueling demand for wireless broadband networks. Since ATM has been accepted as the standard for broadband integrated service networks, the authors consider the problem of providing “ATM-like services” to mobile devices. The fundamental issues that have to be tackled in order to provide broadband services which are currently available (or will be very shortly) to wireline hosts are discussed. The authors compare and contrast the architectures that have been proposed for extending the broadband wireline network infrastructure to the wireless environment. It is argued that transporting small ATM cells over the air leads to inefficient utilization of the already scarce transmission capacity. Subsequently, the authors propose an architecture for integrated wireless and wireline broadband networks which allows the wireline and wireless parts of the network to be designed independently, therefore allowing each to be optimized for the environment in which it operates. At the same time, the proposed architecture also permits simple and efficient interconnection between the wireline and wireless infrastructures     

An exploration of user-generated wireless broadband infrastructures in digital cities

This paper examines the broadband connectivity options available in digital cities. It offers an overview of services provided by commercial operators, the public sector and by citizens themselves, arguing that shortcomings in existing fixed broadband and commercial mobile broadband services provide an opportunity for citizens to share their own wireless broadband connections. It explores Wi-Fi hotspot provider FON’s approach to extending mobile broadband infrastructure by enabling shared connections within communities. The paper outlines some reasons why this specific user-generated approach to infrastructure provision has been unable to deliver highly robust broadband infrastructure, and discusses ways in which users and the public sector can be involved in developing new mobile infrastructures that will meet citizens’ needs.     

WiMAX应用潜力分析

文章分析了WiMAX在固定宽带无线接入场合和便携、移动通信场合的应用前景.文章认为:在固定宽带无线通信中,WiMAX会广泛应用于家庭用户、IP语音用户、传输承载用户和集团客户,为他们提供宽带无线接入;在便携、移动通信中,IEEE802.16即将集成到笔记本电脑和个人数字助理(PDA)等便携式电子设备中,实现在城域网范围内的可移动的宽带无线数据服务;用户需求加上WiMAX设备的批量上市及终端成本的下降,WiMAX的应用潜力巨大,市场将呈几何级增长.     

无线宽带通信系统及其应用分析

移动多媒体在提供服务的过程中,主要是要将文本、图形、语音等信息经过任意整合提供给用户.在这一过程中为了确保移动多媒体能够为用户提供优质的服务必须努力构建覆盖面广、质量高的无线宽带建设.从整体上看,我国无线宽带通信网在2002年之后建造速度不断加快,在进行研究的过程中,文中主要以TD-LTE技术为例进行了研究.     

UniNet: a hybrid approach for universal broadband access usingsmall radio cells interconnected by free-space optical links

A new type of broadband access system is proposed for providing high-quality, bandwidth-upon-demand telecommunication services to the home and office. Communication terminals attach to the network via short radio links, and users can roam freely within a house or building unencumbered by the availability of wired “telecommunications outlets”. Basic service is extended through small, high-capacity radio cells; the base stations are interconnected via short, highly focused free-space optical links in a multihop mesh arrangement; and the need for new broadband access cabling is totally surmounted. A tiered arrangement of radio cells further extends service to both out-of-building pedestrian and vehicular users, and service is universally available. Benefits of the approach are described, and issues involving reliability, availability, capacity, and hand off are identified and addressed. Opportunities to refine the basic approach are suggested for further study     

Broadband Wireless Access Solutions - Progressive Challenges and Potential Valueof Next Generation Mobile Networks

The growth in mobile communication will accelerate over the next years. Today most of the mobile subscribers use cellular services only. But this will change in the near future towards broadband wireless access services like WiFi and WiMAX. This paper describes a fundamental overview of the broadband wireless access technologies and outlines the market view, major trends and introduces OFDM technologies. New developments for integration of broadband wireless access into the operators' infrastructure are also discussed.     

新3G系统——无线移动因特网

本文提出一种新3G系统,这种新3G系统立足于3G框架之内,使用3G的工作频率,采用现有的技术实现具有IMT－2000以后系统特征的宽带无线移动因特网系统。运营商可以利用其已有的固定宽带因特 资源建设发展宽带无线移动因特网,并且可以以极低成本在其上提供新话音和多媒体业务,我国发展新3G系统将引领世界宽带无线移动因特网发展潮流。     

Capacity and delay of hybrid wireless broadband access networks

An optical network is too costly to act as a broadband access network. On the other hand, a pure wireless ad hoc network with n nodes and total bandwidth of W bits per second cannot provide satisfactory broadband services since the pernode throughput diminishes as the number of users goes large. In this paper, we propose a hybrid wireless network, which is an integrated wireless and optical network, as the broadband access network. Specifically, we assume a hybrid wireless network consisting of n randomly distributed normal nodes, and m regularly placed base stations connected via an optical network. A source node transmits to its destination only with the help of normal nodes, i.e., in the ad hoc mode, if the destination can be reached within L (L /spl geq/ 1) hops from the source. Otherwise, the transmission will be carried out in the infrastructure mode, i.e., with the help of base stations. Two transmission modes share the same bandwidth of W bits/sec. We first study the throughput capacity of such a hybrid wireless network, and observe that the throughput capacity greatly depends on the maximum hop count L and the number of base stations m. We show that the throughput capacity of a hybrid wireless network can scale linearly with n only if m = Ω(n), and when we assign all the bandwidth to the infrastructure mode traffics. We then investigate the delay in hybrid wireless networks. We find that the average packet delay can be maintained as low as Θ(1) even when the per-node throughput capacity is Θ(W).     

The future generations of mobile communications based on broadband access technologies

The forthcoming mobile communication systems are expected to provide a wide variety of services, from high-quality voice to high-definition videos, through high data rate wireless channels anywhere in the world. The high data rate requires broad frequency bands, and sufficient broadband can be achieved in higher frequency bands such as microwave, Ka-band, and millimeter-wave. Broadband wireless channels have to be connected to broadband fixed networks such as the Internet and local area networks. The future-generation systems will include not only cellular phones, but also many new types of communication systems such as broadband wireless access systems, millimeter-wave LANs, intelligent transport systems, and high altitude stratospheric platform station systems. Key to the future generations of mobile communications are multimedia communications, wireless access to broadband fixed networks, and seamless roaming among different systems. This article discusses future-generation mobile communication systems.     

支持下一代无线宽带应用自适应QoS模型的研究

作为真正完整的下一代网络 ( NGN,Next Generation Network)解决方案 ,NGN需要在固定通信领域和移动通信领域都能够支持综合多媒体特性。NGN中的新一代移动通信网承载在开放式、层次化结构的分组交换网络之上 ,能够为用户提供端到端的 Qo S解决方案。本文分析了下一代移动通信系统中多媒体宽带应用的 Qo S问题 ,从无线通信系统的多层次结构出发 ,建立了业务流的 Qo S指标评判体系 ,为下一代网络中的无线宽带应用提供了一种自适应Qo S控制模型     

Mobile WiMAX: a technology update

The success and growth of Internet-based services has profoundly impacted the global economies, as well as the ways people communicate and their lifestyles. With ever increasing demands for accessing the Internet via mobile devices, the focus of next-generation mobile wireless technology development is to enable and efficiently deliver broadband mobile multimedia and Internet services to users. The communication industry is making big strides in the design of next-generation broadband mobile networks which are poised to enormously increase the value of the Internet and its usage by bringing the Internet to users as opposed to having users go to the Internet.     

D2D中基于社交关系的按需用户发现策略

无线多媒体业务的爆炸式增长使得D2D(Device-to-Device)通信技术成为下一代移动通信系统的研究热点。用户发现策略,作为D2D关键技术之一,旨在有效发现潜在的D2D邻居用户。基于现有用户发现策略建立D2D链路,正面临着有效性和安全性的巨大挑战。本文考虑到每个用户不可避免地处于移动社交网络中,提出了基于社交关系的按需用户发现策略。主要根据用户请求的文件、具有的社交关系以及基站反馈和更新系统用户的状态信息表,来发现潜在的D2D用户对并建立D2D链路。理论分析及仿真结果表明,该策略可以更有效地发现邻居用户,并提高了D2D链路建立的安全性。      

Going Wireless,Enabling an Adaptive and Extensible Environment

This paper discusses limitations in existing and projected solutions for delivering applications to mobile users (e.g., in 3G) in an increasingly diverse heterogeneous wireless infrastructure in combination with the on-going deregulation of mobile communication and with an increasing number of more narrowly defined roles of parties participating in the delivery of applications to mobile users. Furthermore, for future service growth, users need to be the center of communication via applications that take into account the user's context or the context of their communication based on any event and not just the invocation or release of communication resources. This calls for entirely rethinking the architectures and frameworks for the delivery of services, in order to create open and scalable support for the negotiation between participating entities with a minimum of a priori and shared knowledge, thus providing an adaptive and extensible environment for user-centric communication. This paper presents a novel architecture and components with these properties and discusses the merits of the approach, followed by a discussion of experimental results demonstrating the feasibility of applying this architecture.     

A communication gateway for infrastructure-independent 4G wirelessaccess

Wireless communication infrastructure is characterized by an increasing multitude of heterogeneous systems. At the same time, service provider models are established and services designed to span physical networks irrespective of the access method used. To provide an infrastructure-independent access to services and applications for highly mobile users (e.g., in cars), we present a communication gateway architecture as an important component of fourth generation wireless communication systems. We especially emphasize the role of digital broadcast networks for future mobile networking     

Universal broadband mobility target for post-TINA infrastructure:toward the fourth generation

Future universal broadband mobile services present a challenge for telecommunications architectures, control, and management. The focus of the future mobile (fourth) generation vision is turned from capacity to services, from radio to network-wide issues. New types of applications will evolve that should be supported by an adequate programmable intelligent telecommunications infrastructure. A convergence between telecom and datacom networks will happen based on the communications middleware concept, which will provide universal secure connectivity between mobile users and their applications. Actual specifications of TINA-C do not address all such necessary issues. There is a need for technology evolution, enhancement, and integration to meet these new requirements at different levels. The author the concept of the universal broadband mobile telecommunications systems (UBMTS, or simply UBM) described as fourth-generation mobile systems. The UBMTS objective is both to extend mobile user access to the range of broadband services that will exist for broadband integrated services digital network (B-ISDN) users, and to extend the customization of new services related to personal communications systems (PCS) users     

Adjacent-Cell Interference in Direct-Sequence CDMA Forward Traffic Channels

Each transmission from a base station in a mobile cellular direct-sequence CDMA network is a source of interference for the receivers in the mobile handsets that are operating in adjacent cells. This interference can limit the capacity of the forward traffic channels. The effect of adjacent-cell interference on the performance of the handset receivers is evaluated for a mobile cellular CDMA network that employs quadriphase-shift-key spreading, convolutional coding, and soft-decision decoding. It is demonstrated that acceptable performance may not be possible for a fully loaded cellular network. Of particular interest in this paper are cellular networks in which the base stations are mobile and must be interconnected by wireless communication links. Such networks are important for military applications and certain civilian emergency communications services.     

Channel Allocation to Multiservice Wireless Networks: A Collocation—Based Approach to Enhance Spectrum Utilization

A channel allocation (CA) scheme is proposed for wireless networks serving multiple services. The CA scheme is based on collocating the base stations of the wireless networks and restricting their coverage over common cells. The increased coverage granularity makes feasible a more efficient frequency reuse. A genetic algorithm approach is adopted to minimize the number of channels required by the multiservice networks, taking into account the intranetwork and intraservice constraints over a specific coverage area. To validate the proposed scheme and investigate its performance, the Philadelphia benchmark network is employed. Simulation results corresponding to a mix of digital TV and mobile services of various profiles demonstrate the capability of the proposed scheme to optimally allocate channels to multiservice wireless networks.     

5G双小区协作流动热点补偿研究

在通信用户数密集用户业务总量较多的UMi场景下,无线网络节点较多小区覆盖半径较小,用户在小区间移动导致小区间用户分布不均匀,原有用户数及业务量标准部署的5G异构网络相对稀疏,无法满足用户流动产生热点热时容量需求时,双小区协作流动热点补偿采用异构网络多点协作传输技术对小区进行补热,将处于相同移动状态的多个用户虚拟成一个以中心用户为中心的用户簇,建立3D MIMO流动热点模型,提出在两小区以用户最小传输速率为约束条件,最小化小区基站总功率的优化算法,得出高容量、高速率用户体验的"潮汐效应"解决方案。     

Next Generation Wireless Mobile System Efficient, Fair, Class Based Packet Scheduling Algorithm

Efficient utilization of network resources is a key goal for emerging broadband wireless access systems (BWAS). This is a complex goal to achieve due to the heterogeneous service nature and diverse quality of service (QoS) requirements of various applications that BWAS support. Packet scheduling is an important activity that affects BWAS QoS outcomes. This paper proposes a novel packet scheduling mechanism that improves QoS in mobile wireless networks which exploit IP as a transport technology for data transfer between BWAS base stations and mobile users at the radio transmission layer. In order to improve BWAS QoS the new packet algorithm makes changes at both the IP and the radio layers. The new packet scheduling algorithm exploits handoff priority scheduling principles and takes into account buffer occupancy and channel conditions. The packet scheduling mechanism also incorporates the concept of fairness. Performance results were obtained by computer simulation and compared to the well known algorithms. Results show that by exploiting the new packet scheduling algorithm, the transport system is able to provide a low handoff packet drop rate, low packet forwarding rate, low packet delay and ensure fairness amongst the users of different services.