MASCARA中的调度算法—PRADOS

WAND（Wireless ATM Network Demonstrate）是欧洲ACTS（Advanced Communication Technologies and Services）支持的项目之一。在WAND中采用一种基于集线器式、自适应TDMA方式的MAC协议—MASCARA,它通过预约与竞争相结合的方法,为无线ATM（WATM）终端提供具有QoS保证的宽带无线接入。文章着重分析了MASCARA中基于时延的优先权调节调度（PRADOS）算法,并给出了几种不同情况下的算法性能仿真结果。     

无线ATM网络体系结构及MAC层协议研究

无线ATM网络作为宽带多媒体通信的一种解决方案,近年来得到了广泛的研究。基于高速率、高可靠性的光纤信道的ATM网络扩展到无线环境面临着许多问题。本文介绍了无线ATM网络体系结构、协议栈、应用特点和关键技术,并重点讨论了无线ATM网络的MAC层协议。     

Implementing distributed and dynamic resource allocation in WATM

In this article a pragmatic approach for the dynamic resource allocation within the MAC layer of wireless ATM (WATM) networks is proposed. Emphasising ease of implementation and cost reduction, the protocols of MBS and Magic WAND are compared and evaluated. A novel MAC protocol called Distributed and Dynamic Resource Allocation (DADRA) is outlined. Central to this new scheme is the partial move of traffic prediction and computation into the mobile terminals, leaving the base station to co-ordinate media access based upon precise requests from the mobile terminals. The reduced processing demand on the base station may lower equipment costs and increase the number of supported connections.     

Impact of wireless access on traffic management in ATM networks

Traffic management plays an important role in providing differentiated quality of service and supporting the integration of a variety of broadband services within a common ATM network. Wireless ATM access networks are under definition in standards bodies as well as subject of various research activities and first field trials. The nature of the wireless medium requires new protocols that are able to cope with multiple access, error prone wireless channels, and user mobility. When attaching a wireless ATM network to a fixed ATM network proper interaction of traffic and resource management functions throughout both networks is necessary to achieve stringent QoS objectives. In this paper the relation between mobile specific protocols and traffic management functions as well as their mutual impacts are discussed. Three key areas to enable seamless traffic management integration are identified and possible solutions are outlined.     

无线ATM网介质访问控制协议的研究

近年来无线ATM网络得到广泛研究,扩展ATM网络的宽带业务至无线环境面临许多方面的问题。介质访问控制(MAC)方法是无线ATM网的关键技术之一。MAC层协议的好坏直接影响系统性能和移动终端的复杂性。文中综合分析目前已有的无线ATM介质访问控制协议及方法,指出设计无线ATM网MAC层协议的三条原则,提出下一步研究方向。     

无线ATM及其关键技术

近年来,ATM和无线通信两种技术得到了极为快速的发展.无线ATM(WATM)作为ATM网络的无线延伸的一种解决方案吸引了学术界和工业界广泛的兴趣:重点总结WATM系统的结构.并分析WATM的协议模型、对WATM协议集的每一个组成部分进行逐一探讨;最后介绍WATM的容错方法和与现代通信的融合.     

Ethersim: a simulator for application-level performance modeling of wireless and mobile ATM networks

The paper describes Ethersim, a simulation tool to model and study the performance of multimedia-oriented integrated service ATM networks with mobile hosts and wireless links. The key motivation behind Ethersim is to study the application-level impact of host mobility and wireless channels. Ethersim has a discrete event based simulator core and incorporates models of user applications and transport, network and MAC layer protocols. It provides the capability to specify a cellular wireless ATM network topology and host mobility patterns. The software architecture of Ethersim employs five special entities: an air module, a map, a mover, mobile hosts, and basestations. We also present case-studies of using Ethersim to model and study the interaction of transport layer, connection rerouting protocol, and radio characteristics in the SWAN [P. Agrawal, A. Asthana, M. Cravatts, E. Hyden, P. Krzyzanowski, P. Mishra, B. Narendran, M. Srivastava, J. Trotter, SWAN: A Mobile Multimedia Wireless Network, in: IEEE Personal Commun. Mag., April 1996] mobile and wireless ATM based multimedia network.     

AWACS: ATM Wireless Access System – potential candidate for European HIPERLINK standard

Wireless ATM is receiving a significant attention as a solution for wireless access. The integration of wireless access and ATM is an essential requirement for the future of telecommunications so that emerging wideband services which embody multimedia applications can be made transparently available to mobile terminals. There are many ongoing activities within the European ACTS program (Advanced Communications Technologies and Services) which are related to evolving ATM oriented wireless networks at various frequencies such as 5, 17, 40 and 60 GHz. AWACS (ATM Wireless Access Communication System) is one of these projects and addresses the feasibility of low cost, high-data-rate radio LAN systems based on ATM (both indoor and outdoor) at 19 GHz. This article overviews the AWACS project which has contributed to the definition of emerging European radio LAN standards such as ETSI BRAN HIPERLINK.     

wmATM enhanced software definable radio system

Driven by the markets and subscribers, broadband telecommunication services are getting more and more significant throughout the world. ATM and Internet technologies are taking the leadership in this storm to bring up the new era of information society. Wireless mobile communication is a very potential system in view of its low cost as well as flexible coverage. Constructing a new broadband, high-speed wireless mobile telecommunications, with full compatibility to existing wireless standards will become an emerging demand in the following years. This kind of system can provide real-time multimedia communications, including voice, data and video to each mobile user or host, and support free roaming and handover any time, anywhere and for anyone. Hence, an intelligent broadband software definable base station is proposed to reflect the advancement of the next generation wireless mobile communications. wmATM (wireless mobile ATM) based software radio will greatly contribute to this technology and enhance the system's performance.     

ATM战术网研究与发展

下一代的战术网（Ｔａｃｔｉｃａｌ Ｎｅｔｗｏｒｋｓ）是基于ＡＴＭ技术的。本文指出了把ＡＴＭ技术应用到战术环境中面临的主要问题;介绍了ＡＴＭ战术网及其典型范例ＰＯＳＴ－２０００;分析了无线ＡＴＭ协议体系,把ＡＴＭ战术网与无线ＡＴＭ进行比较;通过ＡＴＮＥＴ工程分析了未解决的问题和研究方向;展望了ＡＴＭ战术网的发展。     

Mobility management and control in intelligent wireless ATM networks

This paper shows how the Asynchronous Transfer Mode (ATM) signaling and the Intelligent Network (IN) concept can be exploited to support mobility in an ATM-based network with wireless access parts and mobile users. The proposed architecture exploits the enhanced service control processing features offered by the IN technology to support location management. The access signaling protocol structure is based on the principles of separation between call and bearer channel control, employed in fixed broadband access networks. The design objective is to minimize the changes required to the wired network signaling, by taking advantage of the well-developed capability sets. This allows the easy introduction of the wireless ATM technology (W-ATM) into the real world. It is shown that the proposed signaling protocol model provides cost-effective implementations without degrading the agreed Quality of Service (QoS) and the system's performance. A comparative signaling performance evaluation is carried-out to demonstrate the impact of the proposed signaling protocol architecture onto various performance measures and to quantify the relative gains. The obtained results can be used for network design purposes in a large-scale private installation supporting many users. The signaling protocol architecture aims for private W-ATM networks, but can be readily extended to fulfill the signaling requirements of public environment broadband wireless systems.     

Can the current generation of wireless mesh networks compete with cellular voice?

Wireless mesh networks are being deployed to provide broadband wireless connectivity to city-wide hotspots. The typical architecture in these deployments thus far is a single-radio architecture: mesh nodes carry only one radio, which is used both to receive the traffic from the clients and to relay this traffic through the mesh to the wired Internet gateway.In this paper, we study the performance of a representative single-radio mesh network both in a live setup and in a laboratory environment. We characterize the performance of different applications (e.g. VoIP), and study some key challenges of mesh networks such as the fairness in bandwidth allocation and hidden node terminal. Finally, we compare the results of the study with traditional cellular networks, and discuss various options to enhance the performance of wireless mesh networks in the future.     

基于ARM11的嵌入式无线视频终端的设计

随着无线局域网的广泛应用,为了在嵌入式系统中整合无线局域网宽带通信技术进行视频传输;提出一种基于ARM11硬件平台和嵌入式Linux操作系统的无线视频终端系统的设计方案,给出系统的总体设计和主要功能模块的实现,其中包括视频采集模块、无线视频传输模块的硬件设计,嵌入式Linux的驱动程序移植、H.264数字视频压缩及应用程序实现等;该系统实现了802.11无线局域网内的视频传输,实时监测网络的数据流量和拥塞状况,提高网络传输质量,保证视频播放流畅性,可靠性高且易于使用;实践证明本系统稳定性高,实时性好,运行可靠,可应用于视频监控领域。     

Transparent and scalable terminal mobility for vehicular networks

Future public transportation systems will provide broadband access to passengers, carrying legacy terminals with 802.11 connectivity. Passengers will be able to communicate with the Internet and with each other, while connected to 802.11 Access Points deployed in vehicles and bus stops/metro stations, and without requiring special mobility or routing protocols to run in their terminals. Existing solutions, such as 802.11s and OLSR, are not efficient and do not scale to large networks, thereby requiring the network to be segmented in many small areas, causing the terminals to change IP address when moving between areas.This paper presents WiMetroNet, a large mesh network of mobile routers (Rbridges) operating at layer 2.5 over heterogeneous wireless technologies. This architecture contains an efficient user plane that optimizes the transport of DHCP and ARP traffic, and provides a transparent terminal mobility solution using techniques that minimize the routing overhead for large networks. We offer two techniques to reduce routing overhead associated with terminal mobility. One approach is based on TTL-limited flooding of a routing message and on the concept of forwarding packets only to the vicinity of the last known location of the terminal, and then forward the packets to a new location of the terminal. The other technique lets the network remain unaware for a very long time that the terminal has moved; only when packets arrive at the old PoA does the PoA send back a “binding update” message to the correspondent node, to correct the route for future packets for the same terminal.Simulation and analytical results are presented, and the routing protocol is shown to scale to large networks with good user plane results, namely packet delivery rate, delay, and handover interruption time.     

A flat wireless ATM LAN architecture with distributed ATM switching in base stations

The infrastructure for cellular wireless ATM systems is normally assumed to be hierarchical with the ATM switching functionality being provided by centralised ATM switches. For easy installation of the infrastructure, a flat architecture is proposed for cellular wireless ATM LAN, which is enabled by a distributed ATM switch concept. In this concept, a smart ATM switching component is embedded into the wireless access point. The same component is used for a fixed ATM access point, too. A number of such switching components are connected in a ring topology to form the ATM backbone. A ring control protocol hides the ring-specific features from the user and assures that a standardised UNI is provided to any wireless and fixed terminal.     

A Parallel Dynamically Reconfigurable Architecture Designed for Flexible Application-Tailored Hardware/Software Systems in Future Mobile Communication

The evolving of current and future broadband access techniques into the wireless domain introduces new and flexible network architectures with difficult and interesting challenges. The system designers are faced with a challenging set of problems that stem from access mechanisms, energy conservation, error rate, transmission speed characteristics of the wireless links and mobility aspects. This paper presents first the major challenges in realizing flexible microelectronic system solutions for future mobile communication applications. Based thereupon, the architecture design of flexible system-on-chip solutions in the digital baseband processing for future mobile radio devices is discussed. The focus of the paper is the introduction of a new parallel and dynamically reconfigurable hardware architecture tailored to this application area. Its performance issues and potential are discussed by the implementation of a flexible and computation-intensive component of future mobile terminals.An erratum to this article can be found at     

Energy efficiency of femtocell deployment in combined wireless/optical access networks

Optical/wireless convergence has become of particular interest recently because a combined radio wireless and optical wired network has the potential to provide both mobility and high bandwidth in an efficient way. Recent developments of new radio access technologies such as the Long Term Evolution (LTE) and introduction of femtocell base stations open new perspectives in providing broadband services and applications to everyone and everywhere, but the instantaneous quality of radio channel varies in time, space and frequency and radio communication is inherently energy inefficient and susceptible to reflections and interference. On the other hand, optical fiber-based networks do not provide mobility, but they are robust, energy efficient, and able to provide both an almost unlimited bandwidth and high availability.In this paper, we analyze the energy efficiency of combined wireless/optical access networks, in which LTE technology provides ubiquitous broadband Internet access, while optical fiber-based technologies serve as wireless backhaul and offer high-bandwidth wired Internet access to business and residential customers. In this contest, we pay a particular attention to femtocell deployment for increasing both access data rates and area coverage. The paper presents a novel model for evaluating the energy efficiency of combined optical/wireless networks that takes into account the main architectural and implementational aspects of both RF wireless and optical parts of the access network. Several hypothetical network deployment scenarios are defined and used to study effects of femtocell deployment and power saving techniques on network’s energy efficiency in urban, suburban and rural areas and for different traffic conditions.     

A network algorithm for 3D/2D IPTV distribution using WiMAX and WLAN technologies

The appearance of new broadband wireless technologies jointly with the ability to offer enough quality of service to provide IPTV over them, have made possible the mobility and ubiquity of any type of device to access the IPTV network. The minimum bandwidth required in the access network to provide appropriate quality 3D/2D IPTV services jointly with the need to guarantee the Quality of Experience (QoE) to the end user, makes the need of algorithms that should be able to combine different wireless standards and technologies. In this paper, we propose a network algorithm that manages the IPTV access network and decides which type of wireless technology the customers should connect with when using multiband devices, depending on the requirements of the IPTV client device, the available networks, and some network parameters (such as the number of loss packets and packet delay), to provide the maximum QoE to the customer. The measurements taken in a real environment from several wireless networks allow us to know the performance of the proposed system when it selects each one of them. The measurements taken from a test bench demonstrate the success of our system.     

A survey on emerging broadband wireless access technologies

Wireless broadband technologies provide ubiquitous broadband access to wireless users, enabling services that were available only to wireline users. In this paper, we summarize emerging wireless broadband access technologies, ranging from WLANs to satellite communications. We explain the latest standards in the IEEE 802.11 and IEEE 802.16 families in detail. The MAC layer mechanisms of IEEE 802.11e, 802.11n, and 802.11s standards are explained as well as the point-to-multipoint and Mesh modes of IEEE 802.16. The recent mobility amendment to the WiMAX family, IEEE 802.16e, is also described. Though the earliest versions of some of these technologies date back to 1996 (such as IEEE 802.11) and some are obsolete (such as HiperLAN), they have been included in this survey for the sake of completeness.Wireless technologies can be categorized based on their coverage areas. IEEE 802.11 and ETSI HiperLAN standards are considered for wireless access in local areas. IEEE 802.16 and 802.22, ETSI HiperACCESS and HiperMAN, WiBro, and HAP technologies can be used to provide service in metropolitan areas. Lastly, IEEE 802.20 and satellite systems provide service as wide area networks. Since the aim of this survey is to summarize wireless broadband technologies for data services, technologies such as Wireless USB are excluded. 3G and 4G systems have also been excluded since they are covered in detail in [C. Smith, D. Collins, 3G Wireless Networks, second ed., McGraw-Hill Osborne Media, 2006; S.G. Glisic, Advanced Wireless Networks: 4G Technologies, Wiley Publishing, 2005].     

Mobility information for resource management in wireless ATM networks

User mobility poses a significant technical challenge to network resource management in wireless ATM (Asynchronous Transfer Mode) networks. In order to guarantee quality of service (QoS) to mobile users and to achieve a high efficiency in network resource management, the information of mobile users' handoff at a future moment is essential for statistical multiplexing. This paper develops a novel fuzzy logic inference system to estimate the user mobility information for a wireless ATM network which uses a direct sequence code division multiple access (DS/CDMA) protocol. The estimation is based on measured pilot signal strengths from a number of the nearest base stations by the mobile user. Numerical results are presented to demonstrate the performance of the proposed technique under various path losses and channel shadowing conditions. The proposed technique can achieve simplicity, accuracy and low cost.