新一代的无线通信技术—软件无线电

软件无线电（ｓｏｆｔｗａｒｅｒａｄｉｏ）是近几年提出的一种实现无线通信的新体制,是无线通信领域的一次重大变革。文章论述了软件无线电的概念和体系结构,分析了实现的关键技术和难点,并介绍了美国军用的Ｓｐｅａｋｅａｓｙ实验系统。     

虚拟无线电

随着现代模数（A／D）转换器和数字信号处理（DSP）芯片的进展,无线通信领域正进行着一次被称为“软件无线电”的新变革,即采用宽带无线接收机来取代原来的窄带接收机,将A／D转换器尽可能地靠近天线,通过软件来实现各种无线通信功能。由美国麻省理工大学提出的虚拟无线电（VR）的思想与其相类似,但另有特殊之处。与大多数软件无线电不同的是,虚拟无线电不是由软件控制的专门数字硬件或者是由DSP芯片实现的,而是从通用机角度出发,充分利用工作站等计算机资源来实现软件无线电的。虚拟无线电是指这样的通信设备：所有的数字信号…     

21世纪无线通信的频谱考虑与实现技术

无线通信可能是下一个世纪的主要接入模式。国际移动通信－２０００系统（ＩＭＴ—２０００）和无线异步传输模式（ＷＡＴＭ）是两种不同的但又可以互操作的，能够提供高速无线接入的手段。无线电频谱资源的限制和无线信道传播对系统发展的特殊影响是必须考虑的问题。本文对上述系统的频谱需求和实现技术进行了论述，并对目前欧洲和亚太地区的频谱指配情况做了简要介绍。     

软件无线电概述

软件无线电是最近几年提出的一种实现无线通信新的体系结构,其基本概念是把硬件作为无线通信的基本平台,而把尽可能多的无线及个人通信功能用软件实现。 作为一种新的无线通信概念和体制,软件无线电在国内外受到广泛重视。本文将介绍软件无线电的发展简史、研究机关、应用范围、技术难点。     

无线ATM技术的研究

为使无线个人通信具有较大的系统容量和能灵活地处理多种宽带业务，在未来的个人通信中采用ＡＴＭ的传输与交换是一种必然的趋势。本文基于ＡＴＭ网络技术，提出了无线ＡＴＭ网络协议参考模型和网络实现体系结构，并探讨了在无线通信体制下的集成智能网络协议模式与实用虚拟网络结构。     

软件无线电技术在通信系统中的应用

无线通信系统往往需要通过不同的制式,通过在不同的频段进行不同的工作从而实现,因此它无法具有互通和兼容性。软件无线电技术则通过构建一个开放性的,标准化的,规模块的通用硬件平台,通过软件来实现各种功能,从而构建了新一代的无线通信系统,实现了通信系统的历史变革。本文首先对软件无线电技术进行了概述,在此基础上对软件无线电技术在通信系统中的应用进行了探讨,给出了一些自己的看法和建议。     

软件无线电数字前端的一种新实现方法

软件无线电（Ｓｏｆｔｗａｒｅ Ｒａｄｉｏ简称ＳＷＲ）是９０提代提出的一种全新的无线通信体系结构，它可使通信系统具有良好的灵活性及可扩展性。为使软件无线电中实现通用无线通信系统，较为理想的情况就是使Ａ／Ｄ和Ｄ／Ａ变换器尽量向射频端靠拢，即完成射频中到中频的下变频后，对整个中频频段作Ａ／Ｄ变换，这之后整个处理都用可编程数字器件以及软件来实现。这样的实现结构将具有非常大的灵活性，可以满足软件无线电的灵活     

软件无线电技术简介

1软件无线电的概念 1992年5月在美国通信系统会议上,Joe Mitola首次提出了“软件无线电”（Software Radio）的概念。软件无线电是一种实现无线通信的新的体系结构。它的基本概念是把硬件作为无线通信的基本平台,把尽可能多的无线通信及个人通信功能用软件实现。这样无线通信新系统、新产品的开发将逐步转到软件上来．而无线通信产品的价值将越来越多地体现在软件上．打破了传统通信功能的实现仅仅依赖于硬件发展的格局。     

DSP＆FPGA在软件无线电中的应用

软件无线电（ＳｏｆｔｗａｒｅＲａｄｉｏ）是近几年来提出的一种实现无线通信的新体系结构。它的提出是针对现在无线通信领域存在的一些问题,如：多种通信体系并存,各种标准竞争激烈,频率资源紧张等等。特别是无线个人通信系统的发展,使得新的系统层出不穷,产品生存...     

移动通信系统中基站接收单元的设计研究

随着越来越大的通信需求，一方面使通信产品的生存周期缩短，开发费用上升；另一方面，新老体制通信共存，各种通信系统之间的互联变得更加复杂和困难。随着通信技术的迅猛发展，新的通信体制与标准不断提出，通信产品的生存周期减小，开发费用上升，导致以硬件为基础的传统通信体制无法适应这种新局面；同时，不同体制间互通的需求日趋强烈，并且随着通信业务的不断增长，无线频带资源变得越来越拥挤，对现有通信系统的频带利用率及抗干扰能力提出了更高的要求。但是沿着现有通信体制的发展，很难对频带重新规划。所以，寻求一种既能满足新一代移动通信系统需求，又能兼容老体制，而且更具有扩展能力的新的个人移动通信系统体系结构成为人们努力的方向。而软件无线电正好提供了解决这一问题的技术途径，成为第3代移动通信系统研究的热点。软件无线电的基本思想是以硬件作为其通用的基本平台，把尽可能多的无线及个人通信的功能用软件来实现，从而将无线通信新系统、新产品的开发逐步转移到软件上来，其产值也在软件上体现出来。     

移动多媒体通信中无线AIM接入和结构

本文讨论移动多媒体通信中无线ＡＴＭ的基本概念和结构，包括无线ＡＴＭ概念，ＡＴＭ无线接入，无线ＡＴＭ网络，协议，信元和传输结构。研究无线信道给移动多媒体通信带来的影响和解决方法。     

Wireless ATM networks: technology status and future directions

The concept of “wireless ATM” (WATM), first proposed in 1992, is now being actively considered as a potential framework for new-generation wireless communication networks capable of supporting integrated, quality-of service (QoS) based multimedia services. In this review paper, we outline the technological rationale for wireless ATM, present a system-level architecture, and discuss key design issues for both mobile ATM switching infrastructure and radio access subsystems. The WATM radio access layer issues covered in this paper include: spectrum allocation; spectrum etiquette; modem technology; and medium access/data link control (MAC/DLC) protocols. Mobile ATM aspects such as ATM signaling extensions for handoff control, location management, and mobile QoS control are discussed. A summary of current wireless/mobile ATM technology development and standardization status is given, including an outline of our WATMnet prototype. The paper concludes with a discussion of future directions for wireless ATM technology such as Internet protocol (IP) integration and mobile multimedia terminals/applications     

A Cross-Layer Adaptive Modulation and Coding Scheme for Energy Efficient Software Defined Radio

In this paper, a simple and novel cross-layer adaptive modulation and coding (AMC) scheme, which increases the energy efficiency of the wireless communication system is proposed. Traditionally, AMC has been used to improve MAC-layer performance in terms of coded bit error rate, packet error rate, and throughput. The modulation and coding scheme is switched according to signal-to-noise ratio thresholds at the PHY layer. We extend the approach, proposing a framework for energy-efficient cross-layer AMC that captures the impact of both MAC layer and PHY layer parameters on the AMC switching criteria. Cross-layer designs are naturally suited to software defined radio applications. Not only are they readily implemented in software, but also they are integral to the radio components. They can optimize performance of the radio either for a given configuration or adaptively. Through examples of WLAN physical layer and Frequency Domain Equalized systems, we demonstrate our AMC scheme and verify its effectiveness by simulation.     

Applying IP over wmATM technology to third generation wirelesscommunications

With the rapid development of third-generation wireless mobile communication systems worldwide, the wireless mobile ATM enhanced software radio platform has taken the lead in the implementation process, which helps construct a broadband wireless pipe and “IP over wmATM” open signaling suite to support various common air interfaces for the wireless industry. This article presents the implementational issues using the IP over wmATM solution for 3G broadband wireless mobile communication systems. It includes the design of the wmATM medium access controller, protocol stack, wmATM module definition, and software radio platform, as well as IP unified 3G wireless networks     

基于SCA无线通信系统的安全体系结构研究

采用软件无线电技术和模块化设计思路,构造新一代的无线通信系统,是无线通信发展的趋势。介绍了软件通信体系结构(SCA)的无线通信系统,描述了基于SCA无线通信系统的安全体系结构,详细分析了加密子系统、信息安全子系统和设备安全子系统。这样定义的安全体系结构保证了基于SCA无线通信系统实现不同的安全模式,提供不同的安全级别。     

Spectrum harvesting for heterogeneous wireless networks integration

Massive capacity demand is a major impetus behind the advances, in various ways, of today and near future wireless communication networks. To face this challenge, more wireless spectrum is needed, efficient usage of this spectrum is necessary, and adequate architectures are required. In this paper, we present a conceptual solution based on a cognitive-radio-inspired cellular network, for integrating idle spectrum resources of different wireless networks into a single mobile heterogeneous wireless network. We describe the conceptual architecture of this integrating network, referred to as Integrating cognitive-radio-inspired cellular network (I-CRICNet), and present a cooperative spectrum-harvesting scheme that keeps the former supplied with spectrum resources. In the latter scheme, we make extensive use of cross-correlated sequences (CSSs), for events signaling purposes. This choice is motived by the particularly interesting characteristics of the CSSs, namely, duration shortness, robustness to bad radio conditions, detection rather than decoding, and low probability of collision. As an illustration, we propose a reporting and detection scheme, in the context of OFDMA systems, and provide performance results from simulations to validate our proposal.

     

Wireless ATM LAN with and without infrastructure

We consider wireless ATM concepts for small LANs, especially for SOHO and future consumer applications. We describe a wireless ATM LAN framework architecture that supports wireless ATM communications in environments with and without fixed ATM infrastructure. For the configuration with an ATM infrastructure, a distributed ATM switched backbone is proposed, which enables a smart ATM switching element to be embedded in every wireless and fixed access point. For bandwidth efficiency and ease of operation (place-and-play), we also propose an ad hoc wireless ATM LAN concept based on the same 5 GHz wireless ATM air interface as is currently under standardization in the ETSI/BRAN and ATM Forum. Unlike CSMA-based ad hoc systems such as HIPERLAN and IEEE802.11, our ad hoc wireless ATM system makes QoS management feasible in an infrastructureless environment by using resource reservation and scheduled medium access protocol. Since cost scalability is essential throughout our system design, we consider forwarding between ad hoc subnets and interworking with the fixed network as important but optional features     

Radio resource sharing for ad hoc networking with UWB

Ultra-wideband (UWB) radio is becoming a promising field for new generation's digital communication systems. This technique, based mainly on the impulse radio paradigm, offers great flexibility and shows enormous potential in view of a future broadband wireless access. We present the main principles to design a multiaccess scheme based on UWB. The potential of UWB is exploited within a distributed ad hoc wireless system, where we describe the principles for the definition of a medium-access control (MAC) for mobile computing applications and we analyze the main performance results derived from simulations. A general framework for radio resource sharing is outlined for classes of traffic requiring both elastic-dynamic and guaranteed-reserved bandwidth. Then, we discuss the issue of supporting the proposed radio resource sharing scheme by means of a distributed MAC protocol.     

Emerging wireless broadband networks

The rapid evolution of mobile wireless access networks toward multimedia support with QoS provision forces the development of advanced wireless broadband systems with high reliability and high data rate. To achieve this goal, new system design concepts with increased system capacity will be required. In that context, ATM is becoming a major infrastructure, receiving a lot of attention for telecommunication systems since ATM networks can most effectively support wireless access systems. Wireless ATM systems have low transmission cost, flexible functionality, mobile ATM protocol, and radio access layer protocols. This article overviews the various wireless broadband systems studied at 5, 19.37, 40, and 60 GHz by European Union funded projects within the ACTS program. Moreover, related standardization activities and network evolution are also addressed     

基于无线信道特征的内生安全通信技术及应用

伴随着信息技术的高速发展,无线通信网络的安全形势日益严峻。数以亿计的设备接入无线通信网络中,针对用户隐私以及基础网络环境的窃听、攻击事件频频发生,无线通信网络的安全问题已成为限制无线通信业务广泛开展的严重障碍。传统认证与加密机制与传输相脱离,以密码算法和分发密钥的私密性为前提,容易受到物理层的攻击。为此,迫切需要深入开展面向物理层的安全机制研究。从无线通信网络的根源出发,面向无线信道的内生属性,研究了基于无线信道特征的内生安全通信架构,并针对此架构提出了基于射频指纹与信道密钥的内生安全通信技术方案。该架构将认证、加密与传输融为一体,从体系结构上增强了防御效果;利用无线信道特征的内生特点,从技术手段上提高了安全性能。