Wireless loops: What are they?

Several loop applications of wireless technology are aimed at reducing the cost of deploying communications services ranging from telephone to wideband video. In these applications, wireless links replace a portion of a wireline loop from a central location (a central office or cable headend) to a subscriber. The replacement of labor-intensive wireline technology by complex mass-produced integrated electronics in wireless transceivers is projected to reduce the overall cost of the resulting loop. These wireless loop applications attempt to provide existing communications services or small modifications to existing communications services. A different interpretation of a wireless loop makes use of low-power digital radio technology to provide the last thousand feet or so of a loop. Low-power low-complexity wireless loop technology in small base units can be integrated with network intelligence to provide the fixed-infrastructure network needed to support economical personal communications services (PCS) to small, lightweight, low-power personal voice and/or data communicators. Low-complexity communicators can provide many hours of “talk time” or data transmission time and perhaps several days of standby time from small batteries (≤ 1.5 oz). Because this application of wireless loop technology can reduce the inherent costs in several parts of a wireline loop, it has the potential to provide convenient widespread PCS at less costs than providing telephone services over conventional wireline loops. This low-power wireless loop application does not fit into any existing communications system paradigm. Wireless technology with tetherless access and wide-ranging mobility, e.g., the personal access communications system (PACS), does not fit the accumulated wisdom of the wireline telephony paradigm. It also does not fit the paradigm of existing cellular radio that has sparsely distributed expensive cell sites, and it is not targeted at fixed video services as is wireless cable. Because a significant change in thinking is required in addressing this new low-power low-complexity widespread wireless loop paradigm, its large economic advantages and service benefits have not yet been embraced by many of the existing communications providers, who appear to be more comfortable pursuing the better-known paradigms of video using wireless cable, or of cellular radio in the guise of high-tier PCS, or in the guise of rapid economical deployment of telephone services in developing nations. This paper discusses the inherent economic advantages and service benefits of low-power low-complexity wireless loop technology integrated with network intelligence aimed at providing economical low-tier PCS to everyone.     

A wireless local loop system based on wideband CDMA technology

This article describes a wireless local loop system based on wideband CDMA technology. The unique features of CDMA technology make it a formidable alternative for fixed wireless telephone applications. The W-CDMA technology used by this WLL system is selected to provide primarily ISDN-like services and data rates to subscribers. This technology also provides a smooth transition into the third generation wireless technology. The air interface used in this WLL system is an interim TTA standard, which specifies a CDMA-based protocol operating in the 2.30-2.40 GHz band. The standard allows two types of bandwidth (5 and 10 MHz). The WLL system described in this article includes the WLL gateway switch, the radio port controller and the radio interface unit. The gateway switch connects the radio system to the PSTN and ISDN. The RPC provides concentration and control functions to a number of base stations called RPs. The RIU is comprised of the fixed units attached to the residential or commercial buildings. Also included are the radio port operation and maintenance (RPOM) unit, which is responsible for maintaining and managing the radio network elements, and the interworking function unit, which is used as a gateway to data services such as the Internet and PSPDN     

Cordless personal communications

The role of digital cordless technology in the transition to personal communication systems (PCSs) is discussed. The evolution of the pan-European digital cordless standards-CT2 and DECT-and industry progress in equipment availability and service implementation are reviewed. The application of cordless access to the domestic market in the United Kingdom and European telepoint, wireless PABXs, and radio drops are described. CT2 product development and availability and cordless data applications are outlined. The migration of microcellular cordless techniques for wider area systems including ETSI's universal mobile telecommunications system (UMTS) and the future public land mobile telecommunications systems (FPLMTS), now under development by CCIR with assistance from CCITT, are also discussed     

Uncoded symbol error rate estimation: methods and analysis

In wireless communications systems, channel quality estimates are often used to provide a measure of the quality of service or to enable resource allocation techniques that improve system capacity and/or user quality. The uncoded bit or symbol error rate (SER) is specified as a channel quality metric in second and third generation cellular systems (e.g., general packet radio service (GPRS), enhanced general packet radio service (EGPRS), and universal mobile telecommunications system (UMTS). Nonetheless, techniques to estimate the uncoded SER are typically outside the scope of these wireless standards and are not specified. In this paper, we analyze the performance of a number of uncoded SER estimation techniques, including a novel technique in which we use the soft information of the received symbols to obtain a fast and accurate estimate of the uncoded SER. The technique we introduce has been found to outperform, in terms of accuracy and required estimation interval, conventional hard-decision based techniques that use test-patterns, or use a decode/re-encode/compare approach . Our technique also outperforms the brute-force technique, which is to send a known test-pattern, demodulate it at the receiver, and count the observed discrepancies.     

Enabling technologies for wireless in-building networkcommunications-four technical challenges, four solutions

A wireless in-building network is proposed, raising the possibility that at least part of the hard-wired infrastructure may no longer be needed. This wireless network is based on the refinement of cellular radio techniques in the 18 GHz range. The basic set of problems this technology addresses is described. These are the minimum performance and features required of a viable in-building wireless technology, the range of options available in selecting a design approach for such a system, and the technical problems that were faced in developing a microcellular wireless in-building system     

Advanced Wireless Access System

The key words for the future telecommunications are personalization, multi-media services and high accessibility to the network. These trends naturally lead to radio media application to access links. In this sense, this paper proposes an advanced wireless access system with a capacity supporting broadband video and data services.Concept of the system can be defined as a new radiocommunication category with advantages of both fixed and mobile systems.The system is designed to transport ATM-based signals using SHF (or EHF) bands to wireless terminals, interconnected with optical fibers at the network side. The basic system configuration is presented as well as examples of system parameters.For radio aspects the maximum service coverages of the radio base stations are calculated based on availability consideration. Preferred frequency bands for actual operation are also discussed.     

Building the FO infrastructure for wireless communications

The next generation of communication systems will provide consumers with a host of new and improved voice, video, and data services. Rapidly developing wireless radio systems are already contributing to the progress, giving consumers the luxury of tetherless access to telephone conversation, on-line computing, and cable-television. Indeed, wireless access to high quality information and entertainment is quickly becoming a key component of the information superhighway. In that context, optical fiber links, which have the bandwidth for providing users with the service of their choice, are an excellent connecting infrastructure for providing uniform radio coverage in wireless networks. Indeed, fast improving analog FO links will serve such networks well. In this article, we will analyze the requirements for such a system     

Electronic Switching Systems in Japan

A recently introduced large-size commercially available electronic switching system has versatility in application to different hierarchies of switching stages and is available not only in the telephone systems, but for forthcoming new telecommunication services such as video telecommunications, data applications, mobile radio telephones, etc. Successive developmental programs are now in progress for remote control switching systems, a small-medium-size electronic switching system and data-switching systems. In the international telecommunication field, an electronic telegraph switching system has been completed and electronic telex and telephone switching systems and a data-switching system are now under development. This paper describes some features of various electronic switching systems available in Japan for domestic and international telecommunications.     

Overview of wireless personal communications

This article presents an overview of the current state of wireless communications, including relevant ongoing activities in technology development, standards, and spectrum allocation. The authors discuss cellular radio, cordless telephony, and wireless data systems. Ongoing and planned future developments are summarized. The presentation is oriented toward broad coverage rather than technical depth. However, brief discussions of the air interfaces for existing digital cellular and digital cordless systems are provided, because the air interface bears heavily on system capacity and the environments in which the system can be used, as well as on the cost and complexity of the equipment     

无线接入——广泛提供基本电话业务的有效方法

本文综述了无线接入的技术要求，无线／蜂窝移动通信的演变，以及针对大范围电话业务采取的无线接入的技术可行性和所遇到的设计挑战。     

5G广播电视演进和主要技术特点

地面无线广播电视作为广播电视最为重要的传输手段,在广播电视发展的很长一段时间内占据主导地位。随着计算机、微电子、移动通信、材料科学等技术飞速发展和人们不断提高的精神、物质、文化需求,无线广播电视技术开始探索向移动终端和个性化领域发展,广播电视与通信技术的融合已经成为全球性话题和探索研究方向。以国际通信组织3GPP为代表的通信与广播电视技术人员,从本世纪初开始了对现代广播电视传播体系的全面系统研究和探讨。本文全面介绍了3GPP广播模式的发展历程和主要技术特点,并基于我国广电兼具广播运营商和电信运营商的双重身份,指出了广电5G广播电视网建设演进路线,建议了未来中国3GPP广播电视分三阶段发展,提出了中国广播电视的核心模式:卫星组网+地面广播+基站覆盖。     

Controversy over cellular mobile-telecommunication base-station-antenna installations

The two most compelling issues that cause cellular-telephone towers to be so controversial are the public health and aesthetic concerns. People love the wireless convenience and instant connectivity, but no one likes the antenna tower that enables it. The siting of the cellular mobile telephone towers remains a divisive issue, worldwide. Some concerns stem from a lack of personal freedom of choice, in being subjected to the radio-frequency radiation emitted by the tower antennas and its potential health effects. Others have raised concerns about aesthetics and property devaluation. Cell-phone towers with graceful and artistic designs that are tastefully constructed would go a long way toward calming the fears of those who abhor the presence of ugly-cell phone towers looming over homes and businesses. It would be propitious both for the wireless telecommunications industry and the local planning and zoning commissions to collaborate in creating innovative solutions to the design, siting, and installation of cellular telecommunication base-station towers.     

基于IEEE 802．15．4标准的调制解调技术软件无线电问题研究

随着微机电、无线通信等关键支撑技术研究的持续发展,无线传感器网络研究也进一步得到深化,无线传感器网络适用的领域也越发宽广。如何实现无线传感器网络在多种应用环境及同一环境下多工作模式的智能化转换,软件无线电技术无疑是一种较好选择。文章就IEEE 802．15．4标准中的调制解调技术的软件无线电化问题进行一些探讨。     

Transport of mobile application part signaling over Internetprotocol

The convergence of voice, data, and video networks is creating a new environment for telecommunications. In response to the changes, telecommunications equipment manufacturers and service providers are competing fiercely to bring an optimum solution to customers. The evolution of GSM to GPRS and to UMTS is a cellular wireless industry endeavour to meet this demand. This evolution will see the core wireless network infrastructure change from circuit-switched to packet-switched where voice and data are transported using IP as the common protocol. However, this poses a number of challenges, one of which is how to run the key mobile application part signaling protocols over IP. MAP defines the application protocols between switches and databases (e.g., MSC, VLR, SGSN, HLR) for supporting mobility management, security management, radio resource management, and mobile equipment management. UMTS supports both circuit-switched and packet-switched services     

MIMO技术的发展

未来无线通信系统需要更高的数据传输速率和更好的服务质量，因此需要系统容量大幅度提高。在有限的无线频谱资源条件下，只有极大地提高频谱利用率才能使系统容量更高。采用多输入多输出（MIMO）天线技术可以满足要求。MIMO技术的主要研究方向包括：MIMO信道、MIM0收发技术、分布式MIM0和MIM0应用。MIM0技术是无线通信领域重大的技术突破，将成为未来无线觅带移动通信系统和无线宽带接入系统的关键技术。     

Low-tier wireless local loop radio systems. I. Introduction

The article provides the results of a set of analyses conducted to compare two major radio technologies, DECT/PWT-E and PACS, for their suitability in the local loop in the United States to provide voice and data services. DECT, digital enhanced cordless telecommunications, is a radio interface standard developed in Europe mainly for indoor wireless applications and being promoted lately for wireless local loop applications as well. PWT, personal wireless telecommunications, is a DECT-based standard developed by the TIA in the United States for the unlicensed PCS applications. PWT-E, enhanced, is the version that is suitable for the licensed PCS applications. PACS, personal access communications systems, is a total system standard (i.e. radio interface and associated network infrastructures) developed in the United States for licensed PCS applications. (PACS-UA and PACS-UB are the standards for the unlicensed PCS applications.) For the wireless local loop (WLL), we make an assumption that the radio technologies operating in the licensed PCS spectrum are more suitable to provide a quality of service that is expected traditionally from a local exchange company (LEC). Therefore, this article focuses on the PACS and PWT-E, rather than PACS-UB and PWT. Also note that the article focuses on the North American version, PWT-E, rather than the European version, DECT. It provides an introduction to the PACS and PWT technologies     

Cell phones answer Internet's call

Cellular service providers, handset manufacturers, and system integrators are captivated by the promise of the wireless Internet using third generation cellular telephony. The leading contender to be the global standard for third-generation cellular telephony is the Universal Mobile Telecommunication System (UMTS). This is a wideband CDMA system designed to be smoothly backward-compatible with GSM, and also the leading member of the IMT-2000 family of third-generation systems sponsored by the International Telecommunication Union (ITU). The developments of this technology and its impact on the telecommunications industry worldwide are discussed     

Wireless technologies for telemedicine

Wireless telemedicine is a new and evolving area in telemedical and telecare systems. Healthcare personnel require realtime access to accurate patient data, including clinical histories, treatments, medication, tests, laboratory results and insurance information. With large-scale wireless networks and mobile computing solutions, such as cellular 3G, Wi-Fi mesh and WiMAX, healthcare personnal can tap into vital information anywhere and at any time within the healthcare networks. The recent introduction of pervasive computing, consisting of radio frequency identification (RFID), Bluetooth, ZigBee, and wireless sensor networks, further extends the potential for exploitation of wireless telecommunications and its integration into new mobile healthcare delivery systems. In this paper, snapshots of current uses and future trends of various wireless communications in the healthcare domain are highlighted. Special attention is given to the challenges of a telemedicine environment equipped with different wireless technologies and how the resulting issues might be addressed in medical services integration to provide flexible, convenient and economical medical monitoring, consultation and healthcare.     

基于认知无线电的载波聚合技术

为了取得高达1 Gbit/s的峰值数据速率,3GPP LTE版本10引入载波聚合技术来扩展系统带宽,使其高达100 MHz.同时,认知无线电技术的发展也将促进各种新兴应用程序的发展,例如,公共安全、智能电网、宽带蜂窝网络等.因此,提出将载波聚合技术与认知无线电技术有效结合,利用载波聚合技术将使用认知无线电技术探测到的空闲频谱进行聚合,并将这两种技术协作得到的带宽资源按比例公平算法进行分配,通过仿真结果验证此项结合带来的带宽与传输速率的提高.毋庸置疑,此项创新将使未来无线通信发生革命性的变化.