WLL的市场前景

ＷＬＬ的市场前景无线本地环路系统近几年来受到了发展中国家和发达国家的共同重视，很快得到市场的普遍欢迎。ＡＴ＆Ｔ分司预计，无线本地环路产品市场总值到１９９８年会超过８０亿美元。据北方电讯分司估计，在亚太地区，至少会有１５％新用户采用ＷＬＬ。由此可见，Ｗ...     

对利用PHS技术实现微小区无线接入系统的探讨

本文介绍了无线本地环路（ＷＬＬ）的发展，并着重分析了一种典型的微小区无线本地环路系统－美国ＵＴＳｔａｒｃｏｍ的ＡＩＲＳＴＡＲ－ＷＬＬ的结构、功能特点及应用。     

“空中之星”无线本地环路

“空中之星”无线本地环路美国ＵＴ斯达康的ＡｉｒＳｔａｒ“空中之星”ＷＬＬ系统是当前各种ＷＬＬ系统产品中的佼佼者．它是ＵＴ斯达康的ＡＮ２０００综合接入网系统与ＰＨＳ技术集成的无线本地接入网系统．ＡＮ２０００与中央交换局连接，主要担任数字复用、光纤传输、...     

无线用户环路技术

本文概念了国际上接入网发展的趋势，分析了无线用户环路（ＷＬＬ）的定义，讨论了ＷＬＬ的适用范围，介绍了国外电信公司ＷＬＬ的各种产品。最后，对我国ＷＬＬ的发展提出了一些建议。     

无线本地环路的研究与应用

无线本地环路（ＷＬＬ）技术发展迅猛。本文在介绍ＷＬＬ系统结构的基础上，着重对其技术类型和业务应用进行了探讨，并就我国发展ＷＬＬ技术的有关问题提出了建议。     

数字无线本地环路系统

本文对数字无线本地环路（ＤＷＬＬ）进行系统的介绍，着重研究和讨论了ＤＷＬＬ的体系结构及关键技术，为开发和利用数字无线本地环路提供一种借鉴和参考。     

无线本地环路（WLL）技术及发展趋势

本文介绍无线本地环路（ＷＬＬ）系统的基本结构及其相关技术，指出无线本地环路ＷＬＬ的优势和关键技术，并就ＷＬＬ的现状和发展趋势作出分析。     

日本PHS-WLL技术在电信网中定位与发展探讨

从ＰＨＳ－ＷＬＬ的概念和系统结构的介绍入手，结合日本的发展现状，探讨ＰＨＳ－ＷＬＬ业务在我国电信网中发展的可能性和使用的最佳场所，也对ＰＨＳ－ＷＬＬ业务与目前我国蜂窝移动电话业务的关系进行了试定位。     

PHS-WLL无线接入系统简介

和有线本地环路相比，无线本地环路（ＷＬＬ－ＷｉｒｅｌｅｓｓＬｏｃａｌＬｏｏｐ）由于具有安装容易，维护方便等优点而应用得越来越多。ＷＬＬ有多种技术解决方案，其中ＰＨＳＷＬＬ是造价较低，性能较好的方案之一。１ＰＨＳ与ＰＨＳＷＬＬ的技术特点ＰＨＳ（Ｐｅ...     

日本PHS—WLL技术在电信网中定位与发展探讨

从ＰＨＳ－ＷＬＬ的概念和系统结构的介绍入手，结合日本的发展现状，探讨ＰＨＳ－ＷＬＬ业务在我国电信网中发展的可能性和使用的最佳场所，也对ＰＨＳ－ＷＬＬ业务与目前我国蜂窝移动电话业务的关系进行了试定位。     

Digital wireless local loop system

The digital access technologies for the wireless local loop (WLL) or fixed wireless system are discussed. WLL is an important means of providing telephone services more cheaply and quickly in the developing countries than through a wireline system. Capacities of a WLL system based on the IS-54 (now IS-136) TDMA, IS-95A CDMA, and ETSI GSM technologies are developed and compared     

The effect of narrowbeam antenna and multiple tiers on systemcapacity in CDMA wireless local loop

The wireless local loop (WLL) system is a local telephone system without wireline connection. It is believed to be a fast and cost-effective means to provide local phone service in rural areas and third world countries. WLL is a fixed radio communication system; narrowbeam antennas can be employed at both the base station and subscriber's side at high spots so that the propagation between base station and house is very close to free space propagation. This gives the WLL system many inherent advantages over the traditional cellular system, such as bigger coverage area, low power, reduced interference, higher capacity, no fast fading, and no handoff. In this article ideal multiple-tier hexagonal cells are used to derive the capacity of a CDMA WLL system. First, the reverse link interference from each tier to the center cell is calculated separately. Then, the interference ratio of reverse links in a WLL system is analytically derived as a function of total tier number. The result shows that interference from other cells is proportional to the beam width of the house antenna. The authors also found that tier number plays a vital role in system capacity in a free-space propagation (20 dB/dec) environment. At the extreme, the system capacity will drop to zero for an infinite-tier cell structure. A WLL simulator is also built to verify the authors' analytical solution     

宽带CDMAWLL系统的数字接收机的实现

无线本地环(WLL)是一种无线接入系统,它用无线的方式代替了传统的铜线连接用户到本地交换机。介绍了一种用于宽带CDMAWLL系统的数字接收机。叙述了WLL的系统组成、网络结构、反向链路信道结构和反向中继接收机设计规范,并论述了代码捕获和代码跟踪模块的功能。接收机的运行时钟频率可达65.536MHz。     

关于无线本地环路未来发展和应用态势的分析

本文详细讨论了无线本地环路的发展态势,指出固定无线接入将是无线本地环路的主要应用方式,而移动接入模式可用于企业内部。     

无限生机的无线接入网

本简要介绍ＷＣＤＭＡ、ＷＬＬ、ＬＤＭＳ（ＷＡＴＭ）和Ｏ／Ｗ ＷＬＬ等几种前沿ＷＬＬ技术。     

Repacking on demand for two-tier wireless local loop

This paper proposes a radio channel assignment scheme called repacking on demand (RoD) for two-tier wireless local loop (WLL) networks. A two-tier WLL overlays a macrocell with several microcells. When a new call arrives at a two-tier WLL with RoD, if no idle channel is available in both the microcell and the macrocell, repacking is performed (i.e., a call in the macrocell is moved to its corresponding microcell), and then the reclaimed macrocell channel is used to serve the new call. An analytic model is proposed to compute the call blocking probability of the two-tier WLL with repacking. This analytic model is validated against simulation experiments. We prove that the blocking probability is not affected by the call holding time distributions, but is only dependent on the mean of the call holding times. Compared with some previous proposed schemes, RoD has low blocking probability and significantly reduces repacking rate.     

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     

Reverse link performance of wireless local loop CDMA networks

We study the effect of directional subscriber antennas on the reverse link performance of a power-controlled code-division multiple access (CDMA) network in wireless local loop deployments. We investigate the capacity gain that is attained in wireless local loop (WLL) CDMA over mobile cellular systems and its variation as a function of the channel statistics. We also determine the overhead that soft handoff and directional subscriber antennas impose on the WLL system capacity