无线电定位技术在蜂窝通信系统中的应用及实现

当前,移动用户对基于无线定位技术的新业务的需求不断增加,推动了对无线测距及定位技术的深入研究,向用户提供精确的定位信息已经成为新一代PCS系统的标准业务之一。主要介绍几种基于现有蜂窝通信系统的无线定位技术的实现原理,所要解决的主要问题和应用前景。     

蜂窝系统无线定位原理及应用

本文介绍了无线定位系统的分类、基本的无线；定位技术及基于蜂窝网络的定位方案，讨论了基于时间的定位法及其特点，分析了定位误差产生的原因及其对策，并介绍了基于蜂窝系统的无线定位技术的各种应用。     

无线电定位技术及其在CDMA中的应用

首先回顾了无线电定位的基本技术及其应用范围,重点讨论了基于ＡＯＡ和ＴＯＡ（ＴＤＯＡ）的各定位算法并分析了各乍的优缺点。从ＣＤＭＡ通信网中实现定位的实际情况出发,分析了定位算法、定位信号的选择及实现精确定位的关键技术。     

TDOA定位技术系统实验

到达时间差（Time Difference Of Arrival,简称TDOA）定位又称为双曲线定位,属无源定位方法,通过测量无线电信号到达不同监测系统的天线单元的时间差,来对发射无线电信号的发射源进行定位。2010年3月22～25日,在山东省无线电管理办公室的协调指导下,     

陆地蜂窝系统用户定位技术

介绍几种陆地蜂窝定位系统的定位算法，并针对ＣＤＭＡ系统对各种定位方法进行比较。讨论定位系统的误差来源和定位精度的衡量方法。     

基于数据融合的蜂窝无线定位算法研究

本文从数理统计角度,利用TOA和TDOA测量数据并结合扇区信息进行数据融合,然后通过定义可信度函数构造了一种基于移动台位置的动态定位算法,从而实现蜂窝网络定位。最后仿真结果表明这种融合算法在保证决策可靠的前提下,有效提高了决策输出的定位精度。     

超宽带无线电技术在通信传输系统中的应用

随着超宽带无线电技术的不断演变,该技术在通信传输系统中起着至关重要的作用。现有无线电技术具有传输速率快、密度低和跟踪定位能力强、功率小的特点,笔者在此进行了详细分析,以便于提供可参考性的依据。     

蜂窝移动通信系统中的定位技术

本文介绍了蜂窝移动通信系统中定位技术的展望、原理及分类，并详细分析了几种典型的定位技术以及当前标准化的情况，最后对定位技术的应用模式和应用前景进行了讨论。     

软件无线电技术及其在蜂窝移动通信系统中的应用研究

软件无线电技术是近年来出现的新的无线通信设计思想与框架。是无线通信领域的一项突破性关键技术。本文详细了软件无线电的概念、系统结构、基本特征,在典型软件无线电体系基础上,描述了应用该设想的蜂窝区基站功能。同时结合关键技术,展望了软件无线电的发展趋势。     

AGPS和室内GPS——移动通信系统的新型定位技术

由于移动通信系统定位功能对人们生活的重要性，在美国联邦通信委员会(FCC)的推动下，蜂窝网定位技术正在迅速发展。FCC的第1阶段目标已经实现，正在全世界许多地方迅速推广。进一步提高精度是第Ⅱ阶段的主要目标。为实现这一目标，人们分别研究了基于网络的方法(包括TOA法、TDOA法等)和基于手机的定位法。结果发现，没有哪一种方法是可以接受的．最近出现的AGPS技术和室内GPS技术以GPS技术为基础，借助于移动通信网的辅助，从而把两种方法有机地结合起来，使得向满足FCC第Ⅱ阶段的目标前进了明显的一步。第1节介绍了移动通信系统定位功能的作用和FCC各阶段所要实现的目标。第2节对基于网络的各种定位技术及其所面，临的问题作了概述，说明在基站布局和资金回收等四个方面，通信与定位功能之间存在固有的矛盾。第3节首先对GPS用于手机定位的优缺点作了介绍，并进而介绍了AGPS和室内GPS技术，说明以GPS系统技术为基础，借助于移动通信网短信服务的帮助，以及把手机芯片技术和先进的GPS接收机技术结合起来，将使移动通信系统的定位功能无论从覆盖范围和精度以及的手机费用和功耗上看，都已接近于满足FCC第Ⅱ阶段的要求。最后介绍了AGPS和室内GPS的试验结果，以及一些公司所开发的产品性能，说日月手机定位正在发展成一个产业。     

Mmic technology for communication systems

MMIC technology is recently progressing at a rapid rate and is now being applied in communications systems. However, there remain few practical applications. This is mainly due to the high cost of conventional mmics because of the small market size and specialized needs. This paper introduces three new technical approaches that overcome the problems: uniplanar mmic, line unified fet^lufet), and multilayer mmic. Concepts and several examples of these technologies are described. It is shown that these technologies are effective not only for cost reduction but also for increased performance. In addition, one example of system application is described.     

Hypergraph models for cellular mobile communication systems

Cellular systems have hitherto been modeled mostly by graphs for the purpose of channel assignment. However, hypergraph modeling of cellular systems offers a significant advantage over graph modeling in terms of the total traffic carried by the system. For example, we show that a 37-cell system when modeled by a hypergraph carries around 30% more traffic than when modeled by a graph. We study the performance of channelized cellular systems modeled by hypergraphs in comparison with those modeled by graphs. For this purpose, we have evaluated the capacities of these cellular networks defined in McEliece and Sivarajan (1994). Evaluation of the capacity necessitates generation of maximal independent sets of hypergraphs. We describe some new algorithms that we have developed for this purpose     

Handover scheme for mobile cellular communication systems

A new scheme for minimising handover failure probability in mobile cellular communication systems, by exchanging channels between two mobiles moving in opposite directions across the endeavour area of adjacent cells is presented. The performance evaluation of the new scheme is carried out by computer simulation of a two cell model     

浅谈移动通信系统数字调制技术

近年来，我国移动通信业务迅猛发展，已深入到社会生活的各个方面。面对移动用户群的持续增长和新业务的层出不穷，移动通信体系要及时适应甚至超前于市场需求的步伐。而作为移动通信核心技术之一的数字调制技术是实现高速、高效的移动通信系统的重要保证。     

Phase-type models of channel-holding times in cellular communication systems

In this paper, we derive the distribution of the channel-holding time when both cell-residence and call-holding times are phase-type distributed. Furthermore, the distribution of the number of handovers, the conditional channel-holding time distributions, and the channel-holding time when cell residence times are correlated are derived. All distributions are of phase type, making them very general and flexible. The channel-holding times are of importance in performance evaluation and simulation of cellular mobile communication systems.     

UWB通信系统简介

UWB(Ultra Wide Band)即超宽带通信,它使用大于0.5GHz或大于中心频率20%的带宽、通过微弱的脉冲信号进行通信,最大数据传输速率可以达到几十Mb/s～几百Mb/s。UWB与现有的无线技术的显著不同是不需要使用载波,而是通过发送纳秒级脉冲来传输数据,而且信号传输时的功耗只有几十μW。UWB在保证了高数据速率传输的同时解决了移动终端的功耗问题。因此它被认为是对目前被炒得沸沸扬扬的无线互联(Wi-Fi)技术最具竞争性的技术。UWB简介UWB技术多年来一直是美国军方使用的作战技术之一,如它可以实现穿墙视物等功能。这项技术在通信领域所具…     

Three-dimensional cellular systems for air/ground personal communication

A new three-dimensional (3-D) cellular system is proposed for air/ground (A/G) personal communications. The proposed system extends the Global System for Mobile Communication (GSM) to enable its subscribers to send and receive calls while traveling in the air using the same subscriber identity module (SIM)-the same mobile number-that is used for the ground network. Modifications to the GSM system architecture to develop the A/G system architecture are outlined. A multilayer service volume is proposed in which the coverage volume is divided into three coaxial cylindrical layers (cells) with each layer serving a limited part of the airspace. Capacity of the new proposed system based on the standard GSM concept is analyzed and compared to other alternative systems: Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA).     

Performance analysis of cellular mobile communication systems fordata transmission

Buffers are used to overcome the data losses due to the interruption of data transmission when a mobile station is handed over in a cellular network. Data traffic from a wireline network to its mobile data terminal, such as access to large commercial databases or data transmission from a main computer to its remote mobile terminal, is studied. Compound Poisson (CP) is used to approximate the arrival process of the data traffic, and a modulated D (MD) distribution is used to approximate the service and handover process. The performance of the queueing model CP/MD/1/N is analyzed. Probability generating functions and characteristic functions are used to evaluate the mean queue length and the mean burst delay for an infinite buffer system and the overflow probabilities versus the buffer size for a finite buffer system. A method is presented to find the probability transition matrix entries by recursively taking derivatives of the probability generating function of the number of the characters arriving during the service-time. The queue length distributions for a finite buffer, both at departure instants and at arbitrary time instants are derived. Comparison with simulation indicates that the model is accurate. The numerical results of the model confirm the effectiveness of the scheme     

Traffic-adaptive aggregate channel allocation for future cellular communication systems

A fundamental problem in third-generation mobile systems is the adaptation of the channel allocation to the traffic volume variation. Traffic adaptation may be partly achieved by the following (aggregate channel allocation) problem: given the set of channels, the cell structure and the load to be accommodated in each cell within a certain time zone, find the optimal allocation of channels to cells subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. In this paper the problem is optimally formulated and efficiently solved by a heuristic. In the sequel the performance of a combined channel management scheme that uses the above problem for handling major traffic variations and a distributed DCA scheme for handling local traffic variations is assessed. Finally, results are presented and some concluding remarks are made. © 1998 John Wiley & Sons, Ltd.     

Radio link design of cellular land mobile communication systems

A procedure for a radio link design of cellular land mobile radio systems is discussed. The relation between the prescribed total outage and the necessary margins for thermal noise and co-channel interference is first derived. It is then shown that the respective margins can be calculated separately. A simple and useful procedure for determining transmitter power and co-channel reuse distance is presented in concrete flowchart form. Based on this procedure, an example of a radio link design for a digital mobile telephone system is shown.