Mobile and Personal Communications in the 60 GHz Band: A Survey

This paper intends to present a summary of the technical issues arising in the exploitation of the 60 GHz mm-wave band for mobile and personal communications. The most significant applications proposed so far are surveyed, with particular emphasis placed on recent experimentation about millimeter-wave propagation for road/railway transportation as well as indoor scenarios. As a case study, the capacity of a (micro-)cellular Code Division Multiple Access (CDMA) network in the 60-GHz band is also evaluated in detail.     

Evaluation of a terrain-based point-to-point propagation model in the 900 MHz band

The accuracy of a semi-empirical point-to-point propagation model, based on terrain data information close to the receiver, is tested. The evaluation is performed through extended transmission loss measurements taken in an urban environment (Athens region) in the 900 MHz band. The prediction error is calculated for each measurement point and coordinated with detailed terrain information. Specifically, the evaluation of the model is separately performed for various categories of measurement data with respect to the measurement point's effective height and line-of-sight conditions. ©1997 by John Wiley & Sons, Ltd.     

K-BAND LAND-MOBILE SATELLITE CHANNEL CHARACTERIZATION USING ACTS

K-band pilot tone data collected by the Advanced communications technology satellite (ACTS) mobile terminal (AMT) during 1994 are used to characterize the K-band land-mobile satellite channel. The characterization is twofold: a probability density model is derived which shows that the fade exceedance levels at K-band are much higher than those at lower frequencies, particularly at L-band. Furthermore, the fade statistics are very dependent on the geometry of the surrounding environment. The difference between good and bad environments is much more pronounced at K-band than at L-band. A discrete time model is used to provide insight into the bursty nature of the errors induced by propagation effects on the channel. For a data rate of 9600 bps, the average fade duration for a fade threshold of 6 dB is of the order of a few thousand bits, which corresponds to a fade duration of 2—5 ms. The fade durations are typical of those at L-band which suggests that whereas the K-band fades are more severe than those at L-band, the durations are approximately the same.     

Design Template and Measurements for Antenna Planning in an Indoor Radio Environment at 1800 MHz

Recently, the demand for an accurate design on the distribution of the antennas in shopping malls is growing rapidly. To provide a guaranteed coverage inside the shopping malls, mobile operators may have installed a lot more antennas than that is really needed. This over-engineering design has increased the installation and operation cost. Therefore, the need to have a relatively more accurate indoor design is the most requesting goal in the telecommunication industry. The purpose of this paper is to derive an indoor design template, which can facilitate mobile operators to evaluate efficiently the optimized number of antennas and their locations within a premises. A tunnel propagation model is used to represent the propagation loss in an indoor environment. Measurements are also taken to derive the losses of various media. Field tests are finally performed to verify the accuracy of the distribution of RF signal strength predicted by the design template.     

实值循环ESPRIT算法

为了降低循环ESPRIT算法的计算复杂度,提出了一种实值循环ESPRIT算法,通过构造了循环自相关矩阵的数据模型,使其具有厄尔米特特性,将复数自相关矩阵映射成实值矩阵,通过实值分解降低了计算量,而且具有信号选择特性。由于空间平滑技术的引入,较好地解决了多径传播环境中信号高度相关问题。仿真实验结果证明,与循环ESPRIT算法相比,该算法适应多径传播环境,具有计算量小和性能好等特点。     

ACTS MOBILE TERMINALS

The development of the advanced communications technology satellite (ACTS) mobile terminal (AMT) and its follow-on, the broadband aeronautical terminal (BAT), have provided an excellent testbed for the evaluation of K- and Ka-band mobile satellite communications systems. Such systems have proved viable for many different commercial and government applications. Combining emerging satellite communications technologies such as ACTS' highly focused spotbeams with the smaller, higher-gain K- and Ka-band antenna technology, results in system designs that can support significantly higher throughput capacity than today's current commercial systems. An overview of both of these terminals is presented in this paper.     

美军E频段通信技术发展述评

美国国防高级研究计划局(Defense Advanced Research Projects Agency,DARPA)采用E频段通信,设计、建立并验证了移动设备与机载平台间的自组织、可扩展的数据回传网络及稳健的、大容量骨干网络。对美军E频段通信的发展情况进行了梳理,针对“移动热点”与“100 Gb/s”两个典型项目从应用场景、性能指标、进度安排、关键技术等方面进行了分析,最后给出了对我国相关领域技术创新的启示与思考。     

移动卫星通信系统的经济性能比较分析

本文介绍了一种基于系统容量和成本的经济分析方法,对几种移动卫星通信系统进行了比较分析,同时还与陆地蜂窝系统进行了比较     

第二代移动通信向第三代的过渡

本文介绍第三代移动通信的基本特点、当前国际通信组织和各国对第三代移动通信的研究开发工作 ,并通过各国从第一代移动通信过渡到第二代的经历和移动通信的发展现状 ,分析了各国对第二代移动通信向第三代过渡的不同观点和可能采取的方式和途径。     

大容量数字蜂窝网的竞赛

大容量数字蜂窝技术不仅可以应用在移动通信方面，还可取代传统的有线通信方式，来提供性能价格比优良的无线电话服务，这一技术可以缩短短设备安装时间，降低运营成本，对于那些想要迅速建立现代电信网络、提高电话普及率的国家和地区尤为适宜。     

个人通信的进展和研究

本文对个人通信的发展作了综述，就个人通信的基本概念，结构模型，途径策略作了简要讨论，并指出了实现个人通信的几个关键技术。     

Statistical channel modelling and performance evaluation in satellite personal communications

This paper is concerned with channel modelling for satellite personal communications and with the associated problem of performance evaluation. Channel characteristics for personal communications tend to differ from those traditionally accepted for vehicular communications. In this paper we report on modelling aspects for both wideband and narrowband personal communications. Then we consider performance evaluation for low-altitude earth orbit (LEO) satellite systems in terms of bit error probability and outage probability. To evaluate the outage probability for LEO systems, a tight and simple upper bound is finally provided. © 1998 John Wiley & Sons, Ltd.     

基于实值分解技术的Unitary Cyclic ESPRIT算法

针对多径传播环境中的信号到来方向估计问题,提出了一种基于实值分解技术的Unitary Cyclic ESPRIT算法,通过重新构造了循环自相关矩阵的数据模型,使其具有厄尔米特特性,较好地解决了多径传播环境中信号高度相关问题,通过实值分解降低了计算量,而且具有信号选择特性.仿真实验结果证明,与Cyclic ESPRIT算法相比,该算法适应多径传播环境,具有计算量小和性能好等特点.     

移动通信,个人通信与全球信息高速公路

本文扼要探讨了移动通信发展现状，个人通信发展趋势和信息高速公路发展展望，并指出数字移动通信，个人通信和全球信息高速公路是当前及今后１０年无线通信发展的主流。     

我国移动通信网从第二代到第三代的演进策略

随着第三代移动通信标准的日趋成熟,其产品预计可在2004年前后投入商用。本文在分析市场需求、技术发展现状和保护已有设备投资的基础上,从保证我国移动通信产业、运营商和移动用户利益出发提出：第一步,在IMT－2000核心网成熟之前,采用现有的GSM／GPRS核心网,通过A和Gb接口提供话音和数据业务;空中接口采用频谱利用率高、符合IMT2000要求的TD－SCDMA技术,以满足高话务量区域的需求。第二步,采用成熟的IMT-2000核心网（Release2000)、IMT2000FDD和TD－SCDMA无线传输技术,逐步形成第三代移动通信系统。     

Dynamic Base Station Selection for Personal Communication Systems with Distributed Control Schemes

Distributed control schemes allow base stations in personal communication systems to be placed at locations corresponding to high expected traffic. This flexible base station placement creates significant overlapping coverage areas that can be utilized to improve system performance [1]. A new technique for dynamic base station selection in systems with overlapping cells is considered and its effect on traffic performance is characterized. The technique realizes robust performance for personal communication systems in fluctuating and heavily tapered traffic. A mathematical analysis based on a state transition model is used to evaluate performance of a system that employs the proposed technique. The results indicate that improved blocking probability and carried traffic performance are obtainable. Computer simulations were undertaken confirm the analytical results.     

三维频率复用环境中的信道偏移指配方法

一种新的信道指配法－信道偏移指配方法正受到越来越多的重视，这种方法能在现有的频率资源条件下，较大地提高移动通信系统的容量。本文主要讨论了三维频率复用环境中的信道偏移指配方法，详细地分析了同频复用和相邻信道使用距离，定量地计量了信道偏移系统的频谱节约效率。本文最后还通过几个实例验证了所提算法的实用性。     

“移动通信”课程的建构性学习教学方法

建构性学习作为当代学习理论的新发展,创设问题情景和协作探究是其主要思想之一。而“移动通信”课程具有技术更新发展迅速以及系统性和实用性强的特点,这些特点非常适合采用建构性学习的教学方法。本文建立了基于建构性学习的“移动通信”课程教学模式。实践证明,这种教学模式不仅提高了学生的积极性,而且还提高了学生的学习能力和分析能力。