Effect of Antenna Aperture Field on Co‐channel Interference,Capacity, and Payload Mass in High Altitude Platform Communications

In a High Altitude Platform (HAP) cellular communications network, each cell may be served by a dedicated spot‐beam antenna. The antennas’ beam properties and their spatial overlap control the co‐channel interference. In prior literature, radiation patterns have been approximated by a main lobe followed by a constant sidelobe floor. A network of 121 cells has been studied and the method is here extended to the use of more realistic radiation patterns based on the theoretical aperture antenna patterns. This allows for the comparison of the effect of different aperture field tapers, which lead to reduced sidelobe levels and hence higher system capacity but also a more massive antenna payload.     

High Altitude Platform Station (HAPS): A Review of New Infrastructure Development for Future Wireless Communications

This paper looks into the relatively new field of high altitude platform stations. HAPS is seen as a ‘middle ground’ between the terrestrial and satellite cases, and aims to exploit of the advantages of both types of system. Since HAPS is such a new field, this paper focuses on the technology behind a HAPS communications system, how this has developed, and compares it to the terrestrial and satellite equivalents. One important area that is being investigated is the applications for which HAPS should be used. This is a critical issue if a significant business case is to be made for HAPS. Worldwide HAPS projects and research issues are also highlighted. Finally, the review concludes with the remarks on the future of HAPS for wireless communications systems.     

平流层多波长自由空间光通信系统

以近地面大气作为传输介质的大气激光通信(FSO)受地面情况和复杂的气象条件影响很大,传输的信号质量会受到很大干扰。本文介绍以底部平流层大气作为远距离激光通信信道选取平台的使用,以及多路多波长激光传输在此平台下的应用。这种技术可以增大传输距离并降低大气不稳定性对通信链路的影响。本文以模拟试验结果为例分析了系统效果和可行性,试验模拟了大气湍流效应对光路的影响。     

High Altitude Platform mm-Wave Aperture Antenna Steering Solutions

This paper compares the performance and complexity of two methods of steering an array of aperture antennas on a high altitude platform for the provision of broadband fixed wireless access using cellular type frequency reuse. The first method is to steer all antennas individually to maintain the boresight at the required cell centre. The paper also presents a second method of compensating for aperture antenna pointing error due to lateral and vertical displacement of the platform from the nominal station using only four actuators plus a gimbal that can correct for roll, pitch and yaw of the platform. Results for signal strength, CIR and handovers are given for both scenarios and conclusions drawn.Myles Capstick received his B.Sc and Ph.D degrees in Electronics from the University of Wales, Bangor, in 1987 and 1991, respectively. His current position is as a Senior Lecturer at the University of York and he has also been a Lecturer at the University of Wales in Bangor and at York. His research interests are centred in RF, microwave and mm-wave circuits and systems. More specifically, mm-wave and microwave filters, diplexers and planar array antennas and the design and modelling of broadband, multiband and compact antennas for MIMO communication. He has particular expertise in the area of EMC for RF and microwave circuits and systems, research that extends into the design of the dosimetry equipment for human exposure to EM fields used in human volunteer trials within the UK’s Human Health and Mobile Telecommunications Research programme. He has been an invited speaker at several conferences and seminars in the fields of mobile communications and EMC. He is a member of the IEE.David Grace received his M.Eng degree in Electronic Systems Engineering D.Phil degree from the University of York, UK in 1993 and 1999, respectively. His D.Phil thesis dealt with ‘Distributed Dynamic Channel Assignment for the Wireless Environment’. Since 1994 he has been a member of the Communications Research Group at York, where he is now a Research Fellow. He has worked on a variety of research contracts including several from the former Defence Evaluation and Research Agency. Current research interests include radio resource management for broadband communications, particularly from high-altitude platform and terrestrial ad hoc networks. He is now Principal Scientific Officer for CAPANINA a major European Framework 6 project that is developing broadband communications from high-altitude platforms. He has been an invited speaker at several conferences and industrial locations in the fields of HAP systems. He is also a nominated Researcher in the European NEWCOM Network of Excellence, and a Director of SkyLARC Technologies Ltd, a York based company, specialising in broadband communications from aerial platforms. He is a member of IEE and IEEE.     

Improved Analysis of Co-Channel Interference in Cellular Communications Systems

1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis…     

覆盖高∈_r材料微带天线的研究

采用高介电常数 ( εγ=38)的陶瓷材料制作矩形微带天线 ,体积缩小了很多 ,但增益下降。若用更高εγ 材料的覆盖层 ,在 90 0 MHz和 1.8GHz频率实验表明 ,增益得到明显提高     

覆盖高εr材料微带天线的研究

采用高介电常数(εr=38)的陶瓷材料制作矩形微带天线,体积缩小了很多,但增益下降。若用更高εr材料的覆盖层,在900MHz和1．8GHz频率实验表明,增益得到明显提高。     

On the Handoff Arrival Process in Cellular Communications

Handoffs in cellular communication systems cause interactions among cells that can be modeled using multi-dimensional birth–death process approaches and the concept of system state. However, exact numerical calculation of traffic performance characteristics is hindered by unmanageably large system state spaces even for systems of modest size. Previous analytical models get around the difficulty by isolating a cell of interestand invoking a Poisson process assumption for handoff arrivals to the cell. Interactions among cells are characterized by relating the mean handoff and departure rates from cells. The current paper seeks to explore the interactions in more detail. Two additional approximate analytical models are developed for this purpose. Each of these is more complicated than the simple Poisson process model, but is analytically tractable – at least for small system sizes. One model isolates a cluster of cells (rather than just the cell of interest) from the system and invokes a Poisson process assumption for cells on the cluster periphery. Performance is calculated for the central cell. The second model also isolates a cluster of cells surrounding the cell of interest, but uses an equivalent two-state Markov Modulated Poisson Process (MMPP) to characterize handoff arrival processes to the cell of interest from each of the neighboring cells. Poisson handoff arrivals to cells on the cluster periphery are assumed. This approach has fewer states than the cluster approach. Finally we present the exact solution for a regional coverage area consisting of a single seven-cell cluster. Teletraffic performance characteristics are computed for each modeling technique and are compared. It was found that all are in close agreement with the original single isolated cell, Poisson handoff arrival model, which requires the least states.     

Performance Analysis of Cellular Mobile Communications under Multipath Interference

In a radio communication environment, no matter whether signal is transmitted outdoors or indoors, the phenomenon of multipath interference is unavoidable. Therefore, it is necessary for us to thoroughly study the effect of multipath interference on cellular mobile systems. In this paper, we first investigate the effect of multipath interference on the performance of a single cell system with finite users. In order to use the Markov chain method, a system model with 2-dimensional state vector is presented. With his model, the system performance under multipath interference has been successfully derived. Next, an extended-slot method to reduce the multipath interference triggered by LOS packets occurring in the previous slot is proposed. Numerical results show that this method can remarkably enhance the system performance. Finally, we further analyze the combined effect of co-channel interference and multipath interference on the performance of multicell systems. Numerical results show that the system performance suffers some degradation compared to the single cell environment. However, the degradation under typical environments with path-loss exponent around 4 is insignificant.     

蜂窝通信的空分多址:概念、算法和性能

蜂窝通信采用空分多址正在移动通信领域引起广泛关注。本文对空分多址的基本概念、空间信道模型及其知识利用、上下行链路的实现方法和算法、以及对系统性能的改善等诸方面,进行了比较全面的论述。对目前空分多址研究中值得关注的问题,表达了作者的观点。     

1999年中国蜂窝移动通信及手机市场走向分析

中国移动电话数已跃居世界第三位,增长速度在部分城市妆近或开始超过普通固定电话。而在设备市场上,中国开发的ＧＳＭ产品正在取得突破性进展,开始了国外产品的角逐,手机市场尤其如此。此外,中国移动通信标准的选择正处于关键时刻,可能影响到第三代移动通信技术的选用。     

快速发展的蜂窝网通信和卫星通信

主要说明无线通信将应用于移动通信、个人通信和全球通信。数字蜂窝网将增设微蜂窝区 ,频率从 90 0MHz升至 1 .8～ 2GHz ,向宽带和多媒体方向发展 ,数据速率从 1 44kb /s升至 2Mb /s。手机将是TDMA /CDMA双模。蜂窝网不仅用于移动通信 ,而且用于固定用户的市内接入网。卫星通信将加快发展低轨道 /中轨道卫星通信网 ,而同步卫星仍需利用。移动卫星网可通电话 ,可进行多媒体通信 ,速率为 2Mb /s,并通过地面信关站 ,与陆地固定通信网结合一起 ,实现全球个人通信。     

蜂窝移动通信系统核心网络的演进与全IP核心网络

分析了现有移动通信网络存在的问题,阐述了第2代移动通信核心网向第3代移动通信核心网演进的必然性：讨论了第2代移动通信核心网向第3代移动通信核心网演进所采用的演进策略,介绍了两种可供选择的全IP核心网络的参考结构。     

Performance of Fixed Channel Assignment for Uplink Transmission and Direct Peer-to-Peer Communications in Multihop Cellular Networks

In this paper, we propose a clustered multihop cellular network （cMCN） architecture and study its performance using fixed channel assignment （FCA） scheme for uplink transmission. The proposed cMCN using FCA can be applied with some reuse factors. An analytical model based on Markov chain is developed to analyze its performance and validated through computer simulation. And then, we implement direct peer-to-peer communication （DC） in cMCN by considering more reasonable conditions in practice. DC means that two calls communicate directly instead of going through base stations. The results show that cMCN with FCA can reduce the call blocking probability significantly as compared with the traditional single-hop cellular networks with FCA and can be further reduced by using DC.     

蜂窝移动通信系统中的一种新的优化信道分配模型

本文提出了一种新的蜂窝移动通信系统最优信道分配模型.首先根据信道分配的特点构造了一种信道分配方程模型;进而建立了信道分配最优模型,利用Pontryain最小值原理获得了模型的最优解;给出的仿真结果验证了分析结论的正确性.该模型可以用来有效地研究信道分配问题的宏观性能,并提供了一种高效、快速的算法.     

捷联式双天线稳定平台设计及坐标系变换

近年来,弹载SAR制导技术已成为SAR技术应用的又一重要方面。在体积有限制的战术导弹应用中,为了消除弹体姿态变化对目标测量的影响,往往采用捷联稳定平台来实现天线稳定。阐述了两轴天线稳定平台的设计思路及结构框架,根据捷联式天线平台的结构特点及稳定平台工作原理,应用坐标变换方法,建立了两轴天线平台的运动学模型。根据不同工作模式对天线尺寸的要求,设计了随工作模式实时切换的同轴双天线,并依据建立的大天线坐标系推导出小天线坐标变换关系。     

Research on the Handover of a Novel Cellular Architecture in Wireless Personal Communication Systems

1　IntroductionHandoverbetweencellsisplayinganimportantroleincellularcommunicationsystems[1～ 1 2 ] .Thehandoverprocedureanditseffectivenessareseriouslylimitedbythecellulararchitectureasaresultofmar ketplanning .Basedonthehexagonalcellulararchi tecture,manyhandoverprocedureshavebeendis cussedandevaluated ,andmostoftheimprovementproposedonthemleadstotheintroductionofsector ingcellularorlayeredcellularmodel.Otherwise ,abetterhandoverprocedureisessentialinmaintainingacallinprogressbutitreflectshi…     

我国公用蜂窝移动通信发展的若干问题

本文在简要介绍国内外蜂窝移动通信发展动态的基础上，针对我国公用蜂窝移动通信发展的若干问题，例如市场分析与预测、技术发展走向、产业发展对策等阐述了作者的观点。     

Effects of Sectorization on Cellular Radio Systems Capacity with Different Traffic Loads

The application of cell sectorization as a mean to improve a cellular radiosystem Signal-to-Interference Ratio (SIR), and hence capacity, is investigated.To assess the usefulness of sectorization, a lower bound to the Shannoncapacity of the uplink channel of a cellular systemis evaluated, with perfect channel state information (CSI) at the receiver,versus the reuse distance and the traffic loading. In the paper, two different rules for the use of sectored antennasare presented and analyzed in terms of their effect on system capacity.The sectorized system performance is compared with the performance ofa conventional system using omni-directional antennas at the base stations (BS).     

On Issues about the Application of MIMO in Mobile Cellular Communications

1　Introduction　Thenewgeneration (beyond 3G/4G)mobilecel lularcommunicationsystemneedstosatisfythehighcapacitydemandsdrivenbysomeapplicationssuchasInternetandmultimediaapplications.Insuchasystem ,thekeytoachievetherequiredratesinahighlylimitedradiospectrumresourceisinadoptionofnoveltransmissiontechniques,whichofferhighspectralefficiencyandhightransmissionreliabilityrelativetothecurrentsystems.Multiple InputMul tiple Output(MIMO)systemusingmultipleantennasattransmitandreceiveendcanincrease…