TD-SCDMA系统链路平衡分析

TD-SCDMA系统TDD的工作方式、丰富多彩的业务以及智能天线的应用,使得链路分析更为复杂,需要考虑多个方面的平衡,包括不同业务间、上行与下行、公共信道与业务信道、链路预算各参数间等.在不同区域,智能天线波束赋形效果不一,必须切实做好不同无线环境下的整体链路平衡.     

TD-SCDMA室内覆盖探讨

一、TD-SCDMA室内覆盖特点 TD-SCDMA室内分布系统具有以下特点. 1.信源无智能天线.用户与基站的通话链路建立后基站没有对下行链路的赋型增益,同室外覆盖的方式相比下行功率要低了6-8dB,缺少了智能天线的基站信源上行灵敏度也要低于使用了智能天线的室外宏基站.     

TD-SCDMA标准错误应用智能天线的问题分析

不少TD-SCDMA标准研究人员认为采用智能天线核心技术后可以克服TDD模式的步行移动通信系统特征。文章从智能天线同时形成多个发射方向波束的可能性出发证明:在CDMA系统中使用智能天线时,无法同时形成多个同频点不同方向的定向发送波束,不可能产生CDMA方式所要求的空分多址作用。此外还从TD-SCDMA的系统特征、智能天线的定向发射方向图、方向性线阵智能天线的合理性等方面讨论了智能天线在TD-SCDMA标准中的不可用性。     

SCDMA无线市话在大庆油田的应用

1 SCDMA无线市话的技术特点大庆石油管理局通信公司采用的是北京信威公司的SCDMA无线用户环路系统,技术先进。基于SCDMA技术提出的TD-SCDMA标准已经成为国际第三代移动通信的主流标准之一。SCDMA系统采用了智能天线、同步CDMA技术,使用了一套自行设计的“同步无线接入信令规范”(SWAP),用软件无线电方法实现连续序列扩频码分多址数字无线环路系统。下面,简单介绍一下智能天线、同步CDMA、软件无线电(即3S技术)和空中接口信令。　　　　　1.1 智能天线(Smart Antenna)智能天线由天线阵和信号处理软件组成。天线阵由8个…     

论提高TD-SCDMA系统覆盖能力的策略

无线覆盖是评估网络质量重要的因素之一,覆盖范围的大小直接和网络基础设施投入成正比.TD-SCDMA是我国自主研发的第三代移动通信标准,与cdma2000和WCDMA等其他制式相比有许多优点和特点,这些优点和特点使得TD-SCDMA在覆盖方面有着广阔的理论研究和实际应用前景.本文介绍了TD-SCDMA的理论覆盖半径以及影响它的覆盖能力的因素,给出了系统级仿真以及链路预算结果,提出了TDSCMDA对应的小区干扰余量算法,并从优化链路质量、降低干扰和采用覆盖技术三个方面论述如何增强TD-SCDMA系统的覆盖能力,最后提出TD-SCDMA的无线覆盖解决方案.     

TD—SCDMA的关键技术—智能天线

智能天线是安装在基站的双向天线,通过一组带有可编程电子相位关系的固定天线单元控制方向,并可以同时控制基站和移动台之间各个链路的方向.以TDD模式运行的TD-SCDMA智能天线,其高效率是基于上行链路和下行链路无线路径的对称性(无线环境和传输条件相同)而获得的.     

TD-SCDMA室内覆盖系统的规划设计

本文对TD-SCDMA系统室内覆盖工程规划设计进行了讨论。重点介绍了室内覆盖系统指标、无线传播、室内链路预算、频率规划和室内覆盖方案等几个重要问题。对TD-SCDMA室内覆盖工程建设方面具有一定的指导意义。     

波束赋形技术在TD-SCDMA网络优化中的应用

波束赋形技术是智能天线在TD-SCDMA系统中的主要应用之一,简要介绍了智能天线波束赋形的原理,并对比了天津地区无线设备厂家和天线厂家的权值设置的波束赋形的仿真效果。在天津TD-SCDMA系统的网络优化中,根据地域信号覆盖特点,通过修改天线权值参数、优化广播信道波速赋形效果达到了改善TD网络信号覆盖的目地。     

TD-LTE无线网络规划研究

本文主要从覆盖规划上简述了TD-LTE系统的规划特点,并比较了TD-LTE系统与TD-SCDMA系统的异同,并就TD-LTE的无线链路预算进行了讨论。     

TD-SCDMA系统中的智能天线技术

智能天线是近年来移动通信领域中的一个研究热点,能有效地提高接收机灵敏度和降低多址干扰,对提高无线系统容量具有巨大潜力。该文介绍了TD-SCDMA标准的发展和智能天线的技术特点,在此基础上着重分析了智能天线在TD-SCDMA系统中的具体实现及其所起的作用。     

中短波段船用小型天线的电磁特性分析

海上无线电导航系统基于扩频体制,工作在中短波段,利用地波进行测距定位,具有定位精度高,保密性好,工作范围大的特点。由于中短波段信号波长长,系统存在接收天线尺寸大,难于安装与维护的问题。为此,提出并设计了一种基于双Hilbert分形的小型天线作为系统接收天线。利用时域有限差分法中的细导线算法、同轴线分析等关键技术建立了天线模型并进行了分析。仿真结果表明:所设计天线高度为13 cm,实现了全向接收,可满足中短波段导航系统要求。     

Ku频段USAT“动中通”系统设计探讨

由于超小口径终端(USAT)卫星通信系统采用小口径天线工作,其在多址接入设计和接入控制设计上与甚小口径终端(VSAT)系统区别较大。结合规范对功率谱密度的强制性要求,对USAT系统上行链路计算分析,给出链路容量与需要的最小信噪比的关系以及采用扩频多址接入建议;为提高系统资源利用率,提出USAT系统上下行链路频率复用的异步载波成对抵消技术的设计思路,并针对阻塞环境条件下,分析了采用本地控制突发和快速捕获技术远端站的反向链路传输性能。     

Smart Antennas with Two-Dimensional Array Configurations for Performance Enhancement of a Joint Detection CDMA Mobile Radio System

Smart antennas for base stations of cellular mobile radio systems offer the potential of system performance enhancement by taking advantage of the directionally inhomogeneous signal reception at the receiver. In this paper, two-dimensional array configurations employed at the uplink receiver of a joint detection CDMA (JD-CDMA) mobile radio system are investigated. This smart antenna concept can be split up into a novel channel estimator and data detector which incorporate explicitely the information of the direction-of-arrival (DOA) of signals emerging from users assigned to the considered base station. Proceeding from channel models that model the directional inhomogeneity of the mobile radio channel with single DOAs, the link level performance of a JD-CDMA mobile radio system using this smart antenna concept is evaluated for the rural propagation environment. The performance evaluation is based on Monte Carlo simulations of data transmission and average bit error rates versus the average signal to noise ratio per net information bit are presented for different array configurations. Although these results should be considered as upper bounds for the link level performance, they reveal the advantages of implementing two-dimensional array configurations at the uplink receiver of a JD-CDMA mobile radio system.     

Software radio architecture with smart antennas: a tutorial onalgorithms and complexity

There has been considerable interest in using antenna arrays in wireless communication networks to increase the capacity and decrease the cochannel interference. Adaptive beamforming with smart antennas at the receiver increases the carrier-to-interference ratio (CIR) in a wireless link. This paper considers a wireless network with beamforming capabilities at the receiver which allows two or more transmitters to share the same channel to communicate with the base station. The concrete computational complexity and algorithm structure of a base station are considered in terms of a software radio system model, initially with an omnidirectional antenna. The software radio computational model is then expanded to characterize a network with smart antennas. The application of the software radio smart antenna is demonstrated through two examples. First, traffic improvement in a network with a smart antenna is considered, and the implementation of a hand-off algorithm in the software radio is presented. The blocking probabilities of the calls and total carried traffic in the system under different traffic policies are derived. The analytical and numerical results show that adaptive beamforming at the receiver reduces the probability of blocking and forced termination of the calls and increases the total carried traffic in the system. Then, a joint beamforming and power control algorithm is implemented in a software radio smart antenna in a CDMA network. This shows that, by using smart antennas, each user can transmit with much lower power, and therefore the system capacity increases significantly     

Radio propagation and anti-multipath techniques in the WINenvironment

The unique characteristics of wireless in-building network (WIN) systems based on microwave radio technology are addressed, focusing on the multipath propagation problem which most distinguishes radio from wired LAN media. This is followed by a discussion of the three principal techniques that have been developed within the radio communication industry to deal with this multipath problem: adaptive equalization, spread spectrum, and antenna diversity. A review of the strengths and weaknesses of each of these techniques reveals that antenna diversity is clearly the preferred choice for use in WIN systems operating in the recently allocated spectrum near 18 GHz. An example of such an antenna system is examined. It is shown how these multiple, directional antenna systems function in three types of environment     

WCDMA无线网络规划中基站覆盖范围的讨论

本文首先分析了CDMA基站小区范围的理论推导,并阐述了WCDMA反向链路预算的计算流程,最后讨论了在WCDMA无线网络规划中覆盖、容量、质量三者之间的折衷关系.     

Smart antennas for combined DOA and joint channel estimation intime-slotted CDMA mobile radio systems with joint detection

In cellular mobile radio systems, the directional inhomogeneity of the mobile radio channel can be exploited by smart antennas to increase the spectral efficiency. In this paper, a novel smart antenna concept applying receiver antenna diversity at the uplink receiver is investigated for a time-slotted code-division multiple-access (CDMA) mobile radio air interface termed time-division CDMA (TD-CDMA), which has been selected by the European Telecommunications Standards Institute (ETSI) in January 1998 to form part of the Universal Mobile Telecommunications System (UMTS) air interface standard. First, a combined direction-of-arrival (DOA) and joint channel estimation scheme is presented, which is based on DOA estimation using the Unitary ESPRIT algorithm and maximum likelihood estimation of the channel impulse responses associated with the estimated DOA's, which can also be used as an input for advanced mobile positioning schemes in UMTS. The performance of the combined DOA and joint channel estimation is compared with the conventional channel estimation through simulations in rural and urban propagation environments. Moreover, a novel joint data detection scheme is considered, which explicitly takes into account the signal DOA's and the associated channel impulse responses. The link level performance of a TD-CDMA mobile radio system using these novel schemes is evaluated by Monte Carlo simulations of data transmission, and average bit error rates (BER's) are determined for rural and urban propagation environments. The simulation results indicate that, depending on the propagation environment, the exploitation of the knowledge of the directional inhomogeneity of the mobile radio channel can lead to considerable system performance enhancements     

Advanced cellular Internet service (ACIS)

The public's desire for mobile communications and computing, as evidenced by the popularity of cellular phones and laptop computers combined with the explosive demand for Internet access suggest a very promising future for wireless data services. The key to realizing this potential is the development and deployment of high-performance radio systems. In this article we describe a basic service concept, advanced cellular Internet service (ACIS), and the technologies for achieving reliable high-speed transmission to wide-area mobile and portable cellular subscribers with very high spectrum efficiency. Such a wireless service, optimized to meet the needs of a client-server model for information retrieval and Web browsing, and combined with evolutionary enhancements in second-generation technologies, can provide an attractive option for third-generation systems. The radio link design combines OFDM with transmit and receive antenna diversity and Reed-Solomon coding to overcome the link budget and dispersive fading limitations of the cellular mobile radio environment. For access, a dynamic packet assignment algorithm is proposed which combines rapid interference measurements, priority ordering, and a staggered frame assignment schedule to provide spectrum efficiencies of two-to-four times existing approaches     

TD—SCDMA移动终端智能天线技术的算法实现

智能天线技术是第三代移动通信标准TD-SCDMA的标志性技术,是TD—SCDMA标准相对于其他标准的最大区别和优势,具有增加系统容量、扩大系统覆盖范围、络逐渐商用,智能天线技术也愈加成熟。本文阐述了TD势,并通过DSP和FPGA分别实现了自适应算法。改善服务质量等一系列优点。随着TD-SCDMA网SCDMA移动终端智能天线的一些知识及相关的优