TD-SCDMA移动终端的智能天线研究

通过TD-SCDMA智能天线移动终端接收特性的数值模拟,对智能天线算法进行了分析,并深入分析了智能天线对多径的抑制作用。通过分析和天线方向图仿真表明在TD-SCDMA系统移动终端采用智能天线可以有效提高信号接收质量、降低误码率和增加系统容量。     

智能天线在TD-SCDMA系统的实现

研究智能天线在TD-SCDMA系统中的实现,详细介绍了该系统所采用的算法(最大功率合成算法)以及采用这种算法所具有的特点。通过对容量、覆盖范围和误码率等方面的具体分析,探讨了智能天线对TD-SCDMA系统性能的改进。最后仿真出该系统在不同业务下的误码率和误块率,由仿真结果可以明显地看出,采用智能天线可以极大地改善系统的性能。     

基于智能天线的TD-SCDMA系统上行容量分析

文中在对TD-SCDMA,系统标准理解和智能天线原理分析的基础上,以8阵元均匀圆阵的智能天线为例从系统级对TD-SCDMA系统的上行容量进行了分析,结合仿真结果给出了智能天线对系统容量的影响.仿真结果表明,由于在TD-SCDAM系统中智能天线的使用,相比于全向天线背景噪声有明显的降低,并结合多用户检测技术,明显地提高了系统的上行容量.     

一种TD-SCDMA系统容量的仿真模型

TD-SCDMA采用智能天线、上行同步、联合检测、动态信道分配等技术使系统容量大大提高,系统投资成本也低于其他3G标准,因此研究容量仿真算法对TD-SCDMA系统的实用化具有现实意义.文章在介绍静态仿真概念、仿真场景、仿真方法的基础上,利用智能天线系统下的干扰计算方法,给出了一种理想功率控制下的TD-SCDMA系统容量仿真算法,并描述了仿真场景模型构架.     

TD-SCDMA系统干扰分析及仿真

主要分析了TD-SCDMA系统的干扰特性提出了干扰模型及所涉及的路径损耗模型,并从负载和天线两个角度对系统干扰进行仿真分析,为实际的网络规划提供参考.     

智能天线技术及其对TD-SCDMA系统网络规划的影响

文章在介绍智能天线技术基本原理、主要形式及其在第三代移动通信TD-SCDMA系统中的应用的基础上，主要从网络规划的角度，分覆盖距离和系统容量两个方面讨论了智能天线技术给TD-SCDMA系统带来的影响。分析计算和仿真结果表明，在相同条件下，采用智能天线技术可以显著的增加TD-SCDMA系统的小区覆盖面积，大幅度的提高系统容量。     

TD——SCDMA系统干扰分析及仿真

主要分析了TD-SCDMA系统的干扰特性．提出了干扰模型及所涉及的路径损耗模型．并从负载和天线两个角度对系统干扰进行仿真分析，为实际的网络规划提供参考。     

基于智能天线的功率控制方法

TD-SCDMA系统是具有我国自主知识产权的新一代移动通信系统,由于采用了CDMA技术,系统本身存在的内部干扰对系统的容量起主要制约作用。系统中使用了特有的智能天线技术,能对小区中所有的用户进行跟踪和定位,如果能根据用户具体的不同位置采用基于位置的功率控制方法,不仅可改变接收信号的衰落特性、减少小区间和同小区的干扰、减少功耗、延长电池寿命、提高小区容量,还可以改变传统功率控制的复杂性。文章从功率控制的必要性出发,分析了传统功率控制方法对于TD-SCDMA系统中所面临的新问题,提出了一种新的基于智能天线的功率控制方法。     

TD-SCDMA系统的容量性能分析

综合考虑了联合检测技术、智能天线技术以及多载波对TD-SCDMA系统性能的影响,并建立了系统容量的数学模型。同时使用Matlab对系统容量与（能噪比）、（干扰消除因子）、（邻本比因子）和（正交因子）的关系进行了数值仿真分析。     

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。     

Potentials of smart antennas in CDMA systems and uplinkimprovements

An overview of the application of smart antennas in DS-CDMA systems, including IS-95 and IS-2000, is presented. Since CDMA systems are interference-limited, adaptive antenna arrays have great potential for improving the performance of such systems in terms of capacity, coverage, and quality of service, In this paper, we study the multiple-access interference that affects a CDMA system, and we describe how smart antennas can be implemented in an IS-2000-based mobile communications system. When smart antennas are used at the base station to transmit in narrow beams, the interference on the downlink is reduced, and C/I is improved. This, in turn, increases the system capacity on the downlink or, alternatively, the quality of service is improved. Such gains will prove very beneficial for asymmetric high-speed data applications, requiring much higher bit rates on the downlink than on the uplink. By reducing the base-station receiver's sensitivity, smart antennas can boost the capacity of the reverse link. Results are presented that outline how this reduction can be employed by the system designer on the uplink to increase capacity, reduce the mobile transmit power, or effect a tradeoff between capacity improvement and coverage or range extension under different system-loading scenarios     

Modeling and performance analysis of multi‐service wireless CDMA cellular networks using smart antennas

In this paper, we present an analytical model to assess the blocking capacity of multi‐service code division multiple access (CDMA) systems. We include smart antenna systems in our model and show how the capacity of CDMA systems can be improved if smart antennas are employed at the base stations. Applying smart antennas can actually transform CDMA systems from being interference limited to being channel/code limited. To investigate this effect, we extend our model to include the limitation of channelization codes in CDMA‐based universal mobile telecommunication system (UMTS) systems. From the point of view of the call admission control (CAC) in a smart antenna CDMA system, we can either accept the capacity loss due to code limitation, or we can additionally apply space division multiple access (SDMA) techniques to re‐use channelization codes and thus re‐approach the capacity which is obtained if no code limitation is considered. Copyright © 2008 John Wiley & Sons, Ltd.     

智能天线的原理和实现

近年来,智能天线技术已经成为移动通信中最具有吸引力的技术之一。在无线基站使用一个天线阵和基于基带数字信号处理技术,对基站的接受和发射波束进行自适应的赋形,可以大大降低系统内的干扰。提高系统容量,降低发射功率并提高接收灵敏度。在大大提高系统的同时,还可以降低设备的成本。此智能天线首先使用在TD－SCDMA系统中,也能使用在CDMA FDD系统中。本文对移动通信中的智能天线技术的原理和在TD－SCDMA系统中的实现作了简要介绍。     

一种低复杂度空-时选择性干扰消除方法

提出了一种行之有效的将智能天线技术同多用户检测技术结合的空-时接收方法,并对其参数进行了优化。它根据误码率信息有选择地实施干扰消除,先并行消除低误码率用户信号的影响,再检测高误码率用户信号。它复杂度低,计算效率高,易于实时实现,具有很好的应用价值。蒙特卡洛仿真实验表明,该方法可以显著改善码分多址移动通信系统的性能。     

Smart versus dumb antennas-capacities and FEC performance

We compare two approaches to use multiple transmit antennas in an FEC coded wireless system: smart antennas use an antenna array to direct a beam in the direction of the dominant transmission path in order to obtain an antenna gain. Another approach is to use multiple transmit antennas for diversity using space-time block codes. Since no knowledge of the channel is required at the transmitter we denote this approach as dumb antennas. Using equivalent single-input channel models we compare smart and dumb antennas in terms of the BER performance and channel capacity and discuss under which conditions it is preferable to use multiple transmit antennas for transmit diversity or for beamforming     

智能天线对CDMA通信系统性能的改善

作为一种发展较快的技术,智能天线技术在移动通信领域中引起了广泛关注,它能够根据所处的电磁环境,智能的调节自身参数,抑制干扰,提高天线增益,增加频谱利用率,从而改善移动通信系统的性能。介绍了智能天线的工作原理、性能和特点,讨论了在CDMA系统中采用智能天线后系统信噪比性能和容量的改善情况。     

Soft capacity analysis of TDMA systems with slow-frequency hoppingand multiple-beam smart antennas

Smart antenna is considered as one of the most effective means for enhancing wireless system capacity. When fractional loading is accompanied with slow-frequency hopping (SFH), soft capacity can be realized in time-division multiple access (TDMA) wireless networks. Then, the interference reduction due to smart antennas, power control, and discontinuous transmission can be directly translated into capacity gain. This paper addresses the capacity gain due to multiple-beam (MB) smart antennas in TDMA wireless systems with soft capacity. The system capacity is determined analytically and by simulation. MB smart antennas with practical antenna pattern are used in this study. Perfect power control and discontinuous transmission are assumed in the simulation and the theoretical analysis. A novel call admission control algorithm is proposed to enhance the system capacity without degrading the signal quality. The TDMA system is assumed to be global system for mobile communications (GSM)-like, however, the analysis can be extended and applied to other TDMA systems     

智能天线在TD-SCDMA中的应用

智能天线技术是TD-SCDMA(时分同步码分多址)中的关键技术之一.在无线基站使用一个天线阵和基于基带数字信号处理技术,对基站的接受和发射波束进行自适应的赋形,可大大降低系统内的干扰,提高系统容量,大大降低发射功率并提高接收灵敏度.文中介绍了有关智能天线的概念、原理、工作过程,以及对通信性能的改善.     

Performance Evaluation for Forward-Link Cellular DS-CDMA over Frequency-Selective Nakagami Multipath Fading Channels

The bit-error rate (BER) for a forward-link cellulardirect-sequence code-division multiple-access (DS-CDMA) systemis evaluated. This analysis takes into account the effects ofmulti-cell interference resulting from Nakagami multipath fading,frequency selectivity, path loss and mobile user spatialdistribution. Exponentially decaying multipath intensityprofile (MIP) is adopted in the model to investigate itssignificance on the overall performance. In order to evaluatethe BER performance efficiently, saddlepoint integration (SPI)is applied in the analysis. By fixing the number of resolvablemultipaths and varying the number of fingers for the RAKEreceiver, it can be shown that the capacity of a DS-CDMAcellular system increases almost linearly with the number ofRAKE fingers.     

Effects of antenna height, antenna gain, and pattern downtiltingfor cellular mobile radio

Results of wideband path loss and delay spread measurements using high gain, high and low antenna heights with pattern tilting are presented. The measurements were done in the frequency range 905-915 MHz, at two existing cellular mobile radio (CMR) sites. Also presented are potential approaches for analyzing data from high gain antennas. It is shown that, to a large extent, existing models can be used to predict path loss for high gain antennas with downtilting. The results further support the notion that high sites together with high gain antennas and suitably selected pattern tilting can result in a significant reduction in path loss and delay spread, as well as reduction in power transmitted from the cell site and reduction in system interference