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文章基于Windows平台,使用Matlab中的软件包Simulink对CDMA2000移动通信系统的反向业务信道进行了仿真,主要是对"CDMA2000移动台发射机"进行了基于时间流的仿真与实现.分析了信号在"CDMA2000移动台发射机"的主要处理流程,包括信源编码,信道编码,数据调制,以及基带滤波等过程. 相似文献
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介绍了CDMA2000系统的物理信道,给出了CDMA2000核心网络的特点、基于IS-95的第3代移动通信移动的演进策略及对CDMA2000系统的展望。 相似文献
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根据给出的cdma2000系统的反向信道基本构成和技术特点,将RC1(即IS-95CDMA)和RC3两种最为常用的无线配置方法进行了对比,并阐述了cdma2000在扩频调制、功率控制、变速率传输、差错控制以及随机接入方法等方面的改进,而这些改进明显提高了cdma2000的通信性. 相似文献
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文章通过对接入信道对反向链路的干扰分析得出了接入信道所允许的利用率,并且在一定假设条件下计算出了现网中一个扇区的接入信道的实际利用率和短消息数,以及呼叫模型及载波数的关系,文章还对CDMA2000的接入控制过程进行了分析,并与IS-95在接入信道方面进行了详细的对比。 相似文献
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本文主要分析了CDMA2000 1X蜂窝系统反向链路的功率控制性能,在分析过程中假设无线信道为独立的瑞利衰落信道,分别从功率调节步长、移动台移动速度、功控比特的BER以及信道参数几个功控参数来加以分析研究,并由此得出提高功率控制性能的一些方法。 相似文献
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定时跟踪是DS-CDMA系统中Rake接收的关键技术,性能的好坏直接影响着扩频系统能否正常接收.文中首先对扩频系统中定时跟踪原理做出分析,然后重点介绍了PN码的"基于能量窗重心的定时跟踪"新算法,并选择了这个算法来实现CDMA2000-1x上行链路的PN码定时跟踪.最后,经过在典型城市环境下的现场实测,误帧率达到CDMA2000-1x的标准要求. 相似文献
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We analyze the performance of a flexible multirate scheme for direct-sequence code division multiple-access (CDMA) mobile radio systems. The proposed scheme uses a variable processing gain serial pseudonoise modulation as a multirate strategy. To reduce the interference effects, the CDMA system utilizes the coherent fast Walsh transform transmission technique. The proposed scheme can be used in the reverse link (mobile-to-base station) of the upcoming third-generation wide-band CDMA system (has the feature of coherent reverse link). We analyze the system performance with and without using a decorrelating multiuser detector. The uncoded bit-error probability (BEP) with and without decorrelating detection on a multipath fading channel is derived analytically. In addition, the validity of the analysis results is demonstrated by computer simulations using the IMT-2000 vehicular multipath channel model. In order to make sure that the proposed processing techniques do not distort the soft values at the demodulator output, the proposed multirate scheme is also simulated in case of using turbo codes. The turbo-coded BEP is calculated for different user data rates and different number of decoding iterations 相似文献
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An effect of multipath fading on the performance of a cellular code-division multiple-access (CDMA) system is analyzed in this paper. A wide-sense stationary uncorrelated scattering (WSSUS) channel model and the coherent binary phase-shift keying (BPSK) with asynchronous direct-sequence (DS) spreading signal are assumed in the analysis. The average error probability for both the forward link and reverse link of a cellular CDMA system over a frequency-selective fading channel using a conventional correlation-type receiver and RAKE receiver are derived. The impact of imperfect power control and channel capacity of a cellular CDMA system is also investigated. The closed forms of average error probability derived in the paper can save a lot of computation time to analyze the performance and channel capacity of a cellular CDMA system. The analytical results show that the performance and maximum transmission rate of cellular CDMA systems degrade with an increase in the number of simultaneous users and the number of interfering cells. The signal-to-interface ratio (SIR) for the reverse link derived in this paper can directly describe the interrelationships among a number of paths, number of users, number of interfering cells, fading factors, and maximum variation of a received unfaded signal 相似文献
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DS/CDMA closed-loop power control with adaptive algorithm 总被引:1,自引:0,他引:1
Sang Kyu Park Ho Sung Nam 《Electronics letters》1999,35(17):1425-1427
Closed-loop power control in the reverse link of a DS/CDMA system is analysed. The transmitter/receiver based on IS-95 and the radio propagation channel under mobile communication environments are modelled and a new power control algorithm is proposed. This algorithm utilises the burst error characteristics of the channel and can be directly applied to the current IS-95 system. The new power control algorithm, with respect to the SIR (signal to interference ratio), increases the service quality, and finally, enhances the system capacity 相似文献
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HDR(high data rate,高速数据率)是面向CDMA2000所开发的高速无线接入技术,它可以在以传输电话语音为主的通道以外,引进可以满足高速数据通信需求的技术.在HDR系统中,由于前向功率恒定,不存在功率控制的问题.功率控制主要指的是反向功率控制,包括开环功率估计和闭环功率校正.本文集中对HDR系统里面的信道系统、反向功率控制、功率校正等几个关键技术进行了深入的研究. 相似文献
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研究了码分多址反向链路数据传输采用不同的调度算法受系统处理时延影响的程度,这种影响与信道估计误差有关,也与传输速率的更新时间有关。通过对CDMA2000的动态系统级仿真,其结果显示反向链路上的最大速率与轮询结合的算法、最小路径损耗算法、以及轮询算法在有处理时延时吞吐量性能都会降低,其中最大速率与轮询结合的算法降低的程度最小,轮询算法降低程度最大,最小路径损耗算法介于中间。性能降低也与快衰信道类型相关,信道变化越快算法性能受到的影响越大。提出了一种对调度算法的改进方法,即根据移动台处理时延的变化,为近期处理时延较小的移动台分配更多的资源,结果表明该方法改善了系统吞吐量。 相似文献
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TD-SCDMA系统通过HSUPA的引入,在上行方向上大幅地提高了数据速率。同以往的WCDMA和CD-MA2000一样,TD-HSUPA反向链路的干扰也将严重影响系统质量,但由于TD-HSUPA在上行方向上的数据信道为共享方式,且干扰控制上不能采用WCDMA中E—RGCH的方式,故对功率控制的有效性和准确性带来了挑战。分析TD-HSUPA的干扰特性,并通过系统级仿真对比几种不同功率授权算法下的系统性能。 相似文献
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将CDMA2000作为无线频谱移动监测系统中数据传输的通道,为无线频谱移动监测系统提供实时的数据,它使得无线频谱移动监测系统更为方便和快捷地对系统内的各种资源进行管理 相似文献