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 共查询到19条相似文献,搜索用时 230 毫秒
1.
谢波  朱世华  胡刚 《通信学报》2003,24(11):79-85
研究了快衰落环境中第三代移动通信空中接口WCDMA(FDD),基于时分复用的导频信号辅助衰落信道下的信道估计。提出了同时根据导频信号及数据信号估计信道参数的信道估计方法,该方法将信道估计分为根据导频信号和数据信号两部分进行并由其加权合并完成。计算了最小均方误差下的合并系数。仿真结果表明该方法能快速跟踪信道的衰落,有效地估计出各时隙中数据段的信道参数。利用该算法,尤其在高速运动情况下,接收机的性能可得到显著的改善。  相似文献   

2.
胡刚  朱世华  谢波 《电子学报》2004,32(2):219-222
第三代移动通信标准cdma2000采用了基于平行连续导频信道辅助的信道估计体制.本文将分形理论引入多径衰落信道的描述,提出了一种利用分形滤波进行最小均方误差意义下信道参数估计的方法.仿真结果表明,本方法不仅对不同运动速度下的信道都能得到比较准确的估计,从而显著地改善Rake接收机的性能,而且可以自适应跟踪信道衰落的快慢变化.研究同时表明,与传统的随机模型相比,新的分形信道模型能更好地刻画多径衰落的行为.  相似文献   

3.
WCDMA中一种新的信道估计方法   总被引:4,自引:0,他引:4       下载免费PDF全文
本文介绍了第三代移动通信标准WCDMA(FDD)中基于时分复用的导引符号辅助瑞利衰落信道下的信道估计.提出了一种新的利用两个连续时隙的导引符号估计出的信道参数进行最小二乘意义下二次曲线内插的信道参数估计方法.仿真表明本方法能有效地估计出时隙中数据段的信道参数,尤其在高速及变速运动情况下,Rake接收机的性能得到了显著的改善.  相似文献   

4.
宽带数字信道化接收机的FPGA实现   总被引:1,自引:0,他引:1  
陈涛  岳玮 《电子设计工程》2011,19(3):166-170
为解决现代电子战对接收机处理带宽宽、灵敏度高及实时性处理的要求,提出一种数字信道化接收机的设计方法。在推导高效信道化接收机模型的基础上,采用多相滤波器结构实现的数字信道化接收机。该接收机利用超高速A/D对数据进行高速采样,然后由高性能FPGA进行数据抽取、多相滤波、CORDIC算法等信道化实时处理。为了提高实时性,采用并行IFFT实现。该信道化接收机不仅能稳定输出载频及相位信息,还能处理三路同时到达的不同信号。实际的性能测试结果表明该接收机的功能正确并达到预定指标。  相似文献   

5.
基于扩展卡尔曼滤波的MIMO迭代信道估计方法   总被引:1,自引:1,他引:0  
针对高速移动场景下信道快衰落、非平稳等特性导致下行链路信道估计性能受限的问题,提出了一种适用于高速移动环境下行链路的MIMO信道估计方法.采用自回归过程对信道建模,构造自反馈的扩展卡尔曼滤波器(EKF)追踪信道响应及其时域相关系数.采用迭代接收机的结构解决了在MIMO环境下观测方程欠定的问题.仿真结果表明,在高速移动环境下所提方法相较于最小二乘估计等传统方法提升了信道估计的均方误差和系统的误码率性能,可应用于高速列车无线通信设备的接收机基带信号处理系统.  相似文献   

6.
OFDM联合信道均衡与I/Q失衡补偿算法   总被引:1,自引:1,他引:0  
分析多径衰落信道下零中频接收机的I/Q失衡对OFDM系统造成的影响,并在此基础上构造一个结合了信道频率响应与I/Q失衡因子的复合信道模型.通过设计OFDM双导频符号进行复合信道均衡,从而能同时补偿多径衰落信道和I/Q失衡对OFDM系统造成的影响.仿真结果表明:这种联合算法大大提高了OFDM系统的性能,而且具有较低的实现复杂度.  相似文献   

7.
宽带CDMA中一种新的自适应信道估计方法   总被引:4,自引:0,他引:4  
在衰落信道中进行相干解调必须知道瞬时的信道参数,但由于信道是时变的,所以信道估计器的频率响应和带宽应该是由衰落信道的统计特性和系统的信干比决定。利用瞬时信道估计的自相关函数,本文提出了信道估计的一种新的自适应算法。在平坦瑞利信道中的计算机仿真表明本方法在3G标准支持的所有多普勒频率范围内都能获得良好的均方误差性能。  相似文献   

8.
雷一昇 《现代导航》2021,12(1):67-70
为了克服多径信道下码间串扰带来的影响,本文对SC-FDE系统中的信道估计和均衡算法进行研究。首先分析了DFT插值算法原理,提出采用格雷互补序列估计信道频率响应的方法,然后对MMSE均衡估计参数进行了详细推导,最后通过Matlab对均衡算法中时域滤波进行仿真验证,结果表明该方法能够有效滤除噪声,提升多径信道下系统接收性能,具有一定的应用价值。  相似文献   

9.
基于小波的频率选择性瑞利衰落信道估计   总被引:2,自引:0,他引:2  
频率选择性快衰落信道的精确估计对接收机性能的提高起着重要作用。本文采用小波基表示频率选择性快衰落信道,并由此提出两种估计时变信道的算法,瑞利快速衰落信道下的仿真结果表明,信道估计精度较之传统的LMS和RLS算法有明显提高。  相似文献   

10.
本文结合正交频分复用(OFDM)、格形编码调制(TCM)与差分编码,提出一种使用子信道交织技术的差分TC—OFDM系统,并在此基础上将信道估计引入系统接收机,提出了与解码相联合的SEWRLS自适应信道估计方法。计算机仿真结果表明,本文提出的联合系统能有效地克服宽带无线通信中的多径衰落,并在快衰落环境中具有很强的抗信道干扰能力。  相似文献   

11.
This paper introduces an improved frequency domain channel estimation method based on interpolation vectors for single carrier frequency domain equalization (SC-FDE) with the multiple-input multiple-output (MIMO) scheme. The proposed algorithm is derived by employing the least squares (LS) criterion, and a specified application for the wide sense stationary uncorrelated scattering (WSSUS) Rayleigh fading channel is presented. The channel frequency domain responses estimated at two adjacent pilot blocks are used to track the time-variant channel information, which can effectively improve the accuracy of channel estimation without significantly increasing complexity. Maximum mean square error (MMSE) frequency domain equalization based on the estimated channel is employed in the receiver to recover transmitted signals. This paper also investigates a training sequence design method for multiple transmit antennas and a noise variance estimation method. Numerical simulation results show that the proposed methods can perform very well for fading channels with long multipath delay and high Doppler spread.  相似文献   

12.
 Turbo均衡技术是水声相干通信克服信道多径、消除码间干扰(ISI)的有效工具。Turbo均衡实际使用时需要对时变、多径信道进行良好的估计。为了提高信道估计的效果,该文基于时变横向滤波和相位旋转信道模型,提出一种水声通信Turbo均衡中的软迭代信道估计算法。该算法采用快速自优化最小均方算法得到各数据符号处的横向滤波器系数矢量并与二阶锁相环联合优化计算。通过仿真比较,该算法明显优于硬迭代信道估计算法,且相位估计性能优于其他文献中的软迭代信道估计算法。在海上试验中,水声通信距离5 km,方向近似垂直,接收阵起伏周期10 s,起伏幅度5 m左右,在此情况下进行数据采集。将该算法用于对海试数据的单通道Turbo均衡处理,实现无误码输出,验证了所提算法在软迭代信道相位估计方面的优势。  相似文献   

13.
Turbo均衡是一种将Turbo原理和均衡技术结合起来的技术。他通过反复均衡和信道译码来提高接收机性能。针时瑞利衰落信道,采用基于线性滤波器的软输入/软输出均衡器来消除码间干扰,其系数由最小均方误差准则确定。译码器采用最大后验概率算法时卷积码译码。考虑到瑞利衰落信道为随机信道,用非相干检测时信道进行估计。接收机通过联合均衡和译码以充分利用已经获得的信息,实现信道估计及信道均衡与信道译码的迭代更新。仿真结果表明其性能不仅远远优于非迭代系统.而且在信噪比高于4dB时几乎可以完全消除符号间干扰的影响,与MAPSE相比其复杂度大大降低。  相似文献   

14.
Delay diversity is an effective transmit diversity technique to combat adverse effects of fading. Thus far, previous work in delay diversity assumed that perfect estimates of current channel fading conditions are available at the receiver and training symbols are required to estimate the channel from the transmitter to the receiver. However, increasing the number of the antennas increases the required training interval and reduces the available time with in whichdata may be transmitted. Learning the channel coefficients becomes increasingly difficult for the frequency selective channels. In this paper, with the subspace method and the delay character of delay diversity, a channel estimation method is proposed, which does not use training symbols. It addresses the transmit diversity for a frequency selective channel from a single carrier perspective in the form of a simple equivalent flat fading model. Monte Carlo simulations give the performance of channel estimation and the performance comparison of our channel-estimation-based detector with decision feedback equalization, which uses the perfect channel information.  相似文献   

15.
This paper presents a new fractionally-spaced maximum a posteriori (MAP) equalizer for data transmission over frequency-selective fading channels. The technique is applicable to any standard modulation technique. The MAP equalizer uses an expanded hypothesis trellis for the purpose of joint channel estimation and equalization. The fading channel is estimated by coupling minimum mean square error techniques with the (fixed size) expanded trellis. The new MAP equalizer is also presented in an iterative (turbo) receiver structure. Both uncoded and conventionally coded systems (including iterative processing) are studied. Even on frequency-flat fading channels, the proposed receiver outperforms conventional techniques. Simulations demonstrate the performance of the proposed equalizer  相似文献   

16.
In the downlink of wideband code division multiple access (WCDMA) or WCDMA- high speed downlink packet access (HSDPA) system, the frequency reuse factor is equal to 1, which leads to more possible co-channel interference from neighbor cells. In this situation, user equipment(UE) with traditional receiver will suffer from significant performance degradation at the edge of the cell. To solve this problem, a receiver structure considering interference mitigation has been proposed for long term evolution(LTE) of third-generation partnership project (3GPP). Such receiver makes use of all the interfering cells' channel information to perform a linear minimum mean square error (LMMSE) equalization algorithm. In this article, an improved equalization algorithm is presented, which simply adds more samples to perform one equalization operation. Simulations show that the proposed algorithm can obtain a considerable performance improvement in frequency selective fading channel, with relative little additional complexity introduced.  相似文献   

17.
Traditional equalizers are very sensitive to carrier frequency offsets between the transmitter and receiver. Coherent receivers with frequency estimation algorithms can remove the offset to prevent the equalizer breakdown, but with a penalty in receiver complexity. On the other hand, noncoherent receivers such as differential detectors are inherently robust to the frequency offsets but cannot employ standard equalization techniques due to their nonlinear front-end. We introduce a simple noncoherent equalizer receiver structure for fading channel environments with short memory (up to two-bit intervals). The receiver consists of a whitened matched filter followed by a differential detector and a maximum likelihood sequence estimation (MLSE) equalizer. We examine the performance of this noncoherent equalizer by both analysis and simulation. It is shown that despite the simplicity, this receiver structure is capable of significant performance improvement as compared to an ordinary differential detector while operating with receiver frequency offsets two orders of magnitude greater than a traditional MLSE equalizer. This structure offers an attractive solution for high-bit-rate cordless transmission systems such as Digital Enhanced Cordless Telecommunications (DECT) that use simple noncoherent receivers whose performance can be constrained by channel dispersion. Using DECT as a case study, we show that the equalizer's performance limits are caused by the receiver nonlinearity and can be improved by adaptation of this nonlinearity to channel conditions.  相似文献   

18.
This paper addresses the performance of fast doubly selective fading channel estimation combined with Inter-Carrier Interference (ICI) cancellation for Long Term Evolution (LTE) communication platform in the High Speed Railway (HSR) environment. We consider the Channel Impulse Response (CIR) coefficients with a critical Doppler frequency shift and multi-path fading that were taken from the WINNER II channel model and the D2a propagation scenario, where the conditions of HSR are analyzed. As multi-path fading increases and the channel varies in the order of the symbol period, we first propose a novel approach for designing a pilot symbol structure in the time domain. Then, we describe the deployment of the proposed pilot symbol structure to estimate the channel in the time domain. Channel information corresponding to the data positions is obtained by linear interpolation. In each OFDM symbol, the slope and the initial value for establishing an interpolation function are estimated to adapt to the time variation of the channel. An accurate estimate of channel state information is used for the purpose of ICI cancellation. The simulation results show that the channel estimated by our proposed method can follow the real channel well, even in a very high Doppler frequency. The estimation method in terms of Mean Squared Error (MSE) significantly outperforms the state-of-the-art methods. The combination of our channel estimator with several interference cancelers provides a considerably better system performance than that achieved when frequency channel estimation is used.  相似文献   

19.
该文研究了多径衰落的分形性质,提出了一种利用分形维数和小波重构来改进最小均方误差方法的新型多径衰落信道估计算法,该算法改进了衰落信道参数估计的准确度,并消除了判决方法的错误传递性。仿真结果表明该算法能较准确地估计出多径衰落信道的参数,显著提高快衰落条件下接收机的误码性能。  相似文献   

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