时延扩展

提出了一种简单有效的信道RMS时延扩展的估计方法。

A simple but effective RMS delay spread estimation method is also presented .

最后给出了一种信道响应及RMS时延扩展联合估计的简单方法。

Finally , the joint estimation of channel response and RMS delay spread is discussed .

最后利用Matlab平台，结合路径损耗和时延扩展的实际测量数据，对它们进行拟合，并分别分析和比较各个拟合的结果。

Ultimately , fitted the measurement data combined path loss and delay spread model with Matlab , and each of the fitting results was analyzed and compared .

而在消除符号间干扰和均衡由无线信道时延扩展引起的频率选择性衰落方面，正交频分复用（OrthogonalFrequencydivisionMultiplexing，OFDM）技术具有明显优势。

In receiver , Orthogonal Frequency Division Multiplexing ( OFDM ) system can easily cancel ISI and equalize frequency-selective fadings that are both caused by time disperse of radio channel .

从缩短信道时延扩展的角度出发，研究了Rake接收机的部分信道均衡能力，并推导出了Rake接收机均衡性能与Rake接收机的复杂度和信道衰减系数之间的关系；

Rake receiver was analyzed for its performance of channel shortening by deriving the delay spread of an equivalent channel after maximal-ratio combination .

但是，决定通信系统调制参数的信道响应和RMS时延扩展由于物体的运动或者环境的变化而动态变化，传统的静态确定OFDM系统调制参数的方法的频谱效率不够高。

But the spectrum efficiency of the traditional OFDM system is limited due to variance of channel parameters such as channel response and RMS delay spread .

实验结果表明，TR在减小多径时延扩展、提高信噪比、降低码间干扰等方面性能显著。

The results show that TR exhibit improved performance in compressing delay spread , improving signal-to-noise , and reducing inter-symbol interference .

但是在信道时延扩展超长的水声信道中，由于保护间隔必须大于多径时延，因此OFDM的传输效率显著降低。

But in the case of long multipath spread , the guard interval must be longer than multipath delay , resulting in significant reduction in the transmission efficiency of OFDM .

本文分析了短波信道的特点，采用Matlab仿真的方法，对由于多径效应而产生的瑞利衰落，时延扩展以及码间干扰等问题进行了仿真和深入的探讨。

The paper analyzes the features of shortwave channel , and the method of Matlab simulation is adopted , simulates and discusses the Rayleigh fading , time delay spread and inter-symbol interference caused by multipath effect .

同其它CDMA系统一样，TDDCDMA系统在无线传输中仍然存在着多径衰落、时延扩展、远近效应、多址干扰等问题，直接影响了系统的容量和服务质量。

But in TDD-CDMA system , there are many problems to solve including multipath fading , perspective effect , multiple access interference which influence its capacity and quality of service .

研究了MIMOOFDM系统中最小描述长度（MDL）准则在均方根时延扩展估计中的应用。

This paper studies the application of minimum description length ( MDL ) criterion for estimating root-mean-squared ( RMS ) delay spread ( RDS ) for MIMO OFDM systems .

在高达几兆bps的传输速率下，传输符号的符号周期小于信道的时延扩展，从而产生ISI。

When the data rate is more than several Mbps , there is ISI because the signal duration is shorter than the channel delay spread .

自适应阵列天线在近年来被称为智能天线，它能够显著提高系统的信号干扰噪声比（SINR），能够减小时延扩展及多径衰落，实现空分多址。

The smart antenna is able to improve SINR significantly and reduce time delay spread and multipath fading at the same time .

最后对MIMO+OFDM技术进行了研究，给出了MIMO+OFDM技术在时延扩展情况下的信道容量表达式，并对MIMO系统和MIMO+OFDM系统在受干扰情况下的容量进行了仿真比较。

Its channel capacity expression in the case of time delay spread is presented . And the emulation to compare MIMO system to MIMO + OFDM system 's capacity in interfered case is carried on .

rms时延扩展和相干带宽均与具体的信道结构有关，大致在数十微秒和数十千赫兹数量级。

The rms delay spread and the coherence bandwidth are in correlation with the network structure , and corresponding values are on the order of ten μ s and ten kilohertz .

在3G微小区的传播环境下，对线性自适应均衡算法进行仿真研究，为此构建了与3G接近的实用系列时延扩展的传播环境和可变多径传播信道。

The simulation research is made to the performance of linear adaptive equalization algorithm under the 3G micro-cell transmission situation . Furthermore , a near 3G practical time delay propagation environment and variable multipath propagation channels are established .

根据弹性波在大地信道中的传输路径，分析多径时延扩展，在保证系统传输速率和频带利用率的基础上，确定保护间隔长度、OFDM符号周期长度。

The multipath time delay is analyzed according to elastic wave transmitting track in the earth channel . And guard interval length and OFDM signal circle length are established to ensure the system transfer rate and spectrum availability ratio .

多输入多输出（MIMO）技术能够显著提高无线信道的频谱效率，正交频分复用（OFDM）技术能够有效对抗宽带信道多径时延扩展造成的频率选择性衰落。

Multiple-input multiple-output ( MIMO ) technology can greatly increase the spectral efficiency of wireless channel , and orthogonal frequency division multiplex ( OFDM ) technology can effectively resist frequency selective fading caused by multi-path time-delay dispersion in wideband channels .

基于移动通信环境中非视距NLOS（Non-LineofSight）传播时延扩展服从指数分布的特性，提出了提高波达时间TOA（TimeOfArrival）定位方法精度的一种数据处理方法。

Based on the statistical property of the non-line of sight ( NLOS ) propagation in the mobile communication environment , a data process method was presented to improve the position location accuracy of the time-of-arrival ( TOA ) .

该系统在2MHz的频率带宽内，数据通信速率最高可达4.86Mbps，可以容忍的时延扩展为2.5μs。

This system can implement 4.86 Mbps data rate and tolerate 2.5 μ s time delay spread .

提出了一种改进的适用于高速相干通信长时延扩展稀疏信道的自适应判决反馈均衡器（DFE）。

In our opinion , conventional adaptive DFE needs to be and can be improved so as to exploit fully the long sparse wireless channels in high-speed digital communication .

常用的最大似然序列估计（MLSE）均衡器采用维特比算法（VA），它只能用于具有较小时延扩展的信道。

The Maximum Likelihood Sequence Estimation ( MLSE ) using the Viterbi Algorithm ( VA ) is commonly recommended for the equalization , which can only accommodate the channels with limited time delay spread .

本文通过将扩展函数在时延扩展域和Doppler扩展域进行采样，得到了CDMA时变色散信迢的离散正则模型，此模型适宜于采用二阶统计量方法对CDMA时变色散系统进行盲信号处理。

In this paper , the discrete-time canonical model of CDMA time-varying ( TV ) dispersive channels is developed by sampling the spreading function in delay-spreading domain and Doppler-spreading domain . The model is suitable for blind signal processing for the CDMA-TV dispersive channels exploiting the second-order statistics-based approaches .

为补偿因空间角扩展和时延扩展同时存在而引起的多径干扰，将CM阵推广至二维结构，利用基于CMA恒模算法的空时联合信号处理技术对其进行均衡。

To equalize the signal distortion caused by multipath interference with the angle spread and the delay spread , it extend the CM array to spatial-temporal structure , using the spatial-temporal combined signal processing technology based on the constant modulus algorithm ( CMA ) to equalize signal .

无线通信中，当符号周期小于信道的多径时延扩展，即出现信道的频率选择性衰落时，接收信号会受到严重的码间干扰（ISI）。

In wireless communications , when the symbol period is smaller than the signal multipath delay spread , in the other words , when a frequency selective fading channel is existed , the received signal will suffer a serious inter-symbol interference ( ISI ) .

针对B3G（Beyond3Generation）室外环境的大时延扩展和时间频率选择性衰落，提出了适用于较大载波数的OFDM系统的一种基于导频辅助的低维KALMAN滤波的信道估计算法。

Based on the research and simulation of OFDM system and the existing channel estimation methods , a low-dimensional Kalman filter method based on pilot signals is presented for the channel estimation of OFDM systems with large number of carriers in Beyond 3 Generation ( B3G ) outdoor environment .

连续相位调制信号在长时延扩展信道下的均衡算法

Equalization Algorithms for Continuous Phase Modulation on Long Delay Spread Channels

减小室内传播时延扩展对提高室内无线通信系统的性能有重要意义。

Mitigation of indoor propagation delay spread has far-reaching meaning in wireless communication .

在时域，信道的冲激响应表现出时延扩展。

In the time domain , the impulse response shows a delay spread .

室内多径时延扩展的实验研究

Experimental Study on Multipath Delay Spread in Building