混合超宽带多微微网干扰模型及性能改善

蓝牙和超宽带核心技术的结合,将会进一步推进无线高数据速率网络的发展.在这篇论文中,提出一种新型的微微网系统模型,即实现蓝牙拓扑和MB-OFDM超宽带技术的结合,考虑路径损失的影响和使用TFC编码来模拟所提出方案的相邻微微网间干扰.用BER 比 Eb/N0曲线图来评估所提出的干扰模型.最后,提出一个6频带的方案来改善所构造的混合系统的性能.仿真结果表明,文中所提出的模拟结构胜过以往传统的模型.     

基于时间反演的超宽带无线通信系统研究

针对室内复杂环境的多径传播特性会严重影响通信性能,引入一种具有时空聚焦特性的时间反演技术.这一技术利用信道信息,使信道本身形成空间和时间的滤波器,对发射信号在发射端进行预滤波,从而实现自适应处理.仿真结果表明,在室内多径情况严重情况下,可有效降低误码率.     

Compact UWB Bandpass Filter Based on Signal Interference Techniques

This letter presents a new type of compact ultra-wideband (UWB) bandpass filter (BPF) based on interference techniques. The structure is formed by a short-ended coupled line coupler connected in parallel to a transmission line. The transmission and reflection zeros of the filter can be controlled through the analytical equations and rules given. To validate the suggested filter scheme, the design, fabrication and measurement of a microstrip UWB BPF is presented.      

基于子空间投影的导航干扰抑制与信号增强方法研究

电磁环境日益恶劣且到达接收机的导航信号非常微弱,导航接收机的输出性能受干扰影响非常明显,因此在干扰背景下提高导航接收机的输出性能是十分重要的。阵列信号处理中的传统抗干扰方法包括采样协方差矩阵求逆 SMI(Sample Matrix Inverse)方法、最小均方误差 LMS(Least Mean Square)迭代方法、功率倒置 PI(Power Inverse)算法等,这些方法具有较高的抗干扰性能,但抗干扰后对信号增强没有效果。本文在子空间投影抗干扰方法的基础上,结合导航信号相关性特点,对子空间投影后信号进行运算,构造最优相关峰矢量,利用该矢量进行波束合成,实现导航信号增强的目的。对实测数据处理可知,该方法可以有效提高抗干扰后导航信号强度。     

Performance Analysis of Narrow-Band Interference Rejection Techniques in DS Spread-Spectrum Systems

Linear least squares estimation (LLSE) techniques can provide an effective means of suppressing narrow-band interference in direct sequence (DS) spread-spectrum systems. In the results presented here, analytical expressions for bit error rate are derived for two DS spread-spectrum systems under the conditions of either tone or narrowband Gaussian interference. It is shown that the most common LLSE filter design can lead to performance inferior to that of various other filter designs. However, results are also presented demonstrating that an LLSE filter design motivated by the structure of the maximum-likelihood receiver leads to consistently superior performance. The performance of a system using this new design criterion is compared with that of an approximation to the maximum-likelihood (ML) receiver for the tone interference model and with that of the exact ML receiver for the Gaussian interference. Finally, it is shown that the bit error rate estimate obtained from application of a Gaussian approximation for the test statistic is overly pessimistic for the systems studied here.     

超宽带(UWB)技术及其抗干扰性能分析

介绍了跳时超宽带(TM-UWB)通信的特点,通过对比传统的RAKE接收机和MMSE-RAKE接收机性能分析了UWB的抗窄带干扰性能,结果表明超宽带在无线个人域网中(WPAN)可以和其它无线电系统共存.     

基于认知的UWB窄带干扰抑制

提出一种基于认知无线电的自适应超宽带窄带干扰抑制方法。基于软频谱思想,利用近似椭球波函数良好的时限-带限特性,设计出一种能够抑制窄带干扰的脉冲波形。通过调整脉冲参数实现对授权频段的动态避让。仿真结果表明：自适应脉冲具有良好的窄带干扰抑制能力,能够自适应地随着感知结果动态地规避授权用户,从而实现UWB系统与其它通信系统的共存。     

超宽带系统在窄带干扰条件下的性能研究

超宽带（Ultra Wide-Band，UWB）系统发射信号的带宽在一个非常大的频段范围内，易与已存在的窄带无线通信系统的带宽形成重叠。因此，有必要研究UWB系统在频段重合范围内的抗干扰能力。文中首先分析了直接扩频超宽带系统在最小均方误差准则检测方式下，RAKE接收机的比特误码率（Bit Error Rate，BERl，然后研究了普通窄带系统的功率谱密度，最后做出了仿真分析。结果表明，在CM1信道传播下，窄带干扰对UWB系统不会造成很大影响，而在CM2信道传播下会照成一定影响，必须通过其他通信手段如信道编码来降低BER，实现通信的可靠性。     

基于RLS算法的直接序列扩频抗窄带干扰技术

在敌方有意的窄带强干扰下,扩频通信系统可以利用时域自适应滤波算法来抑制干扰。介绍了基于时域预测的自适应滤波RLS算法,仿真结果表明其对DSSS系统中的窄带干扰有较好地抑制效果。     

智能天线系统中基于载干比的动态信道分配

智能天线系统实现了同道在同小区的重用,其空域波束分配可以有效抑制同道干扰;信道分配可以充分结合其他信道资源。在Matlab系统级仿真中,充分利用定时器的特性,真实地建立移动台和基站之间在线服务的多线程通信仿真模型,对载频、时隙和码字中任一种或多种结合在空域位置形成的信道,提出基于载干比测量的动态信道分配策略,并对其进行了仿真研究和性能分析。仿真结果与理论分析吻合,同时得到一些有意义的参数。     

基于Turbo编码的超宽带系统性能分析

为了降低严重的时间弥散影响,提出了一种Turbo信道编码方案引入超宽带系统中,分析和仿真了在不同无线室内环境下基于Turho编码的超宽带系统的误比特率性能。无线室内环境是由IEEE802．15．3a提出的修正的SV信道模型。为了降低迭代译码的复杂度,采用了LOG-MAP算法。仿真结果表明,相比于无编码的系统,具有Turbo编码的超宽带系统在不同无线室内环境下提供了可观的编码增益,随着迭代次数的增加,超宽带系统的性能得到了改善。     

Analysis and Design of an Integrated Notch Filter for the Rejection of Interference in UWB Systems

A 0.13-mu m CMOS fourth-order notch filter for the rejection of the 5-6 GHz interference in UWB front-ends is reported. The filter is integrated into an analog front-end for Mode #1 UWB. A thorough analysis based on a simplified model of the filter is carried out. An algorithm for the automatic tuning and calibration of the filter is also discussed and demonstrated. Two versions of the circuit are designed and fabricated: the first comprises a low-noise amplifier and the filter, and the second expands it to a complete front-end. In the latter version the filter was also redesigned. The filter provides more than 35 dB of attenuation and has a tuning range of 900 MHz, adding less than 30% power consumption to the LNA. The out-of-band IIP3 (higher than -13.2 dBm with the filter off) takes a 9-dB advantage from the filter and the compression of the gain due to the out-of-band blocker is reduced by at least 6 dB in the complete front-end. The conversion gain of the front-end is 25 dB per channel, its average noise figure is lower than 6.2 dB, and its in-band 1-dB compression point is higher than - 30 dBm at a power consumption of 32 mW.     

基于变换域通信的OFDM系统窄带干扰抑制方法

为解决宽带OFDM系统易受传统窄带信号干扰的问题,采用基于变换域通信(TDC)的OFDM系统,通过在变换域中的电磁环境采样结果,对OFDM信号进行设计,避免使用受干扰频谱传送信息。该方法在强窄带干扰得到抑制的同时,信噪比也不容易受到变换域滤波的影响。在加性高斯白噪声信道中的仿真结果表明,基于TDC的干扰抑制方法能够有效地抑制宽带OFDM系统的窄带干扰。     

Iterative Frequency-Domain Packet Combining Techniques for UWB Systems with Strong Interference Levels

UWB (Ultra Wideband) systems tend to suffer strong interference from signals that occupy a significant part of the transmission band. This is an important constraint, especially when the channel remains fixed for a long period of time. In order to overcome this limitation, this paper considers UWB systems employing Single-Carrier with Frequency-Domain Equalization techniques. We propose the corresponding receiver, which also allows the soft packet combining associated to different Automatic Repeat ReQuest transmission attempts, as a measure to improve the performance through the exploitation of diversity. Our techniques are able to cope with strong interference levels as well as deep fading, even for fixed channels.     

A Low-Noise Amplifier With Tunable Interference Rejection for 3.1- to 10.6-GHz UWB Systems

An ultrawideband common-gate low noise amplifier with tunable interference rejection is presented. The proposed LNA embeds a tunable active notch filter to eliminate interferer at 5-GHz WLAN and employs a common-gate input stage and dual-resonant loads for wideband implementation. This LNA has been fabricated in a 0.18-$mu$m CMOS process. The measured maximum power gain is 13.2 dB and noise figure is 4.5–6.2 dB with bandwidth of 3.1–10.6 GHz. The interferer rejection is 8.2 dB compared to the maximum gain and 7.6 dB noise figure at 5.2 GHz , respectively. The measured input P1dB is ${-} $11 dBm at 10.3 GHz. It consumes 12.8 mA from 1.8-V supply voltage.      

基于Rake接收机的UWB通信系统性能分析

针对无码间干扰的TH-PPM-UWB通信系统,分析了该系统在IEEE UWB室内多径信道模型下采用Rake接收机时的系统性能,仿真了不同结构Rake接收机的误码率,结果表明,总体上SRake的性能要优于PRake,且两种接收机的性能随着叉指数目的增加都有明显的改善。     

基于空间分集的UWB系统性能分析

将多接收天线应用于跳时(TH)二进制反极性脉冲幅度调制(2PAM)超宽带(UWB)系统中,在存在多用户干扰的环境下以提高系统的误码性能,进而达到高速率通信。分析了在SGA条件下,基于空间分集的SINR的表达式,估计了系统的误比特率,并对2PAM-TH-UWB系统的性能进行仿真。仿真结果表明,随着接收端接收天线数的增加,2PAM-TH-UWB系统误码性能提高。     

PolSK and ASK Modulation Techniques Based BER Analysis of WDM-FSO System for Under Turbulence Conditions

Wireless Personal Communications - This paper details a novel model of Wavelength Division Multiplexed (WDM) system using Polarization Shift Keying (PolSK) modulation to increase the capacity of a...     

符号间干扰对频域差分OFDM误码率性能的影响

在多径衰落信道条件下,分析了符号间干扰对频域差分正交频分复用系统误码率性能的影响,得到了误码率的解析表达式,分析和仿真的结果表明,频域差分的误码率性能受到符号间干扰的影响,但在不同的信道条件下,符号间干扰对系统性能的影响程度也有不同。