【作者】 刘波；

【导师】 龙沪强；

【作者基本信息】 上海交通大学 ， 通信与信息系统， 2010， 硕士

【摘要】 机载无线通信技术作为立体化信息系统的一个重要环节，已经成为近年来的研究热点。机载无线通信信道的特点是快速动态多径衰落，均衡技术是专门消除信道多径干扰的，在机载无线通信系统中非常重要。本文首先对无线信道，机载无线通信信道的特点及其对信号传输的影响进行了分析，并引入了本文算法仿真所使用的四个机载信道模型。信道模型是研究均衡技术的基础，信道的特点决定了均衡器设计和改进的方向。接着本文介绍了单载波自适应均衡技术的原理和分类，以及单载波自适应均衡技术的几种常用准则。机载视频通信上行链路的接收系统在飞机上，受到体积和功耗等限制。盲均衡和差分编码技术联合使用可以克服信号传输中的幅度变化和相位偏移，系统中就不需要同步模块，可以简化通信系统，降低功耗。并且盲均衡不需要训练序列，可以提高信道的利用率。虽然差分编码会造成信噪比性能的损失，但是在上行链路中，可以通过提升地面发射端的发射功率来弥补。所以盲均衡技术适合于机载视频通信上行链路。本文介绍了盲均衡的原理，特点和数学模型，并对几种常用的盲均衡算法进行了理论分析和仿真实验。针对MMMA算法存在先将接收信号拉到单位圆上，再对信号相位进行纠正的两次调整过程，收敛速度较慢的缺陷，提出了一种基于块的混合MMMA与DD-LMS算法，仿真表明新算法的收敛速度比MMMA算法快50%，在机载信道下提高了均衡器的收敛速度和性能。同时本文针对MMMA算法与π/4-DQPSK结合使用时对抗信道中多普勒频移新能较差的问题，引入多滞后高阶瞬时量。公式推导和仿真实验表明，通过将基于块的混合MMMA与DD-LMS算法和多滞后高阶瞬时量结合使用，在粗糙地面信道下，信噪比较高时能够很好的消除信号传输中常相位偏移和多普勒频移引起的相位模糊，适用于机载视频通信上行链路。更多还原

【Abstract】 As an important part in information system, aero-wireless communicationhas become a heated research topic in recent years. Aero-wirelesscommunication systems are dynamic and fast multi-path fading. Equalizer isused to cope with the channel fading, so it’s determinant for the performanceof aero-wireless communication system.In this dissertation, at first I introduce the wireless channel andaero-wireless communication channel and their impact on signal transmission.The four channel models of aero-wireless communication system forsimulation is also introduced.Then different types of single carrier adaptive equalization and arithmeticrules widely used on adaptive equalization are introduced.The receive system of uplink of aero-vedio communication system is onthe plane, so it’s limited on volume and power. The blind equalizer workedonly with differential coding can compensate the amplitude change and phase shift in transmission, so it doesn’t need synchronization module, whichmeans it will synplify communication system and lower the power. The blindequalizer doesn’t need training sequence, which help to improve theutilization of the channel. Although differential coding will cause pofermanceloss of SNR, we can improve the transmission power to compensate it inuplink. Since blind equalizer is suitable for uplink of aero-vediocommunication system, this dissertation introduced the working principle,characters and mathematical model of blind equalizer.This dissertation alsosimulinks and analysis some kinds of common equalization arithmetics.Since the MMMA arithmetic has two adjust process: it first drag thesignals to the unit circle, then adjust the phase of signals, so it has a slowconvergence speed.Aimed at the defect,this dissertation propose a blendedMMMA and DD-LMS arithmetic based on block. Simulations show that thenew arithmetic’s convergence speed is50%faster than the MMMAarithmetic, which improves the perfermance of the equalization underaero-vedio channels. Since the MMMA arithmetic worked with π/4-DQPSKhas a weak performance on the Doppler Frequency Shift in the channels, thisdissertation introduces the Multi-Lag High-order Instantaneous Moment,which can counterwork the Doppler Frequency Shift in the channels whenworked with blind equalizations. Formula derivation and computersimulation show that used with the blended MMMA and DD-LMS blind equalizer arithmetic, the Multi-Lag High-order Instantaneous Moment cancounterwork the phase offset and Doppler Frequency Shift in the signaltransmission, which shows the applicability of blind equalizer in uplink ofaero-vedio communication system.This dissertation introduces the Multi-Lag High-order InstantaneousMoment, which can counterwork the Doppler Frequency Shift in thechannels. Formula derivation and computer simulation show that used withblended MMMA and DD-LMS arithmetic based on block, the Multi-LagHigh-order Instantaneous Moment can counterwork the phase offset andDoppler Frequency Shift under the rough ground channel when the SNR ishigh, which shows the applicability of blind equalizer in uplink of aero-vediocommunication system.更多还原