Haiquan Zhao Badong Chen Efficient Nonlinear Adaptive Filters Design, Analysis and Applications fi Ef cient Nonlinear Adaptive Filters (cid:129) Haiquan Zhao Badong Chen fi Ef cient Nonlinear Adaptive Filters Design, Analysis and Applications HaiquanZhao BadongChen SchoolofElectricalEngineering InstArtificialIntelligence&Robo SouthwestJiaotongUniversity Xi'anJiaotongUniversity Chengdu,China Xi'an,China ISBN978-3-031-20817-1 ISBN978-3-031-20818-8 (eBook) https://doi.org/10.1007/978-3-031-20818-8 ©TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerNatureSwitzerland AG2023 Thisworkissubjecttocopyright.AllrightsaresolelyandexclusivelylicensedbythePublisher,whether thewholeorpartofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseof illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similarordissimilarmethodologynowknownorhereafterdeveloped. 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ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface Inrecentyears,signal-processingtechnologytakengreataleapforward.Especially with the development of digital circuit technology, the efficiency of digital signal processing(DSP)hasbeengreatlyimproved.Digitalfilteringtechnology,animpor- tant branch of DSP, has been widely studied and applied in many fields, which mainly aims to extract the useful information contained in the received signal. In practice,thedevicethatachievesfilteringfunctionisgenerallycalledafilter,which canextractthedesiredinformationfromtheinputsignal. Digitalfilterisusedtoprocessdiscrete-timesignal.Forlineartimeinvariant(LTI) filter,itsinternalparametersandstructurearefixed,andtheoutputsignalisthelinear mapping of the input signal. However, when the statistical characteristics of the signal to be processed are unknown, the LTI filter cannot provide good signal processing capability. At this time, adaptive filter is a very attractive solution, which can optimize its internal free parameters according to the input signal to provideeffectiveperformance.Strictlyspeaking,adaptivefilterisakindofnonlinear filter (itscharacteristics depend onthe inputsignal), soit does notsatisfy superpo- sition andhomogeneity.However,atacertain moment, theparameters ofthefilter arefixed,andtheoutputofthefilterisalinearmappingoftheinputsignal. Atthecruxofadaptivefiltersisthedesignofthefilteringalgorithm,i.e.howthe parametersofthefilterareadaptivelyadjustedtomeettheperformancerequirements inresponsetochangesintheenvironment(inputanddesiredsignal).Thealgorithms discussed in this book are all based on discrete-time signals, because the rapid development of VLSI technology makes the processing of discrete-time signals morerapidandconvenient. An adaptive filter generally consists of three parts: (1) Application. Adaptive filteringtechnologyhasbeenappliedinmanyaspects,suchaschannelequalization, signalprediction,echocancellation,beam-forming,systemidentification,andsignal enhancement.(2)Structure.Adaptivefiltercanbecomposedofmanystructures,and differentstructurecorrespondstodifferentcomputationalcomplexity.Accordingto the form of impulse response, adaptive filter can be divided into finite impulse response (FIR) filter and infinite impulse response (IIR) filter. The most widely v vi Preface usedFIRfilteristransversefilter,itstransferfunctionhasnopolepoint,sothereis no system stability issue. For this structure, the output of the filter is a linear combinationoftheinputsignals.However,mostoftheactualsystemsarenonlinear, thelinearadaptivefilterisnotsuitabletodealwiththiskindofsituationbecauseof itsinherentdefects,sothenonlinearadaptivefilterisproposedtoovercomeabove- mentioned problem, such as Volterra filter, function link artificial neural network (FLANN), spline filter, and kernel function–based filter. (3) Algorithm. The algo- rithmadaptivelyadjuststhecoefficientsofthefiltertominimizeacertainoptimiza- tioncriterion. In fact, the theory of linear adaptive filtering is mature enough, and a large number of journals and books have summarized it in detail. However, there are veryfewbooksonnonlinearadaptivefilters.Therefore,thecorecontentofthisbook is to introduce some nonlinear adaptive filters with complete theoretical systems, includingsomeclassicalapplications,nonlinearfilterstructures,andalgorithms.The first chapter of this book briefly introduces the basic knowledge of classical linear adaptivefiltering.Theunderstandingofthisbasicknowledgeisthebasisforfurther studyofnonlinearadaptivefilteringmethodsinthefollowingchapters. Themaincontentsofthisbookconsistoffivechapters,whicharesummarizedas follows: Chapter 1 mainly introduces the linear adaptive filter and several classical adaptive filtering algorithms. Finally, a brief introduction is given to the nonlinear filterthatwillbedescribedinthefollowingchapters. Chapter2introducestheVolterrafilterfornonlinearsystems,mainlyincludesthe pipelined Volterrafilter,convexcombined Volterra filterandrobustVolterrafilter, andtheircorrespondingnonlinearfilteringalgorithms.Moreover,arobustdiffusion Volterra(DV)algorithmfordistributednonlinearnetworkisalsodescribedindetail. Finally,computersimulationsareprovided. Chapter3describesthefunctionallinkartificialneuralnetwork(FLANN)-based nonlinearfilter,mainlyincludesthestructure,principle,andsomeimprovedmodels of the FLANN-based filter. The nonlinear property and modelling ability of the FLANN-basedfilterareverifiedbycomputersimulations. InChap.4,thenonlinearsplinefilterandadaptivealgorithmsareintroduced.In addition,theconvergencebehaviorofarobustsplinefilteringalgorithmisanalyzed, andthevalidityofanalysisresultsareverifiedbycomputersimulations.Finally,the applicationofsplinefilterinactivenoisecontrolisgiven. In Chap. 5, we introduce the kernel adaptive filter and several classical kernel adaptive filtering algorithms. In particular, in order to reduce the high computing consumptionandstoragespacecausedbythelarge-scalehiddenlayernodesofthese algorithms,severalnetworkoptimizationmethodsarepresented.Finally,computer simulationsareprovidedtoverifythevalidityoftheseoptimizationmethods. This book provides a reference for researchers and students in the field of developing and researching advanced signal processing of adaptive filters, and alsoprovidesaconvenientwayforpracticalengineersinrelatedfieldstounderstand effective algorithms. The readers of this book need to understand some basic principles of digital signal processing, random processes, and matrix theory, Preface vii including finite impulse response (FIR) digital filter realization, random variables, and first-order and second-order statistics. Assuming that the readers have such a background,theywillhavenoproblemreadingthisbook.Inaddition,anumberof referencesaregivenattheendofeachchaptertofacilitatethereaders’furtherstudy ofachapter. Chengdu,China HaiquanZhao Xi’an,China BadongChen Acknowledgments We would like to thank some of my former and current graduate students. In particular, we would like to thank PhD. Yingying Zhu, PhD. Shaohui Lv, PhD. WenjingXu,PhD.DongxuLiu,PhD.PengfeiLi,Dr.ChuangLiu,Ms.YuanGao, Ms.BoyuTian,Ms.JinweiLou,Ms.XinhaoXu,Dr.ZhengdaQin,andDr.LeiXing withwhomwehaveworkedonthetopicofthisbookandwhocontributedtosome oftheresultsreportedhere.ThisworkwaspartiallysupportedbyNationalNatural ScienceFoundationofChina(grant:62171388,61871461),FundamentalResearch Funds for the Central Universities (grant: 2682021ZTPY091), and Southwest Jiaotong University Graduate Teaching Materials (Monograph) Funding Construc- tionProject(grant:SWJTU-ZZ2022-017). ix Contents 1 AdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 LinearAdaptiveFilters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2.1 LMSAlgorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2.2 AffineProjectionAlgorithm. . . . . . . . . . . . . . . . . . . . . . . 2 1.2.3 RecursiveLeast-SquaresAlgorithm. . . . . . . . . . . . . . . . . 4 1.2.4 SubbandAlgorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.5 KalmanFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3 NonlinearAdaptiveFilters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.3.1 VolterraFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.3.2 FLANNAdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.3.3 SplineAdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.3.4 KernelAdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.4 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2 VolterraAdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.2 VolterraFilterModel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3 PipelinedVolterraFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.4 ConvexCombinationofVolterraFilter. . . . . . . . . . . . . . . . . . . . 24 2.4.1 TheAlgorithmI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.4.2 TheAlgorithmII. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2.5 RobustVolterraFilteringAlgorithm. . . . . . . . . . . . . . . . . . .. . . . 33 2.6 TheVolterraExpansionModelBased Filtered-xLogarithmicContinuousLeastMeanp-Norm (VFxlogCLMP)AlgorithmforActiveNoiseControl Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 2.6.1 VFxlogLMPAlgorithm. . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.6.2 VFxlogCLMPAlgorithm. . . . . . . . . . . . . . . . . . . . . . . . . 40 xi xii Contents 2.6.3 PerformanceAnalysisoftheVFxlogCLMP Algorithm. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.6.4 EMSEAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.6.5 ConvergenceConditionoftheVFxlogCLMP Algorithm. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 2.7 DiffusionVolterraNonlinearFilteringAlgorithm. . . . . . . . . . . . . 48 2.7.1 DiffusionLeastMeanSquare(DLMS)Algorithm. . . . . . . 49 2.7.2 ProblemFormulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 2.7.3 TheDVFilteringAlgorithm. . . . . . . . . . . . . . . . . . . . . . . 51 2.8 SimulationResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 2.8.1 PipelinedVolterraFilter. . . . . . . . .. . . . . . . . . . . . . . . . . 56 2.8.2 ConvexCombinationofVolterraFilter. . . . . . . . . . . . . . . 60 2.8.3 RobustVolterraFilteringAlgorithm. . . . . . . . . . . . . . . . . 64 2.8.4 TheVFxlogCLMPAlgorithmforANCApplication. . . . . . 66 2.8.5 DiffusionVolterraFilteringAlgorithm. . . . . . . . . . . . . . . 71 2.9 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 3 FLANNAdaptiveFilter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3.2 NeuralNetworkStructures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.2.1 MLP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.2.2 ChNN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.2.3 FLANN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 3.2.4 LeNN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 3.3 RecursiveFLANN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.3.1 FeedbackFLANNFilter. . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.3.2 ReducedFeedbackFLANNFilter. . . . . . . . . . . . . . . . . . . 91 3.3.3 RecursiveFLANNStructure. . . . . . . . . . . . . . . . . . . . . . . 95 3.4 ConvexCombinationofFLANNFilter. . . . . . . . . . . . . . . . . . . . 100 3.5 RandomFourierFilter. . . . . . . . . .. . . . . . . . . .. . . . . . . . . . .. . 107 3.5.1 RandomFourierFeature. . . . . . . . . . . . . . . . . . . . . . . . . . 107 3.5.2 RF-LMSAlgorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 3.5.3 CascadedRF-LMS(CRF-LMS)Algorithm. . . . . . . . . . . . 110 3.5.4 MeanConvergenceAnalysis. . . . . . . . . . . . . . . . . . . . . . 113 3.5.5 ComputationalComplexity. . . . . . . . . . . . . . . . . . . . . . . . 115 3.6 NonlinearActiveNoiseControl. . . . . . . . . . . . . . . . . . . . . . . . . . 116 3.6.1 RobustControlAlgorithmsforNANC. . . . . . . . . . . . . . . 116 3.7 NonlinearChannelEqualization. .. . . . . .. . . . . .. . . . .. . . . . .. 126 3.7.1 CommunicationChannelEqualization. . . . . . . . . . . . . . . . 126 3.7.2 ChannelEqualizationUsingaGeneralizedNNModel. . . . 127 3.7.3 FLNNEqualizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 3.8 ComputerSimulationExamples..... ..... ..... ...... ..... 135