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Digital Signal Processing II `Advanced Topics’

Digital Signal Processing II `Advanced Topics’. Marc Moonen Dept. E.E./ESAT, K.U.Leuven marc.moonen@esat.kuleuven.be www.esat.kuleuven.be/scd/. Lecture-1 : Introduction. Aims/Scope Why study DSP ? DSP in applications : GSM, ADSL,… Overview Activities

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Digital Signal Processing II `Advanced Topics’

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  1. Digital Signal Processing II`Advanced Topics’ Marc Moonen Dept. E.E./ESAT, K.U.Leuven marc.moonen@esat.kuleuven.be www.esat.kuleuven.be/scd/

  2. Lecture-1 : Introduction • Aims/Scope Why study DSP ? DSP in applications : GSM, ADSL,… • Overview • Activities Lectures - Course Notes/Literature Homeworks/Exercise sessions Project Exam Version 2009-2010Lecture-1 Introduction

  3. Why study DSP ? • Analog Systems vs. Digital Systems - translate analog (e.g. filter) design into digital - going `digital’ allows to expand functionality/flexibility/… (e.g. how would you do analog speech recognition ? analog audio compression ? …? ) OUT OUT IN 2 IN +2 A/D D/A =4 Version 2009-2010Lecture-1 Introduction

  4. DSP in applications : GSM Cellular mobile telephony (e.g. GSM) • Basic network architecture : -country covered by a grid of cells -each cell has a base station -base station connected to land telephone network and communicates with mobiles via a radio interface -digital communication format Version 2009-2010Lecture-1 Introduction

  5. DSP in applications : GSM • DSP for digital communications (`physical layer’ ) : • a common misunderstanding is that digital communications is `simple’…. • While in practice… .99,.01,.96,.95,.07,… Transmitter 1,0,1,1,0,… Channel Receiver x + x decision 1,0,1,1,0,… 1/a a noise Version 2009-2010Lecture-1 Introduction

  6. DSP in applications : GSM • DSP for digital communications (`physical layer’ ) : • In practice… • This calls for channel modeling + compensation (equalization) !! .59,.41,.76,.05,.37,… Transmitter 1,0,1,1,0,… Receiver `Multipath’ Channel ?? + 1,0,1,1,0,… noise Version 2009-2010Lecture-1 Introduction

  7. DSP in applications : GSM • GSM Channel Estimation/Compensation • Multi-path channel is modeled with short (3…5 taps) FIR filter H(z)= a+b.z^-1+c.z^-2+d.z-3+e.z^-4 (interpretation?) • Channel coefficients (cfr. a,b,c,d,e) are identified in receiver based on transmission of pre-defined training sequences, in between data bits (problem to be solved at receiver is: `given channel input and channel output, compute channel coefficients’). This leads to a least-squares parameter estimation procedure (see Linear Algebra course!). • Channel model is then used to design suitable equalizer (`channel inversion’), or (better) for reconstructing transmitted data bits based on Maximum-likelihood sequence estimation (`Viterbi decoding’). • Channel is highly time-varying (e.g. terminal speed 120 km/hr !) => All this is done at `burst-rate’ (+- 100 times per sec). = SPECTACULAR !! Version 2009-2010Lecture-1 Introduction

  8. DSP in applications : GSM • GSM Channel Estimation/Compensation • GSM Speech Coding • Original `PCM’-signal has 64kbits/sec = 8 ksamples/sec * 8bits/sample. • How to reduce this to <11kbits/sec, while preserving quality ? • Coding based on speech generation model (vocal tract,…), where model coefficient are identified for each new speech segment (e.g. 20 msec). • This leads to a least-squares parameter estimation (again), executed +- 50 times per second). Fast algorithm is used, e.g. `Levinson-Durbin’ algorithm (see (Advanced) Linear Algebra course). • Then transmit model coefficients instead of signal samples. • Synthesize speech segment at receiver (that `sounds like’ original speech segment). = SPECTACULAR !! Version 2009-2010Lecture-1 Introduction

  9. DSP in applications : GSM • GSM Channel Estimation/Compensation • GSM Speech Coding • GSM Multiple Access Schemes • Capacity increase by time & frequency `multiplexing’ • FDMA : e.g. 125 frequency channels for GSM/900MHz • TDMA : 8 time slots(=users) per channel, `burst mode’ communication (PS: in practice, capacity per cell << 8*125 ! ) • Etc.. = BOX FULL OF DSP/MATHEMATICS !! Version 2009-2010Lecture-1 Introduction

  10. DSP in applications : ADSL Telephone Line Modems • voice-band modems : up to 56kbits/sec in 0..4kHz band • ADSL modems : up to 8Mbits/sec in 30kHz…1MHz band (3,5…5km) • VDSL modems : up to 52Mbits/sec in …12MHz band (0.3…1.5km) How has this been made possible? X 1000 Version 2009-2010Lecture-1 Introduction

  11. DSP in applications : ADSL Communication Impairments : • Channel attenuation • Received signal may be attenuated by more than 60dB (attenuation increases with line length & larger at high (MHz) frequencies) PS: this is why for a long time, only the voiceband (up to 4kHz) was used • Frequency-dependent attenuation introduces ``inter-symbol interference’’ (ISI). ISI channel can (again) be modeled with an FIR filter. Number of taps will be much larger here (>500!) Version 2009-2010Lecture-1 Introduction

  12. DSP in applications : ADSL Communication Impairments : • Coupling between wires in same or adjacent binders introduces `crosstalk’ • Near-end Xtalk (NEXT) (=upstream in downstream, downstream in upstream) • Far-end Xtalk (FEXT) (=upstream in upstream, downstream in downstream) Meaning that a useful signal may be drowned in (much larger) signals from other users.. …leading to signal separation and spectrum management problems • Other : • Radio Frequency Interference (AM broadcast, amateur radio) • Echo due to impedance mismatch • Etc.. Conclusion: Need advanced modulation, DSP,etc. ! Version 2009-2010Lecture-1 Introduction

  13. DSP in applications : ADSL • ADSL spectrum : divide available transmission band in 256 narrow bands (`tones’), transmit different sub-streams over different sub-channels (tones)(=DMT, `Discrete Multi-tone Modulation’) Version 2009-2010Lecture-1 Introduction

  14. DSP in applications : ADSL ADSL-DMT Transmission block scheme : DFT/IDFT (FFT/IFFT) based modulation/demodulation scheme pointer : www.adslforum.com PS: do not try to understand details here... Version 2009-2010Lecture-1 Introduction

  15. DSP in applications : ADSL ADSL specs • 512-point (I)FFT’s (or `similar’) for DMT-modulation FFT-rate = 4.3215 kHz (i.e. >4000 512-point FFTs per second !!!!) • basic sampling rate is 2.21 MHz(=512*4.3215k) 8.84 MHz A/D or D/A (multi-rate structure) • fixed HP/LP/BP front-end filtering for frequency duplex • adjustable time-domain equalization filter (TEQ) e.g. 32 taps @ 2.21 MHz filter initialization via least-squares/eigenvalue procedure • adaptive frequency-domain equalization filters (FEQ) VDSL specs • e.g. 4096-point (I)FFT’s, etc…. = BOX FULL OF DSP/MATHEMATICS !! Version 2009-2010Lecture-1 Introduction

  16. DSP in applications : Other… • Speech Speech coding (GSM, DECT, ..), Speech synthesis (text-to-speech), Speech recognition • Audio Signal Processing Audio Coding (MP3, AAC, ..), Audio synthesis Editing, Automatic transcription, Dolby/Surround, 3D-audio,. • Image/Video • Digital Communications Wireline (xDSL,Powerline), Wireless (GSM, 3G, Wi-Fi, WiMax CDMA, MIMO-transmission,..) • … Version 2009-2010Lecture-1 Introduction

  17. DSP in applications Enabling Technology is • Signal Processing 1G-SP: analog filters 2G-SP: digital filters, FFT’s, etc. 3G-SP: full of mathematics, linear algebra, statistics, etc... • VLSI • etc... Signals&Systems course (JVDW) DSP-I (PW) DSP-II Version 2009-2010Lecture-1 Introduction

  18. DSP-II Aims/Scope • Basic signal processing theory/principles filter design, filter banks, optimal filters & adaptive filters • Recent/advanced topics robust filter realization, perfect reconstruction filter banks, fast adaptive algorithms, ... • Often `bird’s-eye view’ skip many mathematical details (if possible…  ) selection of topics (non-exhaustive) Version 2009-2010Lecture-1 Introduction

  19. Overview (I) • INTRO : Lecture-1 Lecture-2 : Signals and Systems Review • Part I : Filter Design & Implementation Lecture-3 : IIR & FIR Filter Design Lecture-4 : Filter Realization Lecture-5 : Filter Implementation Version 2009-2010Lecture-1 Introduction

  20. 3 subband processing 3 G1(z) H1(z) OUT IN 3 subband processing 3 G2(z) H2(z) + 3 subband processing 3 G3(z) H3(z) 3 subband processing 3 G4(z) H4(z) Overview (II) • Part II: Filter Banks & Subband Systems Lecture-6 : Filter Banks Intro/Applications (audio coding/CDMA/…) Lecture-7/8 : Filter Banks Theory Lecture-9 : Special Topics (Frequency-domain processing, Wavelets,…) . Version 2009-2010Lecture-1 Introduction

  21. Overview (III) • Part III : Optimal & Adaptive Filtering Lecture-10 : Optimal/Wiener Filters Lecture-11: Adaptive Filters/Recursive Least Squares Lecture-12: Adaptive Filters/LMS Lecture-13: `Fast’ Adaptive Filters Lecture-14: Kalman Filters . Version 2009-2010Lecture-1 Introduction

  22. Prerequisites `Systeemtheorie en Regeltechniek’ (JVDW) `Digitale Signaalverwerking I’ (PW) signaaltransformaties, bemonstering, multi-rate, DFT, … `Toegepaste Algebra en Analytische Meetkunde’ (JVDW) Version 2009-2010Lecture-1 Introduction

  23. Literature / Campus Library Arenberg • A. Oppenheim & R. Schafer `Digital Signal Processing’(Prentice Hall 1977) • L. Jackson `Digital Filters and Signal Processing’(Kluwer 1986) • P.P. Vaidyanathan `Multirate Systems and Filter Banks’(Prentice Hall 1993) • Simon Haykin `Adaptive Filter Theory’(Prentice Hall 1996) • M. Bellanger `Digital Processing of Signals’(Kluwer 1986) • etc... Part-I Part-II Part-III Version 2009-2010Lecture-1 Introduction

  24. Literature / DSP-II Library • Collection of books is available to support course material • List/info/reservation via DSP-II webpage • contact: beier.li@esat (E/C) Version 2009-2010Lecture-1 Introduction

  25. Activities : Lectures Lectures: 14 * 2 hrs Course Material: • Part I-II-III :Slides (use version 2009-2010 !!) ...download from DSP-II webpage • Part III :`Introduction to Adaptive Signal Processing’, Marc Moonen & Ian.K. Proudler = support material, not mandatory ! …(if needed) download from DSP-II webpage Version 2009-2010Lecture-1 Introduction

  26. Activities : Homeworks/Ex. Sessions • `Homeworks’ …to support course material • 6 Matlab/Simulink Sessions …to support homeworks …come prepared ! • contact:amir.forouzan@esat(English+Persian) beier.li@esat(English+Chinese) prabin.kumarpandey@esat(English+Nepali) pepe.gilcacho@esat(English+Spanish) Version 2009-2010Lecture-1 Introduction

  27. Activities : Project • Discover DSP technology in present-day systems examples: 3D-audio, music synthesis, automatic transcription, speech codec, MP3, GSM, ADSL, … • Select topic/paper from list on DSP II webpage (submit 1st/2nd choice by Oct.5 to pepe.gilcacho@esat) • Study & www surfing • Build demonstration model & experiment in Matlab/Simulink • Deliverable : • Project Plan: 1 page status report & time plan (send to marc.moonen@esat by Nov 1st) • Presentation: .ppt or similar, incl. Matlab/Simulink demonstration (December, 20 mins per group) • Software • Groups of 2 Version 2009-2010Lecture-1 Introduction

  28. Activities : Project Topics/Papers • List available under DSP-II web page • Other topics : subject to approval ! (email 1/2-page description to pepe.gilcacho@esat before Oct. 5) Tutoring 10 research assistants/postdocs All PPT presentations will be made available, for ref. Version 2009-2010Lecture-1 Introduction

  29. Activities : Exam • Oral exam, with preparation time • Open book • Grading : 5 pts for question-1 5 pts for question-2 5 pts for question-3 5 pts for project (software/presentation) ___ = 20 pts Version 2009-2010Lecture-1 Introduction

  30. homes.esat.kuleuven.be/~pepe/dspII • Contact: pepe.gilcacho@esat • Slides • Homeworks • Projects info/schedule • Exams • DSP-II Library • FAQs (send questions to pepe.gilcacho@esat or marc.moonen@esat ) Version 2009-2010Lecture-1 Introduction

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