1 / 34

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/. Chapter-1 : Introduction. Aims/Scope Why study DSP ? DSP in applications : GSM, ADSL,… Overview Activities

solada
Download Presentation

Digital Signal Processing II `Advanced Topics’

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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. Chapter-1 : Introduction • Aims/Scope Why study DSP ? DSP in applications : GSM, ADSL,… • Overview • Activities Lectures - Course Notes/Literature Homeworks/Exercise sessions Paper Review Assignment Exam Version 2010-2011Chapter-1 Introduction

  3. Why study DSP ? • Analog Systems vs. Digital Systems - can translate (any) 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 2010-2011Chapter-1 Introduction

  4. Why study DSP ? • Will give two `DSP in applications’ examples • DSP in mobile communications (GSM) • DSP in wireline communications (ADSL/VDSL) • Main message: Consumer electronics products have become supercomputers (Mops/sec…Gops/sec), packed with DSP functionalities… Version 2010-2011Chapter-1 Introduction

  5. 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 2010-2011Chapter-1 Introduction

  6. 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 2010-2011Chapter-1 Introduction

  7. Transmitter 1,0,1,1,0,… Receiver `Multipath’ Channel ?? + noise DSP in applications : GSM • DSP for digital communications (`physical layer’ ) : • In practice… • This calls for channel modeling + compensation (equalization) !! .59,.41,.76,.05,.37,… 1,0,1,1,0,… Version 2010-2011Chapter-1 Introduction

  8. Δ Δ Δ Δ Δ Δ Δ Δ Δ Δ a `Multipath’ Channel b c ≈ + + d e DSP in applications : GSM • GSM Channel Estimation/Compensation • Multi-path channel is modeled with short (3…5 taps) FIR filter H(z)= a+b.zˉ¹+c.z ˉ²+d.z ˉ³+e.z ˉ(interpretation?) 4 Version 2010-2011Chapter-1 Introduction

  9. Δ Δ Δ Δ Δ Δ Δ Δ Δ Δ a b c + d e DSP in applications : GSM • GSM Channel Estimation/Compensation (continued) • Multi-path channel is modeled with short (3…5 taps) FIR filter H(z)= a+b.zˉ¹+c.z ˉ²+d.z ˉ³+e.z ˉ 4 OUT[k] IN[k] =convolution Version 2010-2011Chapter-1 Introduction

  10. DSP in applications : GSM • GSM Channel Estimation/Compensation (continued) • Channel coefficients (cfr. a,b,c,d,e) are identified in receiver based on transmission of pre-defined training sequences (TS), in between data bits. Problem to be solved at receiver is: `given channel input (=TS) and channel output (=observed), compute channel coefficients’. This leads to a least-squares parameter estimation procedure See PART-III on optimal filtering Version 2010-2011Chapter-1 Introduction

  11. DSP in applications : GSM • GSM Channel Estimation/Compensation (continued) • Channel coefficients (cfr. a,b,c,d,e) are identified in receiver based on transmission of pre-defined training sequences (TS), in between data bits. • Channel model is then used to design suitable equalizer (`channel inversion’), or (better) to reconstruct 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 2010-2011Chapter-1 Introduction

  12. DSP in applications : GSM • GSM Channel Estimation/Compensation • GSM Speech Coding • Original `PCM’-signal has 64kbits/sec = 8 ksamples/sec * 8bits/sample. • Aim is 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 PART-III on optimal filtering. • Then transmit model coefficients instead of signal samples. • Synthesize speech segment at receiver (should `sounds like’ original speech segment). = SPECTACULAR !! Version 2010-2011Chapter-1 Introduction

  13. 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 ! ) See PART-II on filter banks/transmultiplexers • Etc.. = BOX FULL OF DSP/MATHEMATICS !! Version 2010-2011Chapter-1 Introduction

  14. 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 2010-2011Chapter-1 Introduction

  15. 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 2010-2011Chapter-1 Introduction

  16. 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 • Radio frequency interference (AM broadcast, amateur radio) • Echo due to impedance mismatch • Etc.. Conclusion: Need advanced modulation, DSP,etc. ! Version 2010-2011Chapter-1 Introduction

  17. 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 2010-2011Chapter-1 Introduction

  18. 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 2010-2011Chapter-1 Introduction

  19. DSP in applications : ADSL ADSL specs • 512-point (I)FFT’s (or `similar’) for DMT-modulation FFT-rate = 4.3215 kHz (i.e. >4000 times 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 See PART-I on filter banks/transmultiplexers • 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) See PART-III on adaptive filters >20M ops/sec >60M ops/sec Version 2010-2011Chapter-1 Introduction = BOX FULL OF DSP/MATHEMATICS !!

  20. DSP in applications : VDSL VDSL specs • 4096-point (I)FFT’s (or `similar’) for DMT-modulation FFT-rate = 4.3215 kHz (i.e. >4000 times 4096-point FFTs per second !!!!) • etc.. >160M ops/sec = BOX FULL OF DSP/MATHEMATICS !! Version 2010-2011Chapter-1 Introduction

  21. 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 2010-2011Chapter-1 Introduction

  22. 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 2010-2011Chapter-1 Introduction

  23. 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 2010-2011Chapter-1 Introduction

  24. Overview (I) • INTRO : Chapter-1 Chapter-2 : Signals and Systems Review • Part I : Filter Design & Implementation Chapter-3 : IIR & FIR Filter Design Chapter-4 : Filter Realization Chapter-5 : Filter Implementation Version 2010-2011Chapter-1 Introduction

  25. 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 Chapter-6 : Filter Banks Intro/Applications (audio coding/CDMA/…) Chapter-7/8 : Filter Banks Theory Chapter-9/10: Special Topics (Frequency-domain processing, Wavelets,…) . Version 2010-2011Chapter-1 Introduction

  26. Overview (III) • Part III : Optimal & Adaptive Filtering Chapter-11 : Optimal/Wiener Filters Chapter-12: Adaptive Filters/Recursive Least Squares Chapter-13: Adaptive Filters/LMS Chapter-14: `Fast’ Adaptive Filters Chapter-15: Kalman Filters . Version 2010-2011Chapter-1 Introduction

  27. 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 2010-2011Chapter-1 Introduction

  28. 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 2010-2011Chapter-1 Introduction

  29. Activities : Lectures Lectures: 18 * 2 hrs Course Material: • Part I-II-III :Slides (use version 2010-2011 !!) ...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 2010-2011Chapter-1 Introduction

  30. 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 2010-2011Chapter-1 Introduction

  31. Activities : Paper Review Assignment • Aim: Learn to read DSP research papers • Aim: Discover DSP technology in present-day systems examples: 3D-audio, music synthesis, automatic transcription, speech codec, MP3, GSM, ADSL, … • Select paper from list on DSP II webpage & submit 1st/2nd choice by Oct.15 to pepe.gilcacho@esat • Study paper & context (=www surfing) • Presentation:December, 20 mins per group(ppt or similar) • Present application, context & contribution • Make it understandable for your fellow students !!! • Everyone attends all presentations !!! • Groups of 2 Time Budget=38h.pp+presentations Version 2010-2011Chapter-1 Introduction

  32. Activities : Paper Review Assignment Papers • List available in DSP-II web page • Other topics : subject to approval ! (email to pepe.gilcacho@esatbefore Oct. 15) Tutoring Research assistants/postdocs (p28) All PPT presentations will be made available, for ref. Version 2010-2011Chapter-1 Introduction

  33. 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 assignment (presentation) ___ = 20 pts Version 2010-2011Chapter-1 Introduction

  34. homes.esat.kuleuven.be/~pepe/dspII/2010-2011 • 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 2010-2011Chapter-1 Introduction

More Related