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Welcome to

Welcome to. Simulation of communication systems (DT001A). Magnus.Eriksson@miun.se and Filip.Barac@miun.se. A project course about MATLAB with SIMULINK and Communications Blockset. MATLAB = Matrix Laboratory.

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  1. Welcome to Simulation of communication systems (DT001A) Magnus.Eriksson@miun.se and Filip.Barac@miun.se

  2. A project course about MATLAB with SIMULINK and Communications Blockset MATLAB = Matrix Laboratory. Tool for numerical calculation and visualization. Commonly used for simulation of the communication system physical layer, signal and image processing research, etc. SIMULINK: Toolbox in Matlab that allows graphical data-flow oriented programming.

  3. Aim of the course • To prepare the student for thesis project and work in the area of telecommunciations development and research. • To give experience of performance analysis of communication systems and algorithms, at the physical layer and datalink layer. • To give experience of simulation tools such as MATLAB and SIMULINK. • This may include modelling and simulation of traffic sources, channel models, modulation schemes, error coding schemes, equalizers, algorithms and protocols. • A real-world project is studied within an application area such as cellular communications, modems for broadband access, wireless networks, short-range communication, digital TV transmission, IP-TV or IP-telephony.

  4. Prerequisites • Computer Networks A 7.5 ECTS credits or similar • Computer Engineering B, Wireless Internet access (most important!) • Computer Engineering AB-level, 30 ECTS credits • TCP/IP networking • Mathematical statistics • Programming Other helpful courses: • Transform theory, 7.5 ECTS credits. • Electrical engineering A, Analog electronics or Circuit theory • Electrical Engineering B, Telecommunications, 7.5 ECTS credits. • Electrical engineering B, Signals and systems, 7.5 ECTS credits. • Markov processes/Queueing theory

  5. Litterature • Matlab and Simulink documentation will be provided electronically. • Please repeat physical layer issues and datalink layer issues in basic books in Computer Networks and Wireless Internet Access.

  6. Requirements • All lectures and supervision lessons are mandatory. • You are expected to devote 20 hours/week to this course, for example in L209. • Quzzes (multiple choice tests): At least 70% correct answers. • Lab: About 20 hours of work. • Homework problem. • Oral presentations. • Project

  7. Requirements on the project Review at least one research paper, and describe some standard and some existing simulation model. Simulate a communications standard, or check the simulations made in a research paper. At least modify an existing simulation model, for exampel a Simulink or Matlab demo, or build a model of your own (more difficult) Produce some plots for several parameter cases, showing for example BER, bit rate or delay as function of at least two different parameters, for example SNR, facing model, modulation scheme, etc. The simulation results should be stable (the plots smooth and not jerky), i.e simulate sufficiently long simulation time, or take the average of sufficiently large number of simulations. Draw some interesting conclusions from this.

  8. Grading is based on • Keeping deadlines. • Quzzes. • Showing good understanding when andwering questions from teachers and other students about your presentations. • Extent of own code. • Research relevance. • Own new results or conclusions.

  9. Time plan and deadlines (prel) • Week 44-45   - Introduction lectures • - Start lab: Intro to Simulink. (About 20 hours of work) • - Electronic quizzes in webct - Choose a standard and en existing model to simulate • Week 46   - Assignment 1 (homework problem). - Conclude lab (demonstrate to teachers) • Week 47-48   - Present chapter 2 for class: Theory study – present a • standard and review a research paper • - Present chapter 3 for class: Model – present an existing simulation model • Week 49-50   - Demonstrate chapter 1 to teachers: Introduction (goal of your project) - Demonstrate chapter 4: Modifications to an existing simulation model, or a new model that you have built. • Week 51-02   - Demonstrate some simulation results to teachers. • Week 03  - Finalreport and project presentations, incl chapter 5: Results, and chapter 6: Conclusions.

  10. ”IMRaD” report disposition Use MIUN template for technical reports. • Abstract • Table of contents. • 1. Introduction • 2. Theory study (describe a standard and review a research paper) • 3. Existing simulation model • 4. Modifications to the simulation model/own simulation model • 5. Simulation results • 6. Conclusions • List of sources • Appendix: Simulation code

  11. Assignment 1: Theory repetition • The first assignment consists of old exam problems in Computer Networks A, Wireless Internet access B and Telecommunications B. • Deadline: At the supervision lesson week 45. Be prepared to present your answers on the whiteboard.

  12. MATLAB MATLAB = Matrix Laboratory. Tool for numerical calculation and visualization. Commonly used for simulation of the communication system physical layer, signal and image processing research, etc.

  13. This is how MATLAB looks like Workspace Commandhistory Command window

  14. More MATLAB windows Figure window Array editor M-file editor

  15. How to get help in MATLAB? help functionsname Shows unformatted text doc funktionsnamn Shows HTML documentation in a browser

  16. SIMULINK SIMULINK: Toolbox in Matlab that allows graphical data-flow oriented programming.

  17. Repetition of some basic concepts • Frequency spectrum • Digitalisation, source coding • Error coding • Modulation • Multiple-access methods • Base-band model • Distorsion, noise • Signal-to-noise ratio • Bit-error ratio • Statistics

  18. Repetition of some basic concepts

  19. Digitalization

  20. AD-converter with seerial output DA- converter Interpolation filter Anti aliasing- filter Sampler 8 bit per sampel i.e. 64000 bps per phone call 28 = 256voltage levels PCM = Pulse Code Modulation = Digital transmission of analogue signals Number exemples from PSTN = the public telephone network 011011010001... 1 0 Loudspeaker Microphone 8000 sampels per sec 300-3400Hz band passfilter. Stopseverything over 4000Hz.

  21. Aliasing

  22. Quantization noice

  23. Digital transmission

  24. Distorsion

  25. Effect of attenuation, distortion, and noise on transmitted signal.

  26. Layer 7 Digitalizatingcompression Source coding Source decoding Layer 6 0110 0110 Error management Error control . Layer 2 0110010 0100010 Bitfel Flow control Flow control Layer 1 Modulation Demodulation Point-to-point communication Mikrofon Högtalare NACK 0110010 ACK

  27. Digital modulation methods Binary signal ASK = Amplitude Shift Keying (AM) FSK = Frequency Shift Keying (FM) PSK = Phase Shift Keying (PSK)

  28. 8QAM example: Below you find eight symbols used for a so called 8QAM modem (QAM=Quadrature Amplitude Modulation). The symbols in the first row represent the messages 000, 001, 011 and 010 respectively (from left to right). The second row representents 100, 101, 111 and 110.

  29. Example 2 cont.

  30. Bit rate vs baud rate Bit rate in bit/s: Where M is the number of symbols and fs is the symbol rate in baud or symbols/s.

  31. Bit and baud rate comparison

  32. Figure 5.14The 4-QAM and 8-QAM constellations Q (Quadrature phase) Q (Quadrature phase) I (Inphase) I (Inphase)

  33. Sine wave example Complex representation 5 Volt л/2 radians = 90º I

  34. Inphase and quadrature phase signal • Sine wave as reference (inphase) signal: • Cosine wave as reference (inphase) signal:

  35. Complex baseband representation jQ C =I+jQ Amplitude: Phase: RF signal (physical bandpass signal, if a cosine is reference signal): |C| C Arg C I

  36. Equivalent baseband signal

  37. Figure 5.11The 4-PSK characteristics

  38. Figure 5.12The 8-PSK characteristics

  39. Figure 5.1616-QAM constellations

  40. Spectrum of ASK, PSK and QAM signal

  41. Figure 3.9Three harmonics

  42. Figure 3.10Adding first three harmonics

  43. Example: Square Wave Square wave with frequency fo Component 1: Component 3: Component 5: . . . . . .

  44. Figure 3.11Frequency spectrum comparison

  45. Filtering the Signal • Filtering is equivalent to cutting all the frequiencies outside the band of the filter • Types of filters • Low pass • Band pass • High pass Low pass H(f) OUTPUT S2(f)= H(f)*S1(f) INPUT S1(f) H(f) f Band pass H(f) OUTPUT S2(f)= H(f)*S1(f) INPUT S1(f) H(f) f High pass H(f) INPUT S1(f) H(f) OUTPUT S2(f)= H(f)*S1(f) f

  46. Figure 6.4FDM (Frequency division multiplex)

  47. Figure 6.5FDM demultiplexing example

  48. Figure 6.19Time division multiplex (TDM) in the american telephone network

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