Communication Systems IK2506

1. Communication SystemsIK2506 Anders Västberg vastberg@kth.se 08-790 44 55

2. IK2506 Advanced Communication Systems • TEN1: 6 HEC. • INL1: 1,5 HEC. • 3 Problem Assignments • Required reading: • Carlson, B., et. al., Communication Systems, McGrawHill, 2002. • Course Webpage: • http://www.kth.se/student/program-kurser/kurshemsidor/kurser-ict/cos/IK2506/HT09-1?l=en_UK

3. Teachers • Anders Västberg (Examiner) • vastberg@kth.se • 08-790 44 55 • Svante Signell • srs@kth.se • 08-790 41 46

4. Supplementary rules for examination • Rule 1: All group members are responsible for group assignments • Rule 2: Document any help received and all sources used • Rule 3: Do not copy the solutions of others • Rule 4: Be prepared to present your solution • Rule 5: Use the attendance list correctly For more information, see KTH rules at: http://www.kth.se/dokument/student/student_rights.pdf

5. Mathematica and MATLAB • Download the programs from: • http://progdist.ug.kth.se/public/ • General introduction to Mathematica • http://www.cos.ict.kth.se/~goeran/archives/Mathematica/Notebooks/General/

6. Carlson: Communication Systems Signals and Spectra Signal Transmission and Filtering Random Signals and Noise Analog Modulation Analog Communication Systems Noise in Analog Modulation Systems Sampling and Pulse Modulation Digital Modulation Information Theory and Channel Coding [Stallings., 2005]

7. COS Wireless Courses IK2511 Wireless Network Project Research Project IK2510 Wireless Networks Radio Resource Management for Wireless Networks Data Transmission over Radio Channels, Error Control Coding for Radio Channels IK2508 Wireless Transmission IK2507 Wireless Communication Systems Radio Propagation, Link Design and Diversity, Spectrum Resource Management IK2506 Advanced Communication Systems Signals, Systems and Spectra Modulation, Stochastic Processes

8. Course Aim • Give the student the ability to analyze the design parameters of a communication system. That means that the student should be able to: • Explain the system structure of analogue and digital communication systems • Use mathematical tools to analyse the performance of communication systems • Use probability theory and stochastic processes in communication system applications.

9. Communication Systems • Main functionality: Information Transfer • Can not cover all types of communication systems • Can not cover the detailed implementation • Look at system level

10. Types of Communication Systems • Analog Communication Systems • Analog message: “Physical quantity that varies with time” • Digital Communication Systems • Digital message: “Ordered sequence of symbols selected from a finite set of discrete elements”

11. Communication Systems Message signal Source of information Transmitter Transmitted signal Channel Estimate of message signal Received signal Receiver Information sink [Ahlin et. al., 2006]

12. Basic Structure • Transmitter • Modulation • Coding • Transmission Channel • Loss or Attenuation • Distortion • Interference • Noise • Receiver • Amplification • Demodulation and decoding • Filtering

13. Alteration of the Signal • Loss or Attenuation • Can be compensated by amplification at the receiver • Alteration of the Signal Shape • Distortion • Disappears when the signal is turned off • Linear distortion may be corrected by the use of equalizers (special filter). • Interference • Contamination by other signals from human sources • Noise • Contamination by signals from natural processes both internal and external to the system

14. Types of Communication • Simplex (SX) • One way communication • Full-duplex (FDX) • Two way communication at the same time • Half-duplex (HDX) • Two way communication, but not at the same time.

15. Fundamental Physical Limitations • Bandwidth • If a signal changes rapidly in time, its frequency content or spectrum extends over a wide range, i.e. the signal has a large bandwidth • Transmission bandwidth • Noise • Thermal noise

16. Analog Communication System Source of information Signal Processing Modulator RF-Stage Channel Information sink Signal Processing Demodulator RF-Stage [Slimane]

17. Modulation • Modulating signal • Represent the message • Carrier Wave • Waveform the suits the application • Modulation is a reversible operation • Modulation – Demodulation • Frequency translation

18. Modulation • Modulation for Efficient Transmission • Antennas should have a dimension of at least 1/10 of the wavelength of the radio signal • Modulation to Overcome Hardware Limitations • Bandwidth should be at most 1/10 of the carrier frequency • Modulation to Reduce Noise and Interference • Wideband noise reduction – Increase bandwidth to reduce signal power • Modulation for Frequency Assignment • Modulation for Multiplexing • Multiple Access

19. Digital Communication System Source of Information Source Encoder Channel Encoder Digital Modulator Modulator RF-Stage Channel Information Sink Source Decoder Demodulator RF-Stage Channel Decoder Digital Demodulator [Slimane]

20. Coding • Modulation – Signal Processing Operation • Coding – Symbol Processing Operation • Encode – Decode • Channel Coding • Source Coding

21. decibels • The bel is a logarithmic unit of power ratios. One bel corresponds to an increase of power by a factor of 10 relative to some reference power, Pref. • The bel is a large unit, so that decibel (dB) is almost always used: • The above equation may also be used to express a ratio of voltages (or field strengths) provided that they appear across the same impedance (or in a medium with the same wave impedance): [Saunders, 1999]

22. decibels [Saunders, 1999]

23. Signals • Deterministic Signals • Periodic Signals • Non-Periodic • Stochastic Signals • Stationary • Non Stationary