Chapter 1. Introduction

Chapter 1. Introduction Husheng Li The University of Tennessee

Course Contents Basics of communications Signals and noise Amplitude modulation Phase and frequency modulations Pulse modulation Analog communication system

Textbook Communication Systems: An Introduction to Signals and Noise in Electrical Communication, by A. B. Carlson and P. B. Crilly, McGraw Hill, 5th edition, 2008

Logistics Homework: 20% (4 problems every Friday; turn in your homework in two weeks) Midterm and final exams: 40% Quiz: 15% (will be 5 quizzes) Experiments: 25%

Office hour and TA 2:15 --- 3:15pm, MWF, MK644 TA: JingchaoBao, jbao2@utk.edu Course website: go to my personal website http://web.eecs.utk.edu/~husheng/

Experiments Experiment 1: Matlab simulation for amplitude modulations. Experiment 2: Matlab simulation for frequency and phase modulations. Experiment 3: USRP hardware board experiment

Concepts A communication system conveys information from its source to a destination some distance away. Some concepts: Information, analog, digital, transducer

Elements of Communication Systems The transmitter involves modulation and coding. The transmission channel is the medium for communications, which could be wireless, optical or even sound. The receiver carries out demodulation and decoding

Negative Factors in Communications Distortion: Waveform perturbation caused by imperfect response of the system to the desired signal itself. Interference: Contamination by extraneous signals Noise: Random and unpredictable electrical signals.

Fundamental Limitations Communications are limited by bandwidth and noise. Bandwidth: the width of frequency band used for the communications. Noise: The signal-to-noise ratio (SNR; S/N) is important. When the noise is Gaussian, the channel capacity is given by

Modulation Modulating signal Amplitude Modulation Pulse train With AM Modulation involves two waveforms: a modulating signal and a carrier wave.

Coding Coding is a symbol processing operation for improved communication when the information is digital or can be approximated in the form of discrete symbols (actually there is also analog coding). Source coding converts source information into a series of bits. Channel coding: add redundancy to improve the robustness of transmission.

EM Transmission there are several effects that enable light as well as electromagnetic (EM) waves to propagate around obstructions or beyond the earth’s horizon

Multipath and Fading In wireless communications, the signal could be received by the receiver after reflections. The superposition of signals from different paths could strengthen or weaken each other.

Emerging Developments Circuit / packet switching Multiple access: TDMA, CDMA, OFDMA. Ultra-wideband (UWB) Computer Networks: WiFi (IEEE 802.11) and WiMAX (IEEE 802.16) Software defined radio

Some History (1)

Assignment Read chapter 1

Chapter 1. Introduction

Chapter 1. Introduction

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Introduction – Chapter 1

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1 - Introduction

Chapter 1 - Introduction

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1: Introduction

Chapter 1 Introduction

Chapter 1. Introduction

Chapter 1 Introduction

Chapter 1: Introduction

Chapter 1 Introduction

Chapter 1: Introduction

Chapter 1—Introduction

Chapter 1: Introduction

Chapter 1: Introduction

CHAPTER 1: Introduction

Chapter 1: Introduction