Communications Systems ASU Course EEE455/591 Instructor: Joseph Hui Monarch Institute of Engineering

Textbook and Labs Primary: Communications System Engineering, 2 nd Edition –Author: John Proakis, Prentice Hall, 2001 –The textbook contains more details than necessary for undergrads. Lecture notes –The PowerPoint files contain almost all information needed –A Word file for each lecture is posted from earlier years. Prerequisite: –Linear system/Transform methods (EEE303) –Probability (EEE350) Lab sessions: –Graduate students now have to take the lab –Undergraduate students always take the lab

Syllabus and Reading Material Syllabus and topics covered: –This course is an introduction to basic communication techniques, including data sources, analog communications, digital communications, channel and source coding, and modern wireless communications. Examples of modern communication systems. Goal of the course: –To understand the principles behind the design of communications systems, such as AM/FM radio, TV broadcasting, the digital telephone network, and cellular telephone networks of different generations. Reading assignment for each lecture: –For today, read textbook sections 1.1 – 1.3 –Reading assignment stated in each PowerPoint I’ll try to work out some examples in each class.

Course Grading Two quizzes –1 st quiz held in class as indicated on course documents –2 nd quiz held in class as indicated on course documents –Each quiz covers half of the material –1 page of formula sheet on two sides allowed –For EEE455, each quiz is 25% of grade –For EEE591, each quiz is 40% of grade For EEE455, 6 labs for 25% of grade 10 homework, roughly one every week –For EEE455, total 15% of grade –For EEE591, total 20% of grade Same letter grade assignment scale for grad and undergrad: A A A B B B C C D E < 50 (For undergraduate)

What you will learn: Analog Communications Signal in time domain Analog signals (baseband)Modulated signal (RF) Signal: Modulated signal: Signal in frequency domain X Carrier spectrum f-f Signal spectrum Modulated signal spectrum frequency f-f

What you will learn: Analog Communications Radio Communications: Off the air TV Broadcasting: Amplitude Modulation (AM)Audio + Black & white TV Frequency Modulation (FM)Color TV

What you will learn: Digital Communications Direct Broadcast Satellite TV Satellite Phone Satellite Base Station How to convert analog signal into digital format: Sampling theorem Quantization of analog samples How to send digital info: On-off keying PAM PSK FSK QAM Error probability Power budgeting Satellite Cellular Coding techniques

What You Will Learn: Cellular Networks 1G – Analog (Cellular, AMPS) 2G – Digital (GSM, TDMA, CDMA) 3G – Voice, video, data (WCDMA, CDMA2000) Backbone Network

What is a Hertz, and in a Hertz? The concept of frequency spectrum Signals in time can be decomposed into frequency components (Fourier transform) A signal is called band limited if signal has frequency components within a frequency band. Often signals are modulated to occupy different frequency bands in a large frequency spectrum Signals can be transmitted in a wired system (copper wire, coaxial cable, fiber) Signal can also be transmitted in a wireless system (microwave, satellite, cellular)

Analog Communications What facilitates communications? Information transmitted over distance. (Speech, video, data) Information often is an analog waveform for analog communication. Information source and input transducer TransmitterReceiver Output traducer and information sink Channel

Digital Communications What does it take to send data over a channel? Time – More time, more bits transmitted Frequency – More bandwidth, the faster you can transmit information Space – The larger the transmitter and receiver, more bits transmitted Power – The signal to noise ratio determines the number of bit per sample Fundamental equations government communication capacity: Nyquist Theorem: To reconstruct a signal band-limited to frequency f, we need only 2f samples per second. Shannon’s channel capacity: A channel of bandwidth W, transmitter power P, and noise power N 0 per hertz has capacity

Frequency Spectrum: