EE 371C / EE 381V: Wireless Communications Lab
Fall 2008
Wireless communication is fundamentally the art of communicating information without wires. In principle, wireless communication encompasses any number of techniques including underwater acoustic communication, semaphores, smoke signals, radio communication, and satellite communication, among others. The term was coined in the early days of radio, fell out of fashion for about fifty years, and was rediscovered during the cellular telephony revolution. Wireless now implies communication using electromagnetic waves -- placing it squarely within the domain of electrical engineering.
Thus the spotlight of this class will focus on digital wireless communication. Every major wireless system being developed and deployed is built around digital communication including cellular communication, wireless local area networking, personal area networking, and high-definition television. The unique perspective of this class is that it approaches wireless communication from the perspective of digital signal processing (DSP). No background in digital communication is assumed, though it would be helpful. The utility of a DSP approach is due to the following fact: wireless systems are bandlimited. This means that with a high enough sampling rate, thanks to NyquistÕs theorem, it is possible to represent the bandlimited continuous-time wireless channel from its samples. This means it is possible to treat the transmitted signal as a discrete-time sequence, the channel as a discrete-time linear time-invariant system, and the received signal as a discrete-time sequence.
This course takes an experimental approach to wireless digital communication. Theory in the classroom is translated directly into practice with the help of National Instruments' software defined radio platform. The emphasis is on physical layer concepts rather than implementation considerations. A three-hour laboratory period will complement the usual three-hour lecture period each week.
Specific topics covered in this course in the lecture and laboratory include
- Bandwidth, sampling, complex baseband equivalent representation
- Upconversion, downconversion, narrowband signals
- Single carrier quadrature amplitude modulation
- Probability of symbol error in Gaussian and fading channels
- Channel estimation
- Linear equalization
- Frame, symbol, and carrier frequency offset synchronization
- Single carrier frequency domain equalization using cyclic prefixes or zero padding
- OFDM modulation including channel estimation, synchronization, and equalization
- MIMO communication including the Alamouti space-time code and spatial multiplexing
- GSM and IEEE 802.11a system design issues
- Principles of software defined radio
- Small scale fading, large scale fading, link budgets
- Cellular principle, sectoring, interference calculation, frequency reuse
This class is quite different from other offerings at UT Austin and is generally unique throughout the world. Here is a brief comparison with other courses at UT Austin:
- EE 345S Real-time Digital Signal Processing deals particularly with real-time implementation issues, DSP architectures, etc. QAM modems are used as a significant design example but digital communication is not the focus of the course. In EE 371C I assume that you already know the basics of DSP (thus the DSP prerequisite). The emphasis will be on using your existing DSP toolset to build a real wireless modem. Along the way you will learn about propagation, synchronization, digital receivers, OFDM, and current wireless standards like IEEE 802.11a and GSM. Programming will be done in LabVIEW thus there will be less concern for real-time DSP implementation.
- EE 360K Digital Communication deals with the principles and theory of digital communication. You deal with topics like signal space, modulation, maximum likelihood detection, and bit error rate analysis. In EE 371C we focus on wireless digital communication, but with an emphasis on building a complete wireless digital communication system in the lab. Thus we deal with the whole physical layer system. In particular we discuss modulation, demodulation, bit error rate analysis, frame synchronization, symbol synchronization, frequency offset correction, and OFDM modulation. We cover a little about each topic, to provide intuition and a foundation for future work. Consequently we don't cover as much digital communication theory, instead focusing on a few key algorithms that we will implement in the lab. We also discuss current standards like IEEE 802.11a and GSM.
- EE 370M Communication Systems provides an introduction to analog and digital modulation but with an emphasis on analog modulation including AM and FM modulation. A portion of the course is spent reviewing Fourier transforms and stochastic processes. In EE 371C we do not discuss analog modulation at all and do not provide an extensive review of transforms. We do not deal with AM or FM modulation, rather we focus on QAM digital modulation techniques. EE 370M is a communication theory course whereas EE 371C is a laboratory course where you build a real wireless modem. Several other topics are included like propagation, synchronization, digital receivers, channel estimation, linear equalization, OFDM, and current wireless standards.
This course grew out of my own experience prototyping wireless systems. I think that actually building a communication link reveals the importance of each component of the system. It provides intuition that becomes a foundation for taking advanced course in wireless or for becoming a practical wireless engineer.
The Wireless Communications Lab fulfils a Technical Area elective in the Communications / Networking area and the Signal / Image processing area.
Note about the graduate cross-listed version EE 381V The graduate realization of this course, EE 371C, additionally requires a final term project in the form of an implementation, survey, or research project. EE 381V counts for graduate credit and is graded differently than EE 371C. Details on the final project and grading criteria can be found here. Graduate students: please note that this course covers several topics that are not taught in any other graduate course at UT Austin including:
- Channel estimation
- Software defined radio
- GSM and IEEE 802.11a system design issues
- Frame, symbol, and carrier frequency offset synchronization
- Single carrier frequency domain equalization using cyclic prefixes or zero padding
- OFDM modulation including channel estimation, synchronization, and equalization
The graduate version and undergraduate versions are graded differently, as indicated in the attached syllabus.
Electronic Course Site
The course materials will be delivered through current offering of the class is available in Blackboard. It will includes a weekly outline, lecture notes, laboratory assignments, and discussion groups. This web page is used primarily to provide information to prospective students.
