Teaching

RF Lab and Remote Software-Defined Radios

The remote SDRs allow you to transmit and receive IQ data anywhere & anytime. You only need MATLAB (UHD driver, toolboxes for SDRs, etc. are not needed). Your PC: pushes your IQ data as a mat file and downloads the received IQ data. At the remote, the server constantly checks if there is any IQ data. If there is, it transmits and receives at a certain carrier frequency. Your MATLAB accesses the PC at the remote and downloads the IQ data. We use this basic platform for ELCT562 and ELCT432 for several lab experiments, e.g., OFDM transmission & reception, or some research tasks as well. 

If you need the server and client MATLAB codes to replicate remote SDRs at your institution, please reach out to me.

ELCT 562 - Wireless Communications - Spring 2020, Spring 2021, Spring 2022, Spring 2023, Spring 2024 @ USC

The goal of the course is to introduce you to the fundamentals of modern wireless communication systems at the physical layer and data link layer. We begin with a very brief review of wireless communications and the main technical challenges facing reliable wireless communication. Link budgets, large-scale fading, and small-scale fading are reviewed, and their effects on signaling are described. The effects of band-limited communications and inter-symbol interference are characterized. After discussing the fundamental limits of digital communications, we focus on a powerful tool for digital communications analysis: signal space representations. This leads to definitions of optimum receivers and expressions for link performance. We comprehensively cover various digital modulation techniques used in modern wireless systems. Orthogonal frequency division multiplexing, which is the most used multicarrier scheme in modern communication systems, will follow. We investigate how to develop a transmitter and receiver for OFDM in detail based on the discussed modulation methods. We also discuss coded schemes. Finally, we describe the basics of cellular principles.

Topics:

• • • Path Loss and Shadowing: Friis transmission equation, small-scale versus large-scale fading, reflection, refraction, diffraction, scattering, two-ray model, path-loss empirical/simplified models, link budget calculation, outage probability, and coverage area 

    • Statistical Multipath Channel Model: Channel impulse response, power-delay profile, RMS delay spread, Doppler spread, coherence time/bandwidth, frequency flat/selective fading, and corresponding models, complex baseband representation including wireless channel impact

    • Fundamentals for Digital Transmission-I: Nyquist’s sampling and dimensionality theorems, the continuous signal generated from discrete signals, geometric representation of the signals

    • Fundamentals for Digital Transmission-II: Orthogonality, matched filter, pulse shaping examples: raised cosine/root raised cosine, rectangular filters, inter-symbol interference, Shannon’s channel capacity

    • Memoryless Digital Modulation Methods-I: Antipodal signaling, on-off keying, basics of M-ary phase-shift keying (PSK), M-quadrature-amplitude modulation (QAM), their error rates, spectral efficiency, and performance relative to Shannon’s channel capacity

    • Memoryless Digital Modulation Methods-II: M-ary pulse-amplitude modulation (PAM), M-ary phase-shift keying (PSK), M-quadrature-amplitude modulation (QAM), and their error probabilities, performance relative to Shannon’s channel capacity

    • Multi-dimensional Digital Modulation-I: Coherent versus non-coherent detection, Differential PSK, M-ary FSK error rate

    • Multi-dimensional Digital Modulation-II: M-ary FSK for coherent and non-coherent detectors, orthogonal signaling with coherent detectors, and non-coherent detectors

    • Multicarrier Modulation Schemes: Waveform design for multi-path channel, single-carrier versus multi-carrier, OFDM modulation/demodulation, cyclic prefix, spectral and temporal characteristics of 

    • A Complete OFDM Simulation: Synchronization, channel estimation, single-tap frequency domain equalization, using FFT for OFDM implementation, the performance in fading channels

    • Coded Signals: Promise of channel coding, linear block codes, generator and parity-check matrices, soft versus hard decoding, examples

    • Diversity & Cellular Basics: Methods for the realization of independent fading channels, receiver diversity, equal-combining, maximum-ratio combining, array gain versus diversity gain, transmit diversity, basics of cellular systems, multiple access

After this course, students understand key fundamental principles of wireless (mostly digital) communications at the physical layer including:

• • • Basic technical challenges of conveying information digitally across a wireless channel,

    • Signal space representations for digital signals and noise,

    • Basic digital modulation techniques and optimum receivers,

    • Effects of band-limited transmission and distortion mitigation techniques,

    • Multiple-access techniques,

    • Basic wireless channel effects: path loss, delay dispersion, Doppler & fading,

    • Diversity techniques.

Books:

 [1] J. G. Proakis, M. Salehi, Digital Communications, McGraw-Hill, 5th ed., 2008.

[2] A. Goldsmith, Wireless Communications, Cambridge University Press, 2005.

[3] D. Tse, Fundamentals of Wireless Communication, Cambridge University Press, 2005.

[4] R. Heath, Introduction to Wireless Digital Communication: A Signal Processing Perspective, Prentice-Hall, 2017.

[5] J. G. Proakis, M. Salehi, Contemporary Communication Systems using MATLAB®, Brooks-Cole, 2000.

ELCT 432 - Fundamentals of Communication Systems - Fall 2019, Fall 2020, Fall 2021, Fall 2023 @ USC

Topics:

• • Introduction to communication systems: Elements of a communication system, information source, transmitter, channel, receiver, information sink, software-defined radios, the frequency spectrum

  • Signals & Linear Systems: Classification of signals, periodic versus non-periodic, continuous versus discrete, random versus deterministic, classification of systems, linear versus non-linear, time-invariant versus time-variant, the impulse response of a system

  • Signals & Linear Systems –Cont: Frequency response of a system, more insights into frequency response, fading due to the multipath, complex exponentials, eigenfunction property, Fourier series

  • Representations in Communication Systems: Fourier transform, important properties for communications, signal bandwidth, representations in Communication Systems, lowpass/bandpass representations, In-phase/quadrature components and IQ modulator, filters, capturing FM signals & filtering

  • Amplitude modulation:  Double-sideband suppressed-carrier AM, conventional AM, single-sideband AM, vestigial-sideband AM, AM broadcasting, and super-heterodyne receiver

  • Angle modulation: Definitions: Angle and instantaneous frequency, phase modulation (PM), frequency modulation (FM), examples & properties, spectrum/bandwidth of FM signals, Bessel functions, Carson’s bandwidth rule

  • Practical Challenges –Transmitting and Receiving Gamecocks Logo over Remote SDRs with DSB-SC AM: Transmit and receive Gamecocks logo at 915MHz with DSB-SC AM, remote Access to SDRs, Transmitter: Image-to-signal conversion, frame structure, synchronization signal, Receiver: coarse time synchronization, frequency offset and correction, fine time synchronization, signal-to-image conversion

  • Probability & random processes: Axioms, conditional probability, Bayes’ rule, independence, Random Variables, PMF, PDF, CDF, Statistical Averages, Mean, variance, standard deviation, random Processes, auto-correlation, wide-sense stationary processes, power spectral density, white noise

  • Effect of Noise on Analog Modulations: Effect of noise on a baseband system, baseband SNR, amplitude modulation under noise, the effect of noise on DSB-AM, the effect of noise on conventional AM, Frequency modulation under noise

  • Sampling Theorem and Quantization: Sampling theorem, quantization, scalar quantization (Uniform versus Non-uniform), Gray coding, pulse code modulation (PCM)

  • Introduction to Digital Modulations:  Comparison: Digital vs. analog modulation, modulation scheme: Binary ASK/BPSK, receiver for binary ASK/BPSK, the optimal linear demodulator for AWGN: Matched filter, threshold design, performance analysis

  • Introduction to Information Theory: Measure of Information, entropy, discrete memoryless source, discrete memoryless channel, channel capacity, reliable communications, spectral efficiency & energy per bit, Shannon's limit

Book:

 [1] J. G. Proakis, M. Salehi, Digital Communications, McGraw-Hill, 5th ed., 2008.

ELCT 321 - Digital Signal Processing - Fall 2021, Fall 2023 @ USC

Topics:

• Introduction & Sinusoids

• Spectrum Representation

• Sampling and Aliasing

• FIR Filters

• Frequency Response of FIR Filters

• Discrete-Time Fourier Transform

• Discrete Fourier Transform

• z-Transform

• IIR Filters

Students who successfully complete the course will at least be able to: 

• Determine the spectral coefficients of discrete-time signals.

• Determine the frequency response and the z-transform representation of discrete-time systems. 

• Determine the discrete Fourier transform of discrete-time signals.

• Calculate the outputs of discrete-time systems in response to inputs.

• Design Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) filters, and evaluate the performance to meet expected system specifications using MATLAB.

Book:

 [1] DSP First, by McClellan, Schafer, and Yoder, 2nd Edition, Pearson