Digital Communications Part 2: Advanced Topics

The degrading effects of a fading (or multipath) channel stem from the multiple echoes that might be received for each transmitted symbol.  With an ordinary receiver, such echoes often result in distortion due to inter-symbol interference (ISI).  In this course, we characterize the various types of fading:  frequency-selective and flat fading, fast and slow fading.  A classical mitigation method for such fading is a RAKE receiver within a spread-spectrum system.  The receiver effectively "rakes in" individual echoes and then coherently combines them.  In this course, we emphasize a more elegant application:  Orthogonal Frequency Division Multiplexing (OFDM) which can mitigating the deleterious effects of fading.  We examine the intricacies of OFDM, and the clever “tricks” that have been designed into it.  Also, we focus on OFDM’s special variant, Single-Carrier OFDM (SC-OFDM).  We look at successful design examples, such as OFDM in WiFi, and LTE.