A digital communication project using OFDM and 32-QAM

1OFDM system

Tahmid blogged about a digital communication project using OFDM and 32-QAM as their ECE4670 final project:

This builds on a previous lab, where orthogonal frequency division multiplexing (OFDM) is used with on/off keying to send data over the channel. This scheme achieved a data rate of about 14,000 bits per second with zero errors, resulting in a figure of merit of about 14,000. The high performance design utilizes orthogonal frequency division multiplexing (OFDM) and quadrature amplitude modulation (QAM) to achieve a figure of merit much higher than the previous lab.
The overall OFDM system block diagram is shown below (taken from Professor Wagner’s course’s Scribe notes)

See the full post on his blog.

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1 Comment

  1. On searching for commcloud, I guess this is what they are using:
    http://www.itsoc.org/people/bog/bog-meeting-chicago-il-2017/cloudproposal.pdf

    If the audio signal path on their commcloud server is simple wiring, then the signal environment would be rather more benign than say, a wireless environment with fading etc. This is fine for the intended pedagogical purposes as shown in the blog post, and readers should adjust their expectations accordingly. There appear to be no error correction, for instance, because the focus is on modulation schemes. Given their FOM score of 56,000, and compared to 56K modems over phone lines, obviously one can get a better data rate over an audio card with error correction.

    It looks like mostly a Matlab exercise, but I guess at audio rates this kind of thing can be done in many cheap DSPs these days. Although math and Mathlab is par for this kind of course, I am still a sucker for hardware examples, ha ha.

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