Lec 19 MIT 6.451 Principles of Digital Communication II
PROFESSOR: We're into chapter 11. I've asked Ashish to hand out today a revision of the previous version of chapter 11, plus chapter 12 on the sum-product algorithm, in case we get to it. I'm giving you a complete copy of the problem seven solutions for both weeks, and to get back on track, we're handing out problem set eight. There probably will only be one more problem set that you hand in. All right. We've been getting to the centerpiece of the second half of the course which is codes on graphs, which is the way we're going to get to capacity-achieving codes by building them on graphs of linear complexity and decoding them on the graphs with iterative decoding. I frame this in the language of behavioral realizations. I say a graph is a realization of a code via a behavior, which is the set of all the possible trajectories on the graph. So this is, again, putting it in system theory language. I want to distinguish between two types of variables. ...