This looks plausible to me. As a formatting note: we usually don't give the non-proposed solutions equal treatment with the proposed solutions. Instead, we usually mark them as not proposed. From this document, I _think_ you're proposing PCSA, and suggesting that we not do the others? But I'm not sure.
For the PCSA portion, we should really have citations to the actual papers where these formulas and algorithms come from.
We should also consider how this proposal would interact with other proposed secure aggregation solutions, like Privcount [1] and/or some other kind of PrivEx [2]. I'd like to hear what the designers of those ideas think of this one.
[1] https://github.com/privcount/privcount [2] http://cacr.uwaterloo.ca/techreports/2014/cacr2014-08.pdf