I made an account just to jump in on this thread.
I don't go to UCSD, but I know quite a bit about their program with regards to communications and DSP. I am a DSP person and am fairly familiar with some of the top schools in that area. UCSD is very strong in communications, it's their strongest area of ECE. I would definitely say it should be included in the conversation with Stanford. I don't know enough about CMU or the international schools to give an opinion on them. UCSD has a lot of top notch communications professors as well as a lot of diversity in their projects. Even the DSP research at UCSD mostly has communications applications. Something else that makes UCSD very good for communications is that it is located in the telecommunications capital of the country. Meaning there are more telecommunications/communications companies located in San Diego than anywhere else in the country. The biggest one is Qualcomm, who hires a ridiculous amount of UCSD students. It also happens that the UCSD school of engineering is named after the co-founder of Qualcomm, Irwin Jacobs.
From my own research and from what professors and industry people have told me, Stanford is a little weaker in both communications and DSP than their high ECE ranking suggests. I'm sure they deserve the overall ECE ranking because some of their focus areas are definitely the best/second best in the country, I just don't think communications and DSP are some of those areas. UCSD is stronger in those areas than their ranking suggests. So all in all I think they are pretty comparable in terms of education and research in those areas. Of course, it depends on the professor you work with.
As far as living goes, I'd highly recommend looking into the graduate housing offered by UCSD if you don't mind having a roommate. I have a friend living there now and the apartments are nice, inexpensive, and located in a nice area. You really can't get much better housing in the area for the price. The stipend is enough to comfortably live on, even if you don't go with the graduate housing, unless you get one of the many $1400+ apartments in San Diego with no roommates.
This came off as more of a sales pitch than I had intended. I promise I'm not affiliated with UCSD! I actually didn't even apply to their PhD program.