"This is the first I have heard of a free-speech area at the DNC."

I have attended three DNC conventions going back to 1976. Each one has a "free-speech area" where protestors are allowed to march. The Republicans do the same thing. Usually the area is kept close to the convention center so that everyone can have the feeling that their protests are heard.   

Take a look at some maps and see where the "free speech areas" were located this year.