mahendar on "Do users need to sign up in every site of multisite network?"

Hello.I have created a multisite network of 5 websites. 4 of them are "user generated content driven websites". I want a user to be registered just once for all the 4 websites. A user registered in one site can submit content to all the other 3 sites. Is this possible? And I dont want to assign the default role as Author or Contributor (because non registered users cannot submit content). Any help would be great. Thank you