Battlefield 4 has an extensive matchmaking system known as Battlelog, but one of the features it's apparently missing is the ability to create squads prior to entering a match. The feature, which was last seen in Battlefield 3, did not make a return to Battlefield 4 and will not be coming any time soon, according to DICE.
Responding to a player's query over on the Battlefield 4 Facebook hub, DICE wrote, “We have a new feature in Battlefield where a new squad is created when a friend joins your game. You can toggle this option on or off by going into the options menu. We’re not offering the old squad join feature because we didn’t feel that the feature in Battlefield 3 was on par with the quality that we wanted to offer our players. We have no plans to add it in the future.”
In other words, it's not possible to create a private lobby, invite your friends to it, and join a game en masse. Instead, the only way to be in a squad with your friends this time around is to join up on them after they've already entered the game.
via MP1st.