CQC is the Arena mode. Normal team deathmatch rules, two teams. If you have less than 8 players, you'll be paired with randoms, and this game mode isn't dead. The best way, if you're able, is to boost this on the way to your 250 CQC wins and your level 50 achievements.
Please note that 2 teams of 4 can't match together. The best way is to have a group of 4, and try to have the other 4 join search for the lobby.
This will take a while... best of luck!