Currently in beta
Battlefield 4 now offers a feature called "Squad Join" that you can currently enjoy on the PS3, PS4, Xbox One, and Xbox 360 platforms. It'll basically allow you to group up with a squad of five, so you can persist with them constantly.
It's not available for all platforms or all modes yet, so don't expect a fully blown rollout at this current time. If you want to see how it's done, check out the new tutorial video above.