star wars - During end battle of Rogue One, why did Bodhi try so hard to establish comms with the Alliance Fleet just to tell them something they already knew?

During the Battle of Scarif, why did Bodhi Rook and the rest of the company on the ground desperately try to contact the Alliance Fleet, just to tell them something they already knew? Surely the Alliance Fleet above the shield gate already knew they had to destroy it as that was going be the only way to receive the data. If they weren't trying to destroy the shield gate from the start, what else were they doing up there?

Answer

This is addressed in the scene where Cassian Andor speaks to the pilot Bodhi.

Cassian: Listen to me. The Rebel fleet is out there. You've got to tell them to blow a hole in the shield-gate so we can transmit the plans

Since the plans are too high density to be transmitted over normal audio channels, the shield needs to be down and the Rebels need to have a high gain receiver pointed toward the planet in order to receive the plans via radio since their chances of getting off the planet at this point are essentially zero.

K-2SO: We could transmit the plans to the Rebel Fleet. We'd have to get a signal out to tell them it's coming

If the fleet simply brings down the shield (expecting the ground forces to escape) that won't do any good.

K-2SO: There's fighting on the beach. They've locked down the base.