Hi Diana,
Every unit in the brigade would have FFR's, in an infantry unit ( my background is infantry) each Rifle coy has 2 land rovers 1GS , 1FFR. BHQ would have 3 or 4 FFR's, one for command net, admin net, and CO. Sig platoon maintains these vehicles and supplies sigs and sig equipment. A sig det from sig platoon would also be attached to each company and deploy in the company FFR. In support coy each platoon would have an FFR ,GS or both. Admin coy would also have an FFR and a sig det from Sig Platoon.
As said earlier the sig Sqn would provide a FFR with 3 sig's , one being a corporal det commander to Battalion HQ to provide communications back to Brigade HQ.
Engineers, would have a FFR at their HQ's and would have FFR's though out the unit, they would also have support from the Bridage sig sqn.