see attached picture, there are 4 modules:
(1) eNB: including tx/rx, scheduler and harq control sub-module,and also deal with DL signalling(DCI via PDCCH)
(2) UE: including tx/rx and feedback sub-module.
(3) channel model
and (4) driver: including the input MCS/SNR range, and theparameter loading module and the result saving module.
the main reference 3GPP specs are:
(1)36.211/212/213: PHY layer spec
(2)36.331: RRC spec
(3) 36.321/322/323: L2 spec
(4)36.101/104: UE/eNB RF
(5) 36.306: UE capability
etc.