/* \brief Function called by PHY to retrieve information to be transmitted using the RA procedure. If the UE is not in PUSCH mode for a particular eNB index, this is assumed to be an Msg3 and MAC attempts to retrieves the CCCH message from RRC. If the UE is in PUSCH mode for a particular eNB index and PUCCH format 0 (Scheduling Request) is not activated, the MAC may use this resource for random-access to transmit a BSR along with the C-RNTI control element (see 5.1.4 from 36.321)