\brief First stage of Random-Access Scheduling. Loops over the RA_templates and checks if RAR, Msg3 or its retransmission are to be scheduled in the subframe. It returns the total number of PRB used for RA SDUs. For Msg3 it retrieves the L3msg from RRC and fills the appropriate buffers. For the others it just computes the number of PRBs. Each DCI uses 3 PRBs (format 1A)
/** \brief First stage of SI Scheduling. Gets a SI SDU from RRC if available and computes the MCS required to transport it as a function of the SDU length. It assumes a length less than or equal to 64 bytes (MCS 6, 3 PRBs).
@param Mod_id Instance ID of eNB
@param frame Frame index
@param subframe Subframe number on which to act
@param Msg3_subframe Subframe where Msg3 will be transmitted