Types of DCI formats in LTE

DCI(Downlink control information) :- It tells the UE how to get its data which is transmitted on PDSCH in the same subframe. Means with the help of DCI only UE can decode the PDSCH from the resource grid and find its data.

     The DCI formats provides the UE details such as number of resource blocks, resource allocation type , Modulation scheme which UE has to use(QPSK,16QAM,64QAM), transport block size, redundancy version, coding rate( Amount of information bits over transmitted bits), For MIMO configuration PMI and RI.

There are 13 DCI formats but we are discussing only below important formats.

Format Name                                Use
DCI-0                                     UL Grant(Scheduling of PUSCH)  
DCI-1A                                  Used during the Random Access Procedure
DCI-1                                     Scheduling of the DL PDSCH for TX diversity
DCI-2A                                 Scheduling of DL PDSCH in Open loop MIMO(TM3)
DCI-2                                    Scheduling of DL PDSCH in closed loop MIMO(TM4)