Used for:
โข DL/UL Resource Assignments
โข Multi-user Transmit Power Control (TPC) commands
โข Paging indicators
Different PDCCH formats are defined:
โข 1-3 OFDM symbols in a sub-frame
โข PCFICH using the first OFDM symbol of each subframe informs PDCCH specific format
PDCCHs are constructed as follows
โข CCE is defined as a unit of 36 REs
โข A PDCCH instance is constructed as 1, 2, 4 or 8 CCEs
PDCCH Carries DCI โ Downlink Control Information
๔บ Uplink assignments:
โ RB assignment, transport block size, retransmission sequence number, power control command, cyclic shift
of DM RS for SDMA, etc.
๔บ Downlink assignments:
โ RB assignment, transport block size, HARQ process number, Redundancy Version index, Uplink power
control command
๔บ Uplink Power Control Commands
๔บ Paging Indicator
L1/L2 control channel for:
๔บ DL scheduling, including:
โ Regular unicast data
โ Scheduling of Paging messages
๔ Acting as a โpaging indicatorโ
โ Scheduling of SIBs
โ Scheduling of random access responses
๔บ UL grants, including:
โ Regular unicast data
โ Requests for aperiodic CQI reports
๔บ Multi-user TPC commands:
โ TPC commands for PUCCH or PUSCH for multiple UEs