1 The cost of a size
Each size doubles the work
The UE doesn't know the DCI size in advance, so it must blind-decode every candidate for every monitored size. Allowing unlimited sizes would explode the decode count. The rule: across a cell the UE monitors at most 4 different DCI sizes, and at most 3 of them use a C-RNTI-scrambled CRC.
2 The budget
Live size budget
Toggle which formats are configured. Identical sizes count once. The alignment procedure forces 0_0 and 1_0 to share a size, which is why enabling the fallback pair only costs one slot. Stay at ≤4 total and ≤3 C-RNTI.
Distinct sizes
—
C-RNTI sizes
—
Budget
—
3 How padding works
Aligning 0_0 and 1_0
When the fallback UL and DL grants differ in size, the smaller one is zero-padded (or its frequency-RA field adjusted) until both match — collapsing two sizes into one. Move the slider to mis-size them and watch the padding equalise the pair.
4 Knowledge check