Localised or distributed
Non-interleaved keeps a CCE's REG bundles contiguous — ideal when the gNB has good CSI and wants a localised, beamformed PDCCH. Interleaved scatters bundles across the whole CORESET for frequency diversity and inter-cell randomisation — the safe default when CSI is stale.
Non-interleaved
Bundle f(x) = x. The CCE occupies consecutive REG bundles. Precoder can be matched to a known channel direction (beamformed PDCCH).
Interleaved
A block interleaver spreads bundles across frequency. One PDCCH samples diverse REs, averaging fading and randomising collisions between cells.
The block interleaver, live
Logical bundle x maps to physical bundle f(x). Adjust the parameters — the connectors re-route in real time. Note how the shift rotates the whole pattern and how R sets the interleaving depth.
Bundle-by-bundle table
Every logical bundle, its (r, c) decomposition, and the physical bundle it lands on — computed straight from the formula above.
| Logical x | r = ⌊x/C⌋ | c = x mod C | R·c + r + shift | Physical f(x) |
|---|
Where the precoder can change
precoderGranularity tells the UE where the gNB may change precoder: sameAsREG-bundle (per bundle — UE estimates per bundle) or allContiguousRBs (one precoder across all contiguous RBs of the CORESET — UE can interpolate widely).
sameAsREG-bundle
Precoder may differ every bundle. Maximum scheduling freedom, but channel estimation is confined to each bundle.
allContiguousRBs
Same precoder across contiguous RBs → the UE interpolates the channel across a wider span for a better estimate.