CORESET
Control Resource Set: a time-frequency resource region in which the UE searches for PDCCH candidates, defined by a set of RBs and OFDM symbols.
A CORESET defines where PDCCH lives — a rectangle of resources, some set of RBs in frequency and 1 to 3 OFDM symbols in time, that the UE knows to examine for control. NR made this configurable on purpose. LTE always spread its control region across the full carrier width at the start of each subframe; NR lets the network confine control to a smaller region, which frees the rest for data and supports beamformed control.
The special one is CORESET#0, carried in the MIB and used before the UE has any dedicated configuration — it's how the device finds the scheduling for SIB1 right after reading the SSB. After that, a UE can have several CORESETs configured. Each CORESET is paired with one or more search spaces (the CORESET is the resource region; the search space is the monitoring schedule and the set of candidate locations inside it), and each can be tied to a TCI state so control can ride a specific beam.
Frequently asked questions
- What's the difference between a CORESET and a search space?
- A CORESET is the time-frequency region — which resource blocks and how many OFDM symbols — where PDCCH can appear. A search space tells the UE how often to look there and which candidate locations (at which aggregation levels) to blind-decode. One CORESET can host multiple search spaces, and a search space always references exactly one CORESET. Roughly: CORESET is the room, search space is the schedule and the seating chart.
Related terms
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