CORESET and search spaces

Defining Where to Find Control Information

In NR, control channel resources are not spread across the entire bandwidth as in LTE. Instead, the network defines CORESETs, or Control Resource Sets, which are specific time-frequency regions where the UE monitors for PDCCH. Each CORESET spans one to three OFDM symbols in time and a configurable set of Resource Blocks in frequency. CORESET zero is special because it is derived from the MIB during initial access and tells the UE where to find the PDCCH carrying SIB1. The network can configure up to three CORESETs per Bandwidth Part.