Difference between Search space and Coreset?

HI folks,

the question might seem dumb but i am stuck at this as the docs i refer are not much clear about this. Can you someone describe teh diff between search space and coreset and how they are linked to each other and asssit UE in decoding the actual PDCCH REs?

Hi , I am writing explanation in very basic terms for understanding.

Coreset is simply an area (freq resources and symbols repeating every slot) that is informed to UE where control signaling “may” appear.

search space is the period (example repeats after every 10 slots) “when” control signaling will appear.

Therefore UE will know where to look (Coreset) and when to look (search space) for PDCCH REs.


Search space can be common and UE specific search space .
Common: used for p-rnti ,si-rnti we have type 0, 0a, etc search space in NR.
UE specific search space used for c-rnti using PDSCH.


“CORESET is a set of physical resources(i.e, a specific area on NR Downlink Resource Grid) and a set of parameters that is used to carry PDCCH/DCI. It is equivalent to LTE PDCCH area (the first 1,2,3,4 OFDM symbols in a subframe). But in LTE PDCCH region, the PDCCH always spread across the whole channel bandwidth, but NR CORESET region is localized to a specific region in frequency domain.”

“Search Space is an area within a CORESET that UE should monitor to detect a specific PDCCH/DCI. There are two large categories of Search Space(SS) called CSS (Common Search Space) and USS(UE specific Search Space). Which SearchSpace UE has to monitor is defined by RNTI type or RRC configuration summarized below. This summary is based on 38.213-10.1”

I don’t think there is pdsch in ue specific search space. It is always pdcch, and decoding it will give you the details of pdsch , pusch resources allocated to UE.