PDCCH monitoring for USS

5G NR
, , ,
1

Hello Experts,
I have query regarding PDCCH monitoring for USS.
Actually for SA case and CSS PDCCH monitoring initially for SIB1 the parameters required are provided as part of mib.pdschSIB1config
But once sib 1 is decoded, how about for USS other slots PDCCH monitoring ?
Will there be any parameters sent over RRC message for upcoming USS data
Because in lte 1st symbol of each sf has the info of no. of PDCCH symbols and with respect to rnti it will be decoded but how about in NR?
Thanks in advance

2

Yup…in Rrc setup—pdcch_config.

1 Like
3

Hi Nitin,

Thanks for information and Yes it’s correct but If we consider LTE, We could see for each sub frame we have PCFICH channel at symbol 1 which provides the info of number of symbols are used for PDCCH for every sub frame but in NR suppose we received “Rrc setup—pdcch_config” at instant of time with param related to search space but same configuration is applied to all slots forever i mean till UE moved to OOS or rebooted.

Ex: Initially in NR when UE booted up, UE will get MIB and SIB via pdcch-common-search-space-0 config and decode it later once RACH established Let’s say RRC setup-pddch-config received at one point but will this configuration continued to be applied for further USS decoding because In LTE we will be getting dynamic CFI values for each subframe as each sf starting symbol will decoded for PDCCH info.

Thanks in advance

5

USS is in RRC setup and inside that pdcch_config.
SIB1 only has pdcch_configcommon.
Cannot define USS in that, only CSS.
In SA.

6

Thanks, but I can see UE Specific search space in RRC reconfig and SIB1 as well to schedule PDSCH type3 UE specific search space.

7

RRC reconfig you can.
SIB1 might have the structure because of common ASN, but you cannot use it for USS.
No sense in giving something UE specific on cell level.
It has to be via dedicated signaling.

8

Yes but in SIB1 and RRC reconfig there are 2 structure pdcch common and pdcch dedicated.

9

RRC reconfig as I said you can, because it is also dedicated signaling.
Can you share screenshot of dedicated pdcch on SIB1?

11

RRC reconfig can be used in SA also.

12

That is for Connected UE is it?

13

Yes.
Basically any dedicated msg which has pdcch_config IE.
Currently I think only RRC setup and RRC reconfig have this.

14

It was good discussion and informative above.
But I have question → After receiving RRC setup for USS param → will this configuration continue till UE moved back to IDLE or OOS or rebooted?
Because to my understanding, In LTE we have PCFICH which will indicate the number symbols used for PDCCH and CFI value might change for each subframe So if we consider the same for NR how USS will be decoded i case of dynamic scenario.

15

Hi @vinod_081, what this USS full form?

16

User Specific Search.

17

Ok. It mean pdcch config dedicated setup you are discussing.
In endc it’s part of RRC connection reconfiguration after sgnb addition.
For SA part of RRC setup.

1 Like
18

Ok thanks got it @ankgitm!

19

Since this is part of RRC config, this information would be lost if RRC connection is terminated/lost.

1 Like
20

Ok thank you @Nitin!

21

Hello Experts,
i have a query regarding PDCCH monitoring. When is UE configured with USS, does UE need to continue to monitor CSS for DCIs scrambled with C-RNTI or monitoring USS is sufficient ?