UE如何获得5G NR Type#0 CSS PDCCH SCS即子载波间隔信息去解码SIB1?

jianglinhua

Sincewe are all learning 5G NR, now I have 2 small/tricky questions below:
After5G UE power on, UE first needs to search out(scan) the strongest SSB beam(ofcourse know the strongest SIB Index and SCS used for SSB) based on itssupported 5G NR Band(FR1 or FR2),
ThenUE can decode PBCH to get MIB content to know the Type#0 PDCCH CSS(CommonSearch Space) info by IE pdcch-ConfigSIB1:
e.g.CORESET#0 for Frequency domain resource-RB number/RB startingpoint(offset)/duration time as well as time domain monitor occasion: SFN(Odd orEven)/Slot/Symbol location.
Afterfully getting Type#0 PDCCH CSS info, UE can blind detect PDCCH via SI RNTI todecode SIB1 to get more other necessary info(e.g. SIB2, BWP info) in order toinitiate the attach/registration.

Q1:How does UE know the SCS(Sub-carrier Spacing) used for Type#0 PDCCH?
BecauseUE needs this SCS info together with pdcch-ConfigSIB1value to lookup many tables to get the detailed Type#0 PDCCH CSS info.
Weknow 5G NR define 5 types of SCSs(15KHz/30KHz/60KHz/120KHz/240KHz), SSB andPDCCH can use different SCS.

Q2: How does UE inform gNB of the strongest SSB index it detected?
SincegNB needs this SSB index to transmit any DL messages(such as MSG2/MSG4 in RAprocedure) to UE in the correct/strongest SSB beam.

These2 question confused me for some time, anyway I got them finally.