What is the difference between Initial DL BWP, Dedicated DL BWP and Active DL BWP?

Hi 5G Experts.
I need to understand difference between initial DL BWP, dedicated DL BWP and active DL BWP.
I am seeing intial DL BWP in spcell config common and dedicated.
Anyone having simple calculation how to calculate starting RB and no of RB from location and BW part of initial DL BWP?


Take a look here:


But I am seeing in logs first active DL BWP there but with no structure.
For initial DL BWP and dedicated BWP parameter can be seen.

firstActiveDownlinkBWP-Id : If configured for an SpCell, this field contains the ID of the DL BWP to be activated upon performing the reconfiguration in which it is received. If the field is absent, the RRC reconfiguration does not impose a BWP switch (corresponds to L1 parameter ‘active-BWP-DL-Pcell’). If configured for an SCell, this field contains the ID of the downlink bandwidth part to be used upon MAC-activation of an SCell. The initial bandwidth part is referred to by BWP-Id = 0

My understanding we have 4DL/UL BWP per carrier.
Initial DL BWP valid for both sib1 and dedicated having identity 0.
Dedicated DL BWP having identity 1 to 4.
First Active DL BWP identity 1.
Default BWP not used.

Sib 1 comes only in SA.

Yes in case of NSA its part of spcell config common IE part of rrc reconfigure.

There can be maximum 4 bwp but not mandatory to be 4 configured.
Anyway only 1 active at any moment in time.

We have 2 IE spcell config common and spcell config dedicated.
And yes, I am seeing 1 in logs.

For calculating bw part formula is on ShareTechNote with examples.

Ok let me check for calculation.
RIV value.

Here is the difference:
Initial BWP is for idle mode till msg3.
The active BWP part is activated by msg4.
A maximum of 4 active BWP parts can be defined.

Below is the parameter for it:

Here is the link to calculate RIV:


Yes, right.
But the formula for RIV is based on S, L with type A and type B table for PDSCH allocation if length L -1 <= 7 then:
RIV = 14 - ( L - 1 ) + S
else = 14 - ( 14 - L + 1 ) + ( 14 + 1 - S )

Initial DL BWP part of dedicated signalling i seen in logs.
Anyone having mac layer content for NR showing DCI format?

Only available in qxdm or apex logs where you can see everything with slot resolution.

Could you please convert in txt and share?

Both are Qualcomm tools.
And I don’t have access to those tools.

But here are some important qxdm packets: