I joined QC recently and see many people coming back from QC SD to QC BDC. How do you get into QC SD and why do you guys come back?
You stay 5 plus years at qcom as a staff engineer, you will be definitely offered for San Diego. This is the most likely pattern I saw with Qcom.
This applies only for "Staff" engineers, is it? Not below ?
Yes in most of the cases, only higher positioned people asked to relocate for San Diego, this is what I have heard from my 4 to 5 friends in their respective team, exceptions might be there.
What is SD and BDC?
San Diego and Bangalore Dev Center (I assume)
Yes, bangalore design center