Qualcomm Systems Engineer interview questions

I applied online and had an in-person recommendation from someone who works at the company. They emailed me to do 2 rounds of technical phone interviews. The interviewers were really nice and helpful. The interviews were about the courses I took in graduate school (I am on my way to PhD by the way), about Probability, Detection/Estimation Theory, Wireless Communications and Signals and Systems. Most were basic things, like definitions of simple things like fading, stability of a filter and so on. I was asked to do some computations on detection in Gaussian channel like error probabilities and detection regions. I was also asked some brain teasers like coin weighing problems. Then I was asked to do an additional third round of interview with similar problems. All the interviewers were nice and helpful.