Qualcomm Senior Systems Engineer interview questions

Several basic questions in wireless communication systems such as difference between wired and wireless networks, advantage of multicast. The interviewer is Indian. He was very nice and patient.

Some basic probability/stochastic process questions about lossy wireless channels. The last question the interview asked was: "Suppose we make 10 packet transmissions per second over a wireless channel, the channel is lossy such that with probability 1/10 a packet transmission will fail. The transmitter knows perfectly whether a transmission succeeds or fails. When it fails, the transmitter retransmit the packet, until it finally succeeds. So what is the throughput we can get?" This was a VERY VERY simple question that the throughput should be 9 packets/second! The interview didn't agree and simply emphasized "because of retransmission, throughput should be reduced more than 1/10" repeatedly. Couldn't achieve a consensus with him after a long debate and that's it.