I was very surprised to learn how different wireless networking is from wired networking. What I expected was to study extensions to what we had already learned which were applicable to wireless. What I learned is that the constraints of wireless motivate drastic changes from the was networking is normally done.
For example, in opportunistic routing for wireless networks an ACK to the sender and new data to the receiver are effectively relayed by some intermediate party in the same message. This is totally different. Another example of the extent of the difference is that routing may be handled to a significant extent below the IP layer, near the MAC.
Another indication of the divide between wired and wireless is that 2 of the 4 papers we have studied so far came from a conference dedicated to mobile computing and wireless.
I expect to see other big differences in the future. I also suspect that much of what I have learned in the context of wired networking may not be very applicable in the context of wireless.