1. Comparing various 4G technologies with a critical perspective
2. Security in wireless networks (you could choose between say LTE-Advanced, 802.11n or something)
3. Bluetooth, and other near area wireless communication protocols, technologies, and their applications
4. Beyond LTE/LTE-Adv what are the future technologies, what are their parameters, where are they being innovated, why are they needed, etc
5. Quality of service over wireless network
6. Ad-hoc wireless networks in non-military applications, what are the challenges, what are the current solutions and applications
7. Security threat models for wireless networks, and mitigation techniques
8. Use of Wireless network in critical infrastructure (power grid, gas pipeline etc) and the security issues associated with that.