you can choose wireless(mobile) communication filed
Topics like GSM/GPRS/UMTS/CDMA, are very interesting, you can detail on modulation/data services/roaming etc., also GPS, IPTV, WiMAX, BLUETOOTH, WiFi, SMART ANTENNA, ULTRA WIDE BAND ANTENNA, MODERN RADAR SYSTEMS. NANO Technology.....
go through recently held conferences, you will get many topics in the field of interest.