Modulation (Electronics) Signal theory (Telecommunication) 23 Digital communications 13 Signal processing 11 Wireless communication systems 11 Coding theory 10 Estimation theory 9 Radio 9 Adaptive antennas 8 Design and construction 8 Transmitter-receivers 8 Radio frequency modulation 6 Telecommunication 6 Adaptive filters 4 Cellular telephone systems 4 Electronic circuit design 4 Mathematics 4 Microwave circuits 4 Modems 4 Radio circuits 4 Antennas (Electronics) 3 Data processing 3 Digital techniques 3 Electric inverters 3 Global system for mobile communications 3 Wavelets (Mathematics) 3 Array processors 2 Bluetooth technology 2 Broadband communication systems 2 Computer networks 2