Telecommunication systems 810 Computer networks 121 Telecommunication 77 Digital communications 74 Universal Mobile Telecommunications System 68 Management 59 Information technology 51 Wireless communication systems 51 Design and construction 47 Computers 44 Signal processing 43 Mobile communication systems 38 Data transmission systems 35 System analysis 33 Computer simulation 32 Internetworking (Telecommunication) 29 Telecommunications systems 27 Global system for mobile communications 26 Quality control 22 Security measures 22 Data processing 21 Optical communications 21 Mathematical models 19 Planning 19 Communication systems 16 Local area networks (Computer networks) 15 Programmable controllers 15 Telephone switching systems, Electronic 15 Artificial satellites in telecommunication 14 Computer security 14