(Huawei TELLIN intelligent network maintenance materials, including chapters: 1. Signal and Communication System; 2. Digital Signal Switching Technology and Equipment; 3. Optical Fiber System; 4. Mobile Communication Technology; 5. IP Technology and Internet; 6. Organization of Communication Network and optimization; 7. Prospects of modern communication technologies; 8. Overview of Huawei's communication products and network solutions; 9. Abbreviations)