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EE 104: Introduction to Communications

EE 104: Introduction to Communications. Professor Andrea Goldsmith. Outline. Course Information and Policies Communication Systems Today Future Systems Design Challenges. Course Information (see web or handout for more details).

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EE 104: Introduction to Communications

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  1. EE 104: Introduction to Communications Professor Andrea Goldsmith

  2. Outline • Course Information and Policies • Communication Systems Today • Future Systems • Design Challenges

  3. Course Information(see web or handout for more details) • Instructor: Andrea Goldsmith, Packard 371, andrea@ee, Ext: 56932, OHs: W 11am-12pm, Th 5:30-6:30. • Class Homepage: www.stanford.edu/class/ee104 • TAs: • Jaron Charles, jcharles@stanford, OHs: Th 7-9pm, Email W 8:30-9:30pm • Nikola Stikov, nikola@stanford, OHs: F 11am-1pm, Email Th 6-7pm • Class mailing list: ee104-students (automatic for registered students), ee104-staff for instructor/TAs, guest list available • Discussion Section: W 6:15-7:15pm; not televised • Book: An Introduction to Analog and Digital Communications • Grading: HWs 30%, Midterm 30%, Final 40% • No Lectures Jan. 15 and Feb. 24 • Other lectures that week start at 12:50pm, or can schedule makeups

  4. Class Policies • Exam policy: Exams must be taken at their scheduled times. Exceptions only in very rare circumstances. • Midterm: 2/12 from 12:30-2:05 • Final: 3/20 from 8:30-11:30am. • HW policy: • Assigned Friday, due following Friday. Lose 25% credit per day late. • Up to 3 students can collaborate on 1 writeup. All collaborators must work out all problems. • SITN students: • HWs must be faxed or postmarked by HW deadline for regular students. Exceptions must be cleared in advance. • Exams must be taken at same time as for regular students.

  5. Communication Systems • Provide for electronic exchange of multimedia data • Voice, data, video, music, email, web pages, etc. • Communication Systems Today • Radio and TV broadcasting (covered later in the course) • Public Switched Telephone Network (voice,fax,modem) • Cellular Phones • Computer networks (LANs, WANs, and the Internet) • Satellite systems (pagers, voice/data, movie broadcasts) • Bluetooth

  6. Local Switching Office (Exchange) Local Switching Office (Exchange) PSTN Design • Local exchange • Handles local calls • Routes long distance calls over high-speed lines • Circuit switched network tailored for voice • Faxes and modems modulate data for voice channel • DSL uses advanced modulation to get 1.5 Mbps Long Distance Lines (Fiber) Fax Modem Local Line (Twisted Pair)

  7. BASE STATION Cellular System Basics • Geographic region divided into cells • Frequencies/timeslots/codes reused at spatially-separated locations (analog systems use FD, digital use TD or CD) • Co-channel interference between same color cells. • Handoff and control coordinated through cell base stations

  8. BS BS BS MTSO MTSO Cell Phone Backbone Network San Francisco New York PSTN Internet

  9. 0101 0101 1011 1011 Local Area Networks (LANs) • LANs connect “local” computers • Breaks data into packets • Packet switching (no dedicated channels) • Proprietary protocols (access,routing, etc.) 01011011 01011011

  10. Wireless Local Area Networks (WLANs) 1011 0101 01011011 Internet Access Point • WLANs connect “local” computers (100m range) • Breaks data into packets • Channel access is shared (random access) • Backbone Internet provides best-effort service

  11. 1011 0101 Wide Area Networks: The Internet Internet 01011011 Bridge LAN MAN Bridge LAN Satellite and Fiber Lines • Many LANs and MANs bridged together • Universal protocol: TCP/IP (packet based). • Guaranteed rates or delays cannot be provided. • Hard to support user mobility. • Highly scalable and flexible topology

  12. Satellite Systems • Cover very large areas • Different orbit heights • Geosynchronous (GEO) versus low earth orbit (LEO) • Optimized for one-way transmission • Paging, radio and movie broadcast • Most two-way systems struggling or bankrupt • Expensive alternative to terrestrial system • A few ambitious systems on the horizon

  13. Bluetooth • Cable replacement for electronic devices • Cell phones, laptops, PDAs, etc. • Short range connection (10-100 m) • 1 data (721 Kbps) and 3 voice (56 Kbps) channels • Rudimentary networking capabilities

  14. Future Systems Ubiquitous Communication Among People and Devices Nth Generation Cellular Nth Generation WLANs Nth Generation Internet Wireless Entertainment Sensor Networks Smart Homes/Appliances Automated Cars/Factories Telemedicine/Learning All this and more…

  15. Design Challenges • Hardware Design • Precise components • Small, lightweight, low power • Cheap • High frequency operation • System Design • Converting and transferring information • High data rates • Robust to noise and interference • Supports many users • Network Design • Worldwide anywhere any-time connectivity • Speed

  16. Main Points • Communication systems send information electronically over communication channels • Many different types of systems which convey many different types of information • Design challenges include hardware, system, and network issues • Communication systems recreate transmitted information at receiver with high fidelity • Focus of this class is design and performance of analog and digital communication systems

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