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ECEN5553 Telecom Systems Week #1 Read [1] "Telecommunications and the IEEE Communications Society", p. 1-9 [2] "The Beginnings of Packet Switching: Some Underlying Concepts" Exam #1 Lecture 15, 21 September (Live) No later than 28 September (Remote DL) Outline 7 October 2015, Lecture 22 (Live) No later than 14 October (Remote DL)
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Exams n Closed Book & Notes n 80-90% on class notes n 10-20% on Required Readings n Start Studying NOW!
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Term Paper n Your Opportunity to Probe Further n Telecommunications topic of your choice n 1,700 - 3,400 words (about 7-14 pages) n Topic MUST be approved by the instructor u Submit 5-10 line Outline ASAP (Due 7 October 2015, Lecture 22) n Due 6 November 2015, Lecture 34 n Remote students: all due dates are +1 week n Visit 5553 Home Page for more details
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Telecommunications n Long Distance Communications via Electro-Magnetic Means n Long Distance = Distance > Normal Voice Conversation
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ECEN 5553 Telecom Systems n Core Course for M.S. Telecom Management B.S. inEngineering Management Information Systems Computer Science n Elective: Electrical Engineering n Elective: Others interested in Data, Voice, & Video Networks
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Student Skill Sets... None Years Experience Technical Background None A Lot Where instructor is pitching the class.
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Cheating n Don’t do it! n My idol: Judge Isaac Parker U.S. Court: Western District of Arkansas 1875-1896 a.k.a. “Hanging Judge Parker” a.k.a. “Hanging Judge Parker”
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Previous Term Paper tolls... n Fall 2001 42 Students in the class 11 F’s for Plagiarism 12 Major Citation Problems -20 to -40 points off n Spring 2002/Fall 2002 6 F's for Plagiarism n Fall 2014 (23 students) 1 Incident
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Accessing OSU Library Databases PCServer OSU Based System IEEE IEEE Server verifies legal user by checking IP Source Address.
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Accessing OSU Library Databases PCServer Home/Office Based System IEEE IEEE Server blocks usage due to incorrect IP Source Address.
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Accessing OSU Library Databases PCServer Home/Office Based System IEEE OSU Proxy Server allows access. Maps your IP address to an OSU address. Server OSU
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Required Readings n Accessing from any OSU campus? u Article links should work fine n Accessing from off campus? u You must log into the proxy server u u Sometimes the Home Page links then work u u Sometimes you have to search for article
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Want a text? Get one of these.
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ISO OSI Seven Layer Model n Layer 7 Application n Layer 6 Presentation Windows API n Layer 5 Session TCP n Layer 4 TransportTCP n Layer 3 Network IP n Layer 2 Data LinkMotherboard n Layer 1 Physical Motherboard
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Five Layer TCP/IP Model n Layer 5 Application Application n Layer 5 Presentation n Layer 4 Session Transport (TCP) n Layer 4 Transport n Layer 3 Network Internet (IP) n Layer 2 Data LinkData Link n Layer 1 Physical Physical
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Business Version of Communications Theory: Moving Bits (OSI Layer 1) n Bandwidth... ‘...an assigned range of frequencies...’ n A sinusoid such as A*cos(2πft + θ) only has energy at a single frequency (f Hertz) n Any waveform can be constructed by adding together a bunch of sinusoids u The frequency range of the sinusoids required to do this constitutes the signal's bandwidth n Fourier Theory specifies the sinusoids required
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200 Hz Cosine Wave 5/100 second plotted
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Generating a Square Wave... 0 1.5 -1.5 0 1.0 0 1.5 -1.5 0 1.0 1 vp 5 Hz 1/3 vp 15 Hz
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Generating a Square Wave... 0 1.5 -1.5 0 1.0 1/5 vp 25 Hz 0 1.5 -1.5 0 1.0 5 Hz + 15 Hz
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Generating a Square Wave... 0 1.5 -1.5 0 1.0 1/7 vp 35 Hz 0 1.5 -1.5 0 1.0 5 Hz + 15 Hz + 25 Hz
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Generating a Square Wave... 0 1.5 -1.5 0 1.0 5 Hz + 15 Hz + 25 Hz + 35 Hz cos2*pi*5t - (1/3)cos2*pi*15t + (1/5)cos2*pi*25t - (1/7)cos2*pi*35t) 5 cycle per second "square wave" generated using first 4 sinusoids, Absolute Bandwidth = 35 Hertz.
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Generating a Square Wave... 5 cycle per second square wave generated using first 50 sinusoids, Absolute Bandwidth = 495 Hertz. 0 1.5 -1.5 0 1.0
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Generating a Square Wave... 5 cycle per second square wave generated using first 100 sinusoids, Absolute Bandwidth = 995 Hertz. 0 1.5 -1.5 0 1.0
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Communications Theory: Moving Bits (OSI Layer 1) n Digital Signal: A finite number of symbols are transmitted. Ex) If we define a capital letter as a symbol, the alphabet is digital (26 symbols, A - Z). n Analog Signal: An infinite number of symbols are transmitted. Example) If we define the instantaneous pressure as a symbol, a voice pressure wave is an analog signal.
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Example: Binary Signal n Serial Bit Stream (a.k.a. Random Binary Square Wave) u One of two possible symbols transmitted every T seconds. Here the symbol is either a positive or negative going pulse. u When two symbols are used, a symbol is known as a ‘bit’. time +1 volts 0 T If T =.000001 seconds, then this signal moves 1 Mbps.
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Example:M-Ary Signal n One of M possible symbols is transmitted every T seconds. EX) 4-Ary signaling. Note each symbol can represent 2 bits. time +1.34 volts +.45 T If T =.000001 seconds, then this 1 MBaud signal moves 2 Mbps. -.45 -1.34
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M-Ary versus Binary n Two Symbols: Binary Signaling n M Symbols: M-Ary Signaling u M is usually a power of 2 u Log 2 M bits/symbol n Baud rates same? Symbol shapes similar? If yes.. u Bandwidth required is similar u M-Ary signaling allows increased bit rate F Symbols get closer together if Power fixed F Noise and/or distortion? Receiver detection errors more likely
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M-Ary signaling MMMM-Ary signaling used when BBBBandwidth is tight SSSSNR's & signal distortion tolerable PPPP(Bit Error) OK DDDDial-Up Phone Modems (3500 Hz Channel Bandwidth) 1111960's: 300 bps using binary signaling 1111980's: 14,400 bps using 128-Ary signaling 1111996: 33,600 bps using 1664-Ary signaling
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Wired Signaling Generally uses square pulse symbols Generally uses square pulse symbols Symbol shape & width → system bandwidth Symbol shape & width → system bandwidth Binary → 2 possible symbols Binary → 2 possible symbols M-ary → M possible symbols M-ary → M possible symbols Can increase system bps with same bandwidth Can increase system bps with same bandwidth So long as symbol width & general shape unchanged So long as symbol width & general shape unchanged Makes receiver's life more difficult Makes receiver's life more difficult Bit Error Rate tends to increase with increasing M Bit Error Rate tends to increase with increasing M If Power Fixed If Power Fixed Can crank up power to get same BER as binary Can crank up power to get same BER as binary
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Untwisted Pairs
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Wired Physical Links Untwisted Pair Cabling Untwisted Pair Cabling Highly susceptible to EM interference Highly susceptible to EM interference Lousy choice for telecom systems Lousy choice for telecom systems Example: Speaker Wires, Power Lines Example: Speaker Wires, Power Lines Twisted Pair Cabling Twisted Pair Cabling Fairly resistant to EM interference Fairly resistant to EM interference Bandwidth typically in 1-2 digit MHz Bandwidth typically in 1-2 digit MHz Examples: LAN wiring, Home telephone cables Examples: LAN wiring, Home telephone cables
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Twisted Pair Cables source: Wikipedia RJ45
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Wired Physical Links Coaxial Cable Coaxial Cable Resistant to EM interference Resistant to EM interference Bandwidth typically in 2-3 digit MHz Bandwidth typically in 2-3 digit MHz Example: Cable TV Example: Cable TV Fiber Optic Cable Fiber Optic Cable Immune to EM interference Immune to EM interference Bandwidth in GHz to THz Bandwidth in GHz to THz
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Coax Cable RG-59 flexible coaxial cable composed of: A: outer plastic sheath B: woven copper shield C: inner dielectric insulator D: copper core source: Wikipedia BNC F
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