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Sripatum University

CIS514 Computer Communication and Networks การสื่อสารคอมพิวเตอร์และเครือข่าย. Asst.Dr.Surasak Mungsing surasak.mu@spu.ac.th mungsing@gmail.com http://www.spu.ac.th/teacher/surasak.mu. Sripatum University. Course description.

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Sripatum University

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  1. CIS514 Computer Communication and Networks การสื่อสารคอมพิวเตอร์และเครือข่าย Asst.Dr.Surasak Mungsing surasak.mu@spu.ac.th mungsing@gmail.com http://www.spu.ac.th/teacher/surasak.mu Sripatum University

  2. Course description ศึกษาสถาปัตยกรรมของเครือข่ายและพิธีการสื่อสารแบบต่างๆ หลักการของการสื่อสารข้อมูล โปรโตคอลพื้นฐานและชั้นสูงที่ใช้ในการติดต่อสื่อสาร ศึกษาอุปกรณ์สำหรับเครือข่ายสื่อสาร การเชื่อมโยงเพื่อสร้างเครือข่ายและรองรับข้อมูลในเครือข่าย การสวิตช์และจัดเส้นทาง เครือข่ายบริเวณเฉพาะที่ (Local Area Network) และบริเวณกว้าง (Wide Area Network) ความมั่นคงของข้อมูล การออกแบบระบบเครือข่ายเพื่อใช้งาน การใช้เครื่องมือวัดสมรรถภาพ การปรับแต่งเครือข่ายเพื่อกระจายการใช้งานในเครือข่าย การเปรียบเทียบสถาปัตยกรรมของเครือข่ายแบบต่างๆ กับระบบดั้งเดิมที่ใช้เครื่องใหญ่และแบ่งกันใช้เวลา ศึกษาเครือข่ายอินเทอร์เน็ตพร้อมยกตัวอย่างประกอบการเรียนการสอน มีการจัดกลุ่มนักศึกษาเพื่อสร้างโครงงานเครือข่ายที่กำหนด

  3. Objectives • To understand computer network architecture and communication protocols • To study network devices and network connections • To learn how to analyze and measure network performance and design high performance networks • To understand and realize the importance of information and network security • To understand and realize the benefits of the Internet • To design computer network

  4. Lecture schedule (BeforeMid-term)

  5. Lecture schedule (AfterMid-term)

  6. Evaluation Project Report &presentation 20 % Term paper 10 % Participation 10 % Mid-term Exam 20 % Final Exam 40 % Total 100 %

  7. Text • Data Communications and Networking, Behrouz A. Forouzan, Fourth Edition: McGraw Hill, 2007 • Business Data Communications, William S. Stallings, Fifth Edition, Pearson Prentice-Hall, 2005 • Computer Networks, Andrew S. Tanenbuam, Fourth Edition: Pearson PrenticeHall, 2003

  8. CIS514Introduction to Computer Communication and Networks

  9. Telecommunication • Communication based on electromagnetic • Light speed vs Sound speed - Sound speed : ~ - Light speed : ~ • Bandwidth : related to amount of data and channel not quantity of communication 670miles per hour 186,000 miles per second

  10. Electronic Communication • Focus on device operations in such a way that data are buffered before transmitting at high speed (store and forward) • Example of communication based onStore-and-forward teechnique: E-mail, voice mail, Facsimile, file transfer and WWW

  11. Analog Data • Continuous signal • Change of frequency (oscillation) as sine wave • Example of analog data: music from record player, which the record of sine-wave signals from a microphone

  12. 1 cycle amplitude (volts) time (sec) frequency (hertz) = cycles per second Analog Signaling Signals in sine-wave form

  13. Analog Terms • Cycle :change of wave for one cycle in a unit of time • Wave frequency: number of cycles of wave per unittime • Wave amplitude: height of wave • Hertz: number of frequency per second

  14. Analog Signaling

  15. Digital Data • Represent data with symbols such as 1or 0 when there is a change in electrical signal • Transmission rate of communication channel in bit per second, e.g a modem has transmission rate at 56 Kbit / sec. (56 * 1000 bps) • Data represented by binary digit (0, 1) • data 0, 1 represented by the level of electrical voltage in a period of time

  16. Digital Terms • Bit: came from Binary Digit 1 is 1 in decimal system 10 is 2 decimal system 10011001 is 153 decimal system • Byte consists of 8 bits

  17. Number of bits and the value they represent 263 = 9,223,372,036,854,775,808  9.223ล้าน ล้าน ล้าน

  18. Storage Term Number of bytes Abbreviation Kilobyte KB 1 thousand Megabyte MB 1 million 1 billion Gigabyte GB Terabyte 1 trillion TB Petabyte PB 1 quadrillion Unit of data

  19. audio VIViD • Voice • Image • Video • Data text Graphics video

  20. Character representation in digital system • Represents electrical pulse with 1 and 0 • Represents any character in binary, e.g. Morse code : dots and dashes • Represents character with ASCII code

  21. ASCII Character Codes • A character is represented by 8 bits • 8 bits of 0 and1 can represent 256 characters (0-255) • Special characters has values between 128 – 255 Table of ASCII code

  22. Example • Assume that a page of paper has 27 line of text and each line contains up to 65 characters. Each character is represented by an ASCII code(8 bits). • Howlong will it take to send a page of message via a modem at the speed of 56,000 bpsand 256Kbps? 27*65*8/56000 = 14040/56000 0.25 seconds 27*65*8/256000 = 0.05484375 0.055seconds

  23. Analog audio transmission • Transmits into receiving devices such as a microphone • Microphone receives wave signals and transform to electrical signal according to the strength of the signals (amplitude of the signal wave) or changes o signal frequency (low/high frequencies) • Examples of frequency generated from audio signal • Telephone: 3000Hz • Hi-Fi system: 15,000 Hz; • Compact Disc system: 20,000 Hz

  24. Digital audio transsmission • Good quality sound: transmits sample amplitude at double speed of highest frequency (Nyquist Theorem) • Measurement is samples per second (smp/sec) • Quality of telephone sound is at 8000 smp/sec each sample is 8 bits • 8 bits * 8000smp/sec = 64kbps to transmit • Quality of CD audio is at 44000 smp/sec , each sample is 16 bits • 16 bits * 44000 *2 smp/sec = 1.41 Mbps to transmit

  25. Converting Images • Image is a collection of pixels • more pixels ->high resolution • Digital image created by assigning value to each piixel, which represented by a group of 0 and 1 ( 0 for light and 1 for dark)

  26. Quality of image • more pixels more quality (sharper image) • more data compression the less quality • Compression ratio 10:1 to 20:1 e.g. replacing 10 pixels with same value of 1 pixel reduces sharpness of the image • less compression  more time to transmit than high compression • user must trade off between quality of image and time for transmission

  27. Example of a 100-pixel black and white image

  28. Eight-Level Gray Scale 1 pixel is represented by 8 bits

  29. Transmission time for sending an image

  30. Video Communication • Composed of a series of continuous images during a period of time • Same principle as image but requires more transmission time for series of images • Requires high channel capacity to satisfy specific application • May need compression to respond to required transmission rate of image (frame/sec)

  31. Next Lecture: Computer network and network taxonomy

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