1. ITGD4103 Data Communications and Networks Lecture-1 Dr. Anwar Mousa University of Palestine Faculty of Information Technology

2. 2 DATETOPICS Week 1  Course introduction-Data Communications Week 2  network models Week 3  Data and signals Week 4  Data Transmission Techniques Week 5  Digital and Analog Signals Week 6  Bandwidth Utilization and multiplexing Week 7  Transmission Media Week 8  Mid-Term Exam Week 9  Wired LANs: Ethernet Week 10  Wireless LANs Week 11  Wireless WANs Week 12  SONET/SDH Week 13  Frame Relay Week 14  ATM Week 15  Switching Week 16  FINAL EXAM

3. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 3  Provide an overview of data communication theory  Provide a basic understanding of networking and telecommunications.  Consider the impact and implications of new communications technology systems.  Describe the roles of switching, transmission, and signaling in providing telecommunications services. Course Objectives

4. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 4 COURSE OUTLINE

5. EE 541/451 Fall 2006 [5][5] Instructor Information Office location: Office hours: Email: anwar_mousa@yahoo.com Phone: Research interests:

6. EE 541/451 Fall 2006 [6][6] Textbook and Software Require textbook: “Data Communications and Networking,” Behrouz A. Forouzan, 4th ed, Mc-Graw Hill, 2007. Reference “Data and Computer Communications,” W. Stallings, 7th ed., Prentice Hall, 2004.

7. EE 541/451 Fall 2006 [7][7] Homework, Project, and Exam Homework  1 assignment per week Exams  Two exams: Midterm and Final  Participations  Attendance and Feedback

8. EE 541/451 Fall 2006 [8][8] Teaching Styles Slides plus White board  Slides can convey more information in an organized way  Whiteboard is better for equations and prevents you from not coming. Course Website  Print handouts with 3 slides per page before you come  Homework assignment and solutions Feedback  Too fast, too slow  Presentation

9. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 9 Introduction to Data Communications Chapter One

10. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 10 What is Data Communications?  Data communications are the exchange of data between two devices via some form of transmission medium.  For Data communications to occur, the communicating devices must be part of a communicating system made up of a combination of hardware (physical equipments) and software (programs).

11. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 11 The effectiveness of data com. system  The effectiveness of data com. System depends on four fundamentals: 1.Delivary Data must be received only by the intended device or user only 2.Accuracy Deliver data accurately (error-free)

12. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 12 The effectiveness of data com. system 3.Timeliness Deliver data without significant delay 4.Jitter Jitter refers to the variation in the packet arrival time.

13. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 13 Components A data com. system has five components:  Message  Sender  Receiver  Transmission medium  Protocol

14. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 14 Data Representation Information today comes in different forms such as:  Text  Text is represented as bit stream (0 or 1). The prevalent coding system is called UNICODE, which uses 32 bits to represent a symbole or character used in any language.  The American Standard Code for Information Interchange (ASCII) constitutes the first 127 characters in UNICODE.

15. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 15 Data Representation  Numbers  The numbers are directly converted to a binary number to simplify mathematical operations.  Images  An image is composed of a matrix of pixels where each pixel is a small dot.  An image can be divided into 1000 pixels or more (better resolution).  Each pixel is assigned a bit pattern.  For an image made of only black and white dots

16. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 16 Data Representation  A 1-bit pattern is enough to represent a pixel.  If an image is not made of a pure black and pure white pixels, you can increase the size of the bit pattern to include gray scale.  For example, to show four levels of gray scale, you can use 2-bit pattern:  A black pixel represented by 00, a dark gray by 01, a light gray by 10 and a white pixel by 11.

17. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 17 Data Representation  To represent color image, one method is called RGB, where each color is made of three primary colors: red, green and blue.  The intensity of each color is measured and a bit pattern is assigned to it.  Audio  Audio is different from text, numbers or image.  It is continuous not discret.

18. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 18 Data Representation Information today comes in different forms such as:  Video  Video can either be produced as a continuous entity (by a TV camera) be a combination of images, each discret entity arranged to convey the idea of motion.

19. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 19 Communications Channels  A communications channel is a pathway over which information can be conveyed.  It may be defined by a physical wire that connects communicating devices, or by a radio, laser, o or other radiated energy source that has no obvious physical presence.  Information sent through a communications channel has a source from which the information originates, and a destination to which the information is delivered.

20. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 20 Communications Channels  Although information originates from a single source, there may be more than one destination, odepending upon how many receive stations are linked to the channel and how much energy the transmitted signal possesses.  In a digital communications channel, the information is represented by individual data bits, which may be encapsulated into multibit message units. oA byte, which consists of eight bits, is an example of a message unit that may be conveyed through a digital communications channel.

21. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 21 Communications Channels, cont...  A collection of bytes may itself be grouped into a frame or other higher-level message unit.  Such multiple levels of encapsulation facilitate the handling of messages in a complex data communications network.  The message source is the transmitter, and the destination is the receiver.

22. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 22 Communications Channels, cont… A channel whose direction of transmission is unchanging is referred to as a simplex channel. oFor example, a radio station is a simplex channel because it always transmits the signal to its listeners and never allows them to transmit back.  A half-duplex channel is a single physical channel in which the direction may be reversed. oMessages may flow in two directions, but never at the same time, in a half-duplex system.

23. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 23 Communications Channels, cont… oOne party speaks while the other listens. After a pause, the other party speaks and the first party listens. Speaking simultaneously results in garbled sound that cannot be understood.  A full-duplex channel allows simultaneous message exchange in both directions. It really consists of two simplex channels, a forward channel and a reverse channel, linking the same points. oThe transmission rate of the reverse channel may be slower if it is used only for flow control of the forward channel.

24. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 24 Any communications channel has a direction associated with it:

25. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 25  Simplex  One way communication only

26. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 26  Half-duplex  One way at a time.

27. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 27  Full-duplex  Communication in both directions simultaneously.

28. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 28 Networks  A network is a set of devices (nodes) connected by com. Links.  Most networks use distributed processing, in which a task is divided among multiple computers.  Network criteria  Performance  Transit time  Response time  Throughput

29. Dr. Anwar M. Mousa anwar_mousa@yahoo.com 29 Networks criteria  Reliability  Accuracy of delivery  Frequency of failure  network’s robustness in a catastrophe  Security  Protecting data from unauthorized access  Protecting data from damage  Recovery from breaches and losses