EE4220 Communications system

1. EE4220 Communications system Dr. Hassan Yousif Electrical Engineering Department College of Engineering Salman Bin Abdulaziz University My home page: http://faculty.sau.edu.sa/h.ahmed EE3220 Dr Hassan Yousif Ahmed

2. Textbooks: J.W.Marks and W.Zhuang, "Wireless Communications and Networking", Prentice Hall, Last Edition.2. “Roy Blake, "Electrical Communication Systems", 2ed., Delmar, Last Edition. EE3220 Dr Hassan Yousif Ahmed

3. EE3220 Dr Hassan Yousif Ahmed

4. The process of sharing data, programs, and information between two or more computers What is Communication? EE3220 Dr Hassan Yousif Ahmed

5. Communication Systems Are electronic systems that transmit data from one location to another Basic elements of a communication system: 1- Sending and Receiving Devices ( computers or specialized communication devices). 2- Communication Channel( transmission medium) (physical wire or cable and wireless connection). 3- Connection Devices (communication devices): Act as an interface between the sending and receiving devices and the communication channel, they convert outgoing message into a form and format so that they can travel across the communication channel. 4- Data Transmission specifications: rules and procedures that coordinate the sending and receiving devices( how the message will be send through the communication channel) EE3220 Dr Hassan Yousif Ahmed

6. Communication Systems Modem Computer Telephone-lines E-mail

7. Communication Channels • Channels carry data from one computer to another • Two categories of communication channels • Physical connection • Wireless connection

8. Physical ConnectionsSolid medium to connect sending and receiving devices • Telephone lines ( twisted pair cable) • Coaxial cablehigh frequency transmission cable deliver television signals and connect computer in a network. 80 times the transmission capacity of twisted pair cable • Fiber-optic cable Transmit data as pulses of light through tiny tubes of glass. 26000 times the transmission capacity of twisted pair cable

9. Wireless Connections • Infrared • Broadcast radio: Communication uses special sending and receiving towers called Transceivers, send and receive radio signals from wireless devices • Microwave: Communication uses high frequency radio waves sending data between buildings in a city • Stations used for long distance • Bluetooth • Satellite • Uplink/Downlink Uplink is a term of sending data to a satellite. Downlink is a term of receiving data from a satellite. • Global Positioning System: Application of satellite communication Note: Check page 239

10. More on Satellites • Global positioning • Network of 24 satellites • Owned by the Defense Department • Global positioning system (GPS) • Devices used to determine location • Provides navigational support

11. Connection Devices • Types of signals • Analog • Digital • Types of modems • Internal: plug-in circuit board • External: wall jack, modem and serial port • PC Card: laptop • Wireless

12. Types of Connections • Digital subscriber line (DSL) • Uses existing phone lines • ADSL (Asymmetric digital subscriber line) • ADSL services can download at up to 8Mb/s and upload up to 832 kb/s, • Cable modems • Uses existing TV cable • Provides speeds as fast as DSL at a lower cost • Satellite/air connection services • Seven times faster than dial-up • Slower than DSL & cable modem

13. User Connection Costs & Speeds

14. Bandwidth • Measurement of the capacity of the channel • Categories • Low bandwidths or Voiceband Used for standard telephone communication • Medium band Used for minicomputer and mainframe • Broadband • Used for high capacity transmission • Used by DSL, cable & satellite

15. Several technical matters affect data communications • One is bandwidth – bits-per-second (bps) transmission capability of a channel • Three types: • Voiceband – low bandwidth; standard phone line; too slow for many types of transmissions – especially high-quality video • Medium band – with special leased lines for larger computer systems; not typically used by individuals • Broadband – used for high-capacity transmissions (DSL, cable, satellite connections); specialized high-speed devices; effectively transmits high-quality video and other communication needs; typically 1.5 mbps; higher speeds possible EE3220 Dr Hassan Yousif Ahmed

16. Protocols • Set of communication rules • Rules for exchanging data between computers. • Standard for Internet: TCP/IP • Transmission control protocol/Internet protocol • Identifies devices : Identifying sending and receiving devices Each computer on the internet has IP address DNS domain name server convert text to IP address. • Reformats information Reformatted or broken into small parts called packets

17. Strategies • Strategy is a way of coordinating the sharing of information and resources • Common network strategies • Terminal Processing power is centralized in one large computer , usually a mainframe. Many airline reservation systems are terminal systems. A large central computer maintain all the airline schedule. • Client/server Use one computer to coordinate and supply services to other nodes on the network. The server provides access to resources such as web pages, database. • Peer-to-peer Nodes have equal authority and can act as both clients and servers, for example one microcomputer can obtain files located on another microcomputer and can also provide files to other microcomputers

18. Organizational Internets

19. Internets and Extranets • Intranets • Private network within an organization • Provides information to employees • Extranets • Private network that connects organizations • Used to allow suppliers and others access • Firewalls • Security system • Protects against external threats

20. A Look to the FutureWireless Robotic Car • Pod car (Personalization on Demand) • Predicts and responds • Designed to learn and adapt to an individual's driving needs and habits