Chapter 7 Telecommunications, the Internet, and Wireless Technology

1. Chapter 7Telecommunications, the Internet, and Wireless Technology Yousub Hwang PhD., College of Business Administration University of Seoul

2. Binary Representation of Characters • A bit is a basic unit of information storage (a contraction of “binary digit” • A byte is a unit of basic addressable element in computer • 1 byte = 1 alpha-numeric character

3. digital analog Digital vs. Analog Signals Transmission • Transmission – sending and receiving messages • Transmission channels – paths through which messages are passed • Signals can be: • Analog – data is in continuous waveforms • Digital – data is in discrete pulses (0’s & 1’s)

4. Effects of Noise in Data Transmission t1 t2 t3 t4 t5 t6 t7 t8 t1 t2 t3 t4

5. Analog and Digital Signals(Data Transmission) • Disadvantage of Analog signal transmission • Any system has noise, that is, random variation in it • As the signal is transmitted over long distances, noise become dominant • The effects of noise make signal loss and distortion impossible to recover • Advantages of Digital signals transmission • Digital Signals transfer much more data than analog signals and at much greater speeds • Easy to recover the effects of noise

6. Data Transmission in Computer • Modems • Transmit data over analog telephone lines (twisted wire) • Modulation – converts digital (from computer) to analog to cross telephone lines • Demodulation – converts analog to digital for computer

7. Physical Transmission Media • Twisted wire • Used for telephone lines • Up to 1 Gbps within 100 meter • Coaxial Cable • Used for Cable TV service • Up to 1 Gbps within 100 meter • Fiber Optics • Thin strands of glass that carry data by means of pulses of light • Can carry more data without loss of signal strength • Up to 6.4 Tbps

8. Wireless Transmission Media • Microwaves • Transmits data through electromagnetic waves with very short frequency • Up to 600 Mbps • Microwave relay stations are built about 60km apart or Communication satellites are utilized • Advantage: It is useful in areas where the use of physical wires is impractical or impossible • Disadvantage: 60km line-of-sight restriction, sensitivity to electromagnetic interference, costs of maintaining relay stations

9. Microwave Relay Station

10. Types of Networks

11. Key Digital Networking Technologies • Client/Server computing • Packet switching • TCP/IP (Transmission Control Protocol/Internet Protocol) • Technical background for packet switching • TCP establishes a connection between computers, sequences the transfer of packets, and acknowledge the packet sent • IP is responsible for the delivery of packets and includes the disassembling and reassembling of packets

12. Domain Name System Figure 7-8 The Domain Name System is a hierarchical system with a root domain, top-level domains, second-level domains, and host computers at the third level.

13. How Internet works

14. TCP IP Packet Switching & TCP/IP

15. Broadband network services

16. Wireless Computer Networks • Bluetooth • Wi-Fi and wireless internet access • WiMax

17. Bluetooth • A short-range radio transmission technology, which enables all kinds of devices (notebook, printer, PDA, cellular phone) to communicate automatically and wirelessly

18. Wi-Fi and Wireless Internet Access • Covers small area (within 100 meter radius)  10Mbps connection • Netspot service: Netspot router and wireless network interface card in your notebook

19. WiMax • Worldwide Interoperability for Microwave Access • Provides up to 144 Mbps Downlink & 35 Mbps Uplink internet connectivity • Covers 3.5 ~7 Km radius • Support for static location only

20. Wireless Revolution • Wireless devices • Digital convergence (Cellular phone + PDA + MP3 + GPS + DMB + Internet Browsing)  Smartphone • Cellular phone generation • First generation – analog cellular service • Second generation – digital cellular service • CDMA (Code Division Multiple Access) • Third generation – transmission for video, graphics, and other rich media • WCDMA (Wideband Code Division Multiple Access)

21. First Generation: Analog • Introduced in Korea (1988) • Frequency Division Multiple Access(FDMA)

22. 1G: FDMA (Analog) • User is assigned to a different frequency channel for each call • Limited number of frequency channels • The conversation time for each call is limited to 3 minutes

23. 2G: CDMA(Digital) • Code Division Multiple Access(CDMA) allows several transmitters to send information simultaneously over a single frequency channel • More people can share the limited frequency channels

24. 2G: CDMA • Qualcomm developed in 1989 • In 1996, Korea became the first country to successfully commercialize CDMA • Popularity of Cellular Phone in Korea • Over 40 million subscribers

25. Structure of CDMA • Current location of each cellular phone is recorded in‘Location Register’

26. 3G: WCDMA (WidebandCDMA) • Extends frequency bandwidth from 1.23 Mhz to 3.84 Mhz • 3 times wider bandwidth means that much larger data can be transmitted • Not only voice communication but also video communication

27. Emerging of 4G Technology • 20 times wider bandwidth than CDMA • Data Speeds upto 3.6Gbps • DVD Movie can be transmitted within 15 seconds • Users can simultaneously receive data from 80 different HD TV channels • LTE (Long Term Evolution) • 1Gbps connectivity • Supports seamless connection to existing 3G networks • Covers only metropolitan area