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Mobile Technologies 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University.

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Presentation on theme: "Mobile Technologies 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University."— Presentation transcript:

1 Mobile Technologies Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University

2 Outline Overview How Cell Phones Work. GSM (2G). GPRS (2.5G). 3G and Other Technologies.

3 Overview

4 Mobile Cells

5 BSCBSC BSCBSC MSCMSC ACHLRVLREIR PSTN Mobile station BSCbasic station controller MSCmobile switching center HLRhome location register VLRvisitor location register ACaccess control EIRequipment identity register Mobile Architecture

6 Transmission Techniques Encoding Schemes Analog. Digital. Multiplexing Schemes FDMA. TDMA. CDMA.

7 CDMA Code Division Multiple Access. Good for digital encoding. Frequency hopping style. One band for all users in the cell. Modulate with a unique code for each user. Analogy: several people in a room speaking different languages to each other.

8 CDMA Pros More capacity than FDMA/TDMA. Require low power for Handset (0.2 Watts). Cons Complicated. Expensive (both handset and cell equipment).

9 Multiplexing Schemes

10 Additional Terminologies Mobile Originator. Mobile Terminator. Hand-off. Roaming.

11 Global System for Mobile communication. The dominated mobile standard 400 network operators in 182 countries. Over 700 million customers (June 2002). Considered “2G”. Transmission Techniques Digital encoding. Extended Time Division Multiple Access (ETDMA).

12 ETDMA TDMA with Signal compression. Silence suppression Use time slot when there are speeches. Similar to frequency hopping.

13 Handset Market Share

14 GPRS General Packet Radio Service Packet switching for Mobile Typical call session (voice) is circuit switched. More efficient. IP-enabled. “Always on”, pay as you send/receive. Speed: 14.4Kbps – 115Kbps. Considered “2.5G” – path to 3G. 114 Kbps 2 Mbps 384 Kbps

15 3G Mobile New mobile architecture is coming For multimedia and internet applications. Up to 2 Mbps bandwidth for data. Standards Universal Mobile Telecommunication System (UMTS). Wide-band Code Division Multiple Access (WCDMA).

16 Killer Applications Short Message Service (SMS) – 2G Become increasingly popular User: easy to use. Operator: bandwidth efficient. Currently being used for Communication. Entertainment (download logo / ringtones). Interactive applications. Future Multimedia Message Service (MMS).

17 SMS Architecture

18 SMS Mechanism Mobile Terminated Side

19 SMS Mechanism Mobile Originated Side

20 Mobile Internet Comparing to typical Internet Bandwidth limitation with long latency. Screen size. Simple browser. Wireless Access Protocol For mobile with limited HTML edition – WML.

21 WML The Wireless Markup Language (WML) WMLScript Adhering to XML standards. Do not assume a QWERTY keyboard or a mouse. Designed for small screen displays. WML documents divided into a set of units of interaction, called cards User navigate back and forth between cards. Reduce long latencies. Smaller set of markup tags (comparing to HTML).

22 WML

23 WAP Stack

24 HTTP vs. WSP Overheads

25 Iridium Global Personal Communication Any place, any time. Use Low Orbit Satellites (LEO) 66 LEO with 6 spares. Each covers small areas. Satellites handoff.

26 References J. Kurose and K. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, Addison Wesley, M. Eng and L. Kirchoff, How Cellular Phone Technologies Compare, About.Com, Digital Technologies (CDMA, TDMA, and GSM),


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