Chapter 6 Wireless and Mobile Networks

Transcription

1 Chapter 6 Wireless and Mobile Networks A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: v If you use these slides (e.g., in a class) that you mention their source (after all, we d like people to use our book!) v If you post any slides on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 All material copyright J.F Kurose and K.W. Ross, All Rights Reserved Wireless, Mobile Networks 6-1

2 Elements of a cellular wireless network This is the figure your textbook uses. network infrastructure I Like these figures better. "PSTN" means the Public Switched Telephone Network "PDN" means the Public Data Network Wireless, Mobile Networks 6-2

3 Elements of a cellular wireless network Wireless, Mobile Networks 6-3

4 Chapter 6 outline 6.1 Introduction Wireless 6.2 Wireless links, characteristics CDMA 6.3 IEEE wireless LANs ( Wi-Fi ) 6.4 Cellular Internet Access architecture standards (e.g., GSM) Mobility 6.5 Principles: addressing and routing to mobile users 6.6 Mobile IP 6.7 Handling mobility in cellular networks 6.8 Mobility and higher-layer protocols 6.9 Summary Wireless, Mobile Networks 6-4

5 Code Division Multiple Access (CDMA) v unique code assigned to each user; i.e., code set partitioning all users share same frequency, but each user has own chipping sequence (i.e., code) to encode data allows multiple users to coexist and transmit simultaneously with minimal interference (if codes are orthogonal ) v encoded signal = (original data) X (chipping sequence) v decoding: inner-product of encoded signal and chipping sequence Wireless, Mobile Networks 6-5

6 CDMA encode/decode sender data bits code d 0 = 1 d 1 = slot 1 slot 0 Z i,m = d i. cm channel output Z i,m slot 1 channel output slot 0 channel output M received input receiver code slot 1 slot 0 D i = Σ Z i,m. c m m=1 M d 1 = -1 slot 1 channel output d 0 = 1 slot 0 channel output Wireless, Mobile Networks 6-6

7 CDMA: two-sender interference Sender 1 channel sums together transmissions by sender 1 and 2 Sender 2 using same code as sender 1, receiver recovers sender 1 s original data from summed channel data! Wireless, Mobile Networks 6-7

8 Chapter 6 outline 6.1 Introduction Wireless 6.2 Wireless links, characteristics CDMA 6.3 IEEE wireless LANs ( Wi-Fi ) 6.4 Cellular Internet access architecture standards (e.g., GSM) Mobility 6.5 Principles: addressing and routing to mobile users 6.6 Mobile IP 6.7 Handling mobility in cellular networks 6.8 Mobility and higher-layer protocols 6.9 Summary Wireless, Mobile Networks 6-8

9 Components of cellular network architecture cell v covers geographical region v base station (BS) analogous to AP v mobile users attach to network through BS v air-interface: physical and link layer protocol between mobile and BS MSC v connects cells to wired tel. net. v manages call setup (more later!) v handles mobility (more later!) Mobile Switching Center Mobile Switching Center Public telephone network wired network Wireless, Mobile Networks 6-9

10 Cellular networks: the first hop Two techniques for sharing mobile-to-bs radio spectrum v GSM/TDMA: divide each channel into time slots v CDMA: code division multiple access Wireless, Mobile Networks 6-10

11 2G (voice and text) network architecture Base station system (BSS) BTS BSC MSC G Gateway MSC Public telephone network Legend Base transceiver station (BTS) Base station controller (BSC) Mobile Switching Center (MSC) Mobile subscribers Wireless, Mobile Networks 6-11

12 3G (voice+data) network architecture radio network controller MSC G Gateway MSC Public telephone network Key insight: new cellular data network operates in parallel (except at edge) with existing cellular voice network v voice network unchanged in core v data network operates in parallel SGSN G GGSN Public Internet Serving GPRS Support Node (SGSN) Gateway GPRS Support Node (GGSN) Wireless, Mobile Networks 6-12

13 3G (voice+data) network architecture radio network controller MSC G Gateway MSC Public telephone network SGSN G GGSN Public Internet radio interface (WCDMA, HSPA) radio access network Universal Terrestrial Radio Access Network (UTRAN) core network General Packet Radio Service (GPRS) Core Network public Internet Wireless, Mobile Networks 6-13

14 Opensignal.com Wireless, Mobile Networks 6-14