Mobile /Wireless Communication What can change for Mobility?

1. Mobile /Wireless CommunicationWhat can change for Mobility? Spring 2008 Instructor: Yuhao Wang

2. What is Mobility? • A device that moves • Between different geographical locations • Between different networks • A person who moves • Between different geographical locations • Between different networks • Between different communication devices • Between different applications

3. Topics in Wireless Communication • Wireless Communications • Space-time, OFDM, MIMO • UWB and Impulse Radio • Channel Modeling and Characterization • Modulation/Coding/Signal Processing • B3G Systems, WiMAX and WLAN • Advances in Wireless Video • RFID Technologies • Mobility and Handoff Management

4. Topics in Wireless Communication • Services and Application • Wireless/mobile networked Applications • Multimedia in Wireless Ad-hoc Networks • Authentication, Authorization and Billing • Advances in Wireless Video • Location Based Services (LBS) • Applications and Services for B3G/4G era • Radio Resource Management

5. Topics in Wireless Communication • Networking and Systems • Wireless sensors networking • Security in wireless networks • Network measurement and Management • Ad hoc and sensor networks • Multimedia QoS and traffic Management • Network protocols for Mobile Networks • Internetworking of WLAN & Cellular Networks

6. Device mobility • Plug in laptop at home/work on Ethernet • Occasional long breaks in network access • Wired network access only (connected => well-connected) • Network address changes • Only one type of network interface • May want access to information when no network is available: hoard information locally • Cell phone with access to cellular network • Continuous connectivity • Phone # remains the same (high-level network address) • Network performance may vary from place to place

7. Device mobility, continued • Can we achieve best of both worlds? • Continuous connectivity of wireless access • Performance of better networks when available • Laptop moves between Ethernet and Wireless LAN • Wired and wireless network access • Potentially continuous connectivity, but may be breaks in service • Network address changes • Radically different network performance on different networks

8. People mobility • Phone available at home or at work • Multiple phone numbers to reach me • Breaks in my reachability when I’m not in • Cell phone • Only one number to reach me • Continuously reachable • Sometimes poor quality and expensive connectivity • Cell phone, networked PDA, etc. • Multiple numbers/addresses for best quality connection • Continuous reachability • Best choice of address may depend on sender’s device or message content

9. Mobility means changes How does it affect the following? • Hardware • Lighter • More robust • Lower power • Wireless communication • Can’t tune for stationary access • Network protocols • Name changes • Delay changes • Error rate changes

10. Changes, continued • Fidelity • High fidelity may not be possible • Data consistency • Strong consistency no longer possible • Location/transparency awareness • Transparency not always desirable • Names/addresses • Names of endpoints may change • Security • Lighter-weight algorithms • Endpoint authentication harder • Devices more vulnerable

11. Changes, continued, again • Performance • Network, CPU all constrained • Delay and delay variability • Operating systems • New resources to track and manage: energy • Applications • Name changes • Changes in connectivity • Changes in quality of resources • People • Introduces new complexities, failures, devices

12. Example changes • Addresses • Phone numbers, IP addresses • Network performance • Bandwidth, delay, bit error rates, cost, connectivity • Network interfaces • PPP, eth0, strip • Between applications • Different interfaces over phone & laptop • Within applications • Loss of bandwidth triggers change from B&W to color • Available resources • Files, printers, displays, power, even routing

13. Summing up Generally, mobility stresses all resources further: • CPU • Power • Bandwidth • Delay tolerance • Radio spectrum • Human attention • Physical size • Constraints on peripherals and GUIs (modality of interaction) • Locations (body parts!) for device placement

14. References • T. S. Rappaport, "Wireless Communications: Principles & Practice," 2nd Ed., Prentice-Hall:Upper Saddle River, NJ, 2002, ISBN 0-13-042232-0. • Jon Mark, Weihua Zhuang, "Wireless Communications and Networking," Prentice Hall. ISBN: 0130409057; 2003. • David Tse, Pramod Viswanath, "Fundamentals of Wireless Communications," Cambridge University Press, 2005. • Harri Holma and Antti Toskala (ed.), ``WCDMA for UMTS : radio access for third generation mobile communications,'' Chichester ; New York : Wiley, c2000.  • John G. Proakis, ``Digital communications,'' 4th ed., Boston : McGraw-Hill, c2001. • . D. Parsons, "The Mobile Radio Propagation Channel," 2nd Edition, Wiley, 2000. • G. L. Stueber, ``Principles of mobile communication,'' 2nd Ed., Norwell, MA: Kluwer, 2001. • http://www.wu.ece.ufl.edu/books/EE/wireless/wireless.html