Mobile Computing and Wireless Networking CS 851 Seminar 2002 Fall University of Virginia

First Thing to Do ! http://www.cs.virginia.edu/~cs851-2/course.html Everything is in the Web Syllabus, materials, http://www.cs.virginia.edu/~cs851-2/course.html

What Are We Going to Learn? What are the challenges facing Mobile Computing? What are fundamental principles in Mobile Computing What is the state-of-the-art research for Mobile Computing? What are the open problems?

Selected Topics Vision and Challenges Wireless Medium Access Control IEEE 802.11   Mobile Ad Hoc  Routing    Mobile IP   TCP over Wireless Link Energy Efficient  and Power Aware Protocols   Capacity of Wireless Network   Mobile Data Access/Dissemination   Address auto configuration   Location Discovery/Tracking    Multicast in Mobile Ad Hoc Network (option)   Security (option)

How Are We Going to Learn? Select new and representative papers for each topic Each student needs to do two presentations Each presentation will cover one or two papers (begin at Sep 10) Before each lecture, every student needs to hand in a simple summary about the presented papers (begin at Sep 10) Term project performed in small group which consists of two students. (Suggested topics will be provided before Sep. 15)

Challenges of Mobile Computing [1] “Some computer science issues in Ubiquitous Computing” by M. Weiser 1993 [2] “The challenges of Mobile Computing” by G. H. Forman & J. Zahorjan 1994 [3] “On some principles of Nomadic Computing and Multi-Access Communications” by L. Kleinrock 2000 [4] “Pervasive Computing: Vision and Challenges” by M. Satyanarayanan 2001

What is Mobile Computing? Building distributed systems with portable computers and wireless communications to allow mobile users to access services and resources at anytime from anywhere Advances of wireless communication & portable computers make computers users do not need to maintain a fixed position in the network and enables almost unrestricted mobility. However, network resources and application software do not follow mobile users. There are many problems to provide computing and communication capacities to mobile users.

Buzzwords Nomadic Computing, Pervasive Computing Ubiquitous Computing, Mobile Computing, Nomadic Computing, Pervasive Computing Mobile Computing and Nomadic Computing are about building distributed systems with portable computers and wireless communications Mobile Computing: focus on out-door mobility with pedestrian or vehicular speed Nomadic Computing: focus on in-door mobility with pedestrian speed Ubiquitous Computing ==Pervasive Computing (AI + Mobile Computing) creating environments saturated with computing and communication capacity yet gracefully integrated with human users (or enhancing computer use by making many computers available throughout the physical environment, but making them effectively invisible to the users)

Many Applications Military environments Civilian environments soldiers, tanks, planes Civilian environments taxi cab network meeting rooms sports stadiums boats, small aircraft Emergency operations search-and-rescue policing and fire fighting Killer application Anywhere and anytime access to the Internet

Evolution of Computing Freedom from Collocation (space & time) Flexible Resource Usage Single User OS Time Sharing Networked Computing Mobile Computing Pervasive Computing

Three Challenges Wireless communication Mobility Poor local resources due to portability

Wireless Communication Limited transmission range (IEEE 802.11 < 300 meters) Limited bandwidth IEEE 802.11 ~ 2 mbps IEEE 802.11a ~54 mbps IEEE 802.11b ~ 11 mbps IEEE 802.11g ~ 20mbps Frequent disconnections or network partitions Uncertainty of performance Variance of bit error Variance of latency Variance of bandwidth Easier for intruders to insert themselves into networks

Mobility Mobility  Dynamic Environment Network Address migration (network access point varies) High performance variability (error rate, latency, cost, connectivity …) Hardware Lighter More robust Lower power Available resources change Correctness of information changes

Poor local resources due to portability CPU Memory limited battery life time All these challenges are instinct and need innovative and system-wide solutions

Five Areas for Achieved Results Mobile networking Mobile information management Adaptive techniques Power management and energy saving Location sensitivity

Mobile Networking Mobile Ad-Hoc networks Mobile IP Wireless TCP Multiple Access Control Distributed scheduling algorithms Mobile ad-hoc routing Security Mobile IP Wireless TCP I-TCP Snoop TCP

Mobile Data Management Data delivery modes Server push Client pull Hybrid Data organization Data consistency management Disconnected operation Weak connected operation

Adaptive Techniques Exploiting dynamical (networking, physical, users) information to perform effective mobile computing Adaptive resource management Adaptive networking Application-aware adaptations Example: a videoconferencing application can display only the speaker if bandwidth is low, else all participants

Power Management and Energy Saving Topology control of ad-hoc networks using transmit power adjustment Power aware routing protocols Power aware MAC protocols

Location Sensitivity Location-aware applications Discover and take advantage of contextual information such as user location, nearby people and devices, and user activity Ex. What resources (printers, ect.) are available “here”? Where is the “nearest” hospital? How do I get from “here” to the nearby public library Location information systems Indoor location tracking system Outdoor logical location determination system without GPS

Summary Dedicate your time and make contributions Mobile computing Very active and evolving research field Plenty of interesting research problems We will learn a lot in this course Understand the state of the art New ideas and new results New ways of using mobile computing It will be Very Rewarding Dedicate your time and make contributions

Evolution of Computing Freedom from Collocation (space & time) Flexible Resource Usage Single User OS Time Sharing Networked Computing Mobile Computing Pervasive Computing