Mobile Computing A Brief Report

Shakir Ali MohammedDept. of Computer Science

University at Albany.

Mobile Computing Introduction Market of Mobile and Wireless

Communication Difference between Mobile and traditional

Computing. Network Architecture for Mobile Computing Applications and Products Challenges in Mobile Computing Some Useful Resources. Conclusion.

Introduction Ubiquitous Computing i.e. Anywhere Anytime Computing Mobile Computing is Portable Computers + Wireless n/w Portable Computers + modem +

Telephone Network Workstation + Wired n/w +mobile users

Computers Everywhere

Vision of ubiquitous computing: hundreds of computers per person, various sizes and capabilities

Marc Weiser: Scientific American article: “The Computer for the 21st Century”

Some Recent Outlook Numbers(Mid 2000)

By the year 2004, Revenue from wireless data will reach $33.5 Billion Globally ( Source Strategies Group)

By the Year 2010, there will one billion wireless subscribes worldwide on 3G Networks. ( Source Strategies Group)

What does Mobile Computing Offer?

Untethered and/or tiny computers yield:–A choice of work environments

•In your garden (but watch out for birds!)•Coffee shops•In the field

–Remote access to important data•Client’s office (no: "can I borrow your computer")•Meetings (e.g., quick access to statistics, reports)•In the grocery store!

Offerings Contd.–Electronic note-taking–While touring a new city

•Where am I? What is this building? How do I get to Lane Avenue? I’m hungry!

–Diversion•E-books: stored, downloadable•Games: e.g., chess, solitaire, poker

–Ubiquitous communication•email, Web•voice•video

Mobile Devices

A variety of computing and communication devices for mobile users

–Watch-sized devices (and usually a watch!)–PDA (Personal Digital Assistants)–Multifunction cellular phones–Palm-sized computers–Wearable computers–Notebook computers

Characteristics of Mobile Devices

Resource-poor compared to their desktop counterparts–Limited processing power–Limited battery life–Limited network connectivity–Poor availability…they sleep a lot!–Poor display resolution (except notebooks)–Tedious data input (except notebooks

Characteristics Contd.

Limitations are a result of tradeoffs between portability and horsepower:

–Very small size limits traditional I/O methods•New ones: handwriting recognition, voice input•Must work well or extreme frustration...

Notebook computers fare better in the comparison with desktops because they ride the edge

–Reasonable screen size–Decent keyboards–Mouse substitutes–Ample memory

Mobile System Architecture Mobile Computing System consists of

Static Host and Mobile Host. Static Host have fixed geographical

locations. Mobile host can move and have a Unique Network Address

Some Static Host with required infrastructure are designated as Mobile Support Service MSS

Mobile System Architecture Communication among the MSS is

done using Backbone Network Communication between MSS and

MH in its cell is done over wireless medium.

Each MH has a Home agent (MSS) which maintains information such as current location, services subscribed, etc.

Mobile System Architecture Each MSS is incharge of a Cell, Picocells (about

100m in diameter), macrocells, or global cells - A Handoff is involved when a MH crosses cell

boundaryHANDOFF:MSS Broadcasts MSS specific information, MH keeps

track of this information and checks with the information previously stored, if the MH changes the cell, this information received from MSS is different from stored, thus MH knows about the change of MSS, and thus a Handoff is said to be taken place.

Network Architecture for Heterogeneous Mobile computing

A Paper presented by Eric A. Brewer, Radny H. Katz summuarizes the resu;ts of BARWAN Project which focused on enabling truly useful mobile networks and mobile devices.

Overlay Networks as discussed in this paper shows that lower levels are comprised of high bandwidth wireless cells that cover a relatively small area, Higher levels in the hierarchy provide a lower bandwidth per unit area connection over a large geographic area.

Vertical Handoff There is difference between Upward

and downward Vertical Handoffs. Upward vertical Handoff is a handoff

to an overlay with a larger cell size and lower bandwidth/area.

Downward vertical Handoff is a handoff to an overlay with smaller cell size and higher bandwidth/area.

Wireless Application Protocol WAP and wireless markup language WML WAP allows mobile phones and other

mobile devices to connect to the internet WAP and WML are extension to HTTP and

HTML specially designed for the wireless technologies.

Unlike pages in HTML WML has Cards, files in WML are called as Decks

WML script is similar to Java script which can be used to validate User, send messages etc.

<?xml version="1.0"?>

<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML1.1//EN"     "http://www.wapforum.org/DTD/wml_1.1.xml">

<wml>

  <card id="Hello" title="Hello">  

   <p> Hello from WML! </p>

  </card>

</wml>

Wml

Applications Various Business Applications like for mobile

computing both horizontla applications that are used by workers and professionals across the industries as well as specific to bussiness process in a vertical industry.

Horizontal applications Internet messaging, Paging etc, Database Inquiry, File Transfer, Sales Force Automation.

Applications Contd. Vertical Applications Airline and Railway Industries, Construction Industry, Distribution Industry, Electronic News Communication, Financial Industry.

Mobile Computing Challenges

Challenges in mobile computing directly related to the resource-poor nature of the devices…Mobile computing isn’t a simple extension of distributed computing

–Power-poor–Hostile environment–Poor (or no) network bandwidth–Higher error rates–Frequent disconnection

–Variable latency–Mobility

Challenges contd. Result: Must rethink many issues; can’t just

“plug in” classic distributed systems theory Adaptability to deal with varying conditions

Transcoding proxies--scale content (e.g., images) to match available bandwidth

Mobile proxies to convert content (e.g., Postscript ASCII)

More clever ways of checking for data consistency

Application callbacks to monitor conditions (network, battery power, etc.)

Challenges Contd.Prevalent network protocols require work…or workarounds… to give good performance for wireless

–Schemes for mobility

–TCP hacksSchemes for intelligent handoff between network interfaces

–Tradeoffs between cost, bandwidth, availability

References and Resources www.mobileinfo.com Mobile computing : An Introduction

Sandeep Gupta Dept of Comp Science Colorado State University, Co.

A Network Architecture for Heterogeneous Mobile computing, Eric A. Brewer, Randy H. Katz,

Mobile Computing : Prof. olden G. Richard III, University of New Orleans.

Conclusion Mobile computing is the computing of 21 century

Vision of ubiquitous computing: Hundreds of computers per person, various sizes and capabilities

Prevalent Network Protocols require work to improve performance

Schemes for intelligent Handoffs required

Development of Applications are done keeping in mind the limited resources of mobile devices.