Mobile And Wireless Computing

Dr. Michael KatchabawThe University of Western

OntarioDepartment of Computer

Science

Outline

• Introduction• Motivating Factors• Mobile and Wireless Technology• Problems and Issues• Wireless at Western• Concluding Remarks

Introduction

• Wireless communication systemshave existed for over 100 years now.– It all began with Marconi’s wireless

telegraph in 1896.– In modern times, it has grown to

include satellite, cellular, and a variety of wireless local area networking (LAN) technologies.

Introduction

• Growth in the past 10 years inparticular has been phenomenal.– In cellular networks alone, subscribers

have increased from 34 million in 1993to more than 1 billion in 2003.

– There are now more subscribers to cellular networks than to wired telephone networks!

Introduction

• Wireless LAN adoption has beenstaggering as well.– It is estimated there are now 100,000

wireless hot spots with public accessin the U.S. alone, and rapidly growing.

– Not to mention all of the private home, corporate, and institutional networks!

Introduction

• Why is there such a push towardswireless and mobile technologies?

• What are the different wirelessand mobile technologies?

• What problems/issues are there?• We will answer all of these

questions very shortly!

Motivating Factors

• Wireless users are free to be relatively mobile.– Wireless service basically allows

anywhere, anytime computing andcommunications, which is a veryattractive feature to some.

Motivating Factors

• Wireless users are able to joinand leave wireless networksrelatively easily.– There is no physical point of

connection or cabling required,which makes this attractive forpublic network access.

Motivating Factors

• Wireless service can be deployedalmost anywhere in the world.– Wired service can be quite difficult

to roll out in some parts of the world,if not impossible.

– Wireless service depends on less physical infrastructure, and can target remote areas.

Motivating Factors

• Wireless service can be deployedmore quickly and cheaply thanwired service in most cases.– No cabling or other physical

infrastructure required with wireless.– All you need is a wireless

interface, and you can be on the network in no time.

Mobile and Wireless Technology

• There are a wide variety of mobileand wireless technologies usedin the world today.

• In the end, there are two main types of wireless networks.

Mobile and Wireless Technology

• Satellite-based networks:– A satellite-based antennae in a stable

orbit above the Earth relays communications between two or more stations on or near the Earth.

– Common types include low earthorbit, medium earth orbit, andgeostationary configurations.

Mobile and Wireless Technology

• Satellite-based networks:– Huge coverage areas.– Very high data rates possible.– Can have enormous deployment costs.– Delays in signal propagation due to

the distance it must travel.– Quality of transmission decent.

Mobile and Wireless Technology

• Terrestrial networks:– All network devices and users are

located on Earth.– There tend to be two main kinds of

terrestrial wireless networks: widearea networks (cellular networks)and local area networks (802.11, Bluetooth, and so on).

Mobile and Wireless Technology

• Terrestrial networks:– Coverage areas relatively small.– Data rates vary with the technology.– Deployment costs vary, but usually

much cheaper than satellite networks.– Propagation delays negligible.– Interference can be common.

Mobile and Wireless Technology

• Wireless wide area networks:– Mobile users communicate through

a base station managed by a service provider and within tens of kilometers.

– Global access is provided through the wireless network, usually as an add-on service provided by the telecommunications provider.

Mobile and Wireless Technology

• Wireless wide area networks:– 1G: Analog, for voice only. (FDMA)– 2G: Digital, voice. (TDMA, GSM, CDMA)– 2.5G: Digital, data service built on

existing 2G services. (GPRS, EDGE)– 3G: Digital, higher speed data

and voice (UMTS, CDMA-2000)– 4G: Next generation?

Mobile and Wireless Technology

• Wireless local area networks:– Mobile users communicate directly

with each other (ad hoc mode) or indirectly through an access point within a few tens of metres.

– Global access is provided by a wired connection from theaccess point.

Mobile and Wireless Technology

• Wireless local area networks:– IEEE 802.11 standards (802.11a,

802.11b, 802.11g, etc.) for true wireless local area network access.

– Bluetooth for lower power, shorterrange personal area network access (in other words, it is a desktop cable replacement).

Problems and Issues

• Wireless networks may be cheaperto deploy in some cases, but theycan also incur usage fees.– Cellular service is still NOT cheap!

Problems and Issues

• Wireless networks tend to havemore security problems.– Most people and organizations do not

secure their private wireless networks!– Many wireless security protocols

(WEP) are seriously flawed,even if they were used.

Problems and Issues

• Wireless networks do not supportthe same high speed data rates aswired networks with the samereliability and robustness.– Wireless broadband is not here (yet).– Problems of interference, signal

strength, and multipath issues.

Problems and Issues

• Too many incompatible standards.– Technology is moving forward. (Great!)– Each new technology is incompatible

with previous technologies, and witheach other. (Bad!)

– Older technologies going obsolete really fast. (Very bad!)

Problems and Issues

• Mobile devices often have software and hardware limitations.– Screens too small. (If they get too

big, they’re not mobile!)– Slower processors, less memory,

and so on.– We can’t always do everything

we want to with them.

Wireless at Western

• The University of Western Ontariowas one of the first universities inCanada to roll out wireless access.– Available to all students, faculty, and

staff in many areas of campus.– Provides wireless LAN access

using the 802.11b standard.

Wireless at Western

• Many interesting issues in this:– The large number of potential users

of the network (30,000+).– The extremely large area to cover.– Potentially sensitive areas where

radio signals must be blocked.– Lots of sources of interference

and signal blocking.

Wireless at Western

• Security has also been an issue:– The overly simplistic WEP method was

of little use in this setting.– Account names and passwords were

used to restrict access initially, without any encryption in place.

– An encrypted service is now being rolled out (802.11x).

Wireless at Western

• Wireless technology is used in a fewcourses in Western’s Department of Computer Science.– Advanced topics in networking

develops software for mobile phones.– Video games development builds

games for Java enabled mobilephones and game systems.

Wireless at Western

• Western Computer Science also has many research projects in mobile and wireless computing.– Performance and benchmarking

of mobile and wireless devices.– Pervasive computing.– Development of wireless

communications protocols.

Concluding Remarks

• Wireless and mobile technologieswill continue to revolutionizecomputing and communication.

• Since these technologies are stillrelatively immature, there will bechallenges for some time to come.

• The future will be quite interesting!