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Mobile And Wireless Computing Dr. Michael Katchabaw The University of Western Ontario Department of Computer Science.

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Presentation on theme: "Mobile And Wireless Computing Dr. Michael Katchabaw The University of Western Ontario Department of Computer Science."— Presentation transcript:

1 Mobile And Wireless Computing Dr. Michael Katchabaw The University of Western Ontario Department of Computer Science

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

3 Introduction Wireless communication systems have existed for over 100 years now. –It all began with Marconis wireless telegraph in –In modern times, it has grown to include satellite, cellular, and a variety of wireless local area networking (LAN) technologies.

4 Introduction Growth in the past 10 years in particular has been phenomenal. –In cellular networks alone, subscribers have increased from 34 million in 1993 to more than 1 billion in –There are now more subscribers to cellular networks than to wired telephone networks!

5 Introduction Wireless LAN adoption has been staggering as well. –It is estimated there are now 100,000 wireless hot spots with public access in the U.S. alone, and rapidly growing. –Not to mention all of the private home, corporate, and institutional networks!

6 Introduction Why is there such a push towards wireless and mobile technologies? What are the different wireless and mobile technologies? What problems/issues are there? We will answer all of these questions very shortly!

7 Motivating Factors Wireless users are free to be relatively mobile. –Wireless service basically allows anywhere, anytime computing and communications, which is a very attractive feature to some.

8 Motivating Factors Wireless users are able to join and leave wireless networks relatively easily. –There is no physical point of connection or cabling required, which makes this attractive for public network access.

9 Motivating Factors Wireless service can be deployed almost 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.

10 Motivating Factors Wireless service can be deployed more quickly and cheaply than wired 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.

11 Mobile and Wireless Technology There are a wide variety of mobile and wireless technologies used in the world today. In the end, there are two main types of wireless networks.

12 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 earth orbit, medium earth orbit, and geostationary configurations.

13 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.

14 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: wide area networks (cellular networks) and local area networks (802.11, Bluetooth, and so on).

15 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.

16 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.

17 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?

18 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 the access point.

19 Mobile and Wireless Technology Wireless local area networks: –IEEE standards (802.11a, b, g, etc.) for true wireless local area network access. –Bluetooth for lower power, shorter range personal area network access (in other words, it is a desktop cable replacement).

20 Problems and Issues Wireless networks may be cheaper to deploy in some cases, but they can also incur usage fees. –Cellular service is still NOT cheap!

21 Problems and Issues Wireless networks tend to have more 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.

22 Problems and Issues Wireless networks do not support the same high speed data rates as wired networks with the same reliability and robustness. –Wireless broadband is not here (yet). –Problems of interference, signal strength, and multipath issues.

23 Problems and Issues Too many incompatible standards. –Technology is moving forward. (Great!) –Each new technology is incompatible with previous technologies, and with each other. (Bad!) –Older technologies going obsolete really fast. (Very bad!)

24 Problems and Issues Mobile devices often have software and hardware limitations. –Screens too small. (If they get too big, theyre not mobile!) –Slower processors, less memory, and so on. –We cant always do everything we want to with them.

25 Wireless at Western The University of Western Ontario was one of the first universities in Canada to roll out wireless access. –Available to all students, faculty, and staff in many areas of campus. –Provides wireless LAN access using the b standard.

26 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.

27 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).

28 Wireless at Western Wireless technology is used in a few courses in Westerns Department of Computer Science. –Advanced topics in networking develops software for mobile phones. –Video games development builds games for Java enabled mobile phones and game systems.

29 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.

30 Concluding Remarks Wireless and mobile technologies will continue to revolutionize computing and communication. Since these technologies are still relatively immature, there will be challenges for some time to come. The future will be quite interesting!


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