Wireless Networks. Why go wireless? C Don’t have to be tied to a N, furniture or infrastructure Can retrieve email, access the Internet, a corporate database.

Wireless Networks

Why go wireless?• C• Don’t have to be tied to a• N , furniture or infrastructure• Can retrieve email, access the Internet , a corporate

database or other info using a cell phone, laptop computer or handheld computer.

• Lots of wireless zones ( ) have been created– libraries, airports, universities, stores and some entire

cities/towns.

• PCs and laptop computers could access the Internet without relying on physical wiring.– Wireless / Access Point Required– Wireless Required– Uses low-frequency to

communicate.

Wireless Standards• 8 (Wi-Fi, for Wireless Fidelity)• B 802.11

• Allows for faster transmissions and can support connections over longer distances than Bluetooth.– 802.11b standard: Up to 11 megabits per second, 300 feet inside

– 802.11g standard: at a 35 foot indoor range– 802.11n standard: with a better range

Bluetooth• Allows for wireless communications within a limited

distance: per second, up to• Less expensive than Wi-Fi chips, consume less

power, easier to build into small devices than run on batteries such as cell phones, palm-top computers, and other PDAs.

• Called a “personal area network” (PAN) technology.

Wireless Networks• Bluetooth: Personal Area Network (PAN)• 802.11 (Wi-Fi): used in

• Disadvantages of 802.11 wireless LANs– S wired LANs – One person can

point to the detriment of all other wireless users.– Inherently . Software tools are easily

available to capture data packets, and thereby “snoop” on someone’s communications.

– While there are many wireless LANs, your computer must be specially configured in order to connect to a specific wireless LAN.

802.11 standards• 802 : can provide transmission speeds of up to 11

mbps, 300 feet inside, 800 feet outside.

• 802 : can provide transmission speeds of up to mbps, at a 35 foot indoor range.

• Both the “b” and “g” standards use the same radio frequency, or wavelength.– 802 : same transmission speeds as the “g” standard, but it

uses a (not used by other Wi-Fi users, microwave ovens and cordless phones)

• Might be good for use in high density/population areas, such as apartment complexes.

• 802.11n is currently being developed (in use, but not finalized) .– Expected to provide transmission speeds over mbps using MIMO technology

( ): signal intensity will also help increase range.

Walt Mossberg Chief Technology columnist for the WallStreet Journal

Q: I’m wondering about wireless specs for a laptop. I suspect the “n” version of Wi-Fi is best but “g” is adequate. Any advice would be appreciated.

A. It depends on how and where you intend to use your laptop’s wireless connectivity. The “n” version of Wi-Fi can be much faster than “g” and can have much greater range. However, the speed difference won’t matter much if your sole use is connecting to the Internet with a typical home or public hotspot service, since the maximum speed of these services is almost always well below “g” and “n” capabilities. But if you are streaming video at home or backing up large files wirelessly among computers and networked hard disks on a home network, you’d be much better off with “n,” assuming all devices involved support it. The same goes for range. In a small apartment, it likely won’t matter. In a large home, it could.

802.11 wireless standards explainedhttp://compnetworking.about.com/cs/wireless80211/a/aa80211standard.htm

http://info.cba.ksu.edu/bkovar/wireless.htm

Researchers explore scrapping and rebuilding the Internet

• In order to address the problems that were not envisioned when the Internet was initially created, some are suggesting rebuilding the Internet using a approach.

• S– The Internet was designed to be open and flexible

and all users were assumed to be trustworthy. Internet protocols were not designed to authenticate users and their data. Firewalls and spam filters are now being used to control security.

– Solution: data not passed along until

• Mobility– Initially, computers were fixed in location so IP addresses were assigned

to devices in a fixed location. Wireless mobile computing is presenting challenges related to data flow.

– Solution: R so that addresses are based on the device, rather than the location.

• Ubiquity (called in our class notes)– When the Internet was first designed, there were relatively few

computers connected to it. The addressing system has become strained due to the proliferation of personal computers and mobile devices.

– Solution: assign and have those same devices connected to an addressed gateway, which is then connected to routers and the rest of the Internet

• Result is fewer devices to keep track of and improved efficiency.

• These changes may happen over the next 10-15 years. They (expected to cost as computer hardware and software and

Internet infrastructure are replaced)

The End