wifi_doc.doc (Size: 76.5 KB / Downloads: 206)
CSIT 4/4 CSIT 4/4
Wi-Fi is quickly gaining in popularity with access points across the United States increasing by approximately 100% in 2003. Wi-Fi refers to a set of wireless networking technologies more specifically referred to as 802.11a 802.11b and 802.11g. These standards are universally in use around the globe, and allow users that have a Wi-Fi capable device, like a laptop or PDA, to connect anywhere there is a Wi-Fi access point that is available. The three standards that are referred to signify the speed of the connection they are capable of producing. 802.11b (which transmits at 11 Megabits per Second) is the most common, although it is quickly getting replaced by the faster Wi-Fi standards. Both 802.11a and 802.11g are capable of 54 MBPS, with 802.11a adding additional capabilities. Across the board, all of these Wi-Fi standards are fast enough to generally allow a broadband connection. Wi-Fi is an emerging technology that will likely be as common as electrical outlets and phone lines within a few years. Wi-Fi adds tremendous levels of convenience and increased productivity for workers whose offices are equipped with Wi-Fi, as well as travelers that can increasingly access Wi-Fi in airports, coffee shops, and hotels around the world.
Definition of Wi-Fi:
Wi-Fi stands for Wireless fidelity - a radio-frequency technology that allows laptop or handheld computer users in the vicinity of a 'hotspot' to access the Web or corporate networks. Wireless fidelity, defined by the Australian Communications Authority (2004:210) as Used generically to refer to WLAN (IEEE 802.11) technology providing short-range, high data rate connections between mobile data devices and access points connected to a wired network. Wireless fidelity; Wireless Ethernet Compatibility Allianceâ„¢s (WECA) brand identity for the IEEE 802.11b standard; WECA certification that ensures productsâ„¢ compatibility. This is another name for IEEE 802.11. It is a term coined by the Wireless Ethernet Compatibility Alliance (WECA). Products certified as Wi-Fi by WECA are interoperable with each other even if they are from different manufacturers. A user with a Wi-Fi product can use any brand of Access Point with any other brand of client hardware that is built to the Wi-Fi standard.
How Does Wi-Fi Work?
The wide use of notebook and other portable computers has driven advances in wireless networks. The most common use for a wireless network is to connect a single notebook computer to a broadband internet connection. Wireless networks use either infrared or radio- frequency transmissions to link these mobile computers to networks. Wi-Fi networks use radio technologies called IEEE 802.11b or 802.11a to provide a secure, fast, and reliable wireless connection. IEEE stands for Institute of Electrical and Electronics Engineers, New York, which is a membership organization that includes engineers, scientists and students in electronics and allied fields.
It has more than 300,000 members and is involved with setting standards for computers and communications. The international standard for wireless networking uses a frequency of 2.4-2.4835GHz. These frequencies are common in microwaves, and cord less phones.
Wi-Fi functions through a transmitting antenna which is usually linked to a DSL or high-speed land-based Internet connection and uses radio waves to beam signals. Another antenna, which is in the laptop or PC, catches the signal. The signal, usually l, has a range of about 300 feet for most home connections. The farther the user is from the signal, the slower the connection speed. Wireless LANS have capacity speeds from less than 1 Mbps to 8 Mbps. Wi-Fi can easily be expanded in the home or business with the simple step of plugging in a card or a USB connection to the new computer or other Wi-Fi certified product. No cords or cables, or wires are necessary.
Wi-Fi is based on the IEEE 802.11 specifications. There are currently four deployed 802.11 variations: 802.11a, 802.11b, 802.11g, and 802.11n. The b specification was used in the first Wi-Fi products. The g and n variants are the ones most often sold as of 2005.
Specification Speed Frequency
11 Mb/s 2.4 GHz b
54 Mb/s 5 GHz a
54 Mb/s 2.4 GHz b, g
100 Mb/s 2.4 GHz b, g, n
In most of the world, the frequencies used by Wi-Fi do not require user licenses from local regulators (eg, the Federal Communications Commission in the US). 802.11a equipment, using a higher frequency, has reduced range, all other things being equal.
Standards of Wi-Fi:
Before you do anything, including buy a single piece of equipment, the first order of business for your home wireless local area network (WLAN) is to determine the type of wireless technology that is most appropriate for your environment. Because each has its own characteristics, strengths, and weaknesses, you'll find some are better suited than others to your particular situation. In the world of WLAN standards there are several you can choose from today, and more on the horizon. While many are similar in the way they operate or the type of equipment they use, there are also key differences that you must be aware of. When comparing the different standards, it's easy to get caught up in a lot of the technical minutiae that differentiate them. When all is said and done though, you'll find three major factors that you need to concern yourself with--cost, speed, and range.
802.11b/2.4GHz vs. 802.11a/5GHz
There are currently two major WLAN standards, and both operate using radio frequency (RF) echnology. The two standards have heretofore been colloquially referred to as 802.11b and 802.11a -- together they're collectively called Wi-Fi .To reduce confusion, however, the wireless standard group called the Wi-Fi Alliance will refer to the two
technologies as 2.4GHz and 5GHz, respectively, as least on product packaging. These monikers refer to the frequency band that each technology utilizes. In the alphabet, "a" comes before "b." In the world of wireless networking though, "b" definitely came before "a." The 802.11b specification was the first to be finalized and reach the marketplace.
802.11b/2.4GHz devices operate in an unlicensed radio band and transmit data on the same frequency as some household appliances, including some cordless phones and even microwave ovens. The 802.11b specification provides for a bandwidth rating of 11 Megabits per second (Mbps). This is just a theoretical maximum, however. Wireless networks, as well as wired LANs, never let you obtain that level of performance, or even close to it. The actual throughput you can expect to obtain from an 802.11b network will typically be between 4 and This level of performance is more than sufficient for most rudimentary computing tasks. When you consider that a typical broadband DSL or cable modem connection might provide you with from 600kbps to 1.6Mbps of downstream bandwidth, you can see that the speed of 802.11b is not be an impediment to activities like Web browsing, e-mail, file transfer, running applications, and even streaming Internet-based audio and video.
On the other hand, it's not hard to envision scenarios where your bandwidth needs might be greater -- when you want to quickly transfer very large files like graphics, audio, or video or stream those same audio and video files, like your collection of MP3s or home movies on your hard disk.
If you often see the need for more speed, consider 802.11a. Products based on this 5GHz specification offer higher performance. 802.11a has a maximum bandwidth of 54Mbps, almost five times that of 802.11b. Like its predecessor though, you won't see anything near that in the real world. Instead, expect a maximum throughput of between 20 and 25Mbps -- still five times what you get from 802.11b.
Designing a Wi-Fi Network:
Setting Up A Wireless Network:
Once you've decided to free yourself by "going wireless," you can reap all the benefits of mobile computing â€ and it's simple and easy to set up and operate a wireless network. Here's how to plan for, install and operate your Wi-Fi network
Â¢ What Makes Up a Wireless Network?
Â¢ Do I Need a Peer-To-Peer Network, or One with a Base Station (An Access Point Or Gateway)?
Â¢ What Are the Wi-Fi Radio Options For My Laptops, Desktops and PDAs?
Â¢ Planning for Access Points and Gateways
Â¢ How Many Users Can Use a Single Access Point?
Â¢ Choosing Components for Your Network
Â¢ Count The Total Number of Users and Computers
Â¢ Place a Wi-Fi Radio In Each Computer
Â¢ Determine the Number Of Base Stations (Access Points or Gateways) You Need
Â¢ How Do You Connect Your Wi-Fi Network to the Internet?
Â¢ How Do You Make Printers Work on Your Wi-Fi Network?
Â¢ Can You Share Devices on Your Network to Save Money?
Types of Equipment
There are currently two types of Wi-Fi components you'll need to build your home or office network: Wi-Fi radio (also known as client devices) devices (desktops, laptops, PDAs, etc.), and access points or gateways that act as base stations. A third type, Wi-Fi equipped peripherals, are emerging and will soon be commonplace. This group includes printers, scanners, cameras, video monitors, set-top boxes and other peripheral equipment
Â¢ PC Card Radio
Â¢ Mini-PCI Modules and Embedded Radios
Â¢ USB Adapters
Â¢ PCI and ISA Bus Adapters
Â¢ Compact Flash and Other Small-Client Formats
Step 3 â€ Set Up
10 Easy Steps to Setting Up Your Home or Small Office Network
Wi-Fi networks are easy to set up and operate but if you've never done this before the process may seem daunting and most likely you don't know where to start. Use this step-by-step guide to help you through the process of planning and setting up your wireless network
1. Count Your Computers
2. Pick out the Right Kind of Wi-Fi Radios for Your Computers
3. Decide Between a Wi-Fi Gateway or Access Point
4. Get the Right Wi-Fi Radio and Accessories
5. Read the Installation Instructions
6. Read the Instructions Again
7. Install Your Access Point or Gateway First
8. Install the First Wi-Fi Radio Device
9. Configure the Access Point
10. Connect the Rest of Your Computers and the Printer
Step 4â€Adding Wi-Fi to a Desktop Computer
The procedures necessary to complete these steps are often different for each manufacturer. Whenever you see this image, you should look in your specific product manual for the correct procedure to follow.
Â¢ USB Radio Installation
Â¢ PCI Adapter Installation
Â¢ Is a USB or a PCI Solution Better For You?
You can easily add Wi-Fi to a laptop computer, but some desktop computers can take a little more effort. For most laptops, you simply slide in a Type II PC Card Wi-Fi radio, install the software, and you're up and running. Since very few desktop computers provide PC Card slots, they require a USB [Universal Serial Bus] Wi-Fi radio adapter or a PCI-based [Peripheral Component Interconnect] Wi-Fi radio adapter to connect to a Wi-Fi network
Securing your Wi-Fi Network
Here are a few simple steps you can take to maximize the security of your wireless network and to protect your data from prying eyes and ears. This section is intended for the home, home office and small office user. The procedures necessary to complete these steps are often different for each manufacturer. Whenever you see this image, you should look in the encryption or security section of your specific product manual for the correct procedure to follow.
Â¢ Deploy WPAâ€žÂ¢ (Wi-Fi Protected Accessâ€žÂ¢) or WPA2â€žÂ¢
Â¢ Change Your Default Password
Â¢ Close Your Network (If Possible)
Â¢ Change Your Network Name
Â¢ Move Your Access Point
Â¢ Use MAC Control Tables
Â¢ Other Simple Solutions
Â¢ Use a VPN (Virtual Private Network)
Â¢ Additional Information
Because chances are that, within the next year or so, you'll use Wi-Fi regularly at work, at home, or on the road. You may well depend on Wi-Fi as much as you do your cell phone, your laptop computer, or your personal digital assistant (PDA). In fact, all those devices increasingly come ready to work with Wi-Fi. (One example: By 2007, according to IDC Research of Framingham, Mass., 98% of all new notebok PCs will be sold with Wi-Fi capability). That means the next time you invest in hardware, you're likely to invest in the Wi-Fi label as well. So it makes sense to learn what Wi-Fi does well -- and where it still needs work.
Wi-Fi refers to products certified to work with the high-tech industry's global standard for high-speed wireless networking .Hardware carrying the Wi-Fi logo has passed rigorous testing by the Wi-Fi Alliance, a trade association based in Mountain View, Calif. Certification means that, regardless of which company manufactured it, the equipment should play nicely with other Wi-Fi devices and networks.
As Wi-Fi compatibility grows -- to date, the alliance has certified nearly 865 products -- so has its popularity. Currently, about 4.7 million Americans regularly use Wi-Fi, according to Stamford, Conn.-based research group Gartner Inc. In four years, that figure will grow to 31 million users in the United States alone.
Why is Wi-Fi so widespread:
It's fast. Wi-Fi's latest version is many times faster than DSL or cable connections, and literally hundreds of times faster than those old dial-up connections. That's particularly handy when you're working on the run, on the road, or from home: If you've ever watched seconds tick by while watching Web pages load, you'll appreciate the potential productivity gain.
It's convenient. As soon as a Wi-Fi-equipped device is within range of a base station, it's online. With no wires, you can move your laptop computer from place to place -- for instance, from your office to a conference room down the hall -- without losing your network connection. (For an online calculator that can help determine ROI on an in-house wireless network," Resources."). When traveling, you can set up shop anyplace equipped with a Wi-Fi network: another company's office, a hotel room, or a convention center.
It's everywhere. Public Wi-Fi access sites -- or "hot spots" -- are multiplying faster than rabbits on Viagra. They're in bookstores, airport lounges, fast-food restaurants (including some McDonald's and Schlotzky's Deli outlets), and coffee shops (including many Starbucks outlets). In addition, local merchants from Cincinnati to Athens, Ga., to Portland, Ore., are footing the bill for bigger hot spots, accessible throughout a business district or neighborhood.
Some companies charge for hot-spot use; others offer free access. All hope they're creating environments where tech-savvy customers will linger -- and, presumably -- spend more money on coffee, books, sandwiches, or whatever the hot-spot host sells. Does the idea pay off? Overall, it's too early to tell. Ultimately, the answer will affect how fast the public hot-spot market heats up. In June 2003, IDC, the Framingham, Mass.-based research company, estimated that the number of commercial Wi-Fi sites would grow 57% annually over the next five years -- but warned that the market is young, volatile, and based on unproven business models. In other words, if hot spots don't generate revenue, expect that growth rate to stall.
For all its wonders, the Wi-Fi world comes with some drawbacks. Among them:
Range: Although you lose the wires, you're still limited to the base station's range, typically 75 to 150 feet indoors and a few hundred feet outdoors, depending on equipment, radio frequency, and obstructions.
Power drain: Networks using early versions of Wi-Fi technology tend to quickly gobble power -- a disadvantage for battery-dependent laptop users.
Interference: Nearby microwave ovens and cordless phones, particularly older models, can slow down Wi-Fi transmissions.
Security: Here's the downside of providing fast, easy access: outsiders can sometimes get into your wireless networks as fast and easily as you can. Check with hardware vendors about the latest security precautions and products. The Wi-Fi Alliance currently recommends using Wi-Fi Protected Access (WPA) technology, which both authenticates users and encrypts data. Look for even tougher security measures within the next year.
Advantages of Wi-Fi:
Â¢ Unlike packet radio systems, Wi-Fi uses unlicensed radio spectrum and does not require regulatory approval for individual deployers.
Â¢ Allows LANs to be deployed without cabling, potentially reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.
Â¢ Wi-Fi products are widely available in the market. Different brands of access points and client network interfaces are interoperable at a basic level of service.
Â¢ Competition amongst vendors has lowered prices considerably since their inception.
Â¢ Many Wi-Fi networks support roaming, in which a mobile client station such as a laptop computer can move from one access point to another as the user moves around a building or area.
Â¢ Many access points and network interfaces support various degrees of encryption to protect traffic from interception.
Â¢ Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi client works in different countries around the world.
Disavantages of Wi-Fi:
Â¢ Use of the 2.4 GHz Wi-Fi band does not require a license in most of the world provided that one stays below the local regulatory limits and provided one accepts interference from other sources, including interference which causes your devices to no longer function. It is sometimes claimed that Amateur Radio operators have permission to boost the power on their Wi-Fi transmitters up to the legal maximum for their Amateur Radio license class under some conditions; this is not permitted in the US, nor in most locations.
Â¢ Legislation/regulation is not consistent worldwide; most of Europe allows for an additional 2 channels over those allowed for b and g; Japan has one more on top of that - and some countries, like Spain, prohibit use of the lower-numbered channels. Furthermore some countries, such as Italy, used to require a 'general authorization' for any WiFi used outside the owned premises; or required something akin to operator registration.
Â¢ The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum, which is crowded with other equipment such as Bluetooth devices, microwave ovens, cordless phones (900 MHz or 5.8 GHz are, therefore, alternative phone frequencies one can use to avoid interference if one has a Wi-Fi network), or video sender devices, among many others. This may cause a degradation in performance. Other devices which use these microwave frequencies can also cause degradation in performance.
Â¢ Closed access points can interfere with properly configured open access points on the same frequency, preventing use of open access points by others.
Â¢ Power consumption is fairly high compared to other standards, making battery life and heat a concern.
WiFi equipment could be used to steal personal information (passwords, financial information, identity information, and so on) transmitted from Wi-Fi users, if sensible protections are not used.
The first and most commonly used wireless encryption standard, Wired Equivalent Privacy or WEP, has been shown to be easily breakable even when correctly configured. Most wireless products now on the market support the Wi-Fi Protected Access(WPA) encryption protocol, which is considered much stronger, though some older access points have to be replaced to support it. The adoption of the 802.11i standard (marketed as WPA2) makes available a rather better security scheme â€ when properly configured