This is default featured post 1 title

Go to Blogger edit html and find these sentences.Now replace these sentences with your own descriptions.

This is default featured post 2 title

Go to Blogger edit html and find these sentences.Now replace these sentences with your own descriptions.

This is default featured post 3 title

Go to Blogger edit html and find these sentences.Now replace these sentences with your own descriptions.

This is default featured post 4 title

Go to Blogger edit html and find these sentences.Now replace these sentences with your own descriptions.

This is default featured post 5 title

Go to Blogger edit html and find these sentences.Now replace these sentences with your own descriptions.

TRANSMISSION TECHNOLOGY FOR WI-FI


There are two technologies for transmission.
1>    Narrowband Technology
2>    Spread Spectrum Technology

1)    Narrowband Technology

A narrowband radio system transmits and receives user information on a specific radio frequency. Narrowband radio keeps the radio signal frequency as narrow as possible just to pass the information. Undesirable cross talk between communications channels is avoided by carefully coordinating different users on different channel frequencies.

A private telephone line is much like a radio frequency. When each home in a neighborhood has its own private telephone line, people in one home can not listen to calls made to other homes. In a radio system, privacy and noninterference are accomplished by the use of separate radio frequencies. The radio receiver filters out all radio signals except the ones on its designated frequency.

From a customer standpoint, one drawback of narrow band technology is that the end-user must obtain an FCC license for each site where it is employed.

2)  Spread Spectrum Technology


Most wireless LAN systems use spread spectrum technology, a wideband radio frequency technique developed by the military for use in reliable, secure, mission critical communications systems. 

Spread spectrum is designed to trade off bandwidth is consumed than in the case of narrowband transmission, but the tradeoff produces a signal that is, in effect, louder and thus easier to detect, provided that the receiver knows the parameters of the spread spectrum signal being broad cast. 

If a receiver is not tuned to the right frequency, a spread spectrum signal looks like background noise. Spread spectrum simply means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range. 
 
There are further 2 types of this technology.

1>    Frequency Hopping Spread Spectrum Technology
2>      Direct Sequence Spread Spectrum Technology


THE FUTURE OF WI-FI


Intel put aside $150 million of this fund to invest in Wi-Fi initiatives. Intel expects to introduce its Banias processors for mobile devices during the first half of 2004, said a company spokes woman. Banias is a low power processor designed specifically for mobile devices that includes integrated 802.11a and 802.11b wireless capabilities.

Cometa aims to roll out a nationwide Wi-Fi network and sell exclusively through the channel, said Lawrence Brilliant, CEO of Cometa, in a recent interview with CRN.

Looking to Wi-Fi rather than 3G , BT (British Telco) has installed some 80 Wi-Fi hotspots, called ‘Openzone’ in Hilton hotels, airports and motorway service stations across the UK, and has agreements to put in place another 40.

BT believes that Wi-Fi  which is expected to be half the price of 3G and three times faster is will be the fastest growing mobile technology. 

The Hilton hotel group, which was one of the first business to trial BT open zone, has allowed the installation of wi-fi hotspots in 36 of their hotels across England, Scotland and Wales. Hilton has agreed to install 15 more hotspots at further hotels in the near feature.

The company hopes to have 400 hotspots by summer this year and 4000 by June 2005. In the future it is expected that BT’s wi-fi hotspots will also reach railway stations.

APPLICATION AREAS OF WI-FI


Wireless networking is applicable to all industries with a need for mobile computer usage or when the installation of physical media is not feasible. Such networking is especially useful when employees must process information on the spot directly in front of customers, via electronic based forms and interactive menus. Wireless networking makes it possible to place portable computers in the hands of mobile front line workers such as doctors, nurses, warehouse clerks, inspectors, claims adjusters, real estate agents, and insurance sales people.

Installation In Difficult to wire Areas

The implementation of Wi-Fi networks offers many tangible cost savings when performing installations in difficult to wire areas. If rivers, freeways, or the other obstacles separate building you want to connect, a Wi-Fi solution may be much more economical than installing physical cable or leasing communication circuits, such as T1 service or 56Kbps lines. Some organizations spend thousands or even millions of dollars to install physical links with near by facilities. If you are facing this type of installation, consider wireless networking as an alternative. The deployment of wireless networking in these situations costs thousands of dollars, but will result in a definite cost savings in the long run.
A Wi-Fi solution in an Historic Building
An observatory in Australia has provided stargazing to astronomy enthusiasts for nearly 140 years. Built in 1858 the observatory is classified by the National Trust as one of Australia’s historical buildings.
When the observatory began investigating ways to share these views of space with a much broader audience, the obvious solution was to download images to multiple PCs and large screens via a local area network. Due to the historical nature of the building however cabling was not an option. Very thick sandstone walls and historic plaster ceilings could not be easily drilled into and strings of cable would have been unsightly and unsafe to the public.
The observatory installed Lucent Wi-Fi radio cards in each of their eight PCs and the network server. Telescopic images are downloaded from the Internet or from electronic cameras housed in the observatory’s telescopes. These images are then displayed on the various PCs for individual viewing or on larger monitors for group viewing.

Retail

Retail organization need to order, price, sell and keep inventories of merchandise. A wireless network in a retail environment enables clerks and storeroom personnel to perform their functions directly from the sales floor. Sales people are equipped with a pen based computer or a small computing device with bar code reading and printing capability, with the wireless link to the store’s database. They are then able to complete transactions such as pricing, bin labeling, placing special orders, and taking inventory from anywhere within the store.

Warehouse

Warehouse staff must manage the receiving, putting away, inventory and picking and shipping of goods. These responsibilities require the staff to be mobile. Warehouse operations have traditionally been a paper intensive and time consuming environment. An organization can eliminate paper, reduce errors, and decrease the time necessary to move items in and out, however, by giving each warehouse employee a handheld computing device with a bar code scanner interfaced via a wireless network to a warehouse inventory system.Upon receiving an item for storage within the warehouse, a clerk can scan the item’s bar coded item number and enter other information from a small keypad into the database via the handheld device. The system can respond with a location by printing a put away label. A forklift operator can then move the item to a storage place and account for the procedure by scanning the item’s bar code. The inventory system keeps track of all transactions, making it very easy to produce accurate inventory reports.
As shipping orders enter the warehouse, the inventory system produces a list of the items and their locations. A clerk can view this list from the database via a handheld device and locate the items needed to assemble a shipment. As the clerk removes the items from the storage bins, the database can be updated via handheld device. All these functions depend heavily on wireless networks to maintain real time access to data stored in a central database.

Healthcare

Healthcare centers such as hospitals and doctor’s offices, must maintain accurate records to ensure effective patient care. A simple mistake can cost someone’s life. As a result, doctors and nurses must carefully record test results, physical data, pharmaceutical orders, and surgical procedures. This paperwork often overwhelms healthcare staff, taking 50 to 70 percent of their time.
Doctors and nurses are also extremely mobile, going from room to room caring for patients. The use of electronic patient records, with the ability to input, view, and update patient data from anywhere in the hospital, increase the accuracy and speed of healthcare. This improvement is possible by providing each nurse and doctor with a wireless pen base computer, coupled with a wireless network to databases that store critical medical information about the patients.
A doctor carrying for someone in the hospital, for example can place an order for a blood test by keying the request into a handheld computer. The laboratory will receive the order electronically and dispatch lab technician to draw blood from the patient. The laboratory will run the tests requested by the doctor and enter the result into the patient’s electronic medical records. The doctor can then check the results via the handheld appliance from anywhere in the hospital.
Another application for wireless networks in hospitals is the tracking of pharmaceuticals. The use of mobile handheld barcode printing and scanning devices dramatically increases the efficiency and accuracy of all drug transactions such as receiving, picking, dispensing, inventory taking and the tracking of drug expiration dates. Most importantly, however, it ensures that hospital staff can administer the right drug to the right person in a timely fashion. This would not be possible without the use of wireless network to support a centralized database and mobile data collection devices.

Real Estate

Real estate salespeople perform a great deal of their work away from the office, usually talking with customers at the property being sold or rented. Before leaving the office, salespeople normally identify a few sites to saw customers print Multiple Listing.
Service (MLS) information that describes the property and than drive to each location with the potential buyer. If the customer is unhappy with the round of sites, the real estate agent must drive back to the office and run more listings. Even if the customer decides to purchase the property, they must both go back to the real estate office to finish paper work that completes the sale.
Wireless networking make the sales of real estate much more efficient. The real estate agent can use a computer away from the office to access wireless MLS records. IBM’s Mobile Networking Group and Software Corporation of America, for example, make wireless MLS information available that enables real estate agents to access information about properties such as descriptions, showing instructions, out standings loans and pricing. An agent can also use a portable computer and printer to produce contracts and loan applications for signing at the point of sale.

Hospitality

Hospitality establishments check customers in and out and keep track of needs, such as room service orders and laundry requests. Restaurants need to keep track of the names and numbers of people waiting for entry, table status and drink and food orders. Restaurant’s staff must perform these activities quickly and accurately to avoid making patrons unhappy. Wireless networking satisfies these needs very well.
Wireless computers are very useful in the situations where there is a large crowd such as a restaurant. For example someone can greet restaurants patterns at the door and enter their names, the size of the party and smoking preferences into a common database via wireless device. The greeter can then query the database and determine the availability of an appropriate table. Those who oversee the tables would also have a wireless device used to update the database to show whether the table is occupied, being cleaned or available. After obtaining a table the waiter transmits the order to the kitchen via the wireless device, eliminating the need for paper order tickets.

Utilities

Utility companies operate and maintain a highly distributed system that delivers power and natural gas to industries and residencies. Utility companies must continually monitor the operation of the electrical distribution systems and gas lines and must check usage meters at least monthly to calculate bills.
Traditionally, this means person must travel from location to location, enter residencies and company facilities, record information and then enter the data at a service or computing center. Today, utility companies employee wireless networks to support the automation of meter reading and system monitoring, saving time and reducing overhead costs.
Kansas City Power and Light operates one of the largest wireless metering systems, serving more than 150,000 customers in eastern Kansas and Western Missouri. This system employs a monitoring device at each customer site that take periodic meter readings and sent the information back to database that tracks usage levels and calculates bills, avoiding the need for the staff of meter readers.

PROBLEMS WITH WI-FI


1>                Speed can fluctuate significantly.
2>                            There is a problem in selection of frequency.
3>                If the range of radio signal is less then ,one should have to put repeater and amplifier in between.
4>                Wi-Fi works on radio signal. It is not provide user privacy because any simple radio receiver can receive the radio signals. So there should be tight security for it unlike wired network.
5>                There will be a problem of multi path fading.
6>                Collision avoidance is the big issue for it.

ADVANTAGES OF WI-FI


1>                It is fast and reliable.
2>                It has long range. 1000 ft or 305m in open areas and 250ft to 400ft or 76m to 
           122m in closed area.
3>                Easily integrated into existing wired Ethernet networks.
4>                Compatible with original 802.11 DSSS devices.
5>                Allows you to connect internet from anywhere.
6>                It give certification to you means you will be able to connect anywhere where there are certified 
products.

No need to initiate connection when up and running automatic connection when approaching 802.11 network.

WI-FI SECURITY


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.

·                     Turn on WEP ( Wired Equivalent Privacy)
·                     Change your default password
·                     If possible than close your network
·                     Change your network name
·                     Move your access point
·                     Use MAC control tables
·                     Other simple solutions
·                     Use VPN (Virtual Private Network)
·                     Enterprise level User Authentication via 802.1x and EAP

1> Turn on WEP

Most important: Turn on WEP(Wired Equivalent Privacy). WEP is the underlying security technology provided by the Wi-Fi (802.11b) standard. Even though WEP is not perfect, it does provide basic security. Some experts say that from 60 to 80 percent of all wireless LAN networks operate with WEP not turned on.
Most home and small office Wi-Fi systems provide 40-bit (also called 64-bit) WEP encryption. To make initial installation simple, most Wi-Fi access points ship with WEP turned off. So once you have your network turned on and working, make sure you activate WEP by following the instructions in your manufacturer's instructions.
You can also increase your security by periodically changing the encryption key.If you're concerned about privacy, change your code every week or two. If you're very concerned, change it more often or use an advanced security technology such as 802.1x, which can change your WEP code automatically every 5 minutes or so.

2> Change your default pass word 

 Most wireless networks ship with a default password provided by the manufacturer. Change it as soon as possible. Most hackers can easily figure out the default password once they identify the make of your network access point.
3> Close your Network
If possible, block the SSID (Service Set Identifier) from being broadcast. This has the effect of "closing" your network. Many Wi-Fi systems enable you to close the network.
All access points ship with a wireless beacon signal so that wireless PCs can more easily find them. In effect, the signal is shouting, "I'm here! Log on!" By turning the SSID off or by "closing" your network, you make it much harder for hackers to find you: If they don't know your network exists, there's less chance they will spend the time to crack your communications. So, If your equipment permits you to close the network, make sure you do so.

4> Change your Network name

Most access points ship with a default Network name. When your network is up and running you should change the name to something personal, yet hard to guess.
5>    Move your access point
To increase privacy, place your access point in the middle of the room, away from open windows and doors. The more metal and wood you put in the way, the less distance your wireless messages can travel. You can test how much of your signal is escaping from your business or home by taking your Wi-Fi equipped laptop outside and checking to see how far you can go and still make a connection. You might be surprised.

6>    Use MAC control tables

Use MAC (Medium Access Control) tables if your access point supports them. Like all networking devices, a Wi-Fi radio, has a unique MAC address coded into its memory. By using the MAC Access Control List (ACL), you can limit the wireless connection to only those Wi-Fi radios whose MAC addresses are directly enabled in your access point. It's like call blocking on a telephone, but for a wireless LAN. If a rogue wireless radio with a MAC address that is not in this table tries to connect to your network, your access point will not let it. 

7> Other simple solutions

There are various ways to set up your computer's directories and network to protect your stored files and data. One way is to turn off "Sharing" and use "Passwords" to access directories holding confidential files. Sharing and Passwords are accessed in Windows by right clicking on the directory and going to the "Properties" command. Also see Windows networking tips and secrets.
Remember that most web sites that handle purchases, credit cards and other financial information usually use encryption methods such as  SSL(secure socket layer) to protect sensitive data. So most financial data transmitted over the Internet is already encoded from the time it leaves your computer until it reaches the web site.
8> Use Virtual Private Network
Many large companies use VPN (Virtual Private Network) technologies for staff that need to remotely access the company's corporate database. VPN systems also work for Wi-Fi wireless networks.
A VPN creates a virtual tunnel from your computer through the local wireless access point, through the Internet, and then to your corporate headquarters. Even though it can be complicated and expensive, using VPN creates an almost impenetrable wall of security for your wireless communications whether you're working from home, an airport lounge or your company's meeting rooms.

9> Enterprise level User Authentication via 802.1x and EAP

WEP has almost no user authentication mechanism. To strengthen user authentication, Wi-Fi protected Access implements 802.1x and the Extensible Authentication Protocol (EAP). To gather, these implementations provide a framework for strong user authentication. This framework utilizes a central authentication server, such as RADIUS, to authenticate each user on the network before they join it, and also employs “mutual authentication” so that the wireless user does not accidentally join a rogue network that might steal its network credentials.

WI-FI VS BLUETOOTH

 
As wi-fi continuous it’s expansion the much hyped personal area networking technology known a bluetooth is recently enter the market. Bluetooth is designed to provide short range connectivity for peripheral such as keyboards, speakers, and headsets. It is design to support low data rate (721kbps) and limited rage(10m) in order to achieve low coast.

When you compare bluetooth with wi-fi you will find the bluetooth is short wire replacement for the mask of the cable. Bluetooth also have network capabilities to maximum of seven users, with one machine as masters on the other hand wi-fi is “long wire” wireless network replacement technology, it is design to allow user to lock on to the office/business network.

Concerning the technical deference, wi-fi users the packet switching multipoint technology as the Ethernet where as Bluetooth users a much simpler time division techniques.

Some problem that Bluetooth face is the Microsoft’s most recent operating system, Windows-XP does not support the bluetooth. The current price for Bluetooth chip sets is still considerably  above the target price US$5. In fact still same range of wi-fi chip sets us $20 to us $30.

WI-FI DRIVERS


As wireless LAN grow within corporations, the desire to extend support       follows naturally. Cahners estimated that the number of 802.11 based access points shipped each year will nearly triple from 1.2 million in 2001 to 3.5 million in 2005. The firm expects yearly 802.11 network interface card (NIC) shipments to jump from 6.3 million last year to 19.4 million in2005.

In fact, most of the major notebook computer markers ship products today with embedded 802.11 NICs. Combine that with the fact that Microsoft has embedded wi-fi capabilities into Windows XP and it is clear that, like it or not, there is a wi-fi user base growing up around you.

The XP operating system automatically searches for a Wi-Fi access point and if it finds one, asks the user if he would like to use the service. “We had users signing up for our service before it was even announced” says Tim Barrett, vice president of Airpath.

Wi-Fi support can indeed draw business. Mark Hedley , CTO at hotelier Wyndham International, based in Dallas, says his company is “most certainly taking conference business away from other hotels “ thanks to the 802.11 connectivity in 148 of its properties.

Wireless provider Wayport ate the up front capital costs, Hedley says. “You will not likely see much more of that in the wake of the dot-com demise. At the time, every one expected a 20% consumption rate, but it is actually been more like 2% to 4%.

WI-FI STANDARDS

There are mainly two standard for Wi-Fi.
1> 802.11a
2> 802.11b

1) 802.11b

The most established wireless LAN technology it’s also the most affordable. Allows wireless connection up to 300 feet from an access point, and can easily be added to existing wired networks. With speeds up to 11Mbps, performance is comparable to standard wired Ethernet network. Industry standard 802.11b products are easy to find and compatible with each other.

2) 802.11a

802.11a provides a bigger pipe for data and supports more simultaneous users. Ideal for deployments where speed and bandwidth are important , 802.11a networks can run at up to 54Mbps and supports more users per access point than a Wi-Fi solution. Wi-Fi is a wireless communications specification for digital devices. Wi-Fi is often referenced by its standards numbers in the 802.11x family.
The popular 802.11b Wi-Fi devices broadcast in the 2.4Ghz band also used by cordless phones. Faster but shorter range of 802.11a devices use the 5Ghz bandwidth. Both can send signals many hundreds of feet in clear territory.

WHO CAN USE WI-FI?

Every one can use Wi-Fi almost every where in the world. Home Wi-Fi networks can connect multiple computers to each other, to peripherals and to the internet. A wi-fi network can connect a family’s computer together to share such hardware and software resources as printer and Internet. That means everyone in the family can share stored files, photos, and documents and print them out on a single printer attached to one desktop computers all without unsightly cables running throughout the home.In a home or home office, using wi-fi certified equipment in your wireless network gives you the ability to share a single high speed broadband cable or DSL connection. A wi-fi network can easily be expanded to ten users or more.

Large corporations and campuses use enterprise level technology and Wi-Fi certified wireless products to extend standard wired Ethernet networks to public areas like meeting rooms, training class rooms, and large auditoria.

Service providers and wireless ISPs use Wi-Fi technology to distribute Internet Connectivity within individual homes and business as well as apartments and commercial complexes.

Busy public places like coffee shops, hotels, airport lounges, and other locations where large crowds gather will be the fastest growing segment of Wi-Fi as more and more travelers and mobile professionals clamour for fast and secure Internet access wherever they are. Soon, Wi-Fi networks will be found in urban areas providing coverage throughout the central city, or even lining major highways, enabling travelers access anywhere they can pull over and stop.

WHY WI-FI?

The main reasons for using Wi-Fi are as below.
• Mobility
• Scalability
• Increased Reliability
• Reduced Installation Time
• Financial benefit
• Long-Term Cost Savings


• Mobility

Mobility enables users to physically move while using an appliance, such as a handheld PC or data collector. Many jobs require workers to be mobile, such as inventory clerks, healthcare workers ,police officers etc. Of course, wireless networks require a physical link between the user’s workstation and networks resources, which makes access to these resources impossible while roaming.
Mobile applications requiring Wi-Fi networking include those that depend on real time access to data usually stored in centralized databases. If your applications requires mobile users to be immediately aware of changes made to data, or information put into the system must immediately be available to others, you have a definite need for wireless networking. For accurate and efficient price markdowns, for example many retail stores use wireless networks to interconnect handheld bar code scanners and printers to databases having current price information. This enables the printing of the correct price on the items, making both the customer and the business owner more satisfied.

• Scalability

Wi-Fi systems can be configured in a variety of topologies to meet the needs of specific applications and installations. Configuration are easily changed and range from peer to peer networks suitable for a small number of users to full infrastructure networks of thousands of users that enable roaming over a broad area.

• Increased Reliability

A problem inherent to wired networks is the downtime that results from cable faults. In fact, cable faults are often the primary cause of system downtime. Moisture erodes metallic conductors via water intrusion during storms and accidental leakage of liquids. With wired networks, users may accidentally break their network connector when trying to disconnect their PCs from the network to move them to different locations. Imperfect cable splices can cause signal reflections that result in unexplainable errors.
The accidental cutting of cables can bring a network down immediately. Wires and connectors can easily break through misuse and even normal use. These problems interfere with the user’s ability to utilize network resources, causing havoc for network managers. An advantages of wireless networking, therefore, results from the use of less cable. This reduces the downtime of the network and the costs associated with replacing cables.

• Reduced Installation Time

The installation of cabling is often a time consuming activity. For LANs, installers must pull twisted-pair wires above the ceiling and drop cables through walls to network.
These tasks can take days or weeks, depending on the size of the installation. The installation of optical fiber between buildings within the same geographical area consist of digging trenches to lay the fiber or pulling the fiber through an existing conduit. You might need weeks of possibly months to receive right-of-way approvals and dig through ground and asphalt.
The deployment of wireless networks greatly reduces the need for cable installation, making the network available for use much sooner. Therefore, many countries lacking a network infrastructure have turned to wireless networking as a method of providing connectivity among computers without the expense and time associated with installing physical media. This is also necessary within the United States to set up temporary offices and “rewire” renovated facilities.

• Financial Benefit

Wi-Fi is a no risk financial decision especially for small business or companies in hard to wired locations, because of its low cost. Consulting firm which spent 30,000$ to wire its office, says the similar Wi-Fi installation today would cost only 500$. This shows that it is really beneficial to install Wi-Fi instead of wired network.

• Long Term Cost Savings

The changes like companies reorganization, resulting in the movement of people, new floor plans, office partition and other renovations often require recabling the network incurring both labor and material costs. In some cases, the recabling costs of organizational changes are substantial, especially with large enterprise networks. A reorganization rate of 15 percent each year can result in yearly reconfiguration expenses as high as $250,000 for networks that have 6,000 interconnected devices. The advantage of Wi-Fi is again based on the lack of cable. You can move the network connection by just relocating an employee’s PCs or access points.

An oil exploration company operating in Colombia, South America, experienced high expenses when relocating its drilling rigs. The oil drilling setup requires two control rooms in portable sheds located approximately 5,000 feet from the drilling platform to provide 500 kbps computer communication between the sheds and drilling rig. The communication system consisted of Ethernet networks at each of the three sites. Each shed had four PCs running on the network and drilling site had one PC for direct drilling control purpose.

Every time the oil company needed to move to a different drilling site, which occurred four or five times each year, it had to spend $50,000 to $75,000 to reinstall optical fiber over the difficult terrain between the sheds.
So naturally in this type of cases Wi-Fi is better option.

WHAT IS WI-FI?

Wi-Fi is a trade-group certified wireless networking standard that rellies on the IEEE 802.11a and 802.11b specifications.

The 802.11b spec allows for the wireless transmission of approximately 11 Mbps of raw data at indoor distances from several dozen to several hundred feet and outdoor distances of several to tens of miles as an unlicensed use of the 2.4GHz band.

The 802.11a spec uses the 5GHz band , and can handle 54 Mbps at typically shorter distances. The distances for both standards depends on impediments, materials, and line of sight.

The 802.11b specification started to appear in commercial form in mid-1999, with Apple Computer’s introduction of its Airport components, manufactured in conjunction with Lucent’s Wave LAN division.

Wi-Fi is an extension of wired Ethernet, bringing the same principles to wireless communication, and as such is ecumenical about the kinds of data that pass over it. It’s primarily used for TCP/IP , but can also handle other forms of networking traffic , such as AppleTalk of PC file sharing standards.

Share

Twitter Delicious Facebook Digg Stumbleupon Favorites