14506 13811 Wireless Technology

8/6/2019 14506 13811 Wireless Technology

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What is Bluetooth, WiFi and WiMAX?

Bluetooth, WiFi and WiMAX are wireless technologies which allow devices to inter-

connect and communicate with each other. Radio waves are electomagnetic waves

and have different frequencies. These technologies are radio frequencies. Similar to

the analogue radio, or FM radio. Bluetooth works on 2.45GHz frequency. WiFi works

in two frequency bands 2.4GHz and 5GHz. WiMAX works in two frequency bands, 2

- 11GHz and 10 - 66GHz. See chart below for a comparison of these technologies.

Bluetooth

Named after the Danish king, Harold Bluetooth,was the first to emerge, several devices like

mobile phones, headsets, keyboards, medical equipment and even cars now come with this

feature. Due to its low cost, manufacturers are willing to implement this technology in most

devices. It is designed for short range communications with a range of about 10m. As a

result, it consumes less power and are suited for very small battery powered devices and

portable devices. Problems associated when devices communicate via infrared or cables are

removed. Infrared requires a line of sight, bluetooth only needs to be in reasonable vicinity.

As cables are not required, it would be less cumbersome carrying a personal bluetooth device

and space would be less cluttered. As bluetooth devices automatically communicate with

each other, it requires very little from the user. Bluetooth allows for a wireless Personal Area

Network (PAN) with it's short range. See chart below for a comparison of these technologies.
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Working

When you use computers, entertainment systems ortelephones, the various pieces and parts

of the systems make up a community of electronic devices. These devices communicate with

each other using a variety of wires, cables, radio signals and infrared light beams, and an

even greater variety of connectors, plugs and protocols.

There are lots of different ways that electronic devices can connect to one another. For

example:

Component cables Electrical wires Ethernet cables WiFi Infrared signals

The art of connecting things is becoming more and more complex every day. In this article,

we will look at a method of connecting devices, called Bluetooth, that can streamline the

process. A Bluetooth connection is wireless and automatic, and it has a number of interesting

features that can simplify our daily lives.

The Problem

When any two devices need to talk to each other, they have to agree on a number of points

before the conversation can begin. The first point of agreement is physical: Will they talk

over wires, or through some form of wireless signals? If they use wires, how many are

required -- one, two, eight, 25? Once the physical attributes are decided, several more

questions arise:

How much data will be sent at a time? For instance, serial ports send data1 bit at a time, while parallel ports send several bits at once.

How will they speak to each other? All of the parties in an electronicdiscussion need to know what the bits mean and whether the messagethey receive is the same message that was sent. This means developing aset of commands and responses known as a protocol.

Bluetooth offers a solution to the problem.
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WiFi

WiFi or Wireless Fidelity, has a range of about 100m and allows for faster data transfer rate

between 10 - 54Mbps. There are three different wireless standards under WiFi, 802.11a,

802.11b and 802.11g. 802.11 being the wireless standard set by The Institue of Electrical and

Electronic Engineers (IEEE). WiFi is used to create wireless Local Area Networks (WLAN).

The most widely used standard is 802.11b and 802.11g is expexcted to grow rapidly. These

two standards are relatively inexpensive and can be found providing wireless connectivity in

airports, railway stations, cafes, bars, restaurants and other public areas. The main difference

between the two is the speed. 802.11b has data transfer rate of upto 11Mbps and 802.11g has

a rate of upto 54Mbps. 802.11g is a relatively new and has yet to be adopted widely. 802.11ais more expensive and as a result it not available for public access. See chartbelow for a

comparison of these technologies.

Definition: Wi-Fi is the industry name for wireless LAN (WLAN) communication

technology related to the IEEE 802.11 family of wireless networking standards.

To some, the term Wi-Fi is synonymous with 802.11b, as 802.11b was the first

standard in that family to enjoy widespread popularity. Today, however, Wi-Fi

can refer to any of the established standards: 802.11a, 802.11b, 802.11g and

802.11n.

Working of wifi

A wireless network uses radio waves, just like cell phones,televisions and radios do. In fact,

communication across a wireless network is a lot like two-way radio communication. Here's

what happens:

1. A computer's wireless adapter translates data into a radio signal andtransmits it using an antenna.

2. A wireless router receives the signal and decodes it. The router sends theinformation to the Internet using a physical, wired Ethernet connection.

The process also works in reverse, with the router receiving information from the

Internet, translating it into a radio signal and sending it to the computer's

wireless adapter.

The radios used for WiFi communication are very similar to the radios used for walkie-

talkies, cell phones and other devices. They can transmit and receive radio waves, and they

can convert 1s and 0sinto radio waves and convert the radio waves back into 1s and 0s.
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WiMAX

WiMAX is Worldwide Interoperability for Microwave Access. The IEEE standard for

WiMAX is 802.16 and falls under the category of wireless Metropolitan Area Network

(WMAN). WiMAX operates on two frequency bands, 2 - 11GHz and 10 - 66GHz and has a

range of about 50km with speeds of upto 80Mbps. This enables smaller wireless LANs to be

interconnected by WiMAX creating a large wireless MAN. Networking between cities can be

achieved without the need for expensive cabling. It is also able to provide high speed wireless

broadband access to users. As it can operate in two frequency bands WiMAX can work by

line-of-sight and non-line-of-sight. At the 2 - 11GHz frequency range it works by non-line-

of-sight, where a computer inside a building communicates with a tower/antenna outside thebuilding. Short frequency transmissions are not easily disrupted by physical obstructions.

Higher frequency transmissions are used for non-line-of-sight service. This enables to

towers/antennae to communicate with each other over a greater distance. Due to

infrastructure and costs involved it would be more suited to provide the backbone services for

ISPs and large corporations providing wireless networking and internet access. See chart

below for a comparison of these technologies.

Think about how you access the Internet today. There are basically three

different options:

Broadband access - In your home, you have either a DSL or cablemodem. At the office, your company may be using aT1 or a T3 line.

WiFi access - In your home, you may have set up a WiFi router that letsyou surf the Web while you lounge with your laptop. On the road, you canfind WiFi hot spots in restaurants, hotels, coffee shops and libraries.

Dial-up access - If you are still using dial-up, chances are that eitherbroadband access is not available, or you think that broadband access istoo expensive.

The main problems with broadband access are that it is pretty expensive and it doesn't reach

all areas. The main problem with WiFi access is that hot spots are very small, so coverage is

sparse.

What if there were a new technology that solved all of these problems? This new technology

would provide:

The high speed of broadband service Wireless rather than wired access, so it would be a lot less expensive

than cable or DSL and much easier to extend to suburban and rural areas Broad coverage like the cell phone network instead of small WiFi hotspots

This system is actually coming into being right now, and it is calledWiMAX. WiMAX is short for Worldwide Interoperability for Microwave

Access, and it also goes by the IEEE name 802.16.
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OR

WiMAX is a wireless digital communications system, also known as IEEE802.16, that is intended for wireless "metropolitan area networks". WiMAX canprovide broadband wireless access (BWA) up to 30 miles (50 km) for fixedstations, and 3 - 10 miles (5 - 15 km) for mobile stations. In contrast, theWiFi/802.11 wireless local area network standard is limited in most cases to only100 - 300 feet (30 - 100m).

With WiMAX, WiFi-like data rates are easily supported, but the issue ofinterference is lessened. WiMAX operates on both licensed and non-licensedfrequencies, providing a regulated environment and viable economic model forwireless carriers.

WiMAX can be used for wireless networking in much the same way as the morecommon WiFi protocol. WiMAX is a second-generation protocol that allows formore efficient bandwidth use, interference avoidance, and is intended to allowhigher data rates over longer distances.

The IEEE 802.16 standard defines the technical features of the communicationsprotocol. The WiMAX Forum offers a means of testing manufacturer's equipmentfor compatibility, as well as an industry group dedicated to fostering thedevelopment and commercialization of the technology.

WiMax.com provides a focal point for consumers, service providers,manufacturers, analysts, and researchers who are interested in WiMAX

technology, services, and products. Soon, WiMAX will be a very well recognizedterm to describe wireless Internet access throughout the world

Wireless Technology Comparison Chart

Bluetooth WiFi (a) WiFi (b) WiFi (g) WiMAX

Standard 802.15 802.11a 802.11b 802.11g 802.16

Frequency (GHz) 2.45 5 2.4 2.4 2 - 66

Speed (Mbps) 0.72 54 11 54 80

Range 10m 50m 100m 100m 50km

Advantages Low Cost Speed Low Cost Speed Speed, Range

Disadvantages Range Cost Speed Cost, Range Cost


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What is a Local Area Network?

A Local Area Network(LAN) is a high-speed communications system

designed to link computers and other data processing devices together

within a small geographic area, such as a workgroup, department, or

building.

Local Area Networks implement shared access technology. This means

that all of the devices attached to the LAN share a single communications

medium, usually a coaxial, twisted-pair, or fiber-optic cable.

A physical connection to the network is made by putting a network

interface card (NIC) inside the computer and connecting it to the networkcable. Once the physical connection is in place, the network software

manages communications between stations on the network.

To send messages to and from computers, the network software puts the

message information in a packet. (If the message to be sent is too big to fit

into one packet, it will be sent in a series of packets.) In addition to the

message data, the packet contains a header and a trailer that carry special

information to the destination. One piece of information in the header is the

address of the destination.

The NIC transmits the packet onto the LAN as a stream of data represented

by changes in electrical signals. As it travels along the shared cable, each

NIC checks its destination address to determine if the packet is addressed to

it. When the packet arrives at the proper address, the NIC copies it and gives

its data to the computer. Since each individual packet is small, it takes very

little time to travel to the ends of the cable. After a packet carrying one

message passes along the cable, another station can send its packet. In this

way, many devices can share the same LAN medium.

Each LAN has its own unique topology, or geometric arrangement. Thereare three basic topologies: bus, ring, and star. Most LANs are a combination

of these arrangements.

In a bus topology all of the devices are connected to a central cable or

backbone.


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In a ring topology the devices are connected in a

closed loop so that each device is connected to two

others, one on either side. This kind of topology is

robust; that is, one device's failure will probably not

cause total network failure.

In a star topology the devices are all connected to a

central hub, which forwards data towards its final

destination. The NCI-Frederick LAN infrastructure is

standardized on the star topology. If the data's

destination is within the local star segment, the hub

will forward data directly to the destination device; if

the data's destination is outside the local star

segment, the hub forwards the data to a router.

Depending on the topology and media that are used, as well as the protocols (formats for

transmitting data) that are implemented, a LAN can permit data transfer rates of up to

100 Million bps.

The following characteristics differentiate one LAN from another:

topology: The geometric arrangement of devices on the network. For

example, devices can be arranged in a ring or in a straight line.

protocols: The rules and encoding specifications for sending data.

The protocols also determine whether the network uses a peer-to-peer or

client/server architecture.

media: Devices can be connected by twisted-pair wire, coaxial cables,

or fiber optic cables. Some networks do without connecting media

altogether, communicating instead via radio waves.
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WAN

Definition: WAN stands for Wide Area Network. As its name suggests, it is a

computer network that covers a far wider area than a LAN (Local Area Network).

WANs cover cities, countries, continents and the whole world.

A WAN is formed by linking LANs together. For example, several major LANs in a city can

connect together forming a WAN.

When networks connect to form a bigger network (a bigger WAN), the resulting network is

called an internetwork, which is generically abbreviated to an internet. Now when all

WANs in the world connect forming a global internet, we call it The Internet, which

everyone knows! Thats why the Internet is always written with a capital I. It is the biggest

WAN we have.

OR

A wide area network(WAN) is a computer networkthat covers a broad area (i.e., any

network whose communications links cross metropolitan, regional, or national boundaries [1]).

This is in contrast withpersonal area networks (PANs), local area networks (LANs), campus

area networks (CANs), ormetropolitan area networks(MANs) which are usually limited to a

room, building, campus or specific metropolitan area (e.g., a city) respectively.

WANs are used to connect LANs and other types of networks together, so that users and

computers in one location can communicate with users and computers in other locations.

Many WANs are built for one particular organization and are private. Others, built by

Internet service providers, provide connections from an organization's LAN to the Internet.

WANs are often built using leased lines. At each end of the leased line, arouterconnects tothe LAN on one side and a hub within the WAN on the other. Leased lines can be very

expensive. Instead of using leased lines, WANs can also be built using less costlycircuit

switching orpacket switching methods. Networkprotocols including TCP/IPdeliver

transport and addressing functions. Protocols includingPacket over SONET/SDH, MPLS,

ATM and Frame relay are often used by service providers to deliver the links that are used in

WANs.X.25 was an important early WAN protocol, and is often considered to be the

"grandfather" of Frame Relay as many of the underlying protocols and functions ofX.25 are

still in use today (with upgrades) by Frame Relay.

Difference Between Lan AND wAN:
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LAN (Local Area Network) is a computer network covering a small geographic area, like a

home, office, or group of buildings

Network in an organisation can be a LAN

Typically owned, controlled, and managed by a single person or organization

Typically owned, controlled, and managed by a single person or organization

LANs have a high data transfer rate

Wan-->WANs (like the Internet) are not owned by any one organization but rather exist

under collective or distributed ownership and management

WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the

longer distances

WANs have a lower data transfer rate as compared to LANs

Have a large geographical range generally spreading across boundaries and need leased

telecommunication lines


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Definition: WLANs provide wireless network communication over shortdistances using radio or infrared signals instead of traditional network cabling.

A WLAN typically extends an existing wired local area network. WLANs are built by

attaching a device called the access point (AP) to the edge of the wired network. Clients

communicate with the AP using a wireless networkadaptersimilar in function to a traditional

Ethernet adapter.

Network security remains an important issue for WLANs. Random wireless clients must

usually be prohibited from joining the WLAN. Technologies like WEPraise the level of

security on wireless networks to rival that of traditional wired networks.

Also Known As: wireless LAN

Examples:

For WLANs that connect to the Internet, Wireless Application Protocol (WAP)

technology allows Web content to be more easily downloaded to a WLAN andrendered on wireless clients like cell phones and PDAs.

Benefits of WLANs

Wireless LANs offer the following productivity, service, convenience, and cost advantages over

traditional wired networks:

Mobility-Wireless LAN systems can provide LAN users with access to real-time information

anywhere in their organization. This mobility supports productivity and service opportunities

not possible with wired networks. Installation Speed and Simplicity-Installing a wireless LAN system can be fast and easy and

can eliminate the need to pull cable through walls and ceilings.

Installation Flexibility-Wireless technology allows the network to go where wire cannot go.

Reduced Cost-of-Ownership-While the initial investment required for wireless LAN hardware

can be higher than the cost of wired LAN hardware, overall installation expenses and life-

cycle costs can be significantly lower. Long-term cost benefits are greatest in dynamic

environments requiring frequent moves, adds, and changes.

Scalability-Wireless LAN systems can be configured in a variety of topologies to meet the

needs of specific applications and installations. Configurations 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 allows roaming over a broad area.

Range/Coverage
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The distance over which RF waves can communicate is a function of product design (including

transmitted power and receiver design) and the propagation path, especially in indoor environments.

Interactions with typical building objects, including walls, metal, and even people, can affect how

energy propagates, and thus what range and coverage a particular system achieves. Most wireless

LAN systems use RF because radio waves can penetrate many indoor walls and surfaces. The range

(or radius of coverage) for typical WLAN systems varies from under 100 feet to more than 500 feet.

Coverage can be extended, and true freedom of mobility via roaming, provided through microcells.

WWAN - Wireless Wide Area Network

Meaning of WWAN - "Wireless Wide Area Network", enables users to establish wireless

connections over remote private or public networks using radio, satellite and mobile phone

technologies instead of traditional cable networking solutions like telephone systems or cable

modems.

These connections can be maintained over large geographical areas, such as cities or

countries, through the use of satellite systems or multiple antenna sites maintained bywireless service providers.

Schools or a businesses in rural areas benefit from Wireless WANs because it is more cost

effective than laying long cable or fibre links. The same can be said for institutions in built up

urban areas. Installing cable into an existing location could be very disruptive, so a wireless

alternative is more cohesive.

Examples of Wireless WANs are Digital Cellular Phone and Data Services, Satellite Modems

or a computer hooked up with a wireless WAN card and used in a city or geographical area

that has WWAN deployed. There are cities that offer wireless internet services to the anyone

who lives within it's reach. Some universities offer WWAN services to students who can

hook up to the school network from outside of the building or across town.

The main WWAN technologies are GSM (Global System for Mobile

Communication), GPRS (General Packet Radio Service), UMTS (Universal

Mobile Telecommunication System), and CDMA (Code Division Multiple

Access).
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WiMAX Wireless Network


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In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances

and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout

areas that currently have no broadband Internet access becausephoneandcablecompanies have

not yet run the necessary wires to those remote locations.

Photo courtesyIntel

WiMAX transmitting tower

A WiMAX system consists of two parts:

A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX towercan provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square

km).

A WiMAX receiver- The receiver and antenna could be a small box orPCMCIA

card, or they could be built into a laptop the way WiFi access is today.

A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection

(for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave

link. This connection to a second tower (often referred to as a backhaul), along with the ability of a

single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote

rural areas.
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What this points out is that WiMAX actually can provide two forms of wireless service:

There is the non-line-of-sight, WiFi sort of service, where a small antenna on

your computer connects to the tower. In this mode, WiMAX uses a lower frequency

range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as

easily disrupted by physical obstructions -- they are better able to diffract, or bend, around

obstacles.

There is line-of-sight service, where a fixed dish antenna points straight at the

WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more

stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions

use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies,

there is less interference and lots more bandwidth.

WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of

coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas,

the WiMAX transmitting station would send data to WiMAX-enabled computers orroutersset upwithin the transmitter's 30-mile radius (2,800 square miles or 9,300 square km of coverage). This is

what allows WiMAX to achieve its maximum range.

The final step in the area network scale is the global area network (GAN). The proposal for GAN

is IEEE 802.20. A true GAN would work a lot like today's cell phone networks, with users able to travel

across the country and still have access to the network the whole time. This network would have

enough bandwidth to offer Internet access comparable to cable modem service, but it would be

accessible to mobile, always-connected devices like laptops or next-generation cell phones

WiMAX Coverage and Speed

Intel Paves the Way

Intel will start making their Centrino laptop

processors WiMAX enabled in the next two to

three years. This will go a long way toward

making WiMAX a success. If everyone's laptop

already has it (which is predicted by 2008), it will

be much less risky for companies to set up

WiMAX base stations. Intel also announced that it

would be partnering with a company called

Clearwire to push WiMAX even further ahead.

Clearwire plans to send data from WiMAX basestations to small wireless modems. See Intel,

Clearwire to Accelerate Deployment of WiMAX

Networks Worldwide (Oct. 25, 2004).

WiMAX operates on the same general principles as WiFi -- it sends data from one computer to

another via radiosignals. A computer (either a desktop or a laptop) equipped with WiMAX would

receive data from the WiMAX transmitting station, probably usingencrypteddata keys to prevent

unauthorized users from stealing access.

The fastest WiFi connection can transmit up to 54 megabits per second under optimal conditions.

WiMAX should be able to handle up to 70 megabits per second. Even once that 70 megabits is split

up between several dozen businesses or a few hundred home users, it will provide at least the

equivalent of cable-modem transfer rates to each user.
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The biggest difference isn't speed; it's distance. WiMAX outdistances WiFi by miles. WiFi's range is

about 100 feet (30 m). WiMAX will blanket a radius of30 miles (50 km) with wireless access. The

increased range is due to the frequencies used and the power of the transmitter. Of course, at that

distance, terrain, weather and large buildings will act to reduce the maximum range in some

circumstances, but the potential is there to cover huge tracts of land.

IEEE 802.16 Specifications

Range - 30-mile (50-km) radius from base station

Speed - 70 megabits per second

Line-of-sight not needed between user and base station

Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed

bands)

Defines both the MAC and PHY layers and allows multiple PHY-layer

specifications (SeeHow OSI Works)

WiMAX Cost

A citywide blanket coverage of wireless Internet access sounds

great, but companies aren't going to go around setting up WiMAX

base stations out of sheer kindness. Who's going to pay for

WiMAX?

It depends how it will be used. There are two ways WiMAX can be

implemented -- as a zone for wireless connections that single

users go to when they want to connect to the Internet on a laptop (the non-line-of-sight "super WiFi"

implementation), or as a line-of-sight hub used to connect hundreds of customers to a steady, always-

on, high-speed wireless Internet connection.

Under the "super WiFi" plan, cities might pay to have WiMAX base stations set up in key areas forbusiness and commerce and then allow people to use them for free. They already do this with WiFi,

but instead of putting in a bunch ofWiFi hot spots that cover a few hundred square yards, a city could

pay for one WiMAX base station and cover an entire financial district. This could provide a strong

draw when city leaders try to attract businesses to their area.

Some companies might set up WiMAX transmitters and then make people pay for access. Again, this

is similar to strategies used for WiFi, but a much wider area would be covered. Instead of hopping

from one hot spot to another, WiMAX-enabled users could have Internet access anywhere within 30

miles of the WiMAX base station. These companies might offer unlimited access for a monthly fee or

a "pay as you go" plan that charges on a per-minute or per-hour basis.

The high-speed wireless hub plan has the potential to be far more revolutionary. If you have high-speed Internet access now, it probably works something like this: The cable (or phone) company has

a line that runs into your home. That line goes to a cable modem, and another line runs from the

modem to your computer. If you have a home network, first it goes to a router and then on to the other

computers on the network. You pay the cable company a monthly fee, which reflects in part the

expense of running cable lines to every single home in the neighborhood.

On the next page, we'll discuss how WiMAX can work for you.

WiMAX Technology at Home

Network Scale

Logo courtesyIntel
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The smallest-scale network is a personal area network (PAN). A

PAN allows devices to communicate with each other over short

distances. Bluetooth is the best example of a PAN.

The next step up is a local area network (LAN). A LAN allows

devices to share information, but is limited to a fairly small central

area, such as a company's headquarters, a coffee shop or your

house. Many LANs use WiFi to connect the network wirelessly.

WiMAX is the wireless solution for the next step up in scale,

themetropolitan area network (MAN). A MAN allows areas the size

of cities to be connected.

Here's what would happen if you got WiMAX. An Internet service provider sets up a WiMAX base

station 10 miles from your home. You would buy a WiMAX-enabled computer or upgrade your old

computer to add WiMAX capability. You would receive a special encryption code that would give you

access to the base station. The base station would beam data from the Internet to your computer (at

speeds potentially higher than today's cable modems), for which you would pay the provider a

monthly fee. The cost for this service could be much lower than current high-speed Internet-

subscription fees because the provider never had to run cables.

If you have a home network, things wouldn't change much. The WiMAX base station would send data

to a WiMAX-enabled router, which would then send the data to the different computers on yournetwork. You could even combine WiFi with WiMAX by having the router send the data to the

computers via WiFi.

WiMAX doesn't just pose a threat to providers of DSL and cable-modem service. The WiMAX protocol

is designed to accommodate several different methods of data transmission, one of which is Voice

Over Internet Protocol (VoIP). VoIP allows people to make local, long-distance and even international

calls through a broadband Internet connection, bypassing phone companies entirely. If WiMAX-

compatible computers become very common, the use of VoIP could increase dramatically. Almost

anyone with a laptop could make VoIP calls.

For more information on WiMAX, wireless networking and related topics, check out the links on the

next page.
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14506 13811 Wireless Technology

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