Wireless network

WIRELESS NETWORKFundamental of wireless network

Introduction

History

Heinrich Hertz discovered and first produced radio waves in 1888 and by 1894 the modern way to send a message over telegraph.

Marconi sent and received signals up to two miles using radio waves. 

In 1901 he was able to transmit across the Atlantic Ocean.

During World War II, the United States Army first used radio signals for data transmission. This inspired a group of researchers in 1971 at the University of Hawaii to create the first packet based radio communications network called ALOHNET.  ALOHNET was the very first wireless local area network (WLAN).

The wireless network generation

The first generation of WLAN technology which later became crowded with interference from small appliances and industrial machinery. A spread spectrum was used to minimize this interference, which operated at 500 kilobits per second. 

  The second generation of WLAN technology was four times faster and operating at 2Mbps per second. 

Third generation WLAN technology operates on the same band as the second generation and we currently use it today.

 In 1990, the IEEE 802 Executive Committee established the 802.11 Working Group to create a wireless local area network (WLAN) standard. The standard specified an operating frequency in the 2.4GHz ISM band. In 1997 the group approved IEEE 802.11 as the world's first WLAN standard with data rates of 1 and 2 Mbps.

Compare between wireless and wired Devices: PCs , laptop , Cellular

phones , handheld computers, wireless printer or fax.

• Speed

:depends on the network and the what’s new in network world.

Compare between wireless and wired

Cost: maintenance, build, rapier, and troubleshoot, area.

• Range of coverage: area, and Distance.

Compare between wireless and wired

Security.

• Flexibility.

Compare between wireless and wired

Mobility.

•Organization

Advantages:- It is easier to add or move workstations. It is easier to provide connectivity in

areas where it is difficult to lay cable. Portable or semi permanent buildings can

be connected using a WLAN. When you have many Branches in same

area or city. In historic buildings where traditional

cabling would compromise the facade.

Disadvantages:- As the number of computers using the network increases,

the data transfer rate to each computer will decrease accordingly.

As standards change, it may be necessary to replace wireless cards and/or access points.

Security is more difficult to guarantee and requires configuration.

Devices will only operate at a limited distance from an access point, with the distance determined by the standard used and buildings and other obstacles between the access point and the user.

A wired LAN is most likely to be required to provide a backbone to the WLAN; a WLAN should be a supplement to a wired LAN and not a complete solution.

Type of wireless network Wireless Personal Area Network.

Wireless Local Area Network.

Wireless Metropolitan Area Network.

Wireless Personal Area Network

Used in the area Approximately 10 meters .

Using a frequency of 2.4 GHz. The most commonly used technique in

this type of networks is Bluetooth. This technical standard 802.15.

Wireless Local Area Network

IEEE.802.11.a : In 1997, using the 5 GHz frequency, the transfer speed of 54 Mbps, area not exceeding 35 meters indoor and outdoor 115 m.

IEEE.802.11.b : In 1997, using the 2.4 GHz frequency, the transfer speed of 11 Mbps, area not exceeding 38 meters indoor and outdoor 125 m. But disadvantage is the range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.

Wireless Local Area Network

IEEE 802.11.g : In 2003, using the 2.4GHz frequency, the transfer speed of 54 Mbps, area not exceeding 38 meters indoor and outdoor 125 m.

IEEE 802.11.n : In 2009, using the 2.4GHz and 5 GHz frequency, the transfer speed of 150 Mbps, range indoor not exceeding 70 meters and outdoor 125 m. no overlap in 5GHz.

The most commonly used technique in this type of networks is Wi-Fi (Wireless Fidelity).

Wireless Metropolitan Area Network IEEE 802.16 It use for the global deployment of

broadband Wireless Metropolitan Area Networks.

It use different frequency and it can transfer speed Approximately 1Gbps.

Coverage area up to 55 km. The most commonly used technique in this

type of networks is WiMAX (Worldwide Interoperability for Microwave Access).

security WEP2 WEP 802.11i (WPA and WPA2)