vendredi 21 juin 2013

Wireless Networks

1. What is wireless networking ?

 The term wireless networking refers to technology that enables two or more computers to communicate using standard network protocols, but without network cabling. Strictly speaking, any technology that does this could be called wireless networking. The current buzzword however generally refers to wireless LANs. This technology, fuelled by the emergence of cross-vendor industry standards such as IEEE 802.11, has produced a number of affordable wireless solutions that are growing in popularity with business and schools as well as sophisticated applications where network wiring is impossible, such as in warehousing or point-of-sale handheld equipment

2. What is a wireless network made up of ?

There are two kinds of wireless networks:
a) An ad-hoc, or peer-to-peer wireless network consists of a number of computers each equipped with a wireless networking interface card. Each computer can communicate directly with all of the other wireless enabled computers. They can share files and printers this way, but may not be able to access wired LAN resources, unless one of the computers acts as a bridge to the wired LAN using special software. (This is called "bridging").


b) A wireless network can also use an access point, or base station. In this type of network the access point acts like a hub, providing connectivity for the wireless computers. It can connect (or "bridge") the wireless LAN to a wired LAN, allowing wireless computer access to LAN resources, such as file servers or existing Internet Connectivity.
There are two types of access points:
  1. Dedicated hardware access points (HAP) such as Lucent's WaveLAN, Apple's Airport Base Station or WebGear's AviatorPRO. (See Figure 2). Hardware access points offer comprehensive support of most wireless features, but check your requirements carefully.
  2. Software Access Points which run on a computer equipped with a wireless network interface card as used in an ad-hoc or peer-to-peer wireless network. (See Figure 3) The Vicomsoft InterGate suites are software routers that can be used as a basic Software Access Point, and include features not commonly found in hardware solutions, such as Direct PPPoE support and extensive configuration flexibility, but may not offer the full range of wireless features defined in the 802.11 standard.
With appropriate networking software support, users on the wireless LAN can share files and printers located on the wired LAN and vice versa. Vicomsoft's solutions support file sharing using TCP/IP.



3. What is IEEE 802.11?

 The IEEE 802.11 is a standard introduced by IEEE in June 1997 used for wireless Ethernet networks. Below is a listing of each of the wireless IEEE standards currently available. Home users should only be concerned about 802.11a, 802.11b, or 802.11g for their home wireless network.
 
Standard Description
IEEE 802.11 The initial release of the standard capable of transmissions of 1 to 2 Mbps and operates in the 2.4 GHz band.
IEEE 802.11a Capable of transmissions of up to 54 Mbps and operates in the 5 GHz band.
IEEE 802.11b Introduced in 1999, 802.11b is capable of transmissions of up to 11 Mbps and operates in the 2.4 GHz band.
IEEE 802.11c Defines wireless bridge operations
IEEE 802.11d Defines standards for companies developing wireless products in different countries.
IEEE 802.11e Defines enhancements to the 802.11 MAC for QoS.
IEEE 802.11f Defines Inter Access Point Protocol (IAPP)
IEEE 802.11g Capable of transmissions of up to 20 Mbps and operates in the 2.4, 3.6 and 5 GHz bands.
IEEE 802.11i Improved encryption (WPA).
IEEE 802.11j 802.11 extension used in Japan.
IEEE 802.11n Operates using the 2.4GHz and 5GHz bandwidths. It utilizes multiple-input, multiple-output (MIMO) antennas to improve data transfer speeds.     

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