Saturday, 10 December 2011

Wireless networking

Wireless networking is the new face of networking. Wireless networking have been around for many years. Cell phones are also a type of wireless communication and are popular today for people talking to each other worldwide.
Wireless networking are not only less expensive than more traditional wired networking but also much easier to install. An important goal of this site is to provide you adequate knowledge for installing a wireless network and get certified in wireless networks as well as.
Perhaps you already using wireless networking in your local coffee shop, at the airport, or in hotel lobbies, and you want to set up a small office or home network. You already know how great wireless networking is, so you want to enjoy the benefits where you live and work. It is truly transformational to one's lifestyle to decouple computing from the wires! If you are looking to set up a wireless network, you've come to the right place. We will show you the best way to set up wireless network easily. Many people are looking to find out how to use wireless networking at home.
In this wireless networking section we provide An Absolute Beginner's Guide provides in the perfect format for easily learning what you need to know to get up to speed with wireless network without wasting a lot of time.
The organization of this site, and the special elements that we have described in this section will help you get the information you need quickly, accurately, and with clarity. In this section you will find inspiration as well as practical information. we believe that Wireless networks is a modest technology that has the power to have a huge and positive impact.. This is wonderful material, and it's lots of fun! So what are you waiting for? It's time to Go for wireless networking.

Wireless Basic

Radio Frequency Transmission Factors

Radio frequencies (RF) are generated by antennas that propagate the waves into the air.
Antennas fall under two different categories:
directional and omni-directional.
Directional antennas are commonly used in point-to-point configurations (connecting two distant buildings), and sometimes point-to-multipoint (connecting two WLANs).
An example of a directional antenna is a Yagi antenna: this antenna allows you to adjust the direction and focus of the signal to intensify your range/reach.
Omni-directional antennas are used in point-to-multipoint configurations, where they distribute the wireless signal to other computers or devices in your WLAN. An access point would use an omni-directional antenna. These antennas can also be used for point-to-point connections, but they lack the distance that directional antennas supply

Three main factors influence signal distortion:

  • Absorption Objects
    that absorb the RF waves, such as walls, ceilings, and floors
  • Scattering Objects
    that disperse the RF waves, such as rough plaster on a wall, carpet on the floor, or drop-down ceiling tiles
  • Reflection Objects
    that reflect the RF waves, such as metal and glass

Responsible body

The International Telecommunication Union-Radio Communication Sector (ITU-R) is responsible for managing the radio frequency (RF) spectrum and satellite orbits for wireless communications: its main purpose is to provide for cooperation and coexistence of standards and implementations across country boundaries.
Two standards bodies are primarily responsible for implementing WLANs:
  • IEEE
    defines the mechanical process of how WLANs are implemented in the 802.11 standards so that vendors can create compatible products.
  • The Wi-Fi Alliance
    basically certifies companies by ensuring that their products follow the 802.11 standards, thus allowing customers to buy WLAN products from different vendors without having to be concerned about any compatibility issues.

Frequencies bands:

WLANs use three unlicensed bands:
  1. 900 MHz Used by older cordless phones
  2. 2.4 GHz Used by newer cordless phones, WLANs, Bluetooth, microwaves, and other devices
  3. 5 GHz Used by the newest models of cordless phones and WLAN devices
  • 900 MHz and 2.4 GHz frequencies are referred to as the Industrial, Scientific, and Medical (ISM) bands.
  • 5 GHz frequency the Unlicensed National Information Infrastructure (UNII) band.
  • Unlicensed bands are still regulated by governments, which might define restrictions in their usage.
A hertz (Hz) is a unit of frequency that measures the change in a state or cycle in a wave (sound or radio) or alternating current (electricity) during 1 second.

Transmission Method

Direct Sequence Spread Spectrum (DSSS)
uses one channel to send data across all frequencies within that channel. Complementary Code Keying (CCK) is a method for encoding transmissions for higher data rates, such as 5.5 and 11 Mbps, but it still allows backward compatibility with the original 802.11 standard, which supports only 1 and 2 Mbps speeds. 802.11b and 802.11g support this transmission method.
OFDM (Orthogonal Frequency Division Multiplexing)
increases data rates by using a spread spectrum: modulation. 802.11a and 802.11g support this transmission method.
MIMO (Multiple Input Multiple Output)
transmission, which uses DSSS and/or OFDM by spreading its signal across 14 overlapping channels at 5 MHz intervals. 802.11n uses it. Use of 802.11n requires multiple antennas.
WLAN Standards
Standards 802.11a 802.11b 802.11g 802.11n
Data Rate 54 Mbps 11 Mbps 54 Mbps 248 Mbps (with 2×2 antennas)
Throughput 23 Mbps 4.3 Mbps 19 Mbps 74 Mbps
Frequency 5 GHz 2.4 GHz 2.4 GHz 2.4 and/or 5 GHz
Compatibility None With 802.11g and the original 802.11 With 802.11b 802.11a, b, and g
Range (meters) 35–120 38–140 38–140 70–250
Number of Channels 3 Up to 23 3 14
Transmission OFDM DSSS DSSS/OFDM MIMO

0 comments: