| Wireless LAN (WLAN) is a wireless | | | | lower data rates. Higher Frequencies (5 |
| broadband technology that utilizes radio | | | | GHz) have less range but higher data |
| frequency (RF) to transmit and receive | | | | rates but is prone to blocking by solid |
| data through the air, minimizing the | | | | objects. These are attributable to |
| need for wired networks. There are two | | | | attenuation and interference. |
| competing RF technologies in the use of | | | | Attenuation or the loss of signal |
| Wireless LAN, the IEEE 802.11 standard | | | | strength during transmission is higher |
| and proprietary technologies. Both fall | | | | when the receiver is farther from the |
| under wireless broadband technology. | | | | transmitter. Obstacles such as mountains |
| Broadband means the ability to transmit | | | | and buildings also contribute to |
| high-speed voice, data and video traffic | | | | attenuation by blocking or weakening |
| using a wide range of frequencies on a | | | | radio signals, causing signal loss or |
| single wireless medium or device. This | | | | dead spots. Depending of what they are |
| page aims to give you an overview about | | | | made of, floors, walls, and ceilings can |
| Wireless Broadband -IEEE 802.11 standard | | | | either strengthen or weaken WLAN |
| commonly called Wireless LAN. 802.11 is | | | | signals. Interference can be caused by |
| a standard agreed by the IEEE (Institute | | | | nearby stations operating in the same |
| of Electrical and Electronics Engineers, | | | | frequency on the same channel. 2.4 GHz |
| Inc.) the world's leading professional | | | | cordless phones for instance can cause |
| association for the advancement of | | | | great interference on 802.11b wireless |
| technology. 802.11 is the standard | | | | networks. Wireless broadband and WLAN |
| adopted by IEEE to define an over the | | | | devices are called transceiver devices |
| air interface between a wireless client | | | | since it both transmit and receive at |
| and base station or between two wireless | | | | the same time. Each component both |
| clients. The 802.11 standard has evolved | | | | transmits and receives IP traffic. |
| over the years and became one of the | | | | Antennas direct RF power into the air |
| most successfully deployed technologies. | | | | over a coverage area. An Antenna |
| The standard now covers 802.11b, 802.11a | | | | provides wireless LAN devices gain, |
| and 802.11g systems. Radio Frequency | | | | direction and polarization. Gain is the |
| (RF) is the medium use by wireless | | | | measure of increase in power while |
| networks in the transmission of | | | | direction is the shape of the |
| information over the air. RF works by | | | | transmission pattern. Polarization is |
| converting electrical current into radio | | | | dependent on antenna alignment and can |
| waves and transmit those waves over the | | | | be typically described as vertical or |
| air using a defined frequency of the | | | | horizontal. Most Access Point antennas |
| radio spectrum. An example, the AM and | | | | are designed to operate in vertical |
| FM radios two most commonly known uses | | | | pattern for maximum horizontal coverage |
| of the RF spectrum. The Federal | | | | plane or polarization. Putting the |
| Communications Commission (FCC) is the | | | | antenna in a horizontal position will |
| one administering the use of radio | | | | result in a vertical plane limiting |
| spectrum between the frequencies of 9 | | | | coverage. The factor to consider in |
| Kilohertz (KHz) and 300 gigahertz (GHz). | | | | increasing the range of Wireless LAN |
| 802.11 WLAN systems operate in the radio | | | | devices is the Antenna and EIRP. EIRP or |
| spectrum available to the public, also | | | | Equivalent Isotropically Radiated Power |
| known as the unlicensed frequency band. | | | | is being governed or limited by FCC |
| These radio spectrum bands are | | | | regulations to a maximum of Four (4) |
| unlicensed, free for use by anyone | | | | watts with additional restrictions |
| provided FCC regulations are complied | | | | limitations depending on type of antenna |
| with. The FCC as a regulatory governs | | | | (directional or omni-directional) and |
| the maximum transmit power of wireless | | | | antenna placement (indoor or outdoors). |
| radios as well as, type of encoding and | | | | Some countries limit EIRP to as much as |
| frequency modulations to be used. In | | | | 100mw, above this will require a license |
| 802.11 operations, it is provided for by | | | | to operate. This applies mostly for |
| the FCC that non-licensed radios (such | | | | outdoor WLAN equipments. To deploy |
| as 802.11) must accept interference from | | | | long-range outdoor wireless broadband |
| licensed electronic systems. FCC | | | | and WLAN devices, please consult your |
| considers licensed device as the primary | | | | country's telecommunication commission |
| equipment. 802.11 Wireless LAN Standard | | | | guidelines on use of outdoor wireless |
| Operating Frequencies: The 802.11 | | | | broadband (WLAN) devices. The goal is to |
| standard are assigned frequencies 2.4 | | | | reach people yearning to start their own |
| GHz (2.4-2.4835 GHz) on ISM Band and 5 | | | | home-based business even in remote |
| GHz (5.15-5.25 GHz, G.25-5.35 GHz, | | | | regions thru cost-effective internet |
| 5.725-5.825 GHz) of the U-NII band. | | | | business and long-range wireless |
| 802.11b and 802.11g operates on 2.4 GHz | | | | communication solutions. |
| while 802.11a is operating on the 5 GHz | | | | The author, Allan Amps is from the |
| band. 802.11 assigned frequency range | | | | Telecom industry and has passion and |
| has different characteristics. Lower | | | | interest in rural, remote internet |
| Frequencies (2.4 GHz ) exhibit better | | | | connectivity solutions, wireless gadgets |
| range but with limited bandwidth and | | | | and internet home-based business. |