Feb 082014

Want To Establish A Long Range WiFi Link? Here Is What You Need To Consider. written by: aishwaryasaxena

We all have used WiFi in our homes and offices. The limited coverage of those links have made us subscribe to the fact that WiFi has limited ranges. However, it is quite possible to transmit WiFi signals over a large distance, say 20 to 25 miles or even more. This is done by establishing a long range WiFi link.

It must be understood that setting up a long distance WiFi link can be frustrating if not carried out carefully. Here are some factors to be considered while setting up a long range WiFi link.

1. Site

This is a decisive factor for your long distance WiFi link. Use a mapping software to know if line of sight link is possible between the transmitter and receiver sites that you have chosen. It is very necessary to survey the sites for any foliage that would obstruct the link.

Look for a site away from transmitters of Multipoint Microwave Distribution System or Instructional Television Fixed Service in the US or their equivalents in your country. However, if by any compulsion you need to set up your antenna near such a site, use vertical polarization because MMDS or IFTS use horizontal polarization.

2. Potential environmental obstacles

WiFi signals are generally unaffected by the ionized atmospheric layers as their transmission takes place at lower levels but temperature inversions can be a potential attenuator. This is essentially because hot air rises with moisture which causes problems in propagation. Hence any area in the route of the signals that has a temperature different than the source and transmitter may spell trouble.

Phenomenon such as refraction, reflection, diffraction and tropospheric reflections can also play a huge role in weakening the signals by scattering them and making them fail even if there is a line of sight communication.

3. Grounding

Ground your antennas properly so as to protect them from lightening and static discharge. It has been seen that many towers are left improperly grounded by using few grounding rounds and round copper cables. This is a wrong practice because round copper cables have high impedance which forces high voltages developed across these cables due to lighting to go to the equipment instead of the ground. It is wise to use at least four grounding rods for each tower leg along with some chemical grounding material. Since copper straps have low inductance, they are ideally suited for connecting ground rods to the tower. Also try to have all transmission lines run inside the tower column to protect them from the wrath of lightening.

Other conditions that may degrade the signals are presence of other services in the same frequency range nearby, errors in receiver and transmitter synchronization and high wind speed over antennas.

i. Access point (AP)

It operates as the central receiver and transmitter of your wireless signals

ii. WDS access point: This is a distribution system that allows many access points to transmit data without linking them using an Ethernet cable. This mode is limited to only one hop.

iii. Client bridge:   A standalone device that connects a Wi-Fi client via an Ethernet cable to another device

iv. Repeater mode:  It allows multiple access expansion without the need for an Ethernet cable

v. WDS bridge:  It is most beneficial in a point to point deployment

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