Wireless LOS Terminology

November 28, 2013 at 10:00 AM

Why Line of Sight (LOS) is so important

 

Sample of LOS and Fresnel Zone Diagram

When designing an outdoor wireless network, ask yourself this: what is between point A (antenna 1) and point B (antenna 2)? This path between two antennas is referred to as the Line of Sight (LOS).

 

There are three main categories of Line of Sight. Full Line of Sight (LOS) is where no obstacles reside between the two antennas. Near Line of Sight (nLOS) includes partial obstructions such as tree tops between the two antennas. Lastly, Non Line of Sight (NLOS) is where full obstructions exist between the two antennas.

 

By determining the specific Line of Sight conditions in the WiFi network area you can then determine the correct type of wireless system to install.

 

Another common term to be aware of is The Fresnel Zone, referenced in the diagram above. It is is an electromagnetic phenomenon where light waves or radio signals get diffracted or bent from solid objects near their path. The radio waves reflecting off the objects may arrive out of phase with the signals that traveled directly to the receiving antenna, thus reducing the power of the received signal.

 

Line of Site (LOS) Overview Diagram

Print and post the above diagram.

 

For indoor wireless network installations it is important to consider obstacles such as walls, ceilings, and furniture that will affect Line of Sight since these all play a role in wireless signal reception. In wireless transmissions, reflections (when wireless signals "bounce" off objects) and multipath (when wireless signals travel in multiple paths arriving at the receiver at different times) are as important as signal strength in determining the success of an installation. A signal will also exhibit peaks and nulls in its amplitude and alteration of its polarization (vertical or horizontal) when propagating through walls, ceilings and reflecting off metallic objects. 

 

Path Loss is another area of concern when dealing with Line of Sight. For instance, although 2.4 GHz signals pass rather well through walls, passing through trees and leaves is a challenge. This is due to the difference of water content in each. Radio waves in the 2.4 GHz band absorb into water very easily, so the high level of moisture in trees or leaves would trap the waves. When faced with nLOS or NLOS conditions due to trees, 900 MHz is your best choice as it is not absorbed like 2.4 GHz.

 

 

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How to Extend the Range of Your Wireless Signal

September 4, 2013 at 10:00 AM

 

 

One of the most common questions we are asked is: "How do I extend my WiFi signal?" Whether you need extension for an indoor or outdoor application, here are your options:

 

Use a higher gain antenna: By using a higher gain antenna you can extend your wireless signal range, though one thing to consider when using a higher gain antenna is potential loss of vertical signal coverage. Typically when you increase the gain on an antenna the RF gain pattern becomes more focused and produces a narrower horizontal beam. Read more about this phenomenon of higher gain causing less vertical signal coverage.

 

Add a WiFi amplifier: By adding a WiFi amplifier you can boost your wireless signal. We suggest trying one of our WiFi booster kits that are available for purchase by anyone in the United States without the need for a special FCC license. These kits offer easy set up and strong signal extension and coverage capabilities. Additionally we offer RF amplifiers for export, military and FCC licensed users supporting frequencies ranging from 900 MHz to 5.8 GHz.

 

Upgrade from 802.11b/g to 802.11n: If you are currently using 802.11b or 802.11g access points and wireless adapters, consider upgrading to the latest IEEE standard, 802.11n. 802.11n offers better range and speed than 802.11b and 802.11g standards products.

 

Use a higher power Access Point: A typical WiFi router or Access Point provides about 30mW of transmit power. By upgrading to a higher power access point or router you can boost your wireless signal resulting in extended coverage.

 

As with any wireless installation, Line of Sight and the Fresnel Zone must be considered along with other factors such as multipath interference. These phenomena and your physical environment (obstacles, obstructions etc.) all affect your signal strength and range.

 

WiFi Antennas WiFi Amplifiers WiFi Access Points
WiFi Antennas WiFi Amplifiers WiFi Access Points

 

By using one or a combination of these aforementioned upgrades and additions you can provide greater wireless signal coverage. Good luck!

 

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