5 common myths of Wireless Communication

21 May

Multiple antennas automatically mean MIMO: A common misconception is that multiple antennas would obviously mean MIMO technology, the truth however is that wireless radios have long since been using multiple antennas for what is called “antenna diversity” where the antenna with better RSSI level is used to receive the information.

Wireless LoS (line of sight) is a simple visual line of sight: Quite often explained as a mere line of sight, a wireless LoS is a little bit more complicated than that. A wireless LoS is best defined with the concept of “Fresnel Zone” where the LoS is actually a ellipse shape area that is required to be at least 60% clear of any obstruction to ensure the highest performance of wireless link. Below shown is the primary Fresnel zone as against a typical understanding of a Line of Sight

 Primary Fresnel Zone

The higher the encryption standard, the lesser the throughput: One of the most common assumptions, is that because WPA2 (key size: 128 bits) is more secure  and uses bigger key sizes than WPA (true key size: 104 bits) or WEP (40 bits).The overheads should consequently be higher. Well the fact is that WEP adds 8 bytes; WPA2 adds 16 bytes, while WPA adds 20 bytes to the overheads.

Mesh can work in non line of sight scenarios: Mesh is a technology implementation of the radios. The behavior, based on the laws of physics, of the radio waves generated by a radio used in a Mesh solution are the same as for other radios. Mesh solutions are often used in an urban environment where the radio waves are reflected by the buildings nearby. These reflections and the use of an omni-directional antenna make it look like that Mesh works in non line of sight conditions. This is only possible when you have your Mesh access points located close to each other (50-200 meter a part) and enough reflection objects.

 Adjacent non-overlapping channels do interfere: Blindly assumed by many, that non-overlapping channels such as channel 1,6,11 in the 2.4 GHz frequency don’t interfere, however the actual fact is that there despite the best efforts, there is a small amount of spillover to the adjacent non-overlapping channels. As a matter of fact ,the transmit power of the radio is directly proportional to the spillover.

Source: http://worpspeed.proxim.com/2013/05/20/5-common-myths-of-wireless-communication/

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