Non-Line Of Sight

What Does Non-Line Of Sight Mean?

Non-line of sight (NLOS) refers to the path of propagation of a radio frequency (RF) that is obscured (partially or completely) by obstacles, thus making it difficult for the radio signal to pass through. Common obstacles between radio transmitters and radio receivers are tall buildings, trees, physical landscape and high-voltage power conductors. While some obstacles absorb and others reflect the radio signal; they all limit the transmission ability of signals.


Non-line of sight is also known as near line of sight.

Techopedia Explains Non-Line Of Sight

Non-line of sight is a term often used when the radio transmitter and receiver are not in the direct visual line of sight, and this is dealt with by the use of multiple paths in signal propagation. Non-line of sight can be overcome with the use of antennas and other such communication devices. Distance also plays a significant role in lowering the receiving power of a signal, leaving a poor transmission system. Modern computer networking’s biggest concern is to effectively reduce the NLOS, and this is done on wireless networks by using relays at various points so that the signal is transmitted around the obstruction without loss of data or transmission quality. Multipath signal propagation is also widely used.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.