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Differences between LOS and NLOS Paths


When communicating, the transmitter and receiver must be in the line of sight or on the same path. There won't be any obstacles in the way. LOS path communications include terrestrial microwave communication, satellite communication (SATCOM), 5G backhaul links, etc.

On the other hand, non-line of sight (NLOS) propagation occurs when the signal is received at the receiver side through a path other than the LOS path. Cellular wireless communication frequently experiences NLOS path communication. Since we are aware that LOS paths between our cell phones and cell towers are less likely, the majority of the time, obstructions like trees, buildings, and other vegetation reflect the signal before it reaches our cell phones.

When comparing their respective signal strengths, LOS has a greater signal strength than the NLOS path. NLOS pathways for higher frequencies degrade to the extent that they cannot reach the receiver. In this situation, communication is only possible on a few more robust NLOS paths.

Even though just a small number of strong NLOS paths or multi-paths (MPCs) reach the receiver, the significance of NLOS paths is still appreciated. In fact, the communication process depends on these paths since LOS paths are uncommon in cellular wireless communication.

Diversity techniques are used in transmitted signals by multi-antenna communication systems, such as MIMO systems, to establish reliable NLOS communication.

On the other hand, Beamforming enables communication in specific directions with a stronger signal while weakening the signal in others. The high path loss is combated by beam-aligning or directional transmission. Additionally, compared to omnidirectional communication, it dramatically lowers the value of the path loss exponent "n." 

# Beamforming
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