Infrared signals used for short range communication. It has the frequency range from 300 GHz to 400 THz. It has wavelength from 1 mm to 770 mm. Infrared communications is achieved by using the transmitters/ receivers that modulate infrared light. Transceivers must be within the line of sight of each other directly or via reflection. One disadvantage of infrared is that is dose not penetrate walls. We can not use infrared outside a building because…"Wireless Transmission and Infrared Waves."
For wireless communication, signals can travel from source to destination in several ways they are ground propagation, sky propagation and line-of-sight propagation. GROUND PROPAGATION: Radio waves travel through the lowest portion of the atmosphere. These low frequency signal emanate in all directions from the transmitting antenna and follow the curvature of the planet. Distance depends on the amount of power in the signal. This type of propagation is called Ground Propagation. SKY PROPAGATION: Higher frequency…"Wireless Transmission of Netwrok."