What type of communication technology relies on line-of-sight?

Infrared (IR) communication technology relies on line-of-sight because it uses infrared light to transmit data wirelessly between devices. This means that for successful communication, the transmitting and receiving devices must be within a direct, unobstructed path of each other. Any physical barriers, such as walls or large objects, can interfere with the infrared signal, making it ineffective if the line of sight is blocked.

In contrast, Bluetooth operates using radio waves and does not require a direct line of sight between devices, allowing for communication even with obstacles in place. Low Earth Orbit Satellites and Geosynchronous Satellites, while they do utilize radio waves for communication, do not depend on a line-of-sight in the same way that infrared does. These satellite technologies allow for broader coverage and can transmit signals across vast distances, regardless of direct sightlines.