Wireless Networks
Wireless transmission moves the data through air and space. It does not need a fixed physical connection between the source and the destination. Radio and television are examples of wireless transmission. Wireless transmission involves microwaves, satellites, wireless networks and mobile phones.
A microwave is a high-frequency radio signal sent through space in a straight line from one antenna to another. Microwaves have been used for several decades to transmit both voice and data. Antennas are placed on tall buildings or mountain tops to continue transmission over long distances. Microwave transmission is faster than telephone lines or coaxial cables. Even though it is reasonably error free, weather conditions or such objects as trees and buildings can obstruct the signal and affect the transmission.
A satellite is a specialised receiver and transmitter that is launched by a rocket and placed in orbit around the earth. A signal is sent from one ground station to the satellite, which receives and retransmits the signal to another ground station. Each ground station uses a satellite dish to send and receive the signals (see Figure 3.16). Satellites can transmit large amounts of data over long distances and at great speeds. There are hundreds of satellites currently in operation. They are used for weather forecasting, television broadcasts, radio communications and Internet communications