RF (Radio Frequency)
Transmission of data is carried out using radio frequencies (RF) in wireless communications. The electromagnetic spectrum contains different radio frequency bands dedicated to different services. Digital cordless phones, personal digital assistants, laptops, pagers, Personal Computer Memory Card International Association (PCMCIA), and other devices operate in the 800 MHz to 2.5 GHz portion of the electromagnetic spectrum. Radiofrequency (RF) signals are used in transmission from one device (transmitter) to another (receiver) through open space. As long as both devices are set to the same frequency (or channel) and communicate using the same protocol, the transmitter, and receiver can always be in communication with one another. An electrical signal is applied at one end and carried to the other end of a wired link to transmit data across it. The signal can spread quite easily because the wire is continuous and conductive. There are no physical cables or other means of signal transmission in a wireless link.
Wireless Principles in CCNA
Wireless communication takes place over free space over RF (Radio Frequency), where one device (transmitter) sends a signal to another device (receiver). Two devices (transmitter and receiver) must use the same frequency (or channel) to communicate with each other. Radio frequencies can cause interference when many wireless devices communicate at the same time. As the number of devices increases, the interference increases. The following topics describe the concept of wireless principles in CCNA.