Frequency reuse is the practice of splitting an area into smaller regions that do not overlap so that each utilizes the full range of frequencies without interference. The introduction of this concept was a major step in the development of mobile phone technology.
Before the advent of cellular phones, radio telephones and other mobile communications devices relied on a single, central antenna tower to service an entire city. Each phone required a large antenna powerful enough to transmit a signal over the potentially great distance to that tower. In addition, there was a limit to the amount of phone traffic that could be supported at a given time because each tower only offered a limited number of channels.
Researchers then realized that they could increase the cap on the number of simultaneous users by applying their current technology to a smaller scale. Accordingly, they introduced frequency reuse. Mobile communications providers increased the total number of towers and reduced the size of each one's service area. Although each tower had a limited number of channels, the non-overlapping nature of the service areas allowed the same frequency to be used in each one without interference. By doing so, mobile communications providers greatly expanded the number of potential users.