When using close frequency reuse technique, system interference is the most important factor for frequency reuse ratio. Usually, power control and discontinuous transmission technologies are adopted to lower system interference. To prevent interference and improve system communication quality under the same interference condition, frequency hopping technology is used.
Therefore, frequency hopping is a very important technology for reducing GSM system interference and improving frequency reuse ratio. According to GSM standard recommendations, slow frequency hopping can be used in GSM communication system. Frequency hopping refers to the regular hopping of carrier frequency within certain range.
The frequency hopping function of the channel group in each cell can be enabled or disabled separately. Since BCCH is the broadcast channel, it does not participate in frequency hopping while TCH and SDCCH channel can utilize frequency hopping. There are two kinds of frequency hopping modes used by BTS, I.e. base-band hopping and radio frequency hopping. The mechanisms of implementation of them are not the same.