Indoor distribution system is a solution to improve the mobile communication environment in buildings for indoor users. Indoor distribution system makes use of indoor antenna to distribute the signal evenly in every corner of the room, so as to ensure that the indoor area has an ideal signal coverage.

Why build an indoor distribution system? With the rapid growth of mobile users in cities and the increasing number of high-rise buildings, the communication in indoor environment is also increasing, and the requirement of users for communication is also increasing. Network coverage, capacity and quality of mobile communication are the key factors for operators to gain competitive advantage. Network coverage, network capacity, network quality fundamentally reflects the level of mobile network services, is the theme of all mobile network optimization work. The indoor mobile communication environment has too many needs to perfect the place: the coverage aspect: because the building own shielding and the absorption function, has caused the radio wave big transmission loss, in terms of capacity, buildings such as shopping malls and conference centres can not meet the demand of users due to the high density of mobile phone usage, the quality aspect: the high-rise building space is easy to have the wireless frequency interference, the service area signal is not stable, appears the ping-pong handoff effect, the voice quality is difficult to guarantee, and the phenomenon of dropped signals.