According to Wikipedia mobile signal repeater is a device used for boosting the mobile phone reception by the usage of three units: a reception antenna, a signal amplifier and an internal rebroadcast antenna. The latter is very much similar to the mobile phone mast used for broadcasting by the network providers. The only difference is they are much smaller and usually used in one building. Modern mobile repeater amplifiers ‘repeat’ or to be more exact rebroadcast mobile signal inside the designated area. This type of systems usually uses an external antenna to collect the best mobile signal, which is then transmitted to an amplifier unit which strengthens the signal and retransmits it locally.