A LTE repeater (also known as cell phone signal booster or amplifier) is a type of bi-directional amplifier used to improve UE reception and address coverage issues.

LTE repeater does not just do power amplification of the received signal from LTE eNB or LTE Base Station, it also selects the band specific signals using one duplexer. After amplification it transmits the signal back to the UEs(User Equipment) or Mobile Subscribers

LTE repeater receives the signal from LTE eNB (e.g., base station) and re-transmits it after amplification towards UEs. As it amplifies noise along with the signal, SNR degrades. As a result, LTE relay is used which has FEC (Forward Error Correction) functionalities in addition to amplification. Hence SNR is maintained.

Duplexer is used in case of FDD LTE repeater, otherwise for TDD repeater, duplexer is replaced with band pass filter.

Both indoor and outdoor cellular repeater deployments are possible, but a majority of deployments occur inside buildings where coverage is weakened by attenuation from building materials