Optical repeater system

An optical relay system comprising:

• a base station interface unit configured to output radio frequency (RF) signals of multiple bands received from a base station to at least one optical distribution unit and transmit the RF signals of the multiple bands received from the at least one optical distribution unit to the base station according to frequency bands;
• the optical distribution unit configured to convert the RF signals received from the base station interface unit into optical signals and transmit the optical signals to at least one remote unit or convert optical signals received from the at least one remote unit into RF signals and output the RF signals;
• and
• the remote unit configured to convert the optical signals received from the optical distribution unit into RF signals of multiple bands, combine the RF signals of the multiple bands and output the combined signal to a mobile terminal or convert an RF signal received from the mobile terminal into optical signals and output the optical signals,
• wherein the remote unit prevents a signal from being transferred in a reverse direction when the RF signals of the multiple bands are combined.