Utilizing a centralized digital CPRI distributed architecture, HELIOS^® TETRA Band Digital CPRI Optical Transport System is a two-tier architecture consisting of the Optical Master Units (OMUs) and Optical Remote Units (ORUs). RF signals from Base Stations, off-air, BDAs or combination thereof can be received. In the case of off-air feed, the OMU has the option to combine the functions of the off-air Repeater and OMU to provide transmission and distribution of radio signals. The signal is filtered and then converted to a digital CPRI data stream. The digital CPRI packet data stream is transported via single mode fiber and received by the ORUs. The ORUs then convert the digital CPRI packet data stream back to RF and amplify the signal for delivery to the antennas. On the reverse path (uplink), the ORUs and OMU perform the inverse functions and delivery the signals back to the corresponding off-air antenna, BDAs or Base Stations.

 The whole system network topologies including star, chain and hybrid to cater to different deployment scenarios. These network topologies provide reduced fiber plant usage and installation cost, and effective fiber loop redundancy configurations.

 Time slot Based AGC function reduces the near-far effect. When a strong signal from portable radio which uses the first time slot near the repeater causes the AGC and it reduces the uplink gain, further away portable radio which uses the second time slot in the same channel will also be affected, due to the gain reduced. With Helios® time slot based AGC function, it equalizes the signal levels between the two time slots calls, fewer dropped calls and higher reliable communication will be achieved.

Optical Master Unit - OMU

The 19” rack-mountable OMU is typically located at a Base Station. On the forward path, the OMU receives the RF signals from the BTS and digitizes the designated RF bands and digitally transports them over single mode fiber to the Remote Units. On the reverse path, the OMU receives the digitized RF signals from the Remote Unit and converts them back to RF for the BTS.

Each OMU has four 10Gbps SFP+ digital optic ports and supports up to 32 ORUs by star, chain, ring and hybrid network topologies. The OMU utilizes an embedded WEB management system for system configuration and network monitoring. The embedded WEB management system collects alarm information from both OMUs and ORUs.