As a common transportation, Railways transportation increases the carrying capacity, shortens the transportation time and decreases the transportation cost which improve the quality of transportation services, yield greater customer satisfaction, and help to create the socioeconomically balanced societies. And this highly efficient transport mode creates significant challenges in terms of investment, technology, industry, and environment.

To handle increasing traffic, ensure passenger safety, and provide real-time multi-media information, GSM-R communication system and more advanced LTE-R communication system is required. GSM-R is essentially the same system as the GSM but with railway-specific functionalities. The GSM-R network serves as a data carrier for the ETCS, which is the signaling system used for railway control. To provide improved and more efficient transmission for railway communication, LET-R has many advantages over GSM in terms of capacity and capabilities. LTE-R which is based LTE standard will replace GSM-R in the future.

HELIOS^® GSM-R Digital Optical Transport System is designed to extend the railway coverage of GSM Based communication.

Utilizing a centralized digital CPRI distributed architecture, HELIOS^® GSM-R Digital 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, can be received. 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, or radiating cable.

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.