Interconnection of Remote GSM-R Dispatcher Terminals to a GSM-R Central Hub over E1s with Ring Protection

Global System for Mobile Communications for Railways or GSM-R is a standardized digital system for railway communications and an integral component of railway safety and security operations throughout much of Europe and other parts of the world. Based on GSM mobile technology, GSM-R streamlines many of the existing broadcast communications systems used to transmit signaling, alarms, maintenance, cargo, and passenger data and supports secure voice among various operational, maintenance and emergency teams.

 

This application illustrates how a Mediterranean railway operator deployed RAD's Megaplex-2100 multiservice multiplexer with 4-port ISDN BRI user interface module and dual E1 G.703 main link module to transmit crucial message and alarms as well as mission-critical voice from remote dispatching sites to central hubs between different railway terminals across the country.

 

The remote dispatcher terminals have a single ISDN BRI interface, which connects to the Megaplex-2100 HS-S module. This card contains four 2B + D interface channels, which operate full duplex over 4-wire twisted-pair at a range of up to 1 km (0.6 miles). For WAN connections, the remote Megaplex-2100 main link offers single or dual E1 tributary uplinks. 1:1 protective switching between any two links provides reliable transmission in case of line failure. 1:1 protective switching between the two links of a dual link module takes place within 50 msec of a link failure, ensuring PDH ring protection.

 

Megaplex-2100s at the central site are connected to a PBX. Depending on the location this may require support for single, double or multiple ISDN BRI channel connections.

 

Management of the Megaplex-2100 elements is performed in-band, using the RADview EMS management platform. RADview manages the elements via Telnet by redundant 10/100BaseT Ethernet connections to the Megaplex common logic card.

 

RAD's multiservice multiplexing system allows railway communications' planners maximum flexibility in extending their GSM-R backhaul network over E1 copper and fiber rings.

Although, the focus of interest for railway operators and their GSM-R communications engineers lays naturally in the GSM-R radio system, the vital contribution made by the backhaul network to GSM-R availability and performance cannot be overlooked. For this reason, major GSM-R turnkey manufacturers deploy RAD's multiservice access equipment to facilitate transport of mission-critical voice and data between remote dispatching terminals and central control hubs.