The GSM-R system in Spain

GSM-R is a communication system for railway operations based on the standard ETSI GSM of public radio with additional railway features defined in the EIRENE (FRS, SRS) and MORANE specifications.These specifications have been developed by mandate of UIC and in collaboration with ETSI, to ensure interoperability between railway networks of different countries.

The GSM-R system is a network support of communications for the following applications of voice and data:

• ERTMS-ETCS Automatic Train Control System (data)
• Ground-Train communication (voice)
• Broadcast voice calls
• Group voice calls and emergency calls
• Location dependent addressing and Functional addressing (train running number)
• Shunting operations in marshalling yards with a link assurance signal (voice)
• Diagnostics and automatic mobile network management (data)
• Services of Value Added to the passengers: Ticket sale on board, consultations to data bases, and information (data)
• Other data services (GPRS)

In 1995, two frequency bands were reserved for railway use across Europe – 876-880 MHz (up link) and 921-925 MHz (down link). This bandwidth of 4 MHz allows a maximum of 19 carriers (number 955 to 973) spaced 200 kHz, with a band guard at the ends. Each carrier takes eight channels of voice/data (7 channels + 1 of signalling).

The radio coverage is formed by elliptical cells throughout the layout, with directional antennas in the direction of the track. During planning, it is necessary to consider a zone of overlapping between cells of approximately 700m (8 seconds to 300km/h), sufficient to carry out the hand over.

In Spain, all the new HSL have been designed for ETCS level 1 and 2 and a greater reliability of the system is required in case of a failure of a repeater (BTS).We have adopted the solution of double coverage by means of redundant installation of BTS and BSC with a total overlapping of all the cells. Thus two layers of completely independent cells are obtained. Each layer can transport all the generated traffic and there is normally a privileged address. For example, the trains that leave Madrid use layer B and those that leave Lérida use layer A. If coverage failure occurs, the trains in that cell exchange to the other layer and return again to the first when the signal levels are higher.

GSM-R network in Spain

The GSM-R system has been developed in Spain for two fundamental reasons:

• The requirements of the HSL (standard rail 1,435 mm. gauge) to have a radio infrastructure of telecommunications with a high level of reliability to the transmission of vital data to the operation of ERTMS-ETCS level 2 system
• In the Conventional Rail Lines (Spanish 1,668 mm. rail gauge), the obsolescent analogical radio system (UIC- 751.3) in 450 Mhz. This network was built mainly between 1984 and 1994. It has an overall length of 7,640 km, circa 2,000 fixed stations of repeaters and is installed in 1,300 locomotives and train units (in two cabins) . This network has a lack of capacity (only 1 voice/data channel)

The GSM-R network in Spain will have an overall length of approximately 12,000km – that’s 7,000km in Conventional Rail Lines and 5,000km in the HSL.

The two models

Firstly, on the Conventional Rail network, an agreement has been reached with Siemens and Nortel – the two GMS-R equipment providers certified by the UIC, for the gradual implementation during the period between 2005 and 2012. The criterion for the distribution has been geographical and thus the optimisation cost has been obtained. The progress of the construction of this network has been slowed down by financial problems. It is necessary to consider not only the radio network cost but also the cost of the complementary civil work (energy, optical fibre cables and transmission equipment, SDH, shelters and towers for antennas).

Secondly, on HSL, because they are new constructions, there is great capacity of telecommunication infrastructure and no problems occur with energy or the location of towers. To give an idea of the equipment implemented in a HSL, here are the main characteristics of the Madrid-Lérida HSL:

• An overall length of 481km double track
• 28 technical buildings
• A maximum operation speed of 350km/h
• 28 tunnels with a total length of 25,869m
• Electrification: 2 x 25 kV, 50 Hz, 9 traction sub-stations and 40 AT centres
• ERTMS-ETCS level 1 and 2 Automatic Train Control System
• 13 (ENCE) electronic blocks
• A telecom infrastructure consisting of 2 cables of 32 and 64 optical fibres by each side of the track
• Transmission equipment SDH: two rings of STM-4 and STM-16
• 33 digital PABX telephony
• Data network IP: two networks operative of real time (exploitation) and multiservice
• ATM network: 5 nodes
• Sensors, video monitoring and access control
• Supervision and management centralised in Madrid-Atocha and Zaragoza (CRC) On

HSL, the network planning requirements are:

• A minimum coverage level of signal power: -85 dBm (-70 dBM inside the tunnels) over 95% of the designated coverage area at least 95% of the time
• Speed of trains up to 500km/h
• Less than 0.5% of calls should be lost in the handover (HO) when a train passes from one cell to the next
• A maximum temporary time cut in the passage of the communication (HO): < 300 ms
• Railway emergency calls: < 2 s
• All operational calls: < 5 s
• All low priority calls: < 10 s

GSM-R is in operation on the following HSL:

• Madrid-Zaragoza-Lérida (481km)
• Zaragoza-Huesca (80km)
• Madrid-Sevilla (471km)
• La Sagra-Toledo (22km)

GSM-R is in construction on:

• Lérida-Tarragona-Barcelona (185km)
• Córdoba-Málaga (200km)
• Madrid-Segovia-Valladolid (150km)

The architecture of the network nowadays:

• 2 MSC. Madrid-Atocha (MSCA, BSCA, O+M, IN, MC) and Zaragoza-Delicias (MSCB, BSCB, O+M)
• 7 BSC of high capacity: 3 in Madrid, 3 in Zaragoza, 1 in Huesca
• 213 BTS in operation, 160 BTS in construction in the new HSL
• 2 Maintenance and Operation Centers: 1 in Madrid and 1 in Zaragoza
• 12 Dispatchers: 8 in Zaragoza and 4 in Madrid