technology

Designing and Planning a GSM-R Network

The first step in the provisioning of a GSM-R network are the design and planning phases. The following describes the most important procedures and considerations for a typical GSM-R network.

Nominal Cell Planning

Translation of operator/customer requirements

For network planning, the coverage level is defined in terms of the area and time where the minimum signal criteria are achieved. This we do in full compliance with the EIRENE specifications and with the customer’s requirements, which in the case of GSM-R typically consist of or include government requirements. The typical level of coverage should be at least 95% of the time over 95% of the designated coverage area for a radio installed in a vehicle containing an external antenna.

A GSM-R system must provide communication for mobile devices travelling at speeds from 0 km/h to at least 140 km/h. However, individual clients specify the maximum speed needed to support their trains; this in turn influences the cell overlap in the nominal design.

For radio network planning, the minimum coverage level is defined as the power measured at the antenna port of an isotropic antenna (antenna gain: 0dBi) on the roof of the train; this is usually 4 meters above the track. This criterion will be met with a certain probability in the coverage area, as the target coverage power level is dependent on the statistical fluctuations caused by the actual propagation conditions. The minimum coverage level might be different, depending on special requirements from railway operators.

Although a network could be designed for minimal cost, a common recommendation is to use the following values:

In addition to the coverage and quality being specified for a train, other factors can be taken into account as well. This can include the required levels for handheld mobile equipment in shunting areas, or indoor for station staff and security operatives. Obviously, customers can specify other factors which may impact the radio network design; for example, the required redundancy in the network can be higher and call for the utilization of a full redundant coverage ETCS design or the Hot Standby TRX option.

Link Budgets

The link budget is created from the translation of the customer requirements into specific coverage/quality levels. This is a theoretical calculation based on a number of assumptions, which provide the radio design engineers with a framework of radio losses and gains for both the downlink and uplink paths.

The information gleaned from the link budget provides a sound assumption for what the cell radius for the coverage will be, as well as an indication of the signal levels sent and received at the antennas. This is essential information for the radio engineers in establishing the site count, handover overlaps and other aspects of the Nominal Cell Plan.

Nominal Cell Plan

The Nominal Cell Plan (NCP) is an official document with specifications of parameters and equipment used for the radio access. It also gives an estimate of the number of sites needed. The nominal cell plan is usually the starting point in the rollout of a GSM-R network.

A typical Nominal Cell Plan contains the following information:

Final Cell Planning

Train Line/Track Survey

A Track and Line Survey is optional, but this can be a very useful exercise before the detailed planning commences.

For a Track and Line survey a train is used in which basic survey equipment is installed (GPS, mapping data). Records on a Tablet PC provide details such as the ground heights and the exact route the track takes. This is coupled with notes taken at various distance markers along the track of features such as bridges, cuttings, tunnels and locations where the track runs through towns or thick forest areas. Together with the GPS reading, a camcorder records the line so that the radio engineers can minimize the number of surveys

Continuous Wave Measurements

Continuous Wave Measurements (CW-measurements) are used in preliminary radio path calculations, to derive initial qualitative and quantitative information in order to design BTS site configurations and in particular to support antenna design. In addition, data obtained here will validate the computing algorithms of the radio planning tool used and adapt them to reality in order to comply with GSM-R requirements; this provides the engineers with accurate topology losses, which add further accuracy to the Final Cell Plan. This is known as model tuning.

CW measurements should be carried out in a variety of environments including cuttings, embankments, bridges, tunnels, routes in built up areas, as well as routes in both flat and hilly terrain. The measurements taken at varying base antenna heights ensure that the analysis takes into account the variation in base station antenna heights.

Site Surveys

It is vital that the engineers carrying out this survey have experience conducting radio surveys and look at the situation through “radio eyes“. If possible, the survey team should be joined by trained radio network engineers who have already performed surveys in other network rollouts.

The required details for a proper site survey are:

All the details above should be included in a Site Survey Report, in so far this is feasible. If there is a choice in sites, these should be ranked from most to least suitable. The relevant parties, including the engineer, acquisition manager and build manger, should then select the best option for inclusion in the Final Cell Plan.

Final Cell Plan

The Final Cell Plan is a detailed document which contains information about specific sites, site positions, antenna types, antenna heights, BTSE type and so forth, on which the rollout of the GSM-R network will be based. The Final Cell Plan includes a detailed Traffic Plan and a Frequency Plan. Depending on customer’s requirements, it may include BCC and LAC codes, a neighbor list for the network and a specification of Voice Group Call Areas. The Final Cell Plan typically contains a number of pictures taken at the site surveys.

The release of the Final Cell Plan is the trigger to start the implementation and building of the sites required for the GSM-R network.

Clear CinCom and GSM-R Network Design and Planning

Clear CinCom is a telecom consultancy with extensive experience in GSM-R network design and planning in Europe and elsewhere. You can read more about our services, the technologies we work with, projects we have recently completed and our specific experience with GSM-R.

Next step: GSM-R Network Optimization

Services

Clear CinCom is a small, flexible, hands-on organization. We can provide you with telecom consulting services including temporary staffing or even complete turnkey project teams. We have an all-round expertise in all types of cellular radio networking, but highly specific experience in GSM-R (GSM-Rail), LTE (4G), UMTS (3G) and Tetra networks. We use advanced equipment and in-house developed software for validation, benchmarking and network audits.

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Martijn Kuijpers

Director, Principal
Radio Planner

Do you have a specific question or would you like to know if Clear CinCom is the right partner for your project? Just send me an e-mail or give me a call on phone or Skype. My name is Martijn Kuijpers and I am director and principal radio planner at Clear CinCom. You can reach me by clicking the below button now.

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Clear CinCom has worked on diverse telecom consulting projects in numerous countries, often alongside the largest telecom consulting companies, network and infrastructure providers.

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