Technical Challenges For Telecom Companies To Build Wireless Networks In The Railway Environment

1. Technical Challenges For Telecom Companies To Build Wireless Networks In The Railway Environment Communications Regulations and Management Conference November 5th & 6th 2008, London Michael Liem GSM-R Solution Manager

2. Introduction • Even for companies specializing in Wireless Telecom, the RF Engineering is by far the most critical and difficult issue when deploying a Wireless Network for the railway environment (such as GSM-R). This presentation gives some key insights into these risks, the root causes for failure and provides practical recommendations for railway operators

3. Agenda • Typical RF issues when deploying GSM-R - What’s the problem? • Technical differences in RF Design for track-side communication networks as opposed to public wireless networks - Why are railways special? • Inventory of key technical skills required in the Telecom Industry - Why do we have a problem? • Associated risks for railway operators and possible mitigation options - How can we solve it?

4. Typical issues when deploying GSM-R • Many RF coverage holes due to missing sites and/or bad positions • Much more radio sites deployed than necessary. (You may not even be aware of this!) • Unexplained Call drops which you cannot solve even after major tuning attempts and after engaging “specialists” • GSM-R QoS does not meet the requirements for ETCS deployment • In dense urban areas, coverage is not limited to rail track, but covers a much wider range (Interference, UMTS900) There are significant technical, operational and financial risks related to RF in GSM-R

5. A quick reminder : The RF Engineering Chain (simplified) Step 2 Step 1 Step 3 (Network is built) Understand the environment & the real world Propagation Plan the sites using RF Planning tools and predict coverage Optimize the coverage & network performance RF Field Engineering RF Planning RF (Network) Optimization There are 3 major phases in RF Engineering when deploying a network

6. Technical differences - Specific RF propagation environment in GSM-R Cuttings have specific waveguide characteristics Bridges are metallic reflectors Tunnels are specific waveguides Measurements along railway lines have shown that railway radio channels have particular characteristics and specific propagation behaviour, that were not considered previously in GSM. Tunnels, Bridges and Cuttings require specific RF design

7. Technical differences- Specific RF model Calibration required for GSM-R Transmitter right alongside the railway track in operation Reception chain in running trains RF propagation models used for public GSM planning are not suitable for the railway environment. Specific measurements for RF model calibration are necessary. These measurements are technically and logistically very difficult to perform due to the safety constraints in the railway environment. Specific RF measurements for model calibration required along the track line

8. GSM-R case GSM case Cell 4 Cell 2 Cell 2 Cell 1 Cell 1 Cell 3 Coverage hole Technical differences - Linear RF coverage in GSM-R In GSM, coverage holes due to imprecise predictions can be filled with surrounding cell coverage. In GSM-R, imprecise RF predictions can easily lead to coverage holes. Coverage predictions in GSM-R must be much more precise than in public GSM

9. Technical differences - Required RF level in GSM-R RF Level of an example GSM-R line To illustrate the difference in RF level: GSM: ~ 1 call drop every 3 hours GSM-R: 1 drop every 100 hours.  RF coverage must allow a 30 x better call drop in GSM-R compared to public GSM ! Mean RF Level 20db Typical mean RF Level in GSM Minimum RF Level for ETCS L2 Conclusion: GSM-R RF Engineering is similar to GSM but much more difficult

10. The key skills required - The RF Engineering Chain RF Field Engineering Network Optimization RF Planning Technology Independent Skills Technology Independent Skills Technology Dependent Skills (WCDMA, WIMAX, GSM, LTE, CDMA) Real world Propagation Field measurements Tunnel Coverage Interference measurements Theoretical Predictions Propagation model tuning RF planning methods & tools Frequency Planning Network Optimization Drive tests with Trace mobile Parameter tuning (once network is built). Practical field Engineering RF Planning Network Optimization Need to have extensive experience in real world propagation. Need to have full understanding between real world and planning method. Understanding of how RF planning is linked to real-world propagation is essential

11. Evolution of RF Engineering in the industry • 1993 – 1997 • Deployment of first GSM networks. Many RF engineers on the market deploying the networks. High focus on understanding the technology requiring field campaigns. • 1997 – 2000 • Industrialization of Network deployment processes. Outsourcing of RF field activities considered as « low value » and maintenance of « higher value » RF planning activities. • High focus on RF planning tools. Many programmers becoming RF planners using complex RF planning tools. • Internet hype luring talented engineers to IP technology. • 2000 – 2007 • Blast of Internet bubble leading to overall increased cost reduction in Telecom industry. Further outsourcing or discontinuing of RF field activities. • High focus on solving System optimization issues in UMTS on top of RF.

12. Current situation of RF skills in the Wireless Industry • Very few experienced RF engineers on the market • Crucial lack of understanding of the RF engineering chain • In many Wireless companies (equipment manufacturers, operators, service companies) the RF chain is divided into sections in which the RF field expertise is nearly absent • Extensive use of RF planning tools, often without the required understanding of risks and implications • Often total absence of the understanding of the RF chain on management level in Telecom companies and little awareness of associated risks • High demand for real experts as same experts are required for all emerging technologies (3G, WiMAX, LTE, etc) • It is unrealistic to believe that you will find an entire team of real RF experts to deploy your GSM-R network. The fact is that the majority of RF engineers you will find will be lacking some major skills RF skills required for GSM-R are very scarce on the market. What can we do ?

13. The solution: The right partner and the right process RF Field Engineering phase RF Planning phase RF planning production (non-expert RF Engineers) Model calibration CW measurements Training Track survey Tunnel Design = Experts Audit Red Audit Audit = Risky activity Audit (Process is an example for illustration and can change depending on project) High RF expertise combined with the right process is the optimum solution for reducing the risk during the RF deployment.

14. Recommendations when outsourcing RF Engineering in GSM-R How to find the right expertise ? Ask potential partners for a technical presentation on RF deployment projects in the railway environment and the lessons learned from it. Checklist for evaluation (not complete): BAD • No experience in railways • Statement: “ GSM-R is the same as GSM” • “..We will outsource CW measurements. Everybody can do it.” • “..We will rent the equipment for field measurements”.( they don’t do it often…) • Presentation focuses on RF planning tool. Engineers seem to be more theoretical. • “We take the propagation model from GSM.” • The RF engineers do not have grey hairs. GOOD • Experience in railway projects • Statement: “GSM-R is more difficult than GSM.” • “…We do the CW measurements ourselves. This requires a lot of experience…” or “..We will extensively audit our subcontractors...” • “…We will use our own equipment..”. • Presentation focuses on experience and visual survey. Proper Transfer from field to the RF tool is key. • “Calibration of the propag. model is a major risk.” • The RF engineers have grey hairs. How to evaluate the processes ? Have a detailed look at the RF Engineering process and make sure that the risky phases are controlled / audited by experts as part of the process. Reducing the risk through this process is key to compensate any gaps in skill levels and to guarantee a quality design .

15. Summary • RF Engineering is by far the most risky technical domain when building a GSM-R network (or another wireless railtrack network). • GSM-R RF Engineering is similar to GSM, but much more difficult due to the specific railway environment and mandatory quality standards. • There are few real RF experts on the market who have the key skills required. It is unrealistic to believe you will find a whole team of these experts to build a larger GSM-R network. • The solution is to find a partner who has the technical expertise and who is able to leverage them through the right processes in order to reduce the risks of larger deployments of GSM-R networks. • When evaluating a partner you should look for visible experience, a clear understanding of the risks in the RF process chain and for solid quality processes which allow risks to be controlled.

16. Questions?

17. Stay in Touch Michael Liem GSM-R Solution Manager Industry & Public Sector Solutions Tel.: +33 1 30 77 07 58 Michael.liem@alcatel.lucent.fr

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