Please view notes for further information on later slides                                                            1
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Mobile telecoms planning is driven primarily by coverage of population andsecondarily by coverage of geographic area, ofte...
The technical difficulties of providing high-capacity services to trains should not beunderestimated. Even with the extra ...
One of the main reasons to be excited about LTE is the associated allocation of newspectrum. The global picture for LTE sp...
Bringing LTE or “4G” to market has been accompanied a lot of hype both toconsumers and within the industry about the data ...
The significant improvement in data rates that users experience with LTE has thepotential to raise expectations for perfor...
Train operators should react to increasing expectations by equipping trains with LTEbackhaul for WiFi. Built-in LTE system...
Four main factors influence coverage.1) Frequency discussed under spectrum2) Network design is a topic in its own right an...
New coverage measurement tools can help in understanding existing coverage andplanning improvements. Conventional “drive t...
We are used to thinking of WiFi as the primary technology to provide wirelesscoverage inside a train. LTE blurs the bounda...
The use of a pure IP applications platform in LTE is a significant break from 2G and 3Gtechnology which had special operat...
We have shown how LTE provides a good technical platform for non-critical services –the main constraints are coverage and ...
We can learn from the experience in other industries on the coexistence of criticaland non-critical apps.In the design of ...
One particularly interesting piece of work is the development driven by the US of a“public safety” application based on th...
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LTE - Service Opportunities; threats and challenges for the Rail Industry

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LTE - Service Opportunities; threats and challenges for the Rail Industry

  1. 1. Please view notes for further information on later slides 1
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  3. 3. Mobile telecoms planning is driven primarily by coverage of population andsecondarily by coverage of geographic area, often with reference to licenceconditions. Railway hubs may be prioritised in this model but rail tracks themselvesare not generally seen as a centre of population and may not be recognised asrequiring any special coverage. Still we see that attitudes are changing in the mobileoperators and that the move to tiered pricing encourages deeper consideration ofhow to bring data traffic on to the mobile network. Features like Mobile LTE Relay(see later) show that mobile industry is starting to think explicitly about railapplications but perhaps not learning fully from past experience.Different investment cycles in telecoms and rail industries make it hard to coordinatea business approach.Success for both sectors will require building a relationship for cooperation andinformation exchange. Aim for telecoms industry to recognise opportunity in railsector but also requirements to address that opportunity. The rail industry tounderstand the business imperatives in the telecoms sector and how best to makeuse of available telecoms technology. 3
  4. 4. The technical difficulties of providing high-capacity services to trains should not beunderestimated. Even with the extra capacity of LTE the passage of a crowded trainhas the potential to cripple the local network and degrade service to other users. LTEon its own will not meet all the challenges of the rail environment. 4
  5. 5. One of the main reasons to be excited about LTE is the associated allocation of newspectrum. The global picture for LTE spectrum is very complicated and fragmentedbut broadly there are two spectrum ranges being allocated in most countries:1) The smaller region at around 700/800MHz in digital dividend which is good for meeting moderate capacity requirements over wide areas2) A larger region at around 2GHz which can provide more bandwidth but with more limited coverage.Where does rail fit in this spectrum plan? Most countries are not reserving LTEspectrum for particular industries or user groups therefore rail will either need to buyits own spectrum access or buy services or spectrum rights from other spectrumowners like mobile operators. One interesting question is whether rail could be asuitable application for “TV white-space”?Notable exception to the general trend of not reserving spectrum for particular usersis in the US where some 700MHz spectrum has been reserved for LTE-based PublicSafety systems. This is potentially interesting for rail as it provides motivation to buildservice capabilities on the LTE platform which might also be relevant to rail. 5
  6. 6. Bringing LTE or “4G” to market has been accompanied a lot of hype both toconsumers and within the industry about the data rates which will be achieved. It isimportant to try and look behind the hype to understand the reality.Early indications are that LTE is indeed a vast improvement over existing technologiesboth in terms of raw bandwidth and other desirable features like latency. Surveyssuggest average data rates of between 10 and 13Mbit/s to stationary handhelddevices on the US LTE networks. Early reports of LTE coverage to trains suggest20Mbit/s averages can be achieved. The effective upper-speed bound of LTE in realworld scenarios is something that still needs to be explored. Of course we don’t yetknow how this performance will change as the networks become more heavily usedand congested.Though the data rates are impressive for a single users a lot of rail applicationsconsolidate multiple users on to a cellular backhaul connection. In this context thespeeds may still be seen as somewhat limited. 10Mbit/s is only around 20simultaneous standard definition YouTube streams so this is hardly sufficient toprovide video entertainment to a whole train (and perhaps not even a wholecarriage) of users. Meeting consumer demand for video is still going to be a challengethat will need particular attention. 6
  7. 7. The significant improvement in data rates that users experience with LTE has thepotential to raise expectations for performance of in-train WiFi to levels that cannotbe achieved by existing solutions based on 3G backhaul. A users experience with apersonal LTE dongle or hot-spot may well be better than they get with in-train WiFi.This may mean that instead of using WiFi the users will attempt to make use of theirLTE connection and then experience difficulties due to the screening effect of the railcarriages.Particularly if users are paying for WiFi or see it as an important reason for choosingrail travel they may be dissatisfied if WiFi does not keep pace with improvements intheir cellular service. 7
  8. 8. Train operators should react to increasing expectations by equipping trains with LTEbackhaul for WiFi. Built-in LTE systems should perform significantly better thanpersonal LTE devices due to the better antenna location and the ability to aggregatemultiple connections (potentially even from several operators).The problem then is how to deal with consistency as the train moves between areasof 3G and LTE coverage – may users in fact find a highly variable service moreannoying than a slower but more consistent service? 8
  9. 9. Four main factors influence coverage.1) Frequency discussed under spectrum2) Network design is a topic in its own right and not expanded in this presentation3) Multi-operator use is going to be more complicated as networks increasingly share resources.4) Mobile unit design – performance of the mobile unit is often overlooked as a determining factor in system coverage and performance. Trade-offs can be made between improvements to networks and improvements to mobile units in order to achieve the same coverage/performance 9
  10. 10. New coverage measurement tools can help in understanding existing coverage andplanning improvements. Conventional “drive testing” is a laborious processparticularly (as the name suggests) for off-road locations. Minimization of DriveTesting allows any supporting mobile unit to log and report coverage measurementsunder network control (even if it is not actually engaged in an active session).Enabling MDT on train mounted mobile units could be an important tool to improverail coverage. MDT will reduce the cost of making coverage measurements and vastlyincrease the amount of coverage data which can be captured. 10
  11. 11. We are used to thinking of WiFi as the primary technology to provide wirelesscoverage inside a train. LTE blurs the boundary between WiFi and cellular and mobileoperators are strongly pushing “small cell” solutions for coverage and capacity thatthey claim provide a more seamless user experience than WiFi.Against this background it is not surprising that the mobile industry thinks in terms ofrelaying the LTE signal as the preferred mechanism for providing data services to trainusers. A new work item under the title of “Moving LTE Relay” has recently started in3GPP, the standards body that defines LTE. This specifically addresses in-traincoverage including support for high-speed group mobility. Combined with mobileoperators’ ability to charge for data services this could be an interesting departurefrom existing in-train systems where billing is difficult. The Moving LTE Relay workitem currently lacks input from the rail community and therefore there is a significantrisk that the requirements being developed will not fulfil the needs of the railindustry.Even though the 3GPP work may not be on the right track it is still important toconsider non-WiFi in-train coverage solutions. 11
  12. 12. The use of a pure IP applications platform in LTE is a significant break from 2G and 3Gtechnology which had special operating modes for voice and SMS. This platform isvery open to the introduction of new user services for both public and privateapplications. 12
  13. 13. We have shown how LTE provides a good technical platform for non-critical services –the main constraints are coverage and cost. LTE can deliver large volumes of data. Canyou afford to pay for it?Why should we consider LTE for critical services?• Existing systems are not always suitable to meet new requirements – eg data intensive applications such as uplink security video.• Existing solutions will reach end-of-life and need replacement.• As there is increasing demand for spectrum it will become more difficult to gain exclusive access to spectrum. Solutions that allow critical rail services to coexist with other spectrum users can prove to be cost effective.For critical services many new requirements are added in to the mix including priorityand reliability. To some extent LTE provides a framework to address thererequirements but the LTE capabilities have not been analysed in the context of thefull rail requirements. The critical question here is to define what set of services wesee as being supported by LTE and then form an action plan to address therequirements. 13
  14. 14. We can learn from the experience in other industries on the coexistence of criticaland non-critical apps.In the design of the 787 Boeing decided to use some common components betweenthe passenger LAN and the flight-control systems. This lead to a special FAA approvalprocess and some initially hysterical headlines. Ultimately though the design wasconsidered secure and approved.We can take away two things from this experience:- Other industries are accepting that “Air gaps” are not the only approach to separating critical and non-critical systems- If we are going to allow coexistence we need to define industry norms for what modes of coexistence are allowable and which must be avoided.Additional notes:Source for quotes:Wired Magazine:http://www.wired.com/politics/security/news/2008/01/dreamliner_security 14
  15. 15. One particularly interesting piece of work is the development driven by the US of a“public safety” application based on the LTE platform. Public safety has a number ofsimilar features to rail communications including group calling, addressing by functionrather than individual and strict priority and preemption protocols. The US is alsoproposing to enhance the LTE platform to include a “direct mode” of communicationwhich does not go via the LTE network. This project is still very new and the success isfar from certain but I think it is reasonable to hope that the public safety work couldpoint the way for a future application of LTE for GSM-R communications.Though IP applications can be easily built on top of LTE interoperability of theseapplications requires additional standards. It would be better to deliver interoperableGSM-R communication than have may different implementations. 15
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