Surfing on the Internet a few weeks ago, I came across what I considered to be a very interesting article. An English University is setting up an innovation center for 5G technology. They have even constructed a dedicated building for 5G investigation.
Nowadays, there are more and more applications running on a mobile environment such as, M2M, services for passengers, telemetering, etc… These applications often rely on several wireless access technologies (LTE, 3G, Wi-Fi, Satellite…) to implement the connectivity to the on-board network.
In these kind of scenarios, very often the WAN IP changes have an impact on the continuity of applications running at the central office or on the internet. Therefore, there have been several initiatives to provide continuous connectivity in scenarios where the WAN IP is dynamic. The most common ones use Mobile IP or a combination of standard protocols, which mix DMVPNs with dynamic routing.
Mobile IP is an open standard that allows users to keep the same IP address, stay connected and maintain ongoing applications, while roaming between different IP networks. Hence ensuring that a roaming device could continue communication without sessions or connections being dropped.
This standard is based on identifying each roaming device, (mobile node, MN) by its home address disregarding its current location in the Internet. Away from its Home Network, a mobile node is associated with a care-of-address (CoA), which identifies its current location in the Foreign Network, and its home address is associated with the local endpoint of a tunnel to its Home Agent.
Mobile IP specifies how a mobile node registers with its home agent and how the home agent routes datagrams to the mobile node through the tunnel.
Due to this standard’s design, telecom carriers need to implement Mobile IP infrastructure inside their core network. Access network equipment (Foreign Agent, FA in the diagram) also need to implement the same standard and have the ability of build up the GRE tunnels. In scenarios where we use two different telecom carriers, the Home Agent should be implemented by a transversal service that is able to build the tunnels through both carriers’ networks.
For the above-mentioned reasons, deploying Mobile IP is complex.
DMVPN an alternative to Mobile IP
There are other safer tunnel-based technologies which allow changes on the WAN IP address. Using a VPN allows to configure connectivity between two LAN networks independently of the routing changes inside the network the tunnel is going through.
DMVPNs are the typical approach used to build a VPN between two devices with dynamic WAN IP and it is a much more mature technology and spread out than Mobile IP. Building a DMVPN requires a public fixed IP at the central side (HUB). While spokes could have dynamic or fixed public IPs.
Using a protocol named NHRP (Next Hop Resolution Protocol) the different Spokes can be registered into the HUB allowing to set up a VPN between two Spokes without going through the HUB. Also, if a Spoke changes its WAN IP, it will send an update to the hub updating its new address.
As well as in Mobile IP, the convergence of the technology requires some time. In addition, the change of two cellular networks from different carriers (LTE module needs to reboot and re-register in the new network) also requires some time. However, in real mobile environments (such as in-vehicle connectivity) the change between carriers is not instantaneous (the coverage from one carrier gradually lowers while the coverage of the other cellular network is improving gradually).
The combination of a device with two cellular modules allow having two simultaneous cellular networks available to provide the service. In this case, each module will connect to each cellular network and build up two tunnels (one through each telecom carrier) which will coexist until the coverage of one of the carriers is much stronger than the other. Adding an appropriate dynamic routing protocol configured at both extremes of the tunnel with fast update features and different priorities in the exported routes, allow application continuity whenever any WAN link is down or quality is not sufficient.
DMVPN , an efficient solution that minimizes costs
Mobile IP requires additional infrastructure and a very complex deployment on the Telecom Carriers’ side. The solution based on DMVPNs is completely independent from the Telecom Carriers and does not require additional costs, as well as allowing to configure simultaneous connections through different Carriers without any difficulty. This is why Teldat deploys DMVPN technology for its mobile scenarios, whether on trains, buses or any other type of vehicles, via our routers H1-Rail, H2-Automotive or similar.
Mobile Internet becomes more and more popular. Whereas mobile Internet has only been used for email checking, it is now used for the same applications as the Internet by cable: surfing the Internet, playing online games, listening to music or streaming videos and films. In addition to this trend there is a further development: The Internet of Things on which more and more devices are connected to the network and among each other. For this increasing demand, the capacity of the 4G standard will not be sufficient anymore.
This technology was taken to another level by the professional market with the appearance of RTLS (Real Time Location Systems). These systems could use GPS signals, RFID (Radio Frequency Identification) or other mechanisms and made it possible to keep track of fleets, position emergency disaster services and control staff or critical resources all from a control center. The devices knew their location and could communicate this information.
GSM Railway (commonly known as GSM-R) is an “international” Wireless communication standard for railways that allows communication in this environment. Indeed it was a system that was developed for Europe, but due to its success it has been deployed in Asia-Pacific, Middle East and Africa.
It is the network that has enabled trains and control centers to communicate with each other for well over 10 years. Similar to a standard GSM network, but the “base stations” run along the railway track (not on a traditional two dimensional system) and hence this is what allows trains and the control centers to communicate even when the trains run at over 400 km/h.
GSM-R has been so successful that forecasts say that this network still has some years of growth left, however there is one very important issue, that causes the market to think that the time has come to find an alternative. The issue is quite clear. GSM-R is a 2G network, and it is not IP based. Carriers only have a limited amount of radio spectrum allowed and they are phasing out older, less efficient 2G technologies in favor of newer systems like LTE. That, some people say, makes GSM-R virtually an outdated system that will soon become too expensive (or impossible) to run.
Is LTE an alternative for GSM-R?
Many say that LTE is definitely a very strong contender. However, for LTE to be the adequate successor of GSM-R, certain hurdles have to be crossed. First of all, LTE will have to prove itself as being a telecommunication system that offers railway operators: Reliability, Availability, Maintainability and Safety. Without all these four requirements covered, no communication network will be taken on by the railway operators as an alternative to GSM-R.
Once LTE accomplishes reliability, availability, maintainability and safety, it will be a much better system for the railway operators, because not only will LTE be able to cover “core services”, but it will also be able to offer “additional communication services”. The latter are passenger services and business support process services. The non-core services may not be a must to operate, but they will definitely gain in importance if the railway operators want to give their passengers added value services and become more efficient from a business perspective. The railway is not alone in the transport market and they have to fight against the other modes of transport to obtain the desired market share, both in the passenger market and the transport of goods market.
For example, when a passenger selects travelling on a train or on another mode of transport, he/she will evaluate the ease with which a route can be planned (traveler information; schedules, delays, etc.) or the ease with which a ticket can be obtained (e-ticketing). Moreover the passenger will most definitely value very highly the availability of broadband internet access and on-board multimedia services.
LTE, the future of communications for transportation
Apart from this business perspective, there are obviously many specific technical issues which have to be studied in great depth. LTE will not only need to prove that it is capable of giving all the features which GSM-R offers for core services, such as Voice Group Calls, Voice Broadcast Calls, Location Addressing, Data Exchange, etc., but it will have to provide many new core services to the railway operators. However, this is totally logical and it is what is expected when a more modern technology and network is put into place. LTE’s high performance and extended operational range argue well for its dominant role in the future.
In conclusion, what is clear, is that over time GSM-R will become a more expensive network than LTE, because by simply being 2G and not IP based, GSM-R cannot compete with LTE to offer these increasingly important expanded operational and passenger services. Indeed, Teldat has a lot to offer in the area of high performance services with LTE. We have been working on many projects across the globe. From USA to the Middle East across Asia up to New Zealand. Especially, offering passengers broadband connection to the internet, using Teldat’s Wi-Fi devices and special LTE routers for the transport sector. Teldat offers communication equipment which is a core element of the mission-critical services of various transport projects.
In 2000 the GPRS technology was introduced. It offered the true possibility of transmitting data through 2G cellular networks, by adapting a circuit-switched network, designed to transmit voice, to a packet-based network. Almost a decade and a half ago, the common speed you were able to reach was 40 kbps on the downstream (from the network to the mobile terminal) and 14 kbps on the upstream (from the mobile terminal to the network).