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Milliseconds are vital Interview with John Cox, CEO of the TETRA MoU Association The TETRA MoU Association supports and promotes the TETRA standard on radio communication systems for public safety and security. Eurescom mess@ge asked the CEO of the TETRA MoU Association, John Cox, about TETRA’s contribution to securing critical communication infrastructures for public safety purposes in Europe. Which communication infrastructures do you consider as the most critical in Europe? Any communication infrastructure which has an impact on safety of life is critical. However, if a hierarchy of importance has to be established then the most critical will relate to those where safety of many lives is involved as opposed to individuals. These are likely to be those required to deal with major incidents, be they man made or natural disasters. The Public Safety authorities play a major role in such incidents, and it is important that they are able to continue to communicate throughout such events. There have been many examples of communication failures in such circumstances, which could have been resolved. One of the latest examples is the Spanish rail incident in March 2004, where the public GSM networks were not able to handle the load of calls following the terrorist attack whilst the incident was successfully managed on the TETRA network. It could be concluded from such examples that it would be unwise to rely on public systems such as GSM for backup in times of difficulties due to the overwhelming demands for public communications required. What are the mechanisms for securing critical communication infrastructures? There are two key mechanisms
to consider: physical security of the network elements and security of the
information, which is being passed through the system. The chosen technology
has little influence on the physical security of the network elements,
switching centres, control rooms, and transmission. Technology choice has
some influence at radio sites in the amount and size of equipment required.
In the case of TETRA, for example, one single base station unit can provide
four separate channels of communication thus saving on space. Transmitted
data can be protected by varying levels of encryption although digital radio
is inherently more secure than analogue. The different levels of encryption
range from full end to end to over the air only using air interface
encryption How can TETRA help to secure critical communication infrastructures? TETRA would be installed as a “private” system for use only by those involved in the incident. Control of the network, its physical and transmission security would be in the hands of the users, and the flexibility inherent in the technology would allow the network to be optimised to suit the particular incident, for example grouping users from different disciplines dynamically. Additionally, TETRA is designed with a “graceful” fallback. This means that if transmission is lost between control and the base station site, then the base station site can continue to offer service to terminals within its transmission range unlike public radio systems such as hierarchical cellular systems. If at the next stage the TETRA site is lost, then terminals fall back into what is known as Direct Mode meaning that radios within range can continue to communicate with each other. Which features of the TETRA system or of other telecommunication systems are the most important for critical communication infrastructures? Key features are to continue to provide communications throughout an incident. In TETRA this is covered by the fallback communications services mentioned above and the fact that all users are under management control, unlike public networks where systems can become overloaded with uncontrolled public calls. Also a variety of backbone transmissions networks can be used with multiple routing in conventional network architectures, including IP which not only offers increasing variety of control elements but also a potential reduction in network costs due to high component availability. Given the increased functionalities of GSM and third generation mobile systems, why are special systems like TETRA necessary? TETRA is specifically designed for emergency situations and other public safety requirements. Mission-critical features include speed of call setup and group communication. Setting up a call from a TETRA phone takes between 300 and 500 milliseconds, compared to three or more seconds in a public mobile network. Think of a fire alarm, and you will understand how critical setup time is. Milliseconds are vital. Another important feature of systems used for public safety purposes are group calls, for example to provide information to all members of a fire brigade at the same time. With TETRA the structure and users in any group can be changed dynamically during the incident with virtually limitless group sizes. This wouldn’t be possible to such an extent with currently available GSM or other hierarchical mobile systems, which are designed for individual communication. To what extent is the TETRA system interoperable with other communications systems? We have to distinguish between interoperability and interworking. Interoperability in the sense that a terminal could operate across various systems, e.g. TETRA, TETRAPOL, and GSM, is not likely to appear on the market. Interworking between different systems, however, is possible. A TETRA network can be connected to a TETRAPOL or GSM network via a gateway at a switching centre or control room. In this scenario, the special functions of the different systems would be very limited. Another practical problem is that cross-border communication, for example between German and French fire brigades, wouldn’t work, because as soon as you cross the border you cannot connect to your own national system with your terminal, because there is no radio coverage. Real interoperability between national systems is only possible, if all use the same standard. In a recent pilot project in the Aachen region across Germany, Belgium, and the Netherlands, fully interoperable cross-border TETRA services were established. The ability to have full interoperability between terminals from different networks would require a duplication of coverage. It is sometimes said that duplication is a fail- safe scenario, but it is an expensive one both in terms of cost and environment. The interview was conducted by Milon Gupta. Please send us your comments on this article. |
