Developments in wireless communications are unfolding at a tremendous pace, giving us access to a broad spectrum of services without the need to connect leads or to bury cables. Civilian wireless systems, however, bring with them much greater vulnerability for both industrial and security applications. We can already see examples of how illegal players are exploiting the sensitivity to interference of civilian wireless systems and how naturally occurring interference signals create incidents affecting vital systems. Despite this, we see no ambitions to employ technology which enables greater resistance to interference where applications critical to society are concerned. This spring the police in Sweden apprehended individuals who had used jamming transmitters to block remote-controlled central locking systems in vehicles, allowing them to gain entry to the vehicles and empty them of goods and equipment. At the time of the riots at the EU Summit in the Swedish town Gothenburg in 2001, several demonstrators exploited the vulnerability of the radio systems used by the police, sabotaging radio traffic while the police were being deployed. On the internet one can now find ready-made products and full description of construction kits for transmitters which jam, for example, GPS, GSM and 3G systems.

It is not just illegal radio interference, however, which is a growing problem. Jamming signals that are generated naturally by all electronic systems have today increased to such an extent that they have already resulted in a number of serious incidents affecting systems critical to society. In Dallas use was made of a vacant digital TV channel, with the result that the transmissions blocked telemetry signals from the monitoring of sixty cardiac patients at the city hospital.
In the UK interference caused a remote-controlled crane to release its load, killing an individual below.

In 2006 the American coastguard service issued a warning that a number of leisure boats in the USA had lost their navigational ability because their GPS systems had either shown an incorrect position or had been completely jammed. The cause was interference from active TV aerials used on board which jammed GPS receivers up to a distance of 700 metres. In 2007 the Swedish Defence Research Agency warned (Ny Teknik no. 16 2007) that radiation from ordinary PCs was capable of jamming GPS receivers. From the perspective of societal security, the increasing dependence on GPS amounts to a growing vulnerability problem. Apart from being used for positioning, the GPS signal is commonly used as a time reference in computer networks, servers and communication systems. In Europe a large number of civilian authorities have chosen the Tetra standard for their radio communications, as in the case of the Swedish Rakel system. Systems that are based on Tetra often rely on GPS for the time synchronisation of their base stations (in addition, in the case of the existing Tetra systems, the actual communications are not particularly resistant to interference). The energy industry uses GPS for its field workers and GSM for monitoring of the power network. The Swedish emergency response call centre SOS Alarm uses GPS in combination with GSM in personal safety applications. In other words, simply through the jamming of civilian GPS receivers and GSM systems, substantial damage and disruption can be inflicted on society.

One fundamental cause of this greater vulnerability is that civilian wireless technology is normally not resistant to interference, for purely commercial reasons. Everyday consumers do not stop using their mobile phones even if they frequently get cut off when travelling by train. Nor do people stop using wireless internet despite sometimes being unable to establish a connection. Account is taken of these facts when assigning priorities to the technical properties of wireless technology for everyday consumers. A high degree of resistance to interference, in fact, is invariably achieved at the cost of the capacity of the system. By capacity we mean, for example, the rate of data transfer (in bits per second) or the number of simultaneous users of a particular system (one should be able to send out as many invoices as possible). In other words, greater priority is given in civilian wireless systems to capacity than to resistance to inference for purely commercial reasons. In military wireless communication systems (as also in space applications), priority is usually given instead to resistance to interference since it is important to remain in contact at all times. This has been learnt from experience as problems of interference can cause losses in terms of equipment and personnel.

The use in critical applications of technology that has been designed for everyday consumers is like releasing domesticated animals into the wild: the environment is simply too tough for them. What is required here is greater awareness and prioritisation of systems that can be considered to be of vital importance for personal and societal security so that we do not get stuck with technical solutions which can be knocked out with ease by an illegal player or which have problems solely as a result of the naturally occurring interference in the environment that is generated by today’s society.

Peter Stenumgaard, Professor and research director at FOI.