The curious case of an electric car jamming a mobile phone network



The National Frequency Agency (ANFR) manages all radio frequencies in France. 

A mobile operator recently sent ANFR a request for intervention with interference affecting its 3G services in the 900 MHz band in the town of Saint-Ambroix in the Gard. A relay antenna was disturbed. The only clue: it was on the grounds of a car garage where an electric car was located …

The agents of the regional service of Aix-Marseille of the ANFR investigated. Very close to the vehicle, spectral analysis confirmed that the interfering signal did indeed come from this car. But it wasn’t the electric nature that caused the problem; it was rather its nature, as a… connected car! Indeed, it turned out to be equipped with a discreet communication box, a TCU or Telematics Control Unit., a device found in some electric vehicles. This TCU, thanks to its SIM card, communicates with the dealer network, in particular to inform it of the use of the battery, the number of kilometers traveled or the proper functioning of the GPS.

It even allows to start the preheating of the car via a smartphone! …

But here it is: this TCU, in default, produced a permanent unwanted radiation in the 900 MHz frequency band, which disturbed the relay antenna, and all surrounding phones.

To put an end to this jamming, the idea seemed simple: deactivate the TCU’s SIM card. But connected cars do not cope well with the loss of their connection! Indeed, the vehicle would have been permanently immobilized.

A qualified mechanic had to be found to fix the problem (which was done after several attempts). This lead to the full dismantling of the dashboard of the vehicle to reach the famous TCU. After several hours of labor, the mechanic managed to reset the TCU, which definitively put an end to the disturbance.

This car was tracked by two companies: its dealer, via the TCU, and the mobile operator, who saw warnings roaming on the monitoring console of his network! This very pernicious jamming thus moved according to the journeys of the car. It was finally tracked with a few clues: the garage where the car was finally identified, the workplace of the owner of the vehicle, and in the evening and at night, the surroundings of his home!

The connected car: a new potential source of interference

The ANFR remains particularly vigilant because two other cases of jamming of a mobile operator by connected electric cars are currently being processed.

The connected vehicle market is developing and more and more cars have a TCU incorporating a SIM card to transmit data to the manufacturer’s network and provide access to packages of services adapted to these vehicles. Access to the mobile network is also necessary for all cars which are equipped with an eCall emergency call system to alert the emergency services in the event of an accident. Finally, these connections pave the way for major industrial developments in autonomous driving.  

This growing connectivity creates vulnerability to cyber attacks, but there are also threats from jamming. The M2M (machine to machine) connectivity of the IoT (Internet of Things) is indeed sensitive to interference, whether it is intentional or unintentional. Conversely, as in the case mentioned above, any connected object is itself potentially disruptive.

To limit these risks, the radio modules of connected objects must in particular comply with the essential requirements of European Directive 2014/53 / EU of April 16, 2014 known as “RED” and include a CE marking and an EU declaration of conformity.

Note: Under Article L.39-1 of the CPCE, disrupting the radio transmissions of an authorized service, using a frequency, equipment or radio installation, under non-compliant conditions, is subject to to a penal sanction of six months’ imprisonment and a fine of 30,000 euros. The ANFR can also apply to the person responsible a tax of 450 € for the costs of intervention caused by the use of a radio installation outside the legal and regulatory conditions, having caused the interference of a regularly allocated frequency (finance law).

This post was auto-translated and adapted from French

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