Femtocell improves in-car mobile connectivity

March 03, 2015 // By Christoph Hammerschmidt
In a joint effort, carmaker BMW, communications equipment vendor Peiker Acoustic and consulting company Nash Technology have developed an in-car femtocell that connects multiple mobile terminals inside the car to the outside world.

The development - currently characterised as a research project - has been initiated by BMW as a reaction to an observation among its customers: BMW said it saw an increase in in-car use of mobile terminals such as smartphones, tablets, wireless-enabled wearables and other devices. The interior of a car however does not offer ideal operating conditions for such products since the vehicle body forms a faraday cage, effectively shielding the RF signals and preventing them to enter or exit the vehicle. This leads to reception problems, in particular when driving in areas with poor cellular coverage. As a reaction, the mobile devices' transmit power control automatically increases the transmission power which however typically does not lead to the desired effect but just increases RF pollution in the car and loads down the batteries. To circumvent the problem, the group started the development of a femtocell for mobile radio networks.

A femtocell is a small cellular base station typically used to provide indoor cellular connectivity in buildings. The Vehicular Small Cell as the group called the device they developed provides access to cellular networks through the vehicle's antenna while at the same significantly time reducing electromagnetic radiation inside the vehicle. At the same time it saves battery power since the mobile devices inside the car can transmit at their lowest possible power level.

The device automatically sets up a wireless connection between multiple mobile devices inside the vehicle and the aerial. The improved connectivity reduces the number of interrupted phone calls and increases the stability and quality of the connections while driving. It enables higher bit rates and improves the user experience during internet surfing, music streaming or mail checking.

The femtocell is demonstrated currently at the Mobile World Congress in Barcelona.