Digital Mobile Communications and the Tetra System

Vulnerability analysis of the wireless infrastructure to intentional electromagnetic interference

“…It is not possible to show a BER threshold for which the transmission of speech fails since TETRA is flexible in terms of different coding rates and error protection [75]. However, in [97] it is stated that the critical input error rates for most coding algorithms is below 25 %.…”

“…For these type of applications, it is crucial that the system continues to function, even under harsh conditions. More information on the TETRA protocols can be found in [75,76]. A brief overview of the TETRA air interface as used by the emergency services in the Netherlands, and the structure of a typical base station, is described in this section.…”

“…It is therefore difficult to obtain the original messages. Furthermore, it is difficult to spoof the communication system since all TETRA devices have TETRA Equipment Identification (TEI) numbers, which uniquely define each device [75]. Without a registered TEI number it is not possible to start a conversation.…”

“…The BER of a data stream is defined as BER = Bit Errors Total Number of Transmitted Bits (3.5) The data stream in TETRA includes redundancy to correct errors, but for a critical BER the base station will not be able to correct the errors and the reception is disturbed. The critical BER is dependent on the error code scheme that is implemented and can be different from system to system [75]. The BER is dependent on the detector scheme implemented in the receiver.…”

“…Furthermore, we set Z 0 at 377 Ω and we assume the polarization mismatch e p between the transmitter and the receiver to be 0. 75.…”