IEEE - Aerospace and Electronic Systems - December 2023 - 25

Mafakheri et al.
Figure 9.
Visualization ofoutput data of protocol-based approaches.
interference scenarios include the signaling description of
in-aircraft and nonaircraft systems. The investigations
focused on the following potential future frequency bands of
wireless communication systems in aircraft:
Industrial Scientific and Medical (ISM) Bands (2.4,
5, and 6 GHz);
Radio Altimeter (RA) Band (4.200-4.400 MHz);
Extension of Microwave Landing System (MLS)
Band (5.031-5.150 MHz);
Weather Radar (WxR) Band (9.300-9.500 MHz);
Ultra Wide Band (UWB) (3.100-10.600 MHz).
For the detection of jamming and the localization of
jammers, different methods and approaches were investigated
[18], [19]. They were divided into protocol-based
methods, spatial methods, frequency-based methods, and
time-based methods. These four different approaches to
jamming detection are explained in more detail. Protocolbased
methods use protocol functions to assess the current
state of the communication channel. The following functions
are available for wireless sensor networks:
packet error ratio (PER);
received signal strength (RSS);
carrier sensing multiple access (CSMA) time.
Two protocol functions are available for estimating the
PER. On the one hand, the " Packet Delivery Ratio "
provides information about the percentage of received
packets that were probably transmitted without errors. This
is determined by means of a checksum (CRC, named after
the calculation method, " Cyclic Redundancy Check " ). On
the other hand, depending on the channel situation, it can
happen that a packet is to be sent, but during the channel
free check, it is determined that it cannot be sent because
the transmission channel is occupied. If the channel is permanently
occupied, e.g., by ajammer, no more packets can
be sent. This is recorded in the " Packet Send Ratio " variable.
Other protocol functions relevant for assessing the
current channel status are the RSS, which can be queried
via the received signal strength indicator (RSSI), and the
time required to send a packet ( " Carrier-Sense Multiple
Access (CSMA) Sensing Time " ). While the signal strength
provides information about whether the transmission channel
is occupied or free at a certain point in time, the CSMA
sensing time can be used to determine how long the channel
was occupied before a packet could be sent. Protocol-based
methods enable the monitoring of some of these variables
on a so-called sensing device. Both software-defined radio
sensor nodes and wireless data concentrators can serve as
sensing devices. These transmit the data to a server, where
the data are then evaluated and visualized. Figure 9 shows
a possible representation ofprotocol-based data.
Time-based methods, on the other hand, analyze
which time slots of a given channel are disturbed. A sensing
device for this algorithm monitors a given channel
over a specified period of time and transmits the busy
times of this channel to a server, which then evaluates and
visualizes the data. This monitoring of the channel can,
for example, again be based on the RSSI. A possible visualization
of the data obtained is shown in Figure 10.
A frequency-based method analyzes the available frequency
spectrum for disturbed and undisturbed frequency
ranges. In this method, a sensing device records RSSI values
at different frequencies, for example, and sends the
data obtained to a server, which in turn visualizes it. The
evaluation is based on the assumption that the transmitted
quality parameter, in this example the RSSI, can generate
a statement regarding the respective frequency. Figure 11
shows a possible form of visualization.
Figure 10.
Visualization ofoutput data of time-based approaches.
Figure 11.
Visualization ofoutput data of frequency-based approaches.
DECEMBER 2023
IEEE A&E SYSTEMS MAGAZINE
25
IEEE - Aerospace and Electronic Systems - December 2023

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