Aerospace and Electronic Systems Magazine February 2018 - 6

Cyber-Secure Multiuser Superposition Covert Avionics System

Figure 1.

High-throughput, cyber-secure MuSC system.

systems. To the best of our knowledge, there is no published work
addressing such challenges in avionics systems that use noise modulation and NOMA operations.
In this article, we compare the performance between NOMA
and OMA. Note that both NOMA and OMA are multiple access
schemes, which provide the means for multiple users to access
and share the system resources simultaneously. Actually, we did
choose OFDMA as a scheme of OMA and compared it with the
proposed NOMA scheme. Whereas orthogonal frequency-division
multiplexing (OFDM) is indeed a frequency-division multiplexing mechanism, which works by dividing a single wideband signal
into a large set of narrowband subcarriers in such a way that, all of
the subcarriers to be orthogonal to each other are evenly spaced.
Therefore, there exists a few slight differences between OFDMA
and OFDM:
C

OFDM supports multiple users (multiple access) via a
TDMA basis only, while OFDMA supports either on a
TDMA or FDMA basis or both at the same time.
OFDMA supports simultaneous low data rate transmission
from several users, but OFDM can only support one user at
given moment.

HIGH-THROUGHPUT, CYBER-SECURE MUSC SYSTEM
This section briefly introduces the overall framework of the proposed high-throughput cyber security MuSC system. As illustrated
in Figure 1, the system mainly consists of two major components: a
cyber security part and a noise-modulated superposition transmission part. Specifically, cyber security includes a watermark-based
6

data validation scheme, which is used to check whether the data
are compromised or manipulated during transmission. In the noisemodulated superposition transmission part, the watermark-coded
data intended for different receivers are first encoded and modulated separately. The output signals are transmitted with different
power levels, with respect to different channel characteristics.
These signals are then superposed together and modulated with a
band-limited Gaussian noise signal. Afterward, the Gaussian noise
signal is deployed with a predetermined delay time and transmitted along with the noise-modulated signal through orthogonally
polarized antennas.

WATERMARK-BASED DATA VALIDATION
To validate the originality of the data, the watermark-based data
validation is used as a data level intelligence technique to embed
digital data inside the information, where the watermark carries
unique information about the owner of the information. The main
advantages of watermarks are that they are low cost, self-secure,
and high efficiency; especially when dealing with streaming
large-scale data. To be specific, threat detection network sensors
will generate identical and synchronized watermarks when sending information about cyber attacks. Before sending the data to
the transmitter, the original data collected from threat detection
sensors could be randomly watermarked and then transmitted
through the network. The watermark data can be predefined so
that only the threat detection sensor and transmitter are aware of
it. When the transmitter receives data collected from the threat
detection sensor, the correlation validation will be carried out
between the watermark and the watermarked data to detect any

IEEE A&E SYSTEMS MAGAZINE

FEBRUARY 2018

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine February 2018