Published in IET Communications
Received on 25th November 2013
Revised on 5th February 2014
Accepted on 28th February 2014
doi: 10.1049/iet-com.2013.1054
ISSN 1751-8628
Minimax robust jamming techniques based on
signal-to-interference-plus-noise ratio and mutual
information criteria
Lulu Wang
1
, Hongqiang Wang
1
, Kai-Kit Wong
2
, Paul V. Brennan
2
1
College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, People’s
Republic of China
2
Department of Electronic and Electrical Engineering, University College London, Torrington Place,
London WC1E 7JE, UK
E-mail: wanglulunudt@163.com
Abstract: Jamming in defence applications is increasingly difficult because of advanced signal processing countermeasures. In
this study, task-dependent power-constraint optimal jamming techniques are investigated. To prevent the target from being
detected, a novel jamming technique is proposed to minimise the signal-to-interference-plus-noise ratio (SINR) of the radar
for extended known and stochastic target. To impair the parameter estimation performance, another jamming technique is
proposed which minimises the mutual information (MI) between the radar return and the stochastic target impulse response.
The optimal jamming spectrum is obtained assuming that the jammer has intercepted the radar waveform generally. However,
the precise characteristic of radar waveform is impossible to capture in practice. To model this, it is considered that the
waveform spectrum lies in an uncertainty class confined by known upper and lower bounds. Then, the minimax robust
jamming is designed based on the SINR and MI criteria, which optimises the worst-case performance. Results demonstrate
that the two criteria lead to different optimal jamming results but they have a close relationship from the Shannon’s capacity
equation which provides useful guidance on jamming power allocation for different jamming tasks. However, their behaviour
with respect to the waveform uncertainty is the same.
1 Introduction
In modern electronic warfare, the competition between radar
and jammer is increasingly intense. The anti-jamming
performance of modern radar has been greatly improved by
advanced waveforms, ultra-low sidelobe antennas, coherent
sidelobe cancellers and sidelobe blankers to inhibit signals
entering through its sidelobes [1], as well as by joint
optimisation of the transmit waveform and the receiver filter
[2, 3]. In these technologies, the radar is assumed to be a
smart sensor and can optimise its transmitted waveform on
a pulse-by-pulse basis. For self-protection, a better jamming
scheme is needed. Motivated by the development of direct
digital synthesis and digital radiofrequency memory, smart
noise jamming waveforms can be used against advanced
threat radars [1]. Thus, smart jamming techniques have
recently drawn much attention [4–6].
Adaptive jamming techniques and the interaction between
adaptive jamming and anti-jamming in communication have
long been a hot research topic [7, 8]. Intelligent jamming
techniques have been proposed for communication systems
in [9, 10]. In radar systems, jamming techniques were
usually studied against synthetic aperture radar (SAR) [11–
13]. However, optimal jamming designs against a general
radar are not well known. In this paper, two novel
task-dependent jamming techniques based on, respectively,
the signal-to-interference-plus-noise ratio (SINR) and
mutual information (MI) criteria against general radar
systems are presented [6]. Minimax robust jamming
techniques are proposed to relax the required prior
knowledge of the jamming techniques.
From the perspective of a general radar, SINR should be
maximised to have the best target detection performance [14,
15], whereas for parameter estimation, the MI between the
reflected echo and the target should be enhanced so that the
reflected echo contains more information about the target [4,
15, 16]. For waveform diversity, it is commonly assumed
that the radar is smart but the target is dumb. However,
many non-cooperative targets are equipped with
countermeasure systems to prevent a radar from operating
effectively. Therefore, as the opponent of a radar, the jammer
should attempt to reduce the SINR and MI to protect the
target from detection and estimation, respectively [4]. In
Section 2, SINR- and MI-based optimal jamming techniques
are proposed under limited jamming power. It is noted that
the problem we consider in this paper can be viewed as a
jamming unilateral optimisation problem, in which the radar
is not aware of the jamming strategy.
A common assumption in the literature of jamming is that
the reconnaissance system has intercepted the radar waveform
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IET Commun., 2014, Vol. 8, Iss. 10, pp. 1859–1867
doi: 10.1049/iet-com.2013.1054
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