wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

23-2 Industrial Communication Systems
Original
Original signal
Digital signal
Compressed and D/A
A/D and decompressed
Digital signal
p(t)
Cryptographic
scheme e()
k(t)
Magnifyingglass
v R (t)
Intruder
v R (t)
~ p(t)
Cryptographic
scheme d()
~ k(t)
Composition Channel Decomposition Magnifyingglass
Chaotic
system
Synchronization
drive impulses
Synchronization
drive impulses
Chaotic
system
Encrypter
Decrypter
FIGURE 23.1 System block diagram of the chaotic cryptosystem. (Reprinted from Li, Z.G. et al., IEEE
Trans. Commun., 51(8), 1306, 2003. Copyright @ 2003 by The Institute of Electrical and Electronics Engineers.
With Âpermission.)
by chaos synchronization. But before 1990, chaos synchronization was very difficult and nearly impossible.
The ground-breaking scheme, called Pecara and Carroll scheme [PC90], firstly offered a method
to control and realize chaos synchronization. From then on, chaos synchronization and its application
to secure communication have seen a flurry of research activities for decades.
The main advantage of a chaotic secure communication system over conventional cryptosystems is
that chaotic secure communication schemas can often be realized using very simple circuits on a part
of a chip [GHGS00] and they can be used in applications that do not require a high level of information
security such as remote keyless entry system, video phone, and wireless telephone [GHGS00]. In this
chapter, some typical control methods for chaos synchronization will be presented first, and then how
they are applied to secure communication will be illustrated.
23.2 Chaos Synchronization
A number of methods have been proposed for the synchronization of chaotic systems, including the
linear and nonlinear feedback control, fuzzy control, adaptive control, sliding mode control, and impulsive
control. In this section, some typical synchronization control methods are introduced with the Chua’s
circuit as an illustrated example.
23.2.1 Feedback Control for Chaos Synchronization via Partial States
One of the important aspects to evaluate the effectiveness of the secure communication schema is the
transmission efficiency, i.e., the ratio of the data information to the entire transferred information. In
order to achieve chaos synchronization, it is unavoidable to occupy the communication channel by synchronization
control information of the driving system that needs to be transmitted to the receiver. In
the full-order synchronization control schema in which synchronization is achieved by controlling all
the system states, information on all the states of the driving system should be sent to the receiver, which
leads to a poor transmission efficiency. In addition, the full-order synchronization control schema is not
feasible for the case when some of the system states are not available or controllable. In order to overcome
the problem for such a case and to improve the transmission efficiency, one may wish to transmit
© 2011 by Taylor and Francis Group, LLC