Physics Letters A 374 (2010) 562–566
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Physics Letters A
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Estimation of chaotic coupled map lattices using symbolic vector dynamics
Kai Wang
a,∗
, Wenjiang Pei
a
, Yiu-ming Cheung
b
,YiShen
a
,ZhenyaHe
a
a
Department of Radio Engineering, Southeast University, Nanjing 210096, China
b
Department of Computer Science, Hong Kong Baptist University, Hong Kong, China
article info abstract
Article history:
Received 7 October 2008
Received in revised form 14 September
2009
Accepted 16 November 2009
Available online 21 November 2009
Communicated by A.R. Bishop
PACS:
05.45.+b
Keywords:
Symbolic vector dynamics
Signal processing
Initial condition estimation
Coupled map lattice
In [K. Wang, W.J. Pei, Z.Y. He, Y.M. Cheung, Phys. Lett. A 367 (2007) 316], an original symbolic vector
dynamics based method has been proposed for initial condition estimation in additive white Gaussian
noisy environment. The estimation precision of this estimation method is determined by symbolic errors
of the symbolic vector sequence gotten by symbolizing the received signal. This Letter further develops
the symbolic vector dynamical estimation method. We correct symbolic errors with backward vector and
the estimated values by using different symbols, and thus the estimation precision can be improved. Both
theoretical and experimental results show that this algorithm enables us to recover initial condition of
coupled map lattice exactly in both noisy and noise free cases. Therefore, we provide novel analytical
techniques for understanding turbulences in coupled map lattice.
© 2009 Elsevier B.V. All rights reserved.
1. Introduction
Coupled map lattice (CML), which utilizes a coarse space–time
discretization and continuous state variable and reproduces the
essential features of spatio-temporal phenomenon, has been inves-
tigated as a theoretical model in the fields of physics, neuroscience
and computer engineering [1]. Today, with studies on its dynami-
cal characters going more thorough, CML has also been applied to
the construction of secure communication systems [2–7].
Recently, a number of symbolic dynamical techniques have fo-
cused on CML in signal estimation [8–16]. Some methods which
could roughly recover the initial conditions from symbolic se-
quences are proposed in Refs. [9–12].However,noneofthesere-
searches has constructed one-to-one correspondence between the
set of global orbits and the set of admissible codes. Based on orig-
inal contribution of symbolic dynamics in CML with respect to
Refs. [11,12], we initiate a solution to the problem of estimation
in CML by introducing symbolic vector dynamics [13–16].
In order to understand and utilize CML efficiently, it is not only
of theoretical interest but also of great importance in practical
application to estimate those signals in noisy environment. Fortu-
nately, various algorithms have been proposed for estimating a 1D
discrete chaotic signal which is embedded in white Gaussian noise
[17–26]. Those works make straightforward the application of CML
*
Corresponding author. Tel.: +86 025 83795996.
E-mail address: kaiwang@seu.edu.cn (K. Wang).
to the study on signal estimation in noisy condition. We can dis-
tinguish two general approaches from those works. One approach,
which is similar to the generalization of optimal filter design for
nonlinear systems, reconstructs the optimum signal by minimiz-
ing some cost functions and using a gradient descent method
[17–21]. The other approach, which utilizes symbolic dynamics of
1D discrete chaotic map, symbolizes received chaotic signals and
estimates initial values/control parameters from those symbolic se-
quences [22–26].
In Ref. [15], an original symbolic vector dynamics based method
has been proposed for initial condition estimation in additive
white Gaussian noisy environment. The estimation precision of
this estimation method is determined by the symbolic error of
the symbolic vector sequence gotten by symbolizing the received
signal. This Letter further develops the symbolic vector dynamical
estimation method. We correct symbolic errors with backward vec-
tor and the estimated values by using different symbols, and thus
the estimation precision can be improved. Both theoretical and ex-
perimental results show that this algorithm enables us to recover
initial condition of coupled map lattice exactly in both noisy and
noise free cases. Therefore, we provide novel analytical techniques
for understanding turbulences in coupled map lattice.
2. Symbolic vector dynamics of CML
Let’s consider the typical CML with N sites. Each site is de-
scribed by a state x
i
n
in the interval I =[a, b] and with local dy-
namics f
i
: I → I . The CML is introduced as follows:
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doi:10.1016/j.physleta.2009.11.053