Application and Performance Evaluation of a ZMSBO-CSC in A Coded
Multiple-Access DS/FFH/TH Hybrid Spread Spectrum System over
Frequency Selective Fading Channel
Hany A. A. Mansour
a
, Yongqing Fu
b
,
College of Information & Communication Engineering,
Harbin Engineering University, Harbin 150001, China
a
hnhn118799@gmail.com,
b
fuyongqing@hrbeu.edu.cn
Keywords: Spread Spectrum, Chaotic Code, Direct Sequence Spread Spectrum, and Gold
Sequence.
Abstract. Spread spectrum communications have a lot of interests in the recent decades. One of the
most important parameter in the spreading process is the spreading code, especially in the direct
sequence spread spectrum. Recently, many researches focused on the chaotic codes, due to its attractive
security properties, in addition to its availability to generate a huge number of spreading codes. In this
paper, a zero mean self-balanced orthogonal chaotic spreading code (ZMSBO-CSC) is applied in a
multiple-access DS/FFH/TH hybrid spread spectrum system. The performance is evaluated and
compared with the traditional Gold code, in addition to the traditional chaotic code, ZM chaotic code,
SB chaotic code, and ZMSB chaotic code under effect of frequency selective fading channel. The
results show that the chaotic codes have generally better performance than the gold code, especially in
the case of high multiple access interference, and sever fading conditions. The results show also that the
ZMSBO CSC outperforms the performance of all the other spreading codes due to its orthogonality
property.
Introduction
In direct-sequence spread spectrum (DS-SS) systems, the information signal is modulated by the
spreading code prior to transmission. The resulting signal becomes a wideband signal, which is
resistant to narrowband jamming, multipath, interference, in addition to providing the multiple-access
capability [1, 2]. Typically, there are many codes types that can be used for the spreading process. The
pseudo-noise (PN) sequences which are generally produced by the linear feedback shift register are the
most popular codes used in the multiusers application. However it has many drawbacks such as the
limitation of the sequences number, in addition to its periodicity feature, which make the intercepted
signal is predictable and is reconstructed by linear regression which leads to security limitations [3].
One of the alternative solutions is the long spreading codes and chaotic code signals. Chaotic codes
have a lot of attractive properties, especially from the security point of view. It is non-periodic, wide
band, and more difficult to predict and to reconstruct. Moreover, Chaos is a deterministic, random-like
process found in non-linear dynamical system, which is non-converging and bounded. It has also a very
sensitive dependence upon its initial condition and parameters, which gives the availability to generate
an infinite number of spreading codes [4-6]. These properties make the chaotic signals more difficult to
intercept, and more secured to decode the information spreaded upon them. In the recent years, many
researchers have studied and discussed the properties of the chaotic codes from different point of views.
The correlation properties is one of the most important point of views that has been studied and
discussed in detail specially the cross-correlation properties, since it has a direct effect on the
performance of the multi-access systems. These studies lead to create many types of maps that are used