Dynamic Logistic Map Based Spread Spectrum Modulation in Wireless Channels

Abstract

Generation of an efficient spreading code in Spread Spectrum Modulation (SSM) is always challenging due to considerations like optimum sequence length, physical layout of registers and power requirements. In this article, a design of a dynamic chaotic spreading sequence for application in a Direct Sequence Spread Spectrum (DS SS) based system with the considerations of wireless channels (Rayleigh and Rician) are presented. Generation of dynamic chaotic sequence for application in linear and nonlinear channels is done and a comparison with static chaotic sequence is presented. Evaluation of performance is done in terms of bit error rate (BER), computational time, mutual information and signal power for faded channel taking into considerations of different modulation schemes, which finally dictates the efficiency of the generated code. The performance of the generated dynamic logistic map-based sequence is compared to that obtained from Gold code under equivalent conditions.

Optimization of Spreading Code Using Modified Differential Evolution for Wireless Communication

“…As compared to the Gold sequences and Kasami sequences, the Bit Error Rate performance in the DS-CDMA communications system is found to be better by using this binary sequences. This article presentation is made on a design of a dynamic chaotic spreading sequence to apply them in a Direct Sequence Spread Spectrum (DSSS) based system along with the considerations of wireless channels (Rayleigh and Rician) in [1]. Moreover, a presentation is made after a comparison of a linear and none linear channels with static chaotic sequence in term of a bit error rate, computational time, mutual information and signal power for faded channel, evaluations of performance is done taking into consideration of different modulation schemes, which finally dictates the efficiency of generated code.…”

“…Binary bits are generated using the thresholding method (method 1) and integer to bit conversion method (method 2) [9]. Properties (Mono bit test, run-length test, computational time) of optimized generated bits are compared with the nonoptimized one [1] as shown in the Table as shown in section 5.…”

“…In modulation data bits are mapped into symbol vector. The modulation scheme used in this work is BPSK [1]. The modulated data is spreaded by an optimized logistic map based spreading code in the transmitter section in Fig.…”

“…The meaning of the spread spectrum in wireless communication means signal bandwidth expansion by multiplying the message signal with another signal called spreading signal (PN sequence). Starting from the military applications, in the current and also in the next generation of wireless communication techniques, spread spectrum plays a vital role [1], [2]. Using chaotic code (Logistic map code) in spread spectrum communication shows powerful properties like interference mitigation, low probability of intercept, less bit error rate (BER), etc.…”

“…Usually, to generate the PN sequence, certain sum-store blocks and LFSR (linear feedback shift register) are used. Also, to generate Gold code LFSR is used because the generation of Gold code is done by exclusive-OR of two PN sequences, hence for both PN and Gold code, a physical structure is needed which consumes more power with less flexibility [1], [20][21][22]. There are deviations in the propagation medium in fading conditions.…”