A chaos-based DS-CDMA transmission and synchronization for multi-leads medical ECG/EEG through AWGN and Rayleigh Channels

For telemedicine purpose, simultaneous transmission of biomedical multichannel signals remains problematic. There is a need to transmit all the channels without creating distortions such as delay, inversion of the signal parts. Multiple access techniques are more indicated. In this paper, we proposed a multi-user direct sequence code division multiple access (DS-CDMA) based chaotic communication system to simulate the transmission of biomedical multichannel electrocardiogram (ECG) signals and electroencephalogram (EEG) signals in the same bandwidth. We used binary chaotic sequences to spread the ECG/EEG signals and the Walsh sequences as pilot signals. The performance of the proposed system is evaluated in the presence of Additive White Gaussian Noise (AWGN) channel and in the presence of the Rayleigh flat fading channel. We achieved the code acquisition that represents the first stage of the synchronization process in the presence of AWGN channel and in the presence of the Rayleigh flat fading channel. We evaluated the code acquisition stage in term of the probability of detection and probability of false alarm. We used the time delay estimated by the code acquisition to despread the received signal. The low bit error rate obtained confirms the effectiveness of the synchronization unit, the effectiveness and the robustness of the proposed system.