Birahime Diouf

Comparative methods of spike detection in epilepsy

Epilepsy is a common neurological condition which affects the central nervous system that causes people to have a seizure and can be assessed by electroencephalogram (EEG). Electroencephalography (EEG) signals reflect two types of paroxysmal activity: ictal activity and interictal paroxystic events (IPE). The relationship between IPE and ictal activity is an essential and recurrent question in epileptology. The spike detection in EEG is a difficult problem. Many methods have been developed to detect the IPE in the literature. In this paper we propose three methods to detect the spike in real EEG signal: Page Hinkley test, smoothed nonlinear energy operator (SNEO) and fractal dimension. Before using these methods, we filter the signal. The Singular Spectrum Analysis (SSA) filter is used to remove the noise in an EEG signal.

Minimizing embedding impact in steganography using polar codes

This paper proposes two approaches that reduce the complexity of the Polar Coding Steganography (PCS). The first is based on lookup tables and the second exploits the form of the syndrome, calculated from cover vector and secret message, to evaluate la position of the cover vector changes. The scheme proposed in this paper allows minimizing the embedding impact and gives similar results as those of PCS scheme with a reduced time complexity.

Practical polar coding method to minimize the embedding impact in steganography

This paper proposes a new practical polar coding methodology for constructing steganographic scheme. We use syndrome coding with binary embedding operation. The approach exploits the form of the syndrome, calculated from cover and secret message. A connection between the syndrome decimal value and the embedding changes position is established and enables defining a new steganographic algorithm. The wet paper codes can also be implemented using this method. Experimental results prove that the scheme minimize the embedding impact with a reduced time complexity compared to the first Polar Coding Steganography (PCS).

Soft output detection for MIMO systems using binary polar codes

Polar codes are proven capacity-achieving and are shown to have equivalent or even better finite length performance than turbo/LDPC codes under some improved decoding algorithm over the Additive White Gaussian Noise (AWGN) channels. Polar coding is based on the so-called channel polarization phenomenon induced by a transform over the underlying binary-input channel. The channel polarization is found to be universal in many signal processing problems and is applied to the coded modulation schemes. In this paper, a small length polar, encoded for a MIMO (Multiple-Input Multiple-Output) systems with soft output MMSE-SIC (Minimum Mean Square Error-Successive Cancellation) detection, is applied to improve the coded performance while reducing the complexity. In order to prove this theory, we compare the proposed MMSE-SIC BER to Zero Forcing (ZF) and Maximum Likelihood (ML) by using 2*2 MIMO systems into Rayleigh channel with BPSK (Binary Phase-Shift Keying) modulation. Simulation results show that MMSE-SIC complexity is lower than the two others detections. We show that the performance of the proposed approach using polar code (128, 64) at 10−2 BER (Bit Error Rate) is around 3dB i.e. 0,66% compared to the optimal ML, while ZF performance is the worst.

Study of polar codes MIMO channels polarization using MIMO system

Polar codes are known as the first provable code construction to achieve Shannon capacity for arbitrary symmetric binary input channels. Several schemes to provides both detection/decoding of the transmitted and the transmit antenna index in Multiple-Input Multiple-Output (MIMO) antenna systems were proposed in the literature for polar codes. In this paper we have critically analyzed various MIMO channel polarization using polar codes extended to the multiple antenna transmission, and also have covered free polar set and frozen polar set for respectively mapping transmitted information and transmit antenna index.

Adaptive linear programming of polar codes to minimize additive distortion in steganography

A new practical syndrome coding method is proposed in this paper to minimize a suitably defined additive distortion function using Adaptive Linear Programming of Polar Codes (ALP-PC). We propose modifications of the ALP-PC based on a new reduced factor graph for steganographic purposes which we denote by ALP-PCS. The implementation of wet paper codes in practice is possible using ALP-PCS. Simulation results show that this method minimizes additive distortion in steganography and gives good embedding efficiency performance.

Small Polar Codes Concatenating to STBC Applied to MIMO Systems

This paper uses a concatenation of small Polar Codes length (N=32) and Space Time Block Code, this Polar-STBC is applied to no diversity (SISO), SIMO, MISO and MIMO systems. Minimum Mean Square Error using Successive Interference Cancellation (MMSE-SIC) is a soft output used to the receiver in order to improve Bit Error Rate (BER) and finally Successive Cancellation Decoder (SCD) is placed to the decoder in order to improve the BER and Frame Error Rate (FER). Comparison between several STBC without concatenation schemes and this small Polar-STBC shown that the proposed allows minimizing the BER and FER performances.

Performances of polar codes in steganographic embedding impact minimization

Syndrome coding is used in practice by many authors to define steganographic schemes that minimize embedding impact. Polar Codes, recently introduced, are the first capacity-achieving codes with low complexity of encoding and decoding. In this paper we propose a new practical polar coding methodology for constructing steganographic scheme. We use syndrome coding with binary embedding operation. The approach exploits the form of the syndrome, calculated from cover and secret message. A connection between the syndrome decimal value and the embedding changes position is established and enables defining a new steganographic algorithm. The wet paper codes can also be implemented using this method. Experimental results prove that the scheme minimizes the embedding impact with a reduced time complexity compared to the first Polar Coding Steganography (PCS). The bit-reversal permutation matrix used in polar coding is also employed in practice to uniformly scatter the changes over the whole image.

Increase MIMO Systems Performances by Concatenating Short Polar Codes to Spatial Time Block Codes

Polar codes, proposed by Erdal Arikan, have attracted a lot of interest in the field of channel coding for their capacity-achieving trait as well as their low encoding and decoding complexity in order O (NlogN) under successive cancellation (SC) decoder. However, there remains one significant drawback, that is, the error correction performance of short and moderate length polar codes is unsatisfactory, especially when compared with low-density parity check (LDPC) codes and turbo codes. In this paper, we propose a concatenation scheme performance, which employs a short polar encoder following to Spatial Time Block Codes (STBC), and we develop an efficient detector for Multiple Input Multiple Output (MIMO) antennas, which adaptively combines Minimum Mean Square Error Successive Interference Canceller together (MMSE-SIC). We also compared to Maximum Likelihood in the literature and finally present a simulation results in binary input Additive White Gaussian Noise (BI-AWGN) with binary phase shift keying (BPSK) modulation, and we observe that, our proposed concatenation scheme significantly outperforms the Maximum Likelihood performance in the high Signal-to-Noise-Ratio (SNR).

Polar Coding Steganographic Embedding Using Successive Cancellation

In this paper, we propose a practical adaptive embedding methodology based on Successive Cancellation (SC) polar coding. The new proposed SC-based Polar Coding Steganography (SC-PCS) defines message bits as frozen bits of the SC decoder and computes path metrics according to embedding costs of pixels of the cover image. Simulation results demonstrate that SC-PCS minimizes an arbitrary embedding distortion while embedding covert message.