Papers by Mahmoud Ahmadian-Attari
This letter is concerned with a frequency-offset estimation technique for OFDM-based transmission... more This letter is concerned with a frequency-offset estimation technique for OFDM-based transmission systems. The frequency estimation technique utilizes a repetitive signal structure inside of a OFDM symbol which is used to enlarge the range and increase the accuracy of offset estimation. Also, an averaged decision-directed channel estimation (ADDCE) technique suitable for burst data is proposed.
Journal of Information Security and Applications
IET Communications
In this paper, a practical coding scheme is designed for the binary Wyner-Ziv (WZ) problem by usi... more In this paper, a practical coding scheme is designed for the binary Wyner-Ziv (WZ) problem by using nested low-density generator-matrix (LDGM) and low-density paritycheck (LDPC) codes. This scheme contains two steps in the encoding procedure. The first step involves applying the binary quantization by employing LDGM codes and the second one is using the syndrome-coding technique by utilizing LDPC codes. The decoding algorithm of the proposed scheme is based on the Sum-Product (SP) algorithm with the help of a side information available at the decoder side. It is theoretically shown that the compound structure has the capability of achieving the WZ bound. The proposed method approaches this bound by utilizing the iterative message-passing algorithms in both encoding and decoding, although theoretical results show that it is asymptotically achievable.
Wireless Personal Communications
IEEE Transactions on Vehicular Technology, 2016
IEEE Transactions on Information Forensics and Security, 2016
IEEE Transactions on Communications, 2016
2011 49th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2011
In this paper, we present a novel way for solving the main problem of designing the capacity appr... more In this paper, we present a novel way for solving the main problem of designing the capacity approaching irregular lowdensity parity-check (LDPC) code ensemble over binary erasure channel (BEC). The proposed method is much simpler, faster, accurate and practical than other methods. Our method does not use any relaxation or any approximate solution like previous works. Our method works and finds optimal answer for any given check node degree distribution. The proposed method was implemented and it works well in practice with polynomial time complexity. As a result, we represent some degree distributions that their rates are close to the capacity with maximum erasure probability and maximum code rate.
The 9th International Conference on Advanced Communication Technology, 2007
... OFDM Systems S. SALARIf, M. ARDEBILIPOURt, M. AHMADIANt, JP CANCES*, and V. MEGHDADI* t KNToo... more ... OFDM Systems S. SALARIf, M. ARDEBILIPOURt, M. AHMADIANt, JP CANCES*, and V. MEGHDADI* t KNToosi University of Technology, Faculty of Electrical Engineering P. 0. Box: 16315-1355, Tehran, IRAN e-mail: {salari, mehrdad, mahmoud}@eetd.kntu.ac.ir ...
Wireless Personal Communications, 2015
ABSTRACT In this paper, the relay selection problem for two-way relaying networks in single and d... more ABSTRACT In this paper, the relay selection problem for two-way relaying networks in single and dual relay selection schemes is addressed. In the single relay selection scheme, the problem is to find the best relay node which leads to the minimum bit error rate (BER) between the source nodes. We then derive the upper and lower bounds for the signal to noise ratio and the end-to-end BER of this scheme. In the dual relay selection scheme, the problem is to find the two best relay nodes. In this scheme, Alamouti space-time coding and physical layer network coding are utilized in order to achieve the higher performance. For improving the system performance, optimal power allocation between the sources and the relays is considered based on decreasing the BER. Finally, simulation results are provided to verify the correctness of analytical results.
7'th International Symposium on Telecommunications (IST'2014), 2014
ABSTRACT In this paper, the performance of single relay selection (SRS) scheme which used in an a... more ABSTRACT In this paper, the performance of single relay selection (SRS) scheme which used in an amplify-and-forward relay network over Rayleigh fading channels is analyzed. In this scheme, each of the two source nodes has an important effect in selecting the best relay node and one of the relay node with the minimum bit error rate (BER) is selected. Then this relay node is used for cooperation between two source nodes. The upper and lower bounds for signal to noise ratio (SNR) and the BER for single relay selection scheme are presented. For improving the system performance, optimal power allocation (OPA) between the sources and the relay node is considered based on decreasing the BER. Simulation results are provided to complement the theoretical analysis.
We study recovering parity check relations for an unknown code from intercepted bitstream receive... more We study recovering parity check relations for an unknown code from intercepted bitstream received from Binary Symmetric Channel in this paper. An iterative column elimination algorithm is introduced which attempts to eliminate parity bits in codewords of noisy data. This algorithm is very practical due to low complexity and use of XOR operator. Since, the computational complexity is low, searching for the length of code and synchronization is possible. Furthermore, the Hamming weight of the parity check words are only used in threshold computation and unlike other algorithms, they have negligible effect in the proposed algorithm. Eventually, experimental results are presented and estimations for the maximum noise level allowed for recovering the words of the parity check matrix are investigated.
In this paper, a new method for decoding Low Density Parity Check (LDPC) codes, based on Multi-La... more In this paper, a new method for decoding Low Density Parity Check (LDPC) codes, based on Multi-Layer Perceptron (MLP) neural networks is proposed. Due to the fact that in neural networks all procedures are processed in parallel, this method can be considered as a viable alternative to Message Passing Algorithm (MPA), with high computational complexity. Our proposed algorithm runs with soft criterion and concurrently does not use probabilistic quantities to decide what the estimated codeword is. Although the neural decoder performance is close to the error performance of Sum Product Algorithm (SPA), it is comparatively less complex. Therefore, the proposed decoder emerges as a new infrastructure for decoding LDPC codes.
Energy detection has been adopted as an alternative spectrum sensing method for cognitive radios ... more Energy detection has been adopted as an alternative spectrum sensing method for cognitive radios due to its low computational complexity and not requiring a priori information of the signal to be detected (1). However, different channel condition and noise power estimation in low Signal-to-noise ratio (SNR), make energy detection practically challenging. To overcome these difficulties, a cooperative framework is proposed
2008 Second International Conference on Electrical Engineering, 2008
For a given multicast network problem, there are different solutions. Sometimes some links of a n... more For a given multicast network problem, there are different solutions. Sometimes some links of a network may be removed by failure and then we will be encountered with link failure in the network. Therefore, one of the objectives of selecting a specific network code solution among different options is to increase the robustness provided by this solution against such failure.
International Journal of Engineering and Technology, 2012
Certificateless cryptosystems were proposed by Al-Riyami and Paterson in 2003 [1] to solve proble... more Certificateless cryptosystems were proposed by Al-Riyami and Paterson in 2003 [1] to solve problems of public key cryptosystems based on PKI and based on identity. Up to now, various types of certificateless cryptographic primitives as encryption functions, signature schemes, key agreement protocols and etc, have been designed. But to the best of our knowledge, multiple-key agreement protocols have not been proposed based on certificateless cryptosystem yet. So in this paper we propose a certificateless authenticated multiple-key agreement protocol with bilinear pairings.
Security and Communication Networks, 2014
ABSTRACT A large number of random key pre-distribution (RKD) schemes have been proposed in the li... more ABSTRACT A large number of random key pre-distribution (RKD) schemes have been proposed in the literature to secure wireless sensor network applications, relying on symmetric key cryptography. However, sensor nodes are exposed to physical compromise by adversaries, who target the symmetric keys stored at each node. With the stolen keys in their possession, the adversaries are then able to compromise communication links between benign nodes. Here, the big challenge arises: how to increase resilience of RKD schemes for wireless sensor networks to node capture, while maintaining the flexibility and low-cost features of RKD? We propose the idea of key splitting to address this problem, without the need of any special-purpose hardware. Our key splitting scheme neither increases per-node storage nor introduces additional computation and communication overheads. Nevertheless, it can achieve better connectivity. More importantly, it significantly increases resilience to node compromise, when the adversary does not have overwhelming computational power. Copyright © 2014 John Wiley & Sons, Ltd.
Uploads
Papers by Mahmoud Ahmadian-Attari