Search for: physical-layers
Total 42 records
Article IEEE Wireless Communications Letters ; 2017 ; 21622337 (ISSN) ; Aref, M. R ; Sharif University of Technology
This letter presents an efficient polar code-based physical layer encryption (PLE) scheme with a short key length in comparison to the conventional symmetric key cryptosystems. By using the properties of polar codes, we consider several efficient techniques to reduce the key length and the computational overhead of the presented PLE scheme. Moreover, the results of the security analyses show that the proposed scheme has a high level of security against conventional attacks on the PLE schemes. In fact, reducing the key length and the computational overhead of the presented PLE scheme has no effect on its security level, which makes it suitable for secure mobile communication devices with...
M.Sc. Thesis Sharif University of Technology ; Mirmohseni, Mahtab
The increasing expansion of wireless communications and the increase in information traffic and the number of communication users, and on the other hand, the frequency and energy frequency limitations have led to the emergence of new generation communications. In the fifth generation of communications, one of the solutions to ensure the optimal use of bandwidth is the use of the non-orthogonal multiple access (NOMA) schema, which of course, the use of such a scheme in the system naturally increases the complexity of the receivers. Unlike most access methods in previous generations of communications, the goal of NOMA is the simultaneous use of multiple users from a frequency band for data...
A comparison between different meta-heuristic techniques in power allocation for physical layer security, Article Iranian Journal of Electrical and Electronic Engineering ; Volume 13, Issue 4 , 2017 , Pages 310-317 ; 17352827 (ISSN) ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
Node cooperation can protect wireless networks from eavesdropping by using the physical characteristics of wireless channels rather than cryptographic methods. Allocating the proper amount of power to cooperative nodes is a challenging task. In this paper, we use three cooperative nodes, one as relay to increase throughput at the destination and two friendly jammers to degrade eavesdropper’s link. For this scenario, the secrecy rate function is a non-linear non-convex problem. So, in this case, exact optimization methods can only achieve suboptimal solution. In this paper, we applied different meta-heuristic optimization techniques, like Genetic Algorithm (GA), Partial Swarm Optimization...
M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza ; Mirmohseni, Mahtab
In this thesis, we investigate the achievable secrecy rate in a relay channel where the source and the destination wish to keep the information confidential from an untrusted relay (potential eavesdropper). The relay has no energy supply, and harvests its required energy for relaying from its received signals. For radio-frequency (RF) Energy Harvesting (EH) at the relay,we adopt power splitting (PS) and time switching (TS) approach. We study the problem of achieving positive secrecy rates between the transmitter and the receiver while making use of an untrusted relay. Energy limitation at the relay makes the problem more interesting. Because,the relay must choose either to eavesdrop the...
Article IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference, 4 July 2011 through 8 July 2011 ; July , 2011 , Pages 1545-1549 ; 9781424495399 (ISBN) ; Khalaj, B. H ; Pasandshanjani, E ; Sharif University of Technology
The focus of the paper is on cross-layer transmission based on rateless coding for relay networks. In the proposed method, rateless coding is used at the packet level and a separate physical layer coding is used at the physical layer. As rateless codes are originally designed and optimized for erasure channels, using these codes at the physical layer can lead to significant performance degradation. The proposed scheme has the advantage of a cross-layer design which uses a rateless code at the packet level modeled by an erasure channel. Based on the analysis and simulation results provided in this paper, the cross-layer scheme results in earlier successful decoding at the destination
Article 2010 5th International Symposium on Telecommunications, IST 2010 ; 2010 , Pages 351-355 ; 9781424481835 (ISBN) ; Hossein Khalaj, B ; Sharif University of Technology
This paper focuses on cross-layer transmission based on rateless coding for relay channels. In the proposed method, rateless coding is used at packet level and a separate physical layer coding is used at the physical layer. As rateless codes are originally designed and optimized for erasure channels, using these codes at the physical layer can lead to significant performance degradation. The proposed scheme has the advantage of a cross-layer design which uses a rateless code at the packet level modeled by an erasure channel. Based on the analysis and simulation results provided in this paper, there is an exact tradeoff between physical layer code rate and rateless code depth, and the optimum...
Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) ; Aminian, G ; Mirmohseni, M ; Gohari, A ; Nasiri Kenari, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2016
In traditional wireless networks, physical layer network coding (PNC) exploits the inverse additivity property of broadcast signals in the medium, an idea which is not directly applicable to molecular networks. In this paper, to make the natural XOR operation possible at the physical layer, we exploit the reaction of different molecule types and we propose a PNC scheme in diffusion-based molecular relay networks. For comparison, we consider the straightforward network coding (SNC) scheme in molecular networks. Assuming the ligand-receptor binding process at the receivers, we investigate the error performance of both schemes. It is observed that in addition to the simplicity of the proposed...
Article 9th International Symposium on Telecommunication, IST 2018, 17 December 2018 through 19 December 2018 ; 2019 , Pages 670-675 ; 9781538682746 (ISBN) ; Azmi, P ; Kuhestani, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2019
In this paper, we investigate the problem of secure communication with covert requirement in untrusted relaying networks. Our considered system model contains one source, one destination, one untrusted relay, and one Willie. The untrusted relay tries to extract the information signal, while the goal of Willie is to detect the presence of the information signal transmitted by the source, in the current time slot. To overcome these two attacks, it is assumed that the destination and the source inject jamming signal to the network in phase I and phase II, respectively. Accordingly, the communication in our proposed system model is accomplished in two phases. In the first phase, when the source...
M.Sc. Thesis Sharif University of Technology ; Behroozi, Hamid
IoT security is an important step in the rapid development of its applications and ser-vices. Many security protocols have been defined to maintain security at higher communication layers, such as the transport layer and the application layer, but with the advent of quantum computers due to high-speed parallel computing, the previous methods are no longer secure and we have to establish security at lower layers such as the physical layer. The efficiency of IoT devices depends on the reliability of their message transmission. Cyber-attacks such as data injection, eavesdropping and man-in-the-middle can lead to security challenges. In this study, we propose a new deep learning based component...
Article IEEE Journal on Selected Areas in Communications, Piscataway, NJ, United States ; Volume 18, Issue 3 , 2000 , Pages 458-471 ; 07338716 (ISSN) ; Rashid Farrokhi, F ; Liu, K. J. R ; Sharif University of Technology
A wireless network with beamforming capabilities at the receiver is considered that allows two or more transmitters to share the same channel to communicate with the base station. A novel approach is introduced, which combines the effects of the digital signal processing (adaptive beamforming) at the physical layer with the traffic policies at the network layer on the overall queuing model of a cell. The effect of signal processing on the queuing model of the cell is represented by a parameter in the final cell model. Each cell is modeled by a multiuser/multiserver service facility, where each server is a beamformed channel formed by the cell's base station. From this effective cell model,...
M.Sc. Thesis Sharif University of Technology ; Pakravan, Mohammad Reza
Considering the advantages of optical communications and code division multiple access technique, Optical Code Division Multiple Access Networks (OCDMANs) was introduced. Thence, many researchers have suggested methods for creating Quality of Service (QoS) differentiated classes in OCDMANs. In this thesis, we have comprehensive review on the QoS assignment methods and enhance them by offering new techniques. In physical layer, we concentrate on variable chip rate OCDMANs and in MAC sub-layer, a new algorithm named Adaptive Level Control (ALC) is introduced. Then, we focus on the physical design of OCDMANs. Firstly, we solve the problem of one-class OCDMAN and introduce few simple and...
Implementation and Development of a New Framework for Flexible Inter-PHY Functional Splitting in Cloud RAN Networks, M.Sc. Thesis Sharif University of Technology ; Hossein Khalaj, Babak
Thorough investigation of the Cloud-RAN (C-RAN) architecture has recently shown that CRAN can bring advanced cooperated and coordinated processing capabilities as well as the multiplexing gains toward future radio access networks. The baseband processing of each base station instance can now be flexibly split into smaller functional components, that can be placed either at remote radio units (RRUs) or baseband units (BBUs), depending on the available resources. In this project, we investigate recent implemented methods in C-RAN. also, we propose, develop and implement new architectural frameworks for C-RAN that can support both a flexible functional split and a new functional splitting known...
M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza
Security for wireless communication networks has become a crucial issue because of the broadcast nature of wireless channels. On every cellular network Since it is possible for passive nodes to easily overhear the confidential information transmitted between transmitter and receiver, it is necessary to provide secure communication.When a cellular user wants to communicate with a node or base station on the cellular network, it expects that information will be transmitted and received without interference, with enough quality and without eavesdropping. On the other hand In practical scenarios, we know that cellular network nodes are not equipped with ideal equipment and some percent...
M.Sc. Thesis Sharif University of Technology ; Behroozi, Hamid ; Hossein Khalaj, Babak
The rapid development of wireless communications, e.g., the sixth generation (6G) networks, together with the emergence of various technologies for exchanging data has made the information security a big concern. In other words, today’s decentralized wireless networks face with major challenges in terms of key distribution and management of traditional cryptographic techniques. In contrast, the approach of PHY layer security, which wisely utilizes the inherent characteristics of wireless links, has been introduced to address provable and lightweight security mechanisms. In addition, learning-based techniques have shown to be able to provide well-established mechanisms in enhancing the...
Physical Layer Security in Wireless Communication Networks in Presence of Intelligent Reflecting Surfaces, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh ; Mirmohseni, Mahtab
The ever-increasing demand for wireless communication has raised the need for better utilization of bandwidth and energy. Intelligent Reflecting Surface (IRS) is an emerging technology that has been proposed for the sixth generation of wireless communication. In this thesis, we study the essential role these surfaces can play in improving the physical layer security.First, we consider a relatively realistic scenario for the location of the eavesdroppers. In this scenario, we will assume that the transmitters, users, and eavesdroppers all use a single antenna configuration, and the eavesdroppers are placed randomly across the studied region. Two notable parameters in physical layer security,...
M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza
In modern wireless communication networks,that we have heterogeneous, asynchronous and ultra low latency networks and Due to the high processing power required by conventional cryptographic systems based on computational security, information theoritc security can play important role in the future development of these systems. Security in this case does not depend on the eavesdropper's computing power, but on the statistical independence between the main message and the received message of the eavesdropper. In recent years, polar codes have created new arenas, as they were the provable channel codes that could achieve capacity and reliability simultaneously. In addition, the clear structure,...
Article IET Communications ; Vol. 8, issue. 11 , July , 2014 , p. 1965-1976 ; Aref, M. R ; Sharif University of Technology
In this study, the authors consider the secrecy of a one-receiver, two-eavesdropper broadcast channel (BC) with three degraded message sets. Consider a three-receiver BC with three messages, where the first message is decoded by all the receivers. The second message is decoded by the first and the second receivers and is to be kept secret from the third receiver. The third message is decoded by the first receiver and is to be kept secret from the second and the third receivers. The authors consider the imperfect secrecy condition at the second receiver, that is, it is allowed to partially decode the third message. However, the perfect secrecy condition at the third receiver, does not allow...
Article 2013 World Congress on Computer and Information Technology, WCCIT 2013 ; June , 2013 , Page(s): 1 - 6 ; 9781479904600 (ISBN) ; Oskoei, H. R. D ; Vazirnezhad, B ; Sharif University of Technology
Considering the weaknesses of cryptography algorithms and the attacks performed against them, cryptography alone cannot guarantee the security of communication in a wireless network. With regard to the developments in wireless communication networks brought about by smart array antennas, security can be sought in the physical layer as well, aiming to restrict the access of the data in a wireless network and limit it to authorized users only in order to further restrain malicious data accesses. In this paper, we analysis a strategy for restricting data access using smart array antennas and present the results in security by a parameter called exposure region. For this strategy afterwards we...
A novel genetic-based resource allocation and cooperative node selection technique for physical layer security designs, Article Wireless Personal Communications ; Volume 95, Issue 4 , 2017 , Pages 4733-4746 ; 09296212 (ISSN) ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
Springer New York LLC 2017
This paper presents a novel approach for power allocation and cooperative node selection to enhance physical layer security in presence of an eavesdropper in a wireless network. Our network consists of a source–destination pair and a number of cooperative nodes which can be used as relays to increase throughput at the destination, or as friendly jammers to confuse eavesdropper. First, we introduce a low complexity method, for which relay−jammer selection and power allocation are performed, simultaneously. Then, we propose self-adaptive genetic algorithm to solve the non-linear non-convex programing problem. Using the proposed method, the number of friendly jammers that ensure the secrecy...
Article 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 374-379 ; 9781509034345 (ISBN) ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2017
Node cooperation approaches improve physical layer security in wireless networks without applying data encryption. Selecting the appropriate nodes to cooperate as relays or friendly jammers, to degrade eavesdropper's link, is a challenging problem which has attracted a lot of attention in recent years. Various approaches, based on conventional exhaustive search, have been suggested for optimal relay-jammer selection and power allocation in the literature. The complexity of these methods is proportional to the number of intermediate nodes. As the number of intermediate nodes exceeds a specific bound, conventional exhaustive search appears infeasible due to high computational complexity. In...