11 results on '"Forouzesh, Moslem"'
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2. Covert communication based on energy harvesting and cooperative jamming
- Author
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Azerang, Seyedeh Fatemeh, Samsami Khodadad, Farid, and Forouzesh, Moslem
- Published
- 2022
- Full Text
- View/download PDF
3. Joint Information Theoretic Secrecy and Covert Communication in the Presence of an Untrusted User and Warden
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Kuhestani, Ali, and Yeoh, Phee Lep
- Subjects
Signal Processing (eess.SP) ,FOS: Electrical engineering, electronic engineering, information engineering ,Data_CODINGANDINFORMATIONTHEORY ,Electrical Engineering and Systems Science - Signal Processing - Abstract
In this paper, we investigate joint information theoretic secrecy and covert communication in a single-input multi-output (SIMO) system where a transmitter (Alice) is communicating with two legitimate users (Bob and Carol). We consider that an untrusted user and a warden node are also present in the network attempting to attack the secure and covert communications to Bob and Carol, respectively. Specifically, Bob requires secure communications such that his messages from Alice are not decoded by the untrusted user, while Carol requires covert communications such that her messages from Alice are not detected by the warden. To do so, we consider that Alice transmits Carol's messages during selected time slots to hide them from the warden while also transmitting Bob's messages in each time slot contentiously. We formulate an optimization problem with the aim of maximizing the average rate subject to a covert communication requirement and a secure communications constraint. Since the proposed optimization problem is non-convex, we utilize successive convex approximation to obtain a tractable solution. We consider practical assumptions that Alice has imperfect knowledge of the warden's location and imperfect channel state information (CSI) of Bob and Carol. Our numerical examples highlight that the imperfect CSI at Carol has a more detrimental impact on the average rate compared to imperfect CSI at Bob., 9 pages, 5 figures, 1 table
- Published
- 2020
4. Covert Transmission with Antenna Selection and Using an External Jammer
- Author
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Sarkheil, Morteza, Azmi, Paeiz, Forouzesh, Moslem, and Kuhestani, Ali
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Signal Processing (eess.SP) ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,FOS: Electrical engineering, electronic engineering, information engineering ,Data_CODINGANDINFORMATIONTHEORY ,Electrical Engineering and Systems Science - Signal Processing - Abstract
This paper adopts the antenna selection technique to enhance the covert rate in a wireless communication network comprised of a source, a destination , an external jammer and an eavesdropper. In the covert communication, the level of transmit power is low and hence a source with multiple antennas can be adopted to send the information toward the single antenna destination while concurrently, the jammer transmits an artificial noise signal. For this system model, we consider a scenario where the source is forced to select one or several of its antennas to transmit its confidential information due to its limited RF chains. Furthermore, we consider two different jamming scenarios to support our covert communication: 1) The destination is unable to cancel the jamming signal, 2) The destination can subtract the jamming signal. For such a communication network, our aim is to maximize the covert rate subject to power constraint and covert communication requirement. In the first scenario, the optimization problem is non-convex, and hence, it can be solved through using Difference of Convex function (DC) method while the optimization problem of the second scenario is intrinsically convex. Our numerical results show that the higher the number of selected antennas at the transmitter, the higher the covert rate will be achieved.
- Published
- 2018
5. Robust Power Allocation in Covert Communication: Imperfect CDI.
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Mokari, Nader, and Goeckel, Dennis
- Subjects
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MARKETING channels , *MULTIPATH channels , *TRANSMITTERS (Communication) , *GAUSSIAN channels - Abstract
The study of the fundamental limits of covert communications, where a transmitter Alice wants to send information to a desired recipient Bob without detection of that transmission by an attentive and capable warden Willie, has emerged recently as a topic of great research interest. Previous work has assumed that the distribution of the multipath fading on the channel, which we term the channel distribution information (CDI), is known to Alice, hence facilitating her characterization of Willie's capabilities to detect the signal. However, in practice, Willie tends to be passive and the environment heterogeneous, implying a lack of signaling interchange between the transmitter and Willie makes it difficult if not impossible for Alice to estimate the CDI exactly and provide covertness guarantees. In this paper, we address this issue by developing covert communication schemes for various assumptions on Alice's imperfect CDI: 1) when the transmitter knows the channel distribution is within some distance of a nominal distribution; 2) when only the mean and variance of the channel distribution are available; 3) when Alice knows the channel distribution is complex Gaussian but the variance is unknown. In each case, we formulate new optimization problems to find the power allocations that maximize covert rate subject to a covertness requirement under uncertain CDI. Moreover, Willie may be able to estimate CDI exactly or be faced with an error in estimation, and we investigate two these issues. Numerical results are presented to compare the proposed schemes from various aspects, for attaining desirable covert system performance. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Robust Physical Layer Security for Power Domain Non-orthogonal Multiple Access-Based HetNets and HUDNs, SIC Avoidance at Eavesdroppers
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Mokari, Nader, and Wong, Kai Kit
- Subjects
Signal Processing (eess.SP) ,FOS: Computer and information sciences ,Computer Science - Cryptography and Security ,Information Theory (cs.IT) ,Computer Science - Information Theory ,FOS: Electrical engineering, electronic engineering, information engineering ,Data_CODINGANDINFORMATIONTHEORY ,Electrical Engineering and Systems Science - Signal Processing ,Cryptography and Security (cs.CR) ,Computer Science::Cryptography and Security ,Computer Science::Information Theory - Abstract
In this paper, we investigate the physical layer security in downlink of Power Domain Non Orthogonal Multiple Access based heterogeneous cellular network in presence of multiple eavesdroppers. Our aim is to maximize the sum secrecy rate of the network. To this end, we formulate joint subcarrier and power allocation optimization problems to increase sum secrecy rate. Moreover, we propose a novel scheme at which the eavesdroppers are prevented from doing Successive Interference Cancellation, while legitimate users are able to do it. In practical systems, availability of eavesdroppers Channel State Information is impractical, hence we consider two scenarios: 1 Perfect CSI of the eavesdroppers, 2 imperfect CSI of the eavesdroppers. Since the proposed optimization problems are nonconvex, we adopt the well known iterative algorithm called Alternative Search Method. In this algorithm, the optimization problems are converted to two subproblems, power allocation and subcarrier allocation. We solve the power allocation problem by the Successive Convex Approximation approach and solve the subcarrier allocation subproblem, by exploiting the Mesh Adaptive Direct Search algorithm. Moreover, in order to study the optimality gap of the proposed solution method, we apply the monotonic optimization method. Moreover, we evaluate the proposed scheme for secure massive connectivity in 5G networks. Numerical results highlight that the proposed scheme significantly improves the sum secrecy rate compared with the conventional case at which the eavesdroppers are able to apply SIC., 14 pages, 7 figures
- Published
- 2018
7. Information-Theoretic Security or Covert Communication
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Mokari, Nader, Wong, Kai Kit, and Goeckel, Dennis
- Subjects
FOS: Computer and information sciences ,Computer Science - Cryptography and Security ,Cryptography and Security (cs.CR) - Abstract
Information-theoretic secrecy, in particular the wiretap channel formulation, provides protection against interception of a message by adversary Eve and has been widely studied in the last two decades. In contrast, covert communications under an analogous formulation provides protection against even the detection of the presence of the message by an adversary, and it has drawn significant interest recently. These two security topics are generally applicable in different scenarios; however, here we explore what can be learned by studying them under a common framework. Under a similar but not identical mathematical formulation, we introduce power optimization problems for each of the secrecy and the covert communications scenario, and we exploit common aspects of the problems to employ similar tools in their respective optimizations. Moreover, due to the practical limitations, we assume only channel, 20 pages, 6 figures, two tables
- Published
- 2018
8. Covert Communication Using Null Space and 3D Beamforming: Uncertainty of Willie's Location Information.
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Mokari, Nader, and Goeckel, Dennis
- Subjects
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BEAMFORMING , *ANTENNA arrays , *TRANSMITTERS (Communication) , *UNCERTAINTY , *ALGORITHMS , *TRANSMITTING antennas - Abstract
Covert communication is often limited in rate because it is difficult to hide the signal in the background noise. Recent work has shown that jamming can significantly improve the rate at which covert communication can be conducted, but this jamming signal has a devastating effect on the receiver. To tackle this issue, we equip the jammer with multiple antennas so that it can employ beamforming to place the intended receiver in the null space of the jamming. Moreover, in order to increase rate in this network, we equip the transmitter with an antenna array to be able to perform 3-dimensional (3D) beamforming toward its intended recipient. To evaluate this design, we formulate an optimization problem and present an iterative algorithm to solve it. Moreover, since Willie is passive, it is possible that Alice is not able to estimate the location of Willie perfectly. Hence, we investigate a new practical scenario in which the information about Willie's location is imperfect at Alice. Numerical results consider both the rate of covert communication with the proposed architecture and the gap between the result from our optimization and that obtained from exhaustive search. Numerical results highlight that the optimality gap is on average approximately 10%, and 3D beamforming compared to 2D beamforming increases covert rate by approximately 70%. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
9. Covert Communication and Secure Transmission Over Untrusted Relaying Networks in the Presence of Multiple Wardens.
- Author
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Forouzesh, Moslem, Azmi, Paeiz, Kuhestani, Ali, and Yeoh, Phee Lep
- Subjects
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ERROR probability , *ERROR detection (Information theory) , *SECRECY , *CONVEX programming - Abstract
In this paper, we address the problem of joint covert communication and secure transmission in untrusted relaying networks when multiple wardens exist in the network. We first consider a system model consisting of one source, one untrusted amplify-and-forward relay, one destination, and one warden. For covert communications, our aim is to prevent the warden from detecting the presence of communications via the source-relay-destination link. For secure transmission, our aim is to prevent the untrusted relay from decoding the source signal. To satisfy these requirements, we propose that the destination and the source inject jamming signals during the source-to-relay and relay-to-destination transmission phases, respectively. For the considered system model, we propose a power allocation strategy to maximize the secrecy rate and satisfy the covert requirements in both of the phases. Given that the proposed optimization problem is non-convex, we employ the successive convex approximation (SCA) approach to derive a tractable solution. To obtain further insights, we generalize our analytical results to consider multiple untrusted relays and multiple wardens. We focus on two scenarios of non-colluding and colluding wardens. Our results highlight that as the number of relays increases, the achievable secrecy rate increases while the average detection error probability decreases. This is a novel observation of a fundamental trade-off between covert requirement and secrecy performance. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Radio resource allocation in heterogeneous cellular networks based on effective capacity maximization: Perspective mobile data offloading.
- Author
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Gholami, Mohamad Hassan, Azmi, Paeiz, Mokari, Nader, and Forouzesh, Moslem
- Subjects
RADIO resource management ,FREQUENCY-division multiple access ,INTERFERENCE (Telecommunication) ,HETEROGENEOUS computing ,DECOMPOSITION method ,MATHEMATICAL optimization - Abstract
In this paper, a new radio resource allocation approach for mobile data offloading, by means of a local access point (LAP) in the heterogeneous cellular networks is proposed. We consider the uplink path in a single-carrier frequency-division multiple access-based multiuser system in a 2-tier cellular network with a macro base station (BS) and set of LAPs. We assume that there is no internetwork interference between macro BS and LAPs due to the use of 2 different sets of frequencies. Our aim is to allocate resources to determine the best strategy for providing the required quality of service with the criterion of minimum delay in terms of effective capacity maximization. The basis of this work is optimization for the strategy selection. In other words, the selection of the best station and power allocation for offloading in a single-carrier frequency-division multiple access multiuser system and solving the problems using the nonlinear optimization with the mesh adaptive direct algorithm solver and the dual decomposition method, respectively. The numerical results validate our analytical outcomes. For example, system delay decreases approximately 10 times if the traffic load of macro BS is decreased by 50%. In addition, we present a comparison of the impact of traffic reduction and consumed bandwidth due to offloading by means of LAPs on the cellular network, which confirms the efficiency of the proposed approach. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
11. Secure Full Duplex Communications in the Presence of Malicious Adversary.
- Author
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Forouzesh, Moslem and Azmi, Paeiz
- Subjects
WIRELESS communications ,WIRELESS sensor networks ,RADAR interference ,MOBILE communication systems ,TELECOMMUNICATION systems - Abstract
In this paper, we study the physical layer security in the presence of an adversary which is able to switch its mode from jamming mode (when transmits jamming signals) to eavesdropping mode (when adversary eavesdrops legitimate link) and vice versa. To combat with this type of adversary and establish security in this communication, we propose two approaches: 1) probabilistic approach (PA), 2) worst case approach (WCA). The system model consists of a source, an adversary and full-duplex destination. A full-duplex destination can receive the private message and transmit jamming signal to deceive the adversary, simultaneously. The simulation results show that the average rate PA, is 50% more than the WCA. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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