Non-orthogonal multiple access (NOMA) has been recognized as a promising technique for providing high data rates in 5G systems. This letter is to study physical layer security single-input single-output (SISO) NOMA system consisting of transmitter, legitimate users and an eavesdropper. The aim this maximize the secrecy sum rate (SSR) subject users' quality service (QoS) requirements. We firstly identify feasible region transmit power satisfying all QoS Then we derive closed-form expression...

In this paper, we address the security of a two-way relay network in presence an eavesdropper, where each node is only equipped with single antenna. We propose two-phase distributed analog coding, or beamforming and power allocation to enhance secrecy sum rate data exchange. first phase, two terminals broadcast their information simultaneously all nodes. second three different schemes are proposed: optimal beamforming, null-space artificial noise beamforming. scheme, objective achieve...

Non-orthogonal multiple access (NOMA) is considered as a promising technology for improving the spectral efficiency in fifth-generation systems. In this correspondence, we study benefit of NOMA enhancing energy (EE) multiuser downlink transmission, wherein EE defined ratio achievable sum rate users to total power consumption. Our goal maximize subject minimum required data each user, which leads nonconvex fractional programming problem. To solve it, first establish feasible range...

In this paper, we study power-efficient resource allocation for multicarrier non-orthogonal multiple access systems. The algorithm design is formulated as a non-convex optimization problem which jointly designs the power allocation, rate user scheduling, and successive interference cancellation (SIC) decoding policy minimizing total transmit power. proposed framework takes into account imperfection of channel state information at transmitter quality service requirements users. To facilitate...

The heterogeneous cellular network (HCN) is a promising approach to the deployment of 5G networks. This paper comprehensively studies physical layer security in multitier HCN where base stations (BSs), authorized users, and eavesdroppers are all randomly located. We first propose an access threshold-based secrecy mobile association policy that associates each user with BS providing maximum truncated average received signal power beyond threshold. Under proposed policy, we investigate...

In this paper, we propose a hybrid cooperative beamforming and jamming scheme to enhance the physical-layer security of single-antenna-equipped two-way relay network in presence an eavesdropper. The basic idea is that both transmission phases, some intermediate nodes help signals legitimate destination adopting distributed beamforming, while remaining jam eavesdropper, simultaneously, which takes data transmissions phases under protection. Two different schemes are proposed, with without...

Recent studies show that millimeter wave (mmWave) communications can offer orders of magnitude, which increases in the cellular capacity. However, secrecy performance an mmWave network has not been investigated so far. Leveraging new path-loss and blockage models for channels, are significantly different from conventional microwave channel, this paper comprehensively network-wide physical layer security downlink transmission under a stochastic geometry framework. We first study secure...

In this letter, we consider an intelligent reflecting surface (IRS) assisted Guassian multiple-input multiple-output (MIMO) wiretap channel in which a multi-antenna transmitter communicates with receiver the presence of eavesdropper. To maximize secrecy rate channel, alternating optimization (AO) algorithm is proposed to jointly optimize transmit covariance R at and phase shift coefficient Q IRS by fixing other as constant. When fixed, existing numerical used search for global optimal R....

Physical layer security, or information-theoretic has attracted considerable attention recently, due to its potential enhance the transmission secrecy of wireless communications. Various signaling and coding schemes have been designed at physical systems guarantee confidentiality against information leakage unauthorized receivers, among which strategy based on idea node cooperation is promising. This article provides an overview recent research enhancing via cooperation. We take a signal...

In applications of the Internet Things (IoT), use short packets is expected to meet stringent latency requirement in ultra-reliable low-latency communications; however, incurred security issues and impact finite blocklength coding on physical-layer are not well understood. This paper investigates performance secure short-packet communications a mission-critical IoT system with an external multi-antenna eavesdropper. An analytical framework proposed approximate average achievable secrecy...

This paper studies multi-antenna-aided covert communications coexisting with randomly located wardens and interferers, considering both centralized distributed antenna systems (CAS/DAS). The throughput performance of the communication is analyzed optimized under a stochastic geometry framework, where joint impact small-scale channel fading large-scale path loss examined. To be specific, two probabilistic metrics, namely, outage probability connectivity probability, are adopted to...

In this article, we consider an intelligent reflecting surface (IRS) assisted Guassian multiple-input multiple-output (MIMO) wiretap channel (WTC), and focus on enhancing its secrecy rate. Due to MIMO setting, all the existing solutions for rate over single-output WTC completely fall work. Furthermore, studies are simply based ideal assumption that full state information (CSI) of eavesdropper (Ev) is available. Therefore, propose numerical enhance under both no Ev's CSI cases. For case, a...

Reconfigurable Intelligent Surface (RIS) draws great attentions in academic and industry due to its passive low power consumption nature, has currently been used physical layer security enhance the secure transmission. However, existence of "double fading" effect on reflecting channel link between transmitter user, RIS helps achieve limited secrecy performance gain compared with case without RIS. In this correspondence, we propose a novel active design wireless transmission, where elements...

Cooperative beamforming and jamming are two efficient schemes to improve the physical-layer security of a wireless relay system in presence passive eavesdroppers. However, most works these techniques adopted separately. In this letter, we propose joint cooperative scheme enhance network, where part intermediate nodes adopt distributed while others jam eavesdropper, simultaneously. Since instantaneous channel state information (CSI) eavesdropper may not be known, artificial noise transmission...

In this paper, we study the secure multi-antenna transmission with artificial noise (AN) under slow fading channels coexisting randomly located eavesdroppers. We provide a comprehensive secrecy performance analysis and system design/optimization stochastic geometry framework. Specifically, first evaluate outage performance, derive closed-form expression for optimal power allocation ratio of information signal to total transmit that minimizes probability (SOP). Subject SOP constraint, then...

This paper studies the cooperative transmission for securing a decode-and-forward (DF) two-hop network where multiple nodes coexist with potential eavesdropper. Under more practical assumption that only channel distribution information (CDI) of eavesdropper is known, we propose an opportunistic relaying artificial jamming secrecy scheme, "best" node chosen among collection N possible candidates to forward confidential signal and others send signals confuse eavesdroppers. We first investigate...

The artificial noise (AN) scheme is an efficient strategy for enhancing the secrecy rate of a multiple-input-single-output channel in presence passive eavesdropper, whose state information unavailable. Recently, randomized beamforming has been proposed deteriorating eavesdropper's bit-error-rate performance via corrupting its receiving signal by time-varying multiplicative noise. However, such not well addressed yet. In this paper, we name it fast fading (AFF) and provide comprehensive...

In this letter, improving the security of an intelligent reflecting surface (IRS) assisted multiple-input single-output (MISO) communication system is studied. Different from ideal assumption in existing literatures that full eavesdropper's (Eve's) channel state information (CSI) available, we consider a more practical scenario without Eve's CSI. To enhance given total transmit power at transmitter (Alice), propose joint beamforming and jamming approach, which minimum firstly optimized Alice...

This paper studies the secure multiple-antenna transmission in slow fading channels for cognitive radio network, where a multiple-input, single-output, multieavesdropper (MISOME) primary network coexisting with multiple-input single-output secondary user (SU) pair. The SU can get opportunity to achieve its own data traffic by providing secrecy guarantee PU artificial noise. Different from existing works, which adopt instantaneous rate as performance metric, only statistical channel state...

The deployment of unmanned aerial vehicle (UAV) for surveillance and monitoring gives rise to the confidential information leakage challenge in both civilian military environments. security covert communication problems a pair terrestrial nodes against UAV are considered this paper. To overcome increase transmission reliability, multi-hop relaying strategy is deployed. We aim optimize throughput by carefully designing parameters network, including coding rates, transmit power, required...

Due to their flexible deployment and on-demand mobility, small-scale unmanned aerial vehicles (UAVs) are anticipated be involved in widespread communication applications the forthcoming fifth-generation networks. However, confidentiality of UAV is vulnerable security threats due broadcast nature dominant line-of-sight channel conditions, physical-layer can applied for secrecy performance enhancement such a context. On other hand, it also promising exploit UAVs cooperatively protect secure...

The idea of multiuser (nodes) cooperation is an efficient way to improve the physical-layer security a wireless transmission in presence passive eavesdroppers. However, due half-duplex constraint practical transceivers, two phases are required for one round data transmission, which grants eavesdroppers opportunities wiretap information. Therefore, protecting transmissions both critical. Toward this end, we propose joint cooperative beamforming, jamming, and power-allocation scheme enhance...

In this paper, we consider the problem of secure communications for a four-node system consisting one source, destination, eavesdropper, and helper. We investigate question which role should helper act to improve secrecy, jam, or relay. Two transmission schemes are investigated: (1) direct scheme (DTS) with jamming (2) relay (RTS). both path-loss fading-in channel models define notion distance normalized signal-to-noise-ratio (DN-SNR) account propagation. The ergodic secrecy rate (ESR) is...