Prior studies on covert communication with noise uncertainty adopted a worst-case approach from the warden's perspective. That is, detection performance of warden is used to assess covertness, which overly optimistic. Instead simply considering worst limit, we take distribution into account evaluate overall covertness in statistical sense. Specifically, define new metrics for measuring are then analyze maximum achievable rate given requirement under both bounded and unbounded models.

In this paper, we study delay-intolerant covert communications in additive white Gaussian noise (AWGN) channels with a finite block length, i.e., number of channel uses. Considering the maximum allowable uses to be N, it is not immediately clear whether actual uses, denoted by n, should as large N or smaller for communications. This because n reduces warden's chance detect due fewer observations, but also transmit information. We show that = indeed optimal maximize amount information bits...

This paper proposes a new design of non-orthogonal multiple access (NOMA) under secrecy considerations. We focus on NOMA system, where transmitter sends confidential messages to users in the presence an external eavesdropper. The optimal designs decoding order, transmission rates, and power allocated each user are investigated. Considering practical passive eavesdropping scenario instantaneous channel state eavesdropper is unknown, we adopt outage probability as metric. first consider...

In this paper, we study covert communication in wireless networks consisting of a transmitter, Alice, an intended receiver, Bob, warden, Willie, and Poisson field interferers. Bob Willie are subject to uncertain shot noise due the ambient signals from interferers network. With aid stochastic geometry, analyze throughput between Alice given requirements on covertness against reliability decoding at Bob. We consider non-fading fading channels. analytically obtain interesting findings impacts...

Physical layer security has recently been regarded as an emerging technique to complement and improve the communication in future wireless networks. The current research development physical are often based on ideal assumption of perfect channel knowledge or capability variable-rate transmissions. In this paper, we study secure transmission design more practical scenarios by considering estimation errors at receiver investigating both fixed-rate Assuming quasi-static fading channels, on-off...

This letter investigates the secret key capacity of generation from correlated wireless channels in a source model. We systematically study practical scenario by taking into account all relevant parameters including sampling delay, eavesdroppers' location, qualities legitimate and eavesdropping channels, Doppler spread, pilot length. Our findings indicate that is determined cross correlation channel measurements, better not necessary when between higher than channels. also find it possible...

In this paper, we study physical layer security in an underlay cognitive radio (CR) network. We consider the problem of secure communication between a secondary transmitter-receiver pair presence randomly distributed eavesdroppers under interference constraint set by primary user. For different channel knowledge assumptions at transmitter, design four transmission protocols to achieve CR give comprehensive performance analysis for each protocol terms delay, security, reliability, and overall...

This work for the first time examines impact of transmitter-side correlation on artificial-noise-aided secure transmission, based which a new power allocation strategy artificial noise (AN) is devised physical layer security enhancement.Specifically, we design correlation-based (CPA) AN, optimality in terms achieving minimum secrecy outage probability analytically proved large system regime with number transmit antennas approaching infinity.In order to fully reveal benefits CPA, derive...

Theoretical studies on physical layer security often adopt the secrecy outage probability as performance metric for wireless communications over quasi-static fading channels. The has two limitations from a practical point of view: a) it does not give any insight into eavesdropper's decodability confidential messages; b) cannot characterize amount information leakage to eavesdropper when an occurs. Motivated by probability, we propose three new metrics secure transmissions first establishes...

Covert communication is to achieve a reliable transmission from transmitter receiver while guaranteeing an arbitrarily small probability of this being detected by warden. In work, we study the covert in AWGN channels with finite blocklength, which number channel uses finite. Specifically, analytically prove that entire block (all available uses) should be utilized maximize effective throughput subject predetermined requirement. This nontrivial result because more results observations at...

We propose a novel artificial noise (AN) injection scheme for wireless systems over quasi-static fading channels, in which single-antenna transmitter sends confidential messages to half-duplex receiver the presence of an eavesdropper. Different from classical AN schemes, rely on multiantenna or external helpers, our proposed is applicable scenario, where legitimate transceivers are very simple. analyze performance and optimize design transmission. Our results highlight that perfect secrecy...

Physical layer security is an emerging technique to improve the wireless communication security, which widely regarded as a complement cryptographic technologies. To design physical techniques under practical scenarios, uncertainty and imperfections in channel knowledge need be taken into consideration. This paper provides survey of recent research development considering imperfect state information (CSI) at nodes. We first present overview main information-theoretic measures secrecy...

The performance of millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems is limited by the sparse nature propagation channels and restricted number radio frequency chains at transceivers. introduction reconfigurable antennas offers an additional degree freedom on designing mmWave MIMO systems. This paper provides a theoretical framework for studying with antennas. Based virtual channel model, we present architecture beamspace hybrid analog-digital beamformers both...

We design linear precoders that perform confidential broadcasting in multi-cell networks for two different forms of base station (BS) cooperation, namely, processing (MCP) and coordinated beamforming (CBf). consider a two-cell network where each cell consists an $N$-antenna BS $K$ single-antenna users. For such network, we precoder based on the regularized channel inversion (RCI) MCP generalized RCI CBf. form derive new channel-independent expressions to approximate secrecy sum rate achieved...

In this paper, we study simultaneous wireless information and power transfer (SWIPT) in relay interference channels (ICs), where energy-constrained relays harvest energy from sources' radio-frequency signals use the harvested to forward destinations. We adopt splitting (PS) protocol alignment (IA) technique jointly realize management. propose two novel transmission schemes for SWIPT IC networks, namely, one-stage PS IA scheme two-stage scheme. For both schemes, investigate optimal ratios...

Recent studies have numerically demonstrated the possible advantages of asynchronous non-orthogonal multiple access (ANOMA) over conventional synchronous (NOMA). The ANOMA makes use oversampling technique by intentionally introducing a timing mismatch between symbols different users. Focusing on two-user uplink system, for first time, we analytically prove that with sufficiently large frame length can always outperform NOMA in terms sum throughput. To this end, derive expression throughput...

The existing research on physical layer security commonly assumes the number of eavesdropper antennas to be known. Although this assumption allows one easily compute achievable secrecy rate, it can hardly realized in practice. In paper, we provide an innovative approach studying secure communication systems without knowing by introducing concept spatial constraint into security. Specifically, is assumed have a limited region place (possibly infinite of) antennas. From practical point view,...

Recent studies have shown that asynchronous non- orthogonal multiple access (ANOMA) outperforms conventional synchronous non-orthogonal (NOMA) by taking advantage of artificial timing mismatch with oversampling. For the first time, we comprehensively study impact errors on performance uplink ANOMA systems in this paper. We consider two types errors, which are synchronization error and coordination error. analyze how affect systems, derive throughput loss incurred both An interesting finding...

The potential dual use of radio-frequency (RF) signals for carrying energy and information brings an exciting opportunity harvesting (EH) from ambient RF in wireless communication networks. To maximize the efficiency energy, it is desirable to have EH node located close transmitter. However, when transmitted confidential, should be regarded as a eavesdropper, hence, preferred far Therefore, placement nodes networks becomes interesting problem secrecy important consideration. In this paper,...

For secure communications over wireless fading channels, the secrecy outage probability is widely used as performance measure. However, current formulation has two major limitations in evaluating performance: a) amount of information leakage to eavesdropper cannot be characterized when an occurs, b) does not give insights into eavesdropper's decodability confidential messages. To overcome such and obtain in-depth understanding this paper proposes three new measures for different practical...

We propose for the first time new transmission schemes based on linear precoding to enable simultaneous confidential broadcasting and power transfer in a multiuser multi-input single-output network, where base station with N antennas simultaneously transmits messages K single-antenna users. design two rules of regularized channel inversion (RCI) both splitting (PS) switching (TS) receiver architectures, namely, RCI-PS RCI-TS schemes. For each scheme, we derive channel-independent expressions...

We propose a novel analytical framework for evaluating the coverage performance of millimeter wave (mmWave) cellular network where idle user equipments (UEs) act as relays. In this network, base station (BS) adopts either direct mode to transmit destination UE, or relay if fails, BS transmits UE and then UE. To address drastic rotational movements UEs in practice, we adopt selection combining at UEs. New expression is derived signal-to-interference-plus noise ratio (SINR) probability...

In this paper, we study secure transmission designs for underlay cognitive radio networks in the present of randomly distributed eavesdroppers. We consider scenario where a secondary transmitter sends confidential messages to receiver subject an interference constraint set by primary user. design two protocols under different channel knowledge assumptions at transmitter. For each protocol, first give comprehensive performance analysis investigate delay, secrecy, and reliability performance....

This paper proposes a new design of non-orthogonal multiple access (NOMA) under secrecy considerations. We focus on NOMA system where transmitter sends confidential messages to users in the presence an external eavesdropper. The optimal designs decoding order, transmission rates, and power allocated each user are investigated. Considering practical passive eavesdropping scenario instantaneous channel state eavesdropper is unknown, we adopt outage probability as metric. first consider problem...

Physical layer security is an emerging technique to improve the wireless communication security, which widely regarded as a complement cryptographic technologies. To design physical techniques under practical scenarios, uncertainty and imperfections in channel knowledge need be taken into consideration. This paper provides survey of recent research development considering imperfect state information (CSI) at nodes. We first present overview main information-theoretic measures secrecy...