126 research outputs found
To Harvest and Jam: A Paradigm of Self-Sustaining Friendly Jammers for Secure AF Relaying
This paper studies the use of multi-antenna harvest-and-jam (HJ) helpers in a
multi-antenna amplify-and-forward (AF) relay wiretap channel assuming that the
direct link between the source and destination is broken. Our objective is to
maximize the secrecy rate at the destination subject to the transmit power
constraints of the AF relay and the HJ helpers. In the case of perfect channel
state information (CSI), the joint optimization of the artificial noise (AN)
covariance matrix for cooperative jamming and the AF beamforming matrix is
studied using semi-definite relaxation (SDR) which is tight, while suboptimal
solutions are also devised with lower complexity. For the imperfect CSI case,
we provide the equivalent reformulation of the worst-case robust optimization
to maximize the minimum achievable secrecy rate. Inspired by the optimal
solution to the case of perfect CSI, a suboptimal robust scheme is proposed
striking a good tradeoff between complexity and performance. Finally, numerical
results for various settings are provided to evaluate the proposed schemes.Comment: 16 pages (double column), 8 figures, submitted for possible journal
publicatio
Transmit optimization techniques for physical layer security
PhD ThesisOver the last several decades, reliable communication has received considerable
attention in the area of dynamic network con gurations and
distributed processing techniques. Traditional secure communications
mainly considered transmission cryptography, which has been developed
in the network layer. However, the nature of wireless transmission introduces
various challenges of key distribution and management in establishing
secure communication links. Physical layer security has been
recently recognized as a promising new design paradigm to provide security
in wireless networks in addition to existing conventional cryptographic
methods, where the physical layer dynamics of fading channels
are exploited to establish secure wireless links. On the other hand, with
the ever-increasing demand of wireless access users, multi-antenna transmission
has been considered as one of e ective approaches to improve
the capacity of wireless networks. Multi-antenna transmission applied
in physical layer security has extracted more and more attentions by
exploiting additional degrees of freedom and diversity gains.
In this thesis, di erent multi-antenna transmit optimization techniques
are developed for physical layer secure transmission. The secrecy rate
optimization problems (i.e., power minimization and secrecy rate maximization)
are formulated to guarantee the optimal power allocation.
First, transmit optimization for multiple-input single-output (MISO) secrecy
channels are developed to design secure transmit beamformer that
minimize the transmit power to achieve a target secrecy rate. Besides,
the associated robust scheme with the secrecy rate outage probability
constraint are presented with statistical channel uncertainty, where the
outage probability constraint requires that the achieved secrecy rate
exceeds certain thresholds with a speci c probability. Second, multiantenna
cooperative jammer (CJ) is presented to provide jamming services
that introduces extra interference to assist a multiple-input multipleoutput
(MIMO) secure transmission. Transmit optimization for this CJaided
MIMO secrecy channel is designed to achieve an optimal power
allocation. Moreover, secure transmission is achieved when the CJ introduces
charges for its jamming service based on the amount of the
interference caused to the eavesdropper, where the Stackelberg game
is proposed to handle, and the Stackelberg equilibrium is analytically
derived. Finally, transmit optimization for MISO secure simultaneous
wireless information and power transfer (SWIPT) is investigated, where
secure transmit beamformer is designed with/without the help of arti -
cial noise (AN) to maximize the achieved secrecy rate such that satisfy
the transmit power budget and the energy harvesting (EH) constraint.
The performance of all proposed schemes are validated by MATLAB
simulation results
Robust Secrecy Beamforming for MIMO SWIPT with Probabilistic Constraints
This paper considers simultaneous wireless information apower transfer (SWIPT) in a multiple-input multiple-output (MIMO) wiretapnd power transfer (SWIPT) in a multiple-input multiple-output (MIMO) wiretap channel with energy harvesting receivers. The main objective is to keep the probability of the legitimate user's achievable secrecy rate outage as well as the energy receivers' harvested energy outage as caused by CSI uncertainties below given thresholds. This probabilistic-constrained secrecy rate maximization problem presents a significant analytical and computational challenge since any closed-form for the probabilistic constraints with log-det functions is intractable. In this paper, we address this challenging issue using codeviation inequalitiesnvex restrictions. In particular, we derive decomposition-based large deviation inequalities to transform the probabilistic constraints into second-order cone (SOC) constraints which are easier to handle. Then we show that a robust safe solution can be obtained through solving two convex sub-problems in an alternating fashion
Beamforming Techniques for Non-Orthogonal Multiple Access in 5G Cellular Networks
In this paper, we develop various beamforming techniques for downlink
transmission for multiple-input single-output (MISO) non-orthogonal multiple
access (NOMA) systems. First, a beamforming approach with perfect channel state
information (CSI) is investigated to provide the required quality of service
(QoS) for all users. Taylor series approximation and semidefinite relaxation
(SDR) techniques are employed to reformulate the original non-convex power
minimization problem to a tractable one. Further, a fairness-based beamforming
approach is proposed through a max-min formulation to maintain fairness between
users. Next, we consider a robust scheme by incorporating channel
uncertainties, where the transmit power is minimized while satisfying the
outage probability requirement at each user. Through exploiting the SDR
approach, the original non-convex problem is reformulated in a linear matrix
inequality (LMI) form to obtain the optimal solution. Numerical results
demonstrate that the robust scheme can achieve better performance compared to
the non-robust scheme in terms of the rate satisfaction ratio. Further,
simulation results confirm that NOMA consumes a little over half transmit power
needed by OMA for the same data rate requirements. Hence, NOMA has the
potential to significantly improve the system performance in terms of transmit
power consumption in future 5G networks and beyond.Comment: accepted to publish in IEEE Transactions on Vehicular Technolog
Artificial Noise-Aided Biobjective Transmitter Optimization for Service Integration in Multi-User MIMO Gaussian Broadcast Channel
This paper considers an artificial noise (AN)-aided transmit design for
multi-user MIMO systems with integrated services. Specifically, two sorts of
service messages are combined and served simultaneously: one multicast message
intended for all receivers and one confidential message intended for only one
receiver and required to be perfectly secure from other unauthorized receivers.
Our interest lies in the joint design of input covariances of the multicast
message, confidential message and artificial noise (AN), such that the
achievable secrecy rate and multicast rate are simultaneously maximized. This
problem is identified as a secrecy rate region maximization (SRRM) problem in
the context of physical-layer service integration. Since this bi-objective
optimization problem is inherently complex to solve, we put forward two
different scalarization methods to convert it into a scalar optimization
problem. First, we propose to prefix the multicast rate as a constant, and
accordingly, the primal biobjective problem is converted into a secrecy rate
maximization (SRM) problem with quality of multicast service (QoMS) constraint.
By varying the constant, we can obtain different Pareto optimal points. The
resulting SRM problem can be iteratively solved via a provably convergent
difference-of-concave (DC) algorithm. In the second method, we aim to maximize
the weighted sum of the secrecy rate and the multicast rate. Through varying
the weighted vector, one can also obtain different Pareto optimal points. We
show that this weighted sum rate maximization (WSRM) problem can be recast into
a primal decomposable form, which is amenable to alternating optimization (AO).
Then we compare these two scalarization methods in terms of their overall
performance and computational complexity via theoretical analysis as well as
numerical simulation, based on which new insights can be drawn.Comment: 14 pages, 5 figure
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Game theory-based resource allocation for secure WPCN multiantenna multicasting systems
This paper investigates a secure wireless-powered multiantenna multicasting system, where multiple power beacons (PBs) supply power to a transmitter in order to establish a reliable communication link with multiple legitimate users in the presence of multiple eavesdroppers. The transmitter has to harvest radio frequency (RF) energy from multiple PBs due to the shortage of embedded power supply before establishing its secure com- munication. We exploit a novel and practical scenario that the PBs and the transmitter may belong to different operators and a hierarchical energy interaction between the PBs and the transmitter is considered. Specifically, the monetary incentives are required for the PBs to assist the transmitter for secure communications. This leads to the formulation of a Stackelberg game for the secure wireless-powered multiantenna multicasting system, where the transmitter and the PB are modelled as leader and follower, respectively, each maximizing their own utility function. The closed-form Stackelberg equilibrium of the formulated game is then derived where we study various scenarios of eavesdroppers and legitimate users that can have impact on the optimality of the derived solutions. Finally, numerical results are provided to validate our proposed schemes
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