25 research outputs found
Energy Harvesting for Secure OFDMA Systems
Energy harvesting and physical-layer security in wireless networks are of
great significance. In this paper, we study the simultaneous wireless
information and power transfer (SWIPT) in downlink orthogonal
frequency-division multiple access (OFDMA) systems, where each user applies
power splitting to coordinate the energy harvesting and information decoding
processes while secrecy information requirement is guaranteed. The problem is
formulated to maximize the aggregate harvested power at the users while
satisfying secrecy rate requirements of all users by subcarrier allocation and
the optimal power splitting ratio selection. Due to the NP-hardness of the
problem, we propose an efficient iterative algorithm. The numerical results
show that the proposed method outperforms conventional methods.Comment: Accepted by WCSP 201
Joint Resource Allocation for eICIC in Heterogeneous Networks
Interference coordination between high-power macros and low-power picos
deeply impacts the performance of heterogeneous networks (HetNets). It should
deal with three challenges: user association with macros and picos, the amount
of almost blank subframe (ABS) that macros should reserve for picos, and
resource block (RB) allocation strategy in each eNB. We formulate the three
issues jointly for sum weighted logarithmic utility maximization while
maintaining proportional fairness of users. A class of distributed algorithms
are developed to solve the joint optimization problem. Our framework can be
deployed for enhanced inter-cell interference coordination (eICIC) in existing
LTE-A protocols. Extensive evaluation are performed to verify the effectiveness
of our algorithms.Comment: Accepted by Globecom 201
Joint Power Splitting and Secure Beamforming Design in the Wireless-powered Untrusted Relay Networks
In this work, we maximize the secrecy rate of the wireless-powered untrusted
relay network by jointly designing power splitting (PS) ratio and relay
beamforming with the proposed global optimal algorithm (GOA) and local optimal
algorithm (LOA). Different from the literature, artificial noise (AN) sent by
the destination not only degrades the channel condition of the eavesdropper to
improve the secrecy rate, but also becomes a new source of energy powering the
untrusted relay based on PS. Hence, it is of high economic benefits and
efficiency to take advantage of AN compared with the literature. Simulation
results show that LOA can achieve satisfactory secrecy rate performance
compared with that of GOA, but with less computation time.Comment: Submitted to GlobeCom201
Secure Transmission in Linear Multihop Relaying Networks
This paper studies the design and secrecy performance
of linear multihop networks, in the presence of randomly
distributed eavesdroppers in a large-scale two-dimensional space.
Depending on whether there is feedback from the receiver
to the transmitter, we study two transmission schemes: on-off
transmission (OFT) and non-on-off transmission (NOFT). In
the OFT scheme, transmission is suspended if the instantaneous
received signal-to-noise ratio (SNR) falls below a given threshold,
whereas there is no suspension of transmission in the NOFT
scheme. We investigate the optimal design of the linear multiple
network in terms of the optimal rate parameters of the wiretap
code as well as the optimal number of hops. These design
parameters are highly interrelated since more hops reduces the
distance of per-hop communication which completely changes the
optimal design of the wiretap coding rates. Despite the analytical
difficulty, we are able to characterize the optimal designs and
the resulting secure transmission throughput in mathematically
tractable forms in the high SNR regime. Our numerical results
demonstrate that our analytical results obtained in the high SNR
regime are accurate at practical SNR values. Hence, these results
provide useful guidelines for designing linear multihop networks
with targeted physical layer security performance.This work was supported in part by the Natural
Science Foundation of China under Grant 61401159 and Grant 61771203,
in part by the Pearl River Science and Technology Nova Program of
Guangzhou under Grant 201710010111, and in part by the Guangdong Science
and Technology Plan under Grant 2016A010101009. The work of X. Zhou
was supported by the Australian Research Council Discovery Projects under
Grant DP150103905ARC Discovery Projects Grant DP150103905
Exploiting Trust Degree for Multiple-Antenna User Cooperation
For a user cooperation system with multiple antennas, we consider a trust
degree based cooperation techniques to explore the influence of the
trustworthiness between users on the communication systems. For the system with
two communication pairs, when one communication pair achieves its quality of
service (QoS) requirement, they can help the transmission of the other
communication pair according to the trust degree, which quantifies the
trustworthiness between users in the cooperation. For given trust degree, we
investigate the user cooperation strategies, which include the power allocation
and precoder design for various antenna configurations. For SISO and MISO
cases, we provide the optimal power allocation and beamformer design that
maximize the expected achievable rates while guaranteeing the QoS requirement.
For a SIMO case, we resort to semidefinite relaxation (SDR) technique and block
coordinate update (BCU) method to solve the corresponding problem, and
guarantee the rank-one solutions at each step. For a MIMO case, as MIMO is the
generalization of MISO and SIMO, the similarities among their problem
structures inspire us to combine the methods from MISO and SIMO together to
efficiently tackle MIMO case. Simulation results show that the trust degree
information has a great effect on the performance of the user cooperation in
terms of the expected achievable rate, and the proposed user cooperation
strategies achieve high achievable rates for given trust degree.Comment: 15 pages,9 figures, to appear in IEEE Transactions on Wireless
communication
Secure Routing in Multihop Wireless Ad-hoc Networks with Decode-and-Forward Relaying
In this paper, we study the problem of secure routing in a multihop wireless
ad-hoc network in the presence of randomly distributed eavesdroppers.
Specifically, the locations of the eavesdroppers are modeled as a homogeneous
Poisson point process (PPP) and the source-destination pair is assisted by
intermediate relays using the decode-and-forward (DF) strategy. We analytically
characterize the physical layer security performance of any chosen multihop
path using the end-to-end secure connection probability (SCP) for both
colluding and non-colluding eavesdroppers. To facilitate finding an efficient
solution to secure routing, we derive accurate approximations of the SCP. Based
on the SCP approximations, we study the secure routing problem which is defined
as finding the multihop path having the highest SCP. A revised Bellman-Ford
algorithm is adopted to find the optimal path in a distributed manner.
Simulation results demonstrate that the proposed secure routing scheme achieves
nearly the same performance as exhaustive search.ARC Discovery Projects Grant DP15010390
Efficient time domain threshold for sparse channel estimation in OFDM system
International audienceA novel efficient time domain threshold based sparse channel estimation technique is proposed for orthogonal frequency division multiplexing (OFDM) systems. The proposed method aims to realize effective channel estimation without prior knowledge of channel statistics and noise standard deviation within a comparatively wide range of sparsity. Firstly, classical least squares (LS) method is used to get an initial channel impulse response (CIR) estimate. Then, an effective threshold, estimated from the noise coefficients of the initial estimated CIR, is proposed. Finally, the obtained threshold is used to select the most significant taps. Theoretical analysis and simulation results show that the proposed method achieves better performance in both BER (bit error rate) and NMSE (normalized mean square error) than the compared methods, has good spectral efficiency and moderate computational complexity