scholarly journals Secure Communication for Two-way Relay Networks with Imperfect CSI

2017 ◽  
Author(s):  
Cong Sun ◽  
Ke Liu ◽  
Dahu Zheng ◽  
Wenbao Ai
Keyword(s):  
Secure Communication ◽  
Relay Networks ◽  
Relay Network ◽  
Imperfect Csi ◽  
Amplify And Forward ◽  
Channel State ◽  
Proposed Model ◽  
Optimality Property ◽  
Quadratic Programming Problems

This paper considers a two-way relay network, where two source nodes exchange messages through several relays in the presence of an eavesdropper, and the channel state information (CSI) of the eavesdropper is imperfectly known. The amplify-and-forward relay protocol is used and the relay beamforming weights are designed. The model is built up to minimize the total relay transmit power while guaranteeing the quality of service at users and preventing the eavesdropper from decoding the signals. Due to the imperfect CSI, a semi-infinite programming problem is obtained. An algorithm is proposed to solve the problem, and the iterative points are updated through the linesearch technique, where the feasibility are preserved during iterations. The optimality property is analyzed. The obtained subproblems are quadratic constrained quadratic programming problems, either with less than $4$ constraints or with only one variable, which are solved optimally. Simulation results demonstrate the importance of the proposed model, and imply that the proposed algorithm is efficient and converges very fast, where more than 85% of the problems are solved optimally.

scholarly journals Dynamic Power Splitting Strategy for SWIPT Based Two-Way Multiplicative AF Relay Networks with Nonlinear Energy Harvesting Model

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Tianci Wang ◽  
Guangyue Lu ◽  
Yinghui Ye ◽  
Yuan Ren
Keyword(s):  
Energy Harvesting ◽  
Iterative Method ◽  
Relay Network ◽  
Power Splitting ◽  
Amplify And Forward ◽  
Channel State ◽  
Dynamic Power ◽  
Energy Constrained ◽  
Af Relay ◽  
Nonlinear Energy

This paper investigates an energy-constrained two-way multiplicative amplify-and-forward (AF) relay network, where a practical nonlinear energy harvesting (NLEH) model is equipped at the relay to realize simultaneous wireless information and power transfer (SWIPT). We focus on the design of dynamic power splitting (DPS) strategy, in which the PS ratio is able to adjust itself according to the instantaneous channel state information (CSI). Specifically, we first formulate an optimization problem to maximize the outage throughput, subject to the NLEH. Since this formulated problem is nonconvex and difficult to solve, we further transfer it into an equivalent problem and develop a Dinkelbach iterative method to obtain the corresponding solution. Numerical results are given to verify the quick convergence of the proposed iterative method and show the superior outage throughput of the designed DPS strategy by comparing with two peer strategies designed for the linear energy harvesting (LEH) model.

scholarly journals Joint Power Allocation and Beamforming in Amplify-and-Forward Relay Networks under Per-Node Power Constraint

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Farzin Azami ◽  
Seyed Mostafa Safavi Hemami ◽  
Abbas Akbarpour-Kasgari
Keyword(s):  
Power Consumption ◽  
Relay Networks ◽  
Critical Issue ◽  
Total Power ◽  
Amplify And Forward ◽  
Joint Power ◽  
Total Power Consumption ◽  
Quadratically Constrained ◽  
Required Quality

Two-way relay networks (TWRN) have been intensively investigated over the past decade due to their ability to enhance the performance assessment of networks in terms of cellular coverage and spectral efficiency. Yet, power control in such systems is a nontrivial issue, particularly in multirelay networks where relays are deployed to ensure a required Quality of Service (QoS). In this paper, we envision to address this critical issue by minimizing the sum-power with respect to per-node power consumption and acceptable users’ rates. To tackle this, we employ a variable transformation to turn the fractional quadratically constrained quadratic problem (QCQP) into semidefinite programming (SDP). This algorithm is also extended to a distributed format. Simulation results of deploying 10 relay stations reveal that the total power consumption will decrease to approximately 8 dBW for 6 bps/Hz sum-rate.

scholarly journals Secure Communication for Two-Way Relay Networks with Imperfect CSI

Entropy ◽  
2017 ◽  
Vol 19 (10) ◽  
pp. 522 ◽  
Author(s):  
Cong Sun ◽  
Ke Liu ◽  
Dahu Zheng ◽  
Wenbao Ai
Keyword(s):  
Secure Communication ◽  
Relay Networks ◽  
Imperfect Csi

scholarly journals Spectral Efficiency of the Multiway Massive System over Rician Fading Channels

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Junyi He ◽  
Junnan Zhang ◽  
Cheng Song ◽  
Mengxiang Wu
Keyword(s):  
Fading Channels ◽  
Spectral Efficiency ◽  
Large Scale ◽  
Scaling Law ◽  
Analytical Approximation ◽  
Relay Network ◽  
Rician Fading ◽  
Amplify And Forward ◽  
Channel State ◽  
Rician Fading Channels

In this study, we consider a multiway massive multi-input multi-output (MIMO) relay network over Rician fading channels, where all users intend to share their information with the other users via amplify-and-forward (AF) relays equipped with a great number of antennas. More practical, the imperfect channel state information (CSI) is taken into account. To evaluate the performance of the considered networks, we derived an analytical approximation expression for the spectral efficiency with zero-forcing (ZF) receivers in a closed form. To obtain more insights, the asymptotic analysis as the number of relay antenna approaching infinity is carried out. Finally, the power scaling law is analyzed for two scenarios. The results reveal that (1) massive MIMO is capable of compensating the loss caused by Rician fading, (2) the sum spectral efficiency increases with the increase of the Rician factor, and (3) deploying large-scale antenna is effective to save cost and keep performance.

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