scholarly journals Secrecy Analysis of Multiuser Untrusted Amplify-and-Forward Relay Networks

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Dan Deng ◽  
Xutao Li ◽  
Lisheng Fan ◽  
Wen Zhou ◽  
Rose Qingyang Hu ◽  
...  
Keyword(s):  
Asymptotic Expression ◽  
Information Leakage ◽  
Relay Node ◽  
Relay Networks ◽  
Destination Node ◽  
Amplify And Forward ◽  
Secrecy Rate ◽  
Close Form ◽  
The Impact ◽  
Untrusted Relay

This paper investigates the secure communications of multiuser untrusted amplify-and-forward relay networks in the presence of direct links. In the considered system, one user is selected among multiple ones for secure transmission to the destination node with the help of an untrusted relay node. To reduce the information leakage to the untrusted relay, the paper considers two selection criteria to select the user based on the direct and the relaying links, respectively. The impact of direct and the relaying link on the system secrecy performance is studied by deriving the close-form ergodic secrecy rate (ESR) as well as the asymptotic expression. From the asymptotic expression, it can be found that the asymptotic ESR increases linearly with the logarithm of the average channel gain ratio of the direct link to the relaying link.

scholarly journals Evaluation of PLC Channel Capacity and ABER Performances for OFDM-Based Two-Hop Relaying Transmission

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Sana Ezzine ◽  
Fatma Abdelkefi ◽  
Jean Pierre Cances ◽  
Vahid Meghdadi ◽  
Ammar Bouallégue
Keyword(s):  
Channel Capacity ◽  
Orthogonal Frequency Division Multiplexing ◽  
Low Cost ◽  
Relay Node ◽  
Destination Node ◽  
Direct Link ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Maximum Ratio Combining ◽  
The Impact

Powerline network is recognized as a favorable infrastructure for Smart Grid to transmit information in the network thanks to its broad coverage and low cost deployment. The existing works are trying to improve and adapt transmission techniques to reduce Powerline Communication (PLC) channel attenuation and exploit the limited bandwidth to support high data rate over long distances. Two-hop relaying BroadBand PLC (BB-PLC) system, in which Orthogonal Frequency Division Multiplexing (OFDM) is used, is considered in this paper. We derive and compare the PLC channel capacity and the end-to-end Average BER (ABER) for OFDM-based direct link (DL) BB-PLC system and for OFDM-based two-hop relaying BB-PLC system for Amplify and Forward (AF) and Decode and Forward (DF) protocols. We analyze the improvements when we consider the direct link in a cooperative communication when the relay node only transmits the correctly decoded signal. Maximum ratio combining is employed at the destination node to detect the transmitted signal. In addition, in this paper, we highlight the impact of the relay location on the channel capacity and ABER for AF and DF transmission protocols. Moreover, an efficient use of the direct link was also investigated in this paper.

Study on Channel Estimation in Time-Varing Amplify and Forward Relay Networks

2014 ◽  
Vol 519-520 ◽  
pp. 934-938
Author(s):  
Wang Xin ◽  
Xiao Xue Yang ◽  
You Zheng Wang
Keyword(s):  
Channel Estimation ◽  
Performance Improvement ◽  
Relay Node ◽  
Relay Networks ◽  
Destination Node ◽  
Amplify And Forward ◽  
Realistic Simulation

In this paper, we study the different channel estimation strategies applied in an AF network, including ordinary channel estimation which estimate the whole source-relay-destination (SRD) channel at the destination, and a new proposed equalized AF (EAF) which make channel estimation separately at relay node and destination node. The EAF carries out the equalization at relay node by the channel estimation, which leads to performance improvement. The analysis of achievable rates is given and the performance benefit of EAF is verified by both numeric and realistic simulation.

scholarly journals Robust Relay in Narrow-Band Communications for Ubiquitous IoT Access

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Qinghe Du ◽  
Nan Lu ◽  
Li Sun ◽  
Xuelin Zhang ◽  
Bo Sun
Keyword(s):  
Narrow Band ◽  
Relay Node ◽  
Relay Network ◽  
Destination Node ◽  
Artificial Noise ◽  
Amplify And Forward ◽  
Limited Bandwidth ◽  
Wireless Relay ◽  
Core Idea ◽  
Untrusted Relay

We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF) untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN), which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability.

scholarly journals Performance Analysis of Full-Duplex Amplify-and-Forward Relay System with Hardware Impairments and Imperfect Self-Interference Cancellation

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Ba Cao Nguyen ◽  
Xuan Nam Tran
Keyword(s):  
Interference Cancellation ◽  
Signal To Noise Ratio ◽  
Relay Node ◽  
Analytical Framework ◽  
Full Duplex ◽  
High Signal ◽  
Amplify And Forward ◽  
Relay System ◽  
Hardware Impairments ◽  
The Impact

In this paper, we analyze the performance of a full-duplex (FD) amplify-and-forward (AF) relay system with imperfect hardware. Besides the aggregate hardware impairments of the imperfect transceiver, we also consider the impact of residual self-interference (RSI) due to imperfect cancellation at the FD relay node. An analytical framework for analyzing the system performance including exact outage probability (OP), asymptotic OP, and approximate symbol error probability (SEP) is developed. In order to tackle these impacts, we propose an optimal power allocation scheme which can improve the outage performance of the FD relay node, especially at the high signal-to-noise ratio (SNR) regime. Numerical results are presented for various evaluation scenarios and verified using the Monte Carlo simulations.

scholarly journals Robust Destination Jamming Aided Secrecy Precoding for an AF MIMO Untrusted Relay System

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Feng Zhou ◽  
Rugang Wang ◽  
Jiahong Bian
Keyword(s):  
Relay Network ◽  
Amplify And Forward ◽  
Secrecy Rate ◽  
Relay System ◽  
Worst Case ◽  
Alternating Optimization ◽  
Cooperative Jamming ◽  
Sign Definiteness ◽  
The Difference ◽  
Untrusted Relay

We consider a secrecy dual-hop amplify-and-forward (AF) untrusted relay network, where the relay is willing to forward the signal to the destination while acting as a potential eavesdropper. Assuming that all these nodes are equipped with multiple antennas, we propose a joint destination aided cooperative jamming and precoding at both the source and the relay scheme, with the objective to maximize the worst case secrecy rate. The formulated problem is highly non-convex due to the maximization of the difference of several logarithmic determinant (log-det) functions in the CSI uncertainty region. To handle this challenge, we propose to linearize these log-det terms. After linearization, we tackle the CSI uncertainty based on epigraph reformulation and the sign-definiteness lemma. Finally, an alternating optimization (AO) algorithm is proposed to solve the reformulated problem. Numerical results are provided to demonstrate the performance of the proposed scheme.

scholarly journals Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Xianwen He ◽  
Gaoqi Dou ◽  
Jun Gao
Keyword(s):  
Channel Estimation ◽  
Relay Node ◽  
Spatial Diversity ◽  
Relay Network ◽  
Destination Node ◽  
Training Design ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Training Scheme ◽  
Data Signal

We consider the training design and channel estimation in the amplify-and-forward (AF) diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM) mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI) of second-hop link due to the multiaccess interference (MAI) and cooperative data interference (CDI). To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ) relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

scholarly journals Full-Duplex Mode in Amplify-and-Forward Relay Channels: Outage Probability and Ergodic Capacity

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Rongyi Hu ◽  
Chunjing Hu ◽  
Jiamo Jiang ◽  
Xinqian Xie ◽  
Lei Song
Keyword(s):  
Outage Probability ◽  
Relay Node ◽  
Ergodic Capacity ◽  
Full Duplex ◽  
Relay Channels ◽  
Amplify And Forward ◽  
Half Duplex ◽  
Single Relay ◽  
Close Form ◽  
Loop Interference

This paper investigates the outage probability and ergodic capacity performances for full-duplex mode in two-way amplify-and-forward relay channels. The two-way relay channels which consist of two source nodes and a single relay node working in full-duplex mode, are assumed as independent and identically distributed as Rayleigh fading. The self-interference or loop interference of the relay is unavoidably investigated for full-duplex mode. And the close-form expressions for the outage probability and ergodic capacity of full-duplex mode are derived, considering both loop interference and the coefficients of two-way relay amplify-and-forward channels. To further facilitate the performance of full-duplex mode, the half-duplex modes over different transmission time slots are analyzed. Simulation results point out the effect of loop interference on outage probability and ergodic capacity of two-way amplify-and-forward relay channels with full-duplex mode and show that full-duplex mode can achieve better performance in terms of capacity and even outperform half-duplex modes in the presence of loop interference.

scholarly journals Machine Learning-Based Antenna Selection in Untrusted Relay Networks

2019 ◽  
Author(s):  
Rugui Yao ◽  
Yuxin Zhang ◽  
Nan Qi ◽  
Theodoros A. Tsiftsis
Keyword(s):  
Machine Learning ◽  
Antenna Selection ◽  
Relay Networks ◽  
Support Vector ◽  
Secrecy Outage Probability ◽  
Secrecy Rate ◽  
Transmit Antenna Selection ◽  
K Nearest Neighbors ◽  
Selection Scheme ◽  
Untrusted Relay

This paper studies the transmit antenna selection based on machine learning (ML) schemes in untrusted relay networks. First, we state the conventional antenna selection scheme. Then, we implement three ML schemes, namely, the support vector machine-based scheme, the naive-Bayes-based scheme, and the k-nearest neighbors-based scheme, which are applied to select the best antenna with the highest secrecy rate. The simulation results are presented in terms of system secrecy rate and secrecy outage probability. From the simulation, we can conclude that the proposed ML-based antenna selection schemes can achieve the same performance without amplification at the relay, or small performance degradation with transmitted power constraint at the relay, comparing with conventional schemes. However, when the training is completed, the proposed schemes can perform the antenna selection with a small computational complexity.

scholarly journals Energy Efficient Design for Two-Way AF Relay Networks

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Yong Li ◽  
Zhengguang Zheng ◽  
Mingyue Zhao ◽  
Yunli Chen ◽  
Chuanyong Liu
Keyword(s):  
Power Allocation ◽  
Energy Efficient ◽  
Relay Node ◽  
Relay Networks ◽  
Efficient Design ◽  
Amplify And Forward ◽  
Iterative Search ◽  
Suboptimal Solution ◽  
Af Relay ◽  
Efficient Power

Conventional designs on two-way relay networks mainly focus on the spectral efficiency (SE) rather than energy efficiency (EE). In this paper, we consider a system where two source nodes communicate with each other via an amplify-and-forward (AF) relay node and study the power allocation schemes to maximize EE while ensuring a certain data rate. We propose an optimal energy-efficient power allocation algorithm based on iterative search technique. In addition, a closed-form suboptimal solution is derived with reduced complexity and negligible performance degradation. Numerical results show that the proposed schemes can achieve considerable EE improvement compared with conventional designs.

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