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.

A Scheme of HARQ Resending Nodes Selection in RCC Network

2013 ◽  
Vol 347-350 ◽  
pp. 2137-2142
Author(s):  
Xue Hua Li ◽  
Zhen Song Li ◽  
Ya Fei Wang
Keyword(s):  
Power Efficiency ◽  
Relay Node ◽  
Relay Network ◽  
Destination Node ◽  
Relay Nodes ◽  
Selection Scheme ◽  
High System ◽  
Selection For ◽  
The Difference ◽  
System Power

A scheme of HARQ re-sending nodes selection for relay network is purposed in this paper. The study is focused on how to select relay node with minimum resending power under the particular required receiving performance of the destination node. The candidate relay nodes are divided into several regions according to the difference of resending power required. With this selection scheme, the diversity gain and high system power efficiency can all be achieved. The effectiveness of this scheme is proved by the simulation results.

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.

Sum-Rate Optimization Constrained by Consumed Power for Multi- Antenna Non-Regenerative Relay Network

2020 ◽  
Vol 10 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Maryam Alibeigi ◽  
Shahriar S. Moghaddam
Keyword(s):  
Relay Network ◽  
Minimization Algorithm ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Convex Problem ◽  
Semidefinite Programming Problem ◽  
Total Leakage ◽  
Sum Rate ◽  
Rate Optimization ◽  
Novel Algorithm

Background & Objective: This paper considers a multi-pair wireless network, which communicates peer-to-peer using some multi-antenna amplify-and-forward relays. Maximizing the throughput supposing that the total relay nodes’ power consumption is constrained, is the main objective of this investigation. We prove that finding the beamforming matrix is not a convex problem. Methods: Therefore, by using a semidefinite relaxation technique we find a semidefinite programming problem. Moreover, we propose a novel algorithm for maximizing the total signal to the total leakage ratio. Numerical analyses show the effectiveness of the proposed algorithm which offers higher throughput compared to the existing total leakage minimization algorithm, with much less complexity. Results and Conclusion: Furthermore, the effect of different parameters such as, the number of relays, the number of antennas in each relay, the number of transmitter/receiver pairs and uplink and downlink channel gains are investigated.

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.

scholarly journals Outage Performance of Bidirectional Full-Duplex Amplify-and-Forward Relay Network with Transmit Antenna Selection and Maximal Ratio Combining

2018 ◽  
Vol 1 ◽  
pp. 62-69
Author(s):  
R. Rajesh ◽  
P. G. S. Velmurugan ◽  
S. J. Thiruvengadam ◽  
P. S. Mallick
Keyword(s):  
Antenna Selection ◽  
Relay Node ◽  
Maximal Ratio Combining ◽  
Full Duplex ◽  
Relay Network ◽  
Amplify And Forward ◽  
Transmit Antenna Selection ◽  
Outage Performance ◽  
Half Duplex ◽  
Af Relay

In this paper, a bidirectional full-duplex amplify- and-forward (AF) relay network with multiple antennas at source nodes is proposed. Assuming that the channel state information is known at the source nodes, transmit antenna selection and maximal ratio combining (MRC) are employed when source nodes transmit information to the relay node and receive information from the relay node respectively, in order to improve the overall signal-to-interference plus noise ratio (SINR). Analytical expressions are derived for tight upper bound SINR at the relay node and source nodes upon reception. Further, losed form expressions are also derived for end-to-end outage probability of the proposed bidirectional full-duplex AF relay network in the Nakagami-m fading channel environment. Although self-interference at the relay node limits the performance of the full-duplex network, the outage performance of the proposed network is better than that of conventional bidirectional full-duplex and half-duplex AF relay networks, due to the selection diversity gain in TAS and diversity and array gain in MRC.

scholarly journals Superimposed Training-Based Channel Estimation for MIMO Relay Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaoyan Xu ◽  
Jianjun Wu ◽  
Shubo Ren ◽  
Lingyang Song ◽  
Haige Xiang
Keyword(s):  
Channel Estimation ◽  
Multiple Input Multiple Output ◽  
Estimation Algorithm ◽  
Relay Network ◽  
Mimo Channel ◽  
Amplify And Forward ◽  
Error Performance ◽  
Superimposed Training ◽  
Training Strategy ◽  
The Individual

We introduce the superimposed training strategy into the multiple-input multiple-output (MIMO) amplify-and-forward (AF) one-way relay network (OWRN) to perform the individual channel estimation at the destination. Through the superposition of a group of additional training vectors at the relay subject to power allocation, the separated estimates of the source-relay and relay-destination channels can be obtained directly at the destination, and the accordance with the two-hop AF strategy can be guaranteed at the same time. The closed-form Bayesian Cramér-Rao lower bound (CRLB) is derived for the estimation of two sets of flat-fading MIMO channel under random channel parameters and further exploited to design the optimal training vectors. A specific suboptimal channel estimation algorithm is applied in the MIMO AF OWRN using the optimal training sequences, and the normalized mean square error performance for the estimation is provided to verify the Bayesian CRLB results.

scholarly journals Asymptotic Capacity of Large Fading Relay Networks with Random Node Failures

2011 ◽  
Vol 59 (8) ◽  
pp. 2306-2315 ◽  
Author(s):  
Chuan Huang ◽  
Jinhua Jiang ◽  
Shuguang Cui
Keyword(s):  
Large Scale ◽  
Signal To Noise Ratio ◽  
Relay Node ◽  
Relay Network ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Attack Model ◽  
Random Node ◽  
Rate Loss ◽  
Node Failures

To understand the network response to large-scale physical attacks, we investigate the asymptotic capacity of a half-duplex fading relay network with random node failures when the number of relays N gets infinitely large. In this paper, a simplified independent attack model is assumed where each relay node fails with a certain probability. The noncoherent relaying scheme is considered, which corresponds to the case of zero forward-link channel state information (CSI) at the relays. Accordingly, the whole relay network can be shown equivalent to a Rayleigh fading channel, where we derive the ε-outage capacity upper bound according to the multiple access (MAC) cut-set, and the ε-outage achievable rates for both the amplify-and-forward (AF) and decode-and-forward (DF) strategies. Furthermore, we show that the DF strategy is asymptotically optimal as the outage probability ε goes to zero, with the AF strategy strictly suboptimal over all signal to noise ratio (SNR) regimes. Regarding the rate loss due to random attacks, the AF strategy suffers a less portion of rate loss than the DF strategy in the high SNR regime, while the DF strategy demonstrates more robust performance in the low SNR regime.

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