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 Hybrid AF/DF Cooperative Relaying Technique with Phase Steering for Industrial IoT Networks

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Sangku Lee ◽  
Janghyuk Youn ◽  
Bang Chul Jung
Keyword(s):  
Spectrum Sharing ◽  
Low Cost ◽  
Relay Node ◽  
Access Point ◽  
Radio Spectrum ◽  
Cooperative Relaying ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Decode And Forward ◽  
Industrial Iot

For the next generation of manufacturing, the industrial internet of things (IoT) has been considered as a key technology that enables smart factories, in which sensors transfer measured data, actuators are controlled, and systems are connected wirelessly. In particular, the wireless sensor network (WSN) needs to operate with low cost, low power (energy), and narrow spectrum, which are the most technical challenges for industrial IoT networks. In general, a relay-assisted communication network has been known to overcome scarce energy problems, and a spectrum-sharing technique has been considered as a promising technique for the radio spectrum shortage problem. In this paper, we propose a phase steering based hybrid cooperative relaying (PSHCR) technique for the generic relay-assisted spectrum-shared WSN, which consists of a secondary transmitter, multiple secondary relays (SRs), a secondary access point, and multiple primary access points. Basically, SRs in the proposed PSHCR technique operate with decode-and-forward (DF) relaying protocol, but it does not abandon the SRs that failed in decoding at the first hop. Instead, the SRs operate with amplify-and-forward (AF) protocol when they failed in decoding at the first hop. Furthermore, the SRs (regardless of operating with AF or DF protocol) that satisfy interference constraints to the primary network are allowed to transmit a signal to the secondary access point at the second hop. Note that phase distortion is compensated through phase steering operation at each relay node before second-hop transmission, and thus all relay nodes can operate in a fully distributed manner. Finally, we validate that the proposed PSHCR technique significantly outperforms the existing best single relay selection (BSR) technique and cooperative phase steering (CPS) technique in terms of outage performance via extensive computer simulations.

scholarly journals Performance Assessment of Channel Capacity of Co-operative Communication based System over Dual-hop Asymmetric RF/FSO system

2020 ◽  
Vol 9 (4) ◽  
pp. 439-442
Keyword(s):  
Channel Capacity ◽  
Communication Systems ◽  
Distribution Channel ◽  
Relay Node ◽  
Simulation Method ◽  
Destination Node ◽  
Free Space Optical ◽  
Decode And Forward ◽  
Analytical Expressions

Cooperative Communication Systems and Relay Selection approaches are recent techniques of wireless communication system that enhance the quality of service (QoS). This research paper probes the execution of the Radio-Frequency and Free Space Optical (RF/FSO) Co-operative system using network of relays. The Co-operative relay system is typically composed of node of a source, the nodes of relays and node of a destination. The source and relay link (S-R link) follow the Generalized-K Fading distribution channel. The link connecting the relay node/device and the destination (R-D link) follows - Fading distribution channel. The relay is considered to adopt according to DF i.e Decode and Forward method of relaying and cooperatively assists in transmission to the destination node from the source node. The channel capacity is modelled using PDF (Probability Density Function) for the - distribution channel of fading for evaluation of the Dual-hop Asymmetric RF-FSO system. The performance and the analytical expressions of the new system proposed i.e. RF/FSO system were verified and validated using Monte Carlo simulation method

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 Positioning of a Wireless Relay Node for Useful Cooperative Communication

2018 ◽  
Vol 10 (3) ◽  
pp. 959
Author(s):  
Tariq Muhamad Amjad ◽  
Elsheikh Mohamed Ahmed Elsheikh
Keyword(s):  
Relay Node ◽  
Cooperative Relaying ◽  
Maximal Ratio Combining ◽  
Destination Node ◽  
Relay Channel ◽  
Decode And Forward ◽  
Sustainable Solutions ◽  
Wireless Relay ◽  
Increasing Demand ◽  
The Impact

<span>Given the exorbitant amount of data transmitted and the increasing demand for data connectivity in the 21st century, it has become imperative to search for pro-active and sustainable solutions to the effectively alleviate the overwhelming burden imposed on wireless networks. In this study a Decode and Forward cooperative relay channel is analyzed, with the employment of Maximal Ratio Combining at the destination node as the method of offering diversity combining. The system framework used is based on a three-node relay channel with a source node, relay node and a destination node. A model for the wireless communications channel is formulated in order for simulation to be carried out to investigate the impact on performance of relaying on a node placed at the edge of cell. Firstly, an AWGN channel is used before the effect of Rayleigh fading is taken into consideration. Result shows that performance of cooperative relaying performance is always superior or similar to conventional relaying. Additionally, relaying is beneficial when the relay is placed closer to the receiver. </span>

scholarly journals A Comparative Study on the Performance of LLR- and SNR-Based Hybrid Relaying Schemes

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Ahmed El-Mahdy ◽  
Wassim Alexan
Keyword(s):  
Comparative Study ◽  
Signal To Noise Ratio ◽  
Relay Node ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Probability Of Error ◽  
Hybrid Schemes ◽  
Relay Location ◽  
The Impact ◽  
Hybrid Relaying

A comparative study on the theoretical bit error rate (BER) is presented for hybrid relaying schemes that toggle between adaptive decode-and-forward (ADF) and amplify-and-forward (AF) protocols, for a typical three-node wireless network. Toggling between the two forwarding protocols is based on the log-likelihood ratio (LLR) or the signal-to-noise ratio (SNR) of the received signal at the relay node. Closed-form expressions for the probability of error are presented, as well as the expressions of the proposed schemes’ gains over classical ADF and AF protocols. Comparisons are carried out among the two schemes and other hybrid schemes found in the literature. Moreover, the impact of relay location on the probability of error is investigated.

An Efficient IR-HARQ Power Allocation for Relay-Aided Cellular Networks

2018 ◽  
Vol 27 (12) ◽  
pp. 1850195
Author(s):  
P. Mangayarkarasi ◽  
J. Raja
Keyword(s):  
Power Allocation ◽  
Cellular Networks ◽  
Channel Capacity ◽  
Energy Efficient ◽  
Base Station ◽  
Relay Station ◽  
Decode And Forward ◽  
Relay Placement ◽  
Cell Coverage ◽  
The Impact

Energy-efficient and reliable data transmission is a challenging task in wireless relay networks (WRNs). Energy efficiency in cellular networks has received significant attention because of the present need for reduced energy consumption, thereby maintaining the profitability of networks, which in turn makes these networks “greener”. The urban cell topography needs more energy to cover the total area of the cell. The base station does not cover the entire area in a given topography and adding more number of base stations is a cost prohibitive one. Energy-efficient relay placement model which calculates the maximum cell coverage is proposed in this work that covers all sectors and also an energy-efficient incremental redundancy-hybrid automatic repeat request (IR-HARQ) power allocation scheme to improve the reliability of the network by improving the overall network throughput is proposed. An IR-HARQ power allocation method maximizes the average incremental mutual information at each round, and its throughput quickly converges to the ergodic channel capacity as the number of retransmissions increases. Simulation results show that the proposed IR-HARQ power allocation achieves full channel capacity with average transmission delay and maintains good throughput under less power consumption. Also the impact of relaying performance on node distances between relay station and base station as well as between user and relay station and relay height for line of sight conditions are analyzed using full decode and forward (FDF) and partial decode and forward (PDF) relaying schemes. Compared to FDF scheme, PDF scheme provides better performance and allows more freedom in the relay placement for an increase in cell coverage.

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 Bandwidth Allocation of Cognitive Relay Networks with Energy Harvesting for Smart Grid

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yupeng Li ◽  
Zihao Wang ◽  
Ling Luo ◽  
Zhiyong Chen ◽  
Bin Xia ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Smart Grid ◽  
Bandwidth Allocation ◽  
Relay Node ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Secondary Users ◽  
Optimal Bandwidth Allocation ◽  
Outage Probabilities ◽  
Primary Transmission

In this paper, we investigate an energy harvesting scheme in a smart grid based on the cognitive relay protocol, where a primary transmitter scavenges energy from the nature sources and then employs the harvested energy to forward the primary signal. Depending on the intensity of the energy harvesting from nature, a secondary user dynamically acts as a relay node to assist the primary transmission or does not. When the energy is not enough powerful to support the direct transmission between two primary users, the secondary users share the spectrum by assisting the primary transmission. For the relaying scheme, both amplify-and-forward (AF) and decode-and-forward (DF) protocols are investigated. We analytically obtain the exact transmission rates for both primary and secondary networks and derive the exact expressions of the system outage probabilities for both primary and secondary users in the smart grid. Moreover, we develop the analytically optimal bandwidth allocation strategy to maximize the total sum rate of the proposed scheme. Numerical results are presented to demonstrate the performance gain of the proposed scheme over the nonoptimal scheme.

scholarly journals Layered Capacity-Based Relay-and-Antenna Joint Selection for MIMO-AF-Multiple-Relay Systems in Correlated Channels

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Chia-Chang Hu ◽  
Jheng-Siang Li ◽  
Bo-Liang Wu
Keyword(s):  
Fading Channels ◽  
Channel Capacity ◽  
Antenna Selection ◽  
Selection Strategy ◽  
Destination Node ◽  
Hardware Complexity ◽  
Amplify And Forward ◽  
Relay Systems ◽  
Capacity Maximization ◽  
Multiple Relay

A computationally efficient two-stage greedy capacity maximization (GCM) relay-and-antenna joint selection is proposed for a dual-hop nonregenerative amplify-and-forward (AF) multiple-input multiple-output (MIMO) multiple-relay system with multiple antennas equipped at each node in correlated fading channels. This modified GCM (MGCM) antenna selection strategy selects a subset of antenna pairs from available relays based on the concept of channel capacity maximization subject to an optimal power allocation constraint across the activated antenna pairs. In order to reduce system hardware complexity, antenna selection schemes are performed at the destination node as well. Finally, simulations are conducted to compare the channel capacity of the proposed two-layered antenna selection technique with other existing antenna selection algorithms for half-duplex AF-MIMO multiple-relay systems.

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.

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