scholarly journals Performance Evaluation for Cooperative NOMA Using Combined Relay Selection Scheme

2021 ◽  
Author(s):  
Nidhi chaudhary ◽  
Niraj Pratap Singh ◽  
Gaurav Verma
Keyword(s):  
Outage Probability ◽  
Relay Selection ◽  
System Capacity ◽  
Time Varying ◽  
Relay Nodes ◽  
Rate System ◽  
Selection Scheme ◽  
Significant Performance ◽  
High System ◽  
Sum Rate

Abstract Effective relay selection in non-orthogonal multiple access (NOMA) is an efficient way to attain a significant performance gain in terms of achieving a high system capacity, ergodic sum rate and a low outage probability. This become more promising when NOMA is treated under cooperation of more than one relay nodes. Relay selection performs well when the source node has an accurate and updated channel state information (CSI). As having perfect CSI is very difficult, therefore the relay selection with continuous time varying CSI is of paramount importance. This paper proposes a combined relay selection (CRS) scheme with time varying CSI which uses failure probability as an important criterion to improve the overall performance of cooperative NOMA system. The proposed approach is compared with most commonly used relay selection schemes: round robin relay selection (RRRS), opportunistic relay selection (ORS) and balanced criteria relay selection (BCRS) scheme. The simulation results show that proposed scheme outperforms the RRRS, BCRS and ORS in terms of ergodic sum rate, system capacity and outage probability.

Enhanced Relay Selection and Scheduling for Better Load Balancing in Multi-Hop Networks

2012 ◽  
Vol 8 (4) ◽  
pp. 17-31
Author(s):  
Soumaya Hamouda ◽  
Tarek Bejaoui
Keyword(s):  
Resource Allocation ◽  
Load Balancing ◽  
Outage Probability ◽  
Relay Selection ◽  
Path Selection ◽  
System Capacity ◽  
Relay Station ◽  
Selection Scheme ◽  
Scheduling Strategy ◽  
Simulation Results

Relaying technology is likely to bring real progress to the next generation cellular networks due to its capability of boosting the system capacity and coverage. However, despite recent advances in relay deployment, some challenging problems still remain such as radio resource allocation and relay selection. The authors investigate both relay selection and scheduling strategy in order to improve the system radio capacity as well as the network load balancing. They propose a new path selection scheme based on the radio channel quality and the relay station load criteria. Performance analysis showed that the authors approach outperforms the existing path selection algorithms in terms of outage probability and global throughput in the system, especially in high traffic conditions. It is revealed that most of the cell edge users which would be rejected when applying common selection scheme, can now have access to a selected relay station and achieve a high end-to-end throughput. A new scheduling strategy is proposed in the second part of this paper, on the basis of a dynamic subframe partitioning. Simulation results show that the outage probability is reduced and more balanced resource allocation is provided. Simulation results showed that some relay stations which were not able to offer any service with the fixed subframe partitioning, can achieve a high data rate with the authors proposed dynamic scheduling strategy.

scholarly journals Power Optimized Single Relay Selection with an Improved Link-Adaptive-Regenerative Protocol

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Jie Li ◽  
Jianrong Bao ◽  
Shenji Luan ◽  
Bin Jiang ◽  
Chao Liu
Keyword(s):  
Outage Probability ◽  
Cooperative Communications ◽  
Power Efficiency ◽  
Relay Selection ◽  
Relay Node ◽  
Link Quality ◽  
Selection Strategy ◽  
Amplify And Forward ◽  
Selection Scheme ◽  
Single Relay

To improve the reliability and efficiency in cooperative communications, a power optimized single relay selection scheme is proposed by increasing the diversity effort with an improved link-adaptive-regenerative (ILAR) protocol. The protocol determines the forwarding power of a relay node by comparing the signal-to-noise ratio (SNR) at both sides of the node; thus it improves the power efficiency. Moreover, it also proposes a single relay selection strategy to maximize the instantaneous SNR product, which ensures the approximate best channel link quality for good relay forwarding. And the system adjusts the forwarding power in real time and also selects the best relay node participated in the cooperative forwarding. In addition, the cooperation in the protocol is analyzed and the approximate expression of the bit-error-rate (BER) and the outage probability at high SNRs are also derived. Simulation results indicate that the BER and outage probability of the relay selection scheme by the ILAR protocol outperform other contrast schemes of current existing protocols. At BER of 10−2, the proposed scheme with ILAR protocol outperforms those of the decoded-and-forward (DF), the selected DF (SDF), and the amplify-and-forward (AF) protocols by 3.5, 3.5 and 7 dB, respectively. Moreover, the outage probability of the relay system decreases with the growth of the relay number. Therefore, the proposed relay selection scheme with ILAR strategies can be properly used in cooperative communications for good reliability and high power efficiency.

Joint Power Allocation and Relay Selection Optimization for Cognitive Radio Networks

2013 ◽  
Vol 791-793 ◽  
pp. 1153-1159
Author(s):  
Li Ping Su ◽  
Dong Chen ◽  
Wei Hua Huang ◽  
Ning Li
Keyword(s):  
Cognitive Radio ◽  
Power Allocation ◽  
Cognitive Radio Networks ◽  
Relay Selection ◽  
Radio Networks ◽  
System Capacity ◽  
System Throughput ◽  
Joint Power ◽  
Selection Scheme ◽  
Multiple User

This paper investigates the joint power allocation (PA) and relay selection scheme (RS) in two-way relaying cognitive radio networks consisting of multiple user-pairs and multiple relays. In order to reduce the computational complexity for practical scenario, we propose a branch and bound based (BnB-based) power allocation and relay selection scheme and a greedy power allocation and relay selection scheme to maximize the system throughput. The system is assumed under the constraint that the interference power from the secondary nodes in two way relay systems to primary user (PU) shall be less than a predefined interference threshold which can guarantee the normal communication of PU. Numerical simulation results show that the optimal PA and RS scheme has the highest system capacity, however, the greedy PA and RS scheme has the lowest complexity. The proposed BnB-based PA and RS scheme has the better tradeoff of system throughput and complexity than the above two 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.

RELAY BEAMFORMING TO MITIGATE INTER-RELAY INTERFERENCE IN MULTI-CELL SCENARIO

2016 ◽  
Vol 78 (6-2) ◽  
Author(s):  
Moubachir Madani Fadoul ◽  
Chee Yen Leow
Keyword(s):  
Outage Probability ◽  
Ergodic Capacity ◽  
System Capacity ◽  
Relay Network ◽  
Relay Nodes ◽  
Backhaul Link ◽  
Cooperative Relay Network ◽  
Value Decomposition ◽  
Beamforming Technique

In relay assisted Long Term Evolution-Advanced (LTE-A) network, enhanced Node B (eNB) autonomously selects different backhaul sub-frame configurations to adopt traffic variations, which might cause inter-relay interference (IRI) between relay nodes (RNs) in adjacent cells.  IRI can happen due to asynchronous transmission between adjacent cells, which results in IRI from the access link to the backhaul link of adjacent relay in the downlink direction and vice versa. This causes severe loss in system capacity and introduces high outage probability.  In this article, we consider the IRI problem in a multi-cell relaying system.  Previous studies consider the beamforming design for cooperative relay network as a single-cell problem, without taking into account the occurrence of IRI.  However, the performance of the RN assisted network is limited by the IRI from adjacent RN.  A hybrid zero-forcing and singular value decomposition (ZF-SVD) beamforming technique is proposed to eliminate the IRI. Simulation results show that the proposed scheme out-performs the comparable scheme in both the ergodic capacity and outage probability.

scholarly journals Optimal Relay Selection Scheme with Multiantenna Power Beacon for Wireless-Powered Cooperation Communication Networks

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 147
Author(s):  
Oussama Messadi ◽  
Aduwati Sali ◽  
Vahid Khodamoradi ◽  
Asem A. Salah ◽  
Gaofeng Pan ◽  
...  
Keyword(s):  
Communication Network ◽  
Energy Harvesting ◽  
Outage Probability ◽  
Cooperative Communication ◽  
Relay Selection ◽  
System Throughput ◽  
Selection Scheme ◽  
Harvesting Time ◽  
Comparison Results ◽  
Multiple Relays

Unlike the fixed power grid cooperative networks, which are mainly based on the reception reliability parameter while choosing the best relay, the wireless-powered cooperative communication network (WPCCN) and in addition to the reception reliability the transmission requirement consideration is important for relay selection schemes. Hence, enabling efficient transmission techniques that address high attenuation of radio frequency (RF) signals according to the distance without increasing the total transmission power is an open issue worth studying. In this relation, a multiantennas power beacon (PB) that assists wireless-powered cooperative communication network (PB-WPCCN) is studied in this paper. The communication between source and destination is achieved with the aid of multiple relays, where both the source and the multiple relays need to harvest energy from the PB in the first place to enable their transmission functionalities. A novel relay selection scheme is proposed, named as two-round relay selection (2-RRS), where a group of relays that successfully decode the source information is selected in the first round selection. In the second round, the optimal relay is selected to forward the recorded information to the destination. The proposed 2-RRS scheme is compared with two existing relay selection schemes, i.e., partial relay selection (PRS) and opportunistic relay selection (ORS). The analytical closed-form expressions of outage probability and average system throughput are derived and validated by numerical simulation. The comparison results between different relay selection schemes show: (I) The superiority of the proposed 2-RRS scheme as it achieves around 17% better throughput compared to the conventional ORS scheme and 40% better than the PRS scheme, particularly when PB transmit power is 10 dB; (II) The proposed 2-RRS scheme guarantees the lowest outage probability, especially when the PB is equipped with multiantennas and performs beamforming technique; (III) The optimal localisation of the PB between the source and N relays depends on the adopted relay selection scheme; (IV) The exhaustive search of the maximum system throughput value shows that the proposed 2-RRS scheme required shorter energy harvesting time compared to other schemes. The increase in energy harvesting time and number of relays do not necessarily reflect positively on the system throughput performance; hence tradeoffs should be taken into consideration.

scholarly journals Performance Analysis of Secrecy Outage Probability for AF-Based Partial Relay Selection with Outdated Channel Estimates

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Kyu-Sung Hwang
Keyword(s):  
Outage Probability ◽  
Relay Selection ◽  
Information Source ◽  
Integral Form ◽  
Secrecy Outage Probability ◽  
Amplify And Forward ◽  
Selection Scheme ◽  
Partial Relay Selection ◽  
Channel Information ◽  
Secrecy Outage

We study the secrecy outage probability of the amplify-and-forward (AF) relaying protocol, which consists of one source, one destination, multiple relays, and multiple eavesdroppers. In this system, the aim is to transmit the confidential messages from a source to a destination via the selected relay in presence of eavesdroppers. Moreover, partial relay selection scheme is utilized for relay selection based on outdated channel state information where only neighboring channel information (source-relays) is available and passive eavesdroppers are considered where a transmitter does not have any knowledge of eavesdroppers’ channels. Specifically, we offer the exact secrecy outage probability of the proposed system in a one-integral form as well as providing the asymptotic secrecy outage probability in a closed-form. Numerical examples are given to verify our provided analytical results for different system conditions.

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