scholarly journals Throughput Analysis and Optimization of Relay Selection Techniques for Millimeter Wave Communications

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Raed Alhamad ◽  
Hatem Boujemaa
Keyword(s):  
Power Allocation ◽  
Fading Channels ◽  
Millimeter Wave ◽  
Relay Selection ◽  
Performance Enhancement ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Reactive Relay Selection ◽  
Significant Performance ◽  
Millimeter Wave Communications

In this paper, we optimize the throughput of millimeter wave communications using relay selection techniques. We study opportunistic amplify and forward (OAF), opportunistic decode and forward (ODF), and partial and reactive relay selection (PRS and RRS). Our analysis is valid for interference-limited millimeter wave communications. We suggest a new optimal power allocation (OPA) strategy that offers significant performance enhancement with respect to uniform power allocation (UPA). The proposed OPA offers up to 2 dB gain with respect to UPA. Our analysis is confirmed with extensive simulation results for Nakagami fading channels.

scholarly journals Partial Relay Selection for Secure Cooperative NOMA Networks

2021 ◽  
Author(s):  
Wided Hadj Alouane
Keyword(s):  
Fading Channels ◽  
Relay Selection ◽  
Signal To Noise Ratio ◽  
Secrecy Outage Probability ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Partial Relay Selection ◽  
Asymptotic Expressions ◽  
Selection For ◽  
Secrecy Outage

Abstract In this paper, we investigate physical layer security of multi-relay non-orthogonal multiple access (NOMA) networks with partial relay selection considering decode-and-forward (DF) and amplify-and-forward (AF) protocols. We propose a partial relay scheme aiming to select the best relay based on the highest signal-to-noise-ratio (SNR) of the first link. We derive new exact and asymptotic expressions for strictly positive secrecy capacity (SPSC) and secrecy outage probability (SOP) considering Rayleigh fading channels. Numerical results demonstrate that AF and DF provide almost a similar secrecy performance. Moreover, they prove that partial relay selection improves SPSC and reduces SOP when the relay-cluster is closer to the legitimate receiver.

Threshold-based hybrid relay selection and power allocation scheme

2016 ◽  
Vol 8 ◽  
pp. 16
Author(s):  
Xin Song ◽  
MingLei Zhang ◽  
WenMIn Liu ◽  
ShengBao Wang
Keyword(s):  
Outage Probability ◽  
Power Allocation ◽  
Relay Selection ◽  
Cooperative Relaying ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Opportunistic Relaying ◽  
Transmit Power ◽  
Probability Threshold ◽  
Relaying System

Abstract—To minimize total transmit power in a system while guaranteeing the outage probability at the same time in a cooperative system, we propose and analyse two threshold-based hybrid relay selection and power allocation schemes for a three-node cooperative relaying system. They are designated as: the hybrid amplify-direct-forward relaying (HADF) and incremental hybrid decode-direct-forward relaying (IHDDF) schemes. In the HADF scheme, a specific outage probability threshold is derived to determine that the system chooses to optimize power allocation of its source and relay in amplify-and-forward (AF) mode or optimize the power of its source in direct-transmit (DT) mode without a relay. In IHDDF, according to the outage probability threshold, the system chooses to optimize its power in turn with incremental decode-and-forward opportunistic relaying (IDFO) mode or DT mode. Closed-form expressions of the total transmit power of the proposed HADF and IHDDF schemes are derived. The proposed schemes have low computational complexity and system cost. Theoretical analysis and simulation results show that the HADF scheme outperforms the AF and DT schemes, and the total transmission power of the IHDDF scheme is reduced significantly compared with the IDFO and DT schemes. Compared with the HADF scheme, the IHDDF scheme has a better total transmit power in special channel condition.Keywords—power allocation, three-node cooperative relaying system, amplify-and-forward, incremental decode-and-forward opportunistic relaying.

Power Allocation and Relay Selection Algorithm in Multi-Relay Amplify-and-Forward Networks

2014 ◽  
Vol 513-517 ◽  
pp. 3423-3428
Author(s):  
Zhi Kang Zhou ◽  
Qi Zhu
Keyword(s):  
Power Allocation ◽  
Relay Selection ◽  
Relay Network ◽  
Total Power ◽  
Selection Algorithm ◽  
Amplify And Forward ◽  
Power Constraint ◽  
Lower Complexity ◽  
Relay Selection Algorithm ◽  
The Ideal

In this paper, an amplify-and-forward (AF) multi-relay network is considered. In order to minimize the system outage probability, a new power allocation and multi-relay selection algorithm is proposed under total power constraint and each node power constraint. In the proposed algorithm, the ideal of ordering is adopted, which leads to the remarkable decrease of the computation complexity together with simple power reallocation. Simulation results show that the proposed multi-relay selection algorithm performs close to the optimal scheme with optimal power allocation and exhaustive search (OPA-ES) but with much lower complexity.

scholarly journals A Coordinated Direct AF/DF Relay-Aided NOMA Framework for Low Outage

2021 ◽  
Author(s):  
Anand Jee ◽  
KAMAL AGRAWAL ◽  
Shankar Prakriya
Keyword(s):  
Energy Efficiency ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Outage Probability ◽  
Closed Form ◽  
Power Allocation ◽  
Multiple Access ◽  
Performance Gain ◽  
Amplify And Forward ◽  
Decode And Forward

This paper investigates the performance of a framework for low-outage downlink non-orthogonal multiple access (NOMA) signalling using a coordinated direct and relay transmission (CDRT) scheme with direct links to both the near-user (NU) and the far-user (FU). Both amplify-and-forward (AF) and decode-and-forward (DF) relaying are considered. In this framework, NU and FU combine the signals from BS and R to attain good outage performance and harness a diversity of two without any need for feedback. For the NU, this serves as an incentive to participate in NOMA signalling. For both NU and FU, expressions for outage probability and throughput are derived in closed form. High-SNR approximations to the outage probability are also presented. We demonstrate that the choice of power allocation coefficient and target rate is crucial to maximize the NU performance while ensuring a desired FU performance. We demonstrate performance gain of the proposed scheme over selective decode-and-forward (SDF) CDRT-NOMA in terms of three metrics: outage probability, sum throughput and energy efficiency. Further, we demonstrate that by choosing the target rate intelligently, the proposed CDRT NOMA scheme ensures higher energy efficiency (EE) in comparison to its orthogonal multiple access counterpart. Monte Carlo simulations validate the derived expressions.

scholarly journals AWGN and Rayleigh Fading Behavior of the Wireless Decode-and-Forward Relay Channel with Arbitrary Time and Power Allocation

2018 ◽  
Vol 10 (1) ◽  
pp. 248
Author(s):  
Muhammad Zarol Fitri Khairol Fauz ◽  
Elsheikh Mohamed Ahmed Elsheikh
Keyword(s):  
Mutual Information ◽  
Power Allocation ◽  
Fading Channels ◽  
Time Allocation ◽  
Rayleigh Fading ◽  
Cellular Systems ◽  
Base Stations ◽  
Relay Channel ◽  
Decode And Forward ◽  
Half Duplex

Relying has in use for decades to tackle some of the challenges of wireless communication such as extending transmitting distance, transmitting over rough terrains. Diversity achieved through relaying is also a means to combat the random behavior of fading channels. In this work, effect of time and power allocation on relay performance is studied. The channel considered is the three-node channel with half-duplex constraint on the relay. The relaying technique assumed is decode-and-forward. Mutual information is used as the criteria to measure channel performance. There is half-duplex constraint and a total transmission power constraint on the relay source node and the relay node. A model is established to analyze the mutual information as a function of time allocation and power allocation in the case of AWGN regime. The model is extended to the Rayleigh fading scenario. In both AWGN and Rayleigh fading, results showed that the importance of relaying is more apparent when more resources are allocated to the relay. It was also shown that quality of the source to destination link has direct impact on the decision to relay or not to relay. Relatively good source to destination channel makes relaying less useful. The opposite is true for the other two links, namely the source to relay channel and the relay to destination channel. When these two channels are good, relaying becomes advantageous. When applied to cellular systems, we concluded that relaying is more beneficial to battery-operated mobile nodes than to base stations.

scholarly journals Performance Enhancement for Multihop Cognitive DF and AF Relaying Protocols under Joint Impact of Interference and Hardware Noises: NOMA for Primary Network and Best-Path Selection for Secondary Network

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tran Trung Duy ◽  
Pham Thi Dan Ngoc ◽  
Phuong T. Tran
Keyword(s):  
Spectrum Sharing ◽  
Performance Enhancement ◽  
Path Selection ◽  
Secondary Source ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Transmit Power ◽  
Primary Network ◽  
Secondary Network ◽  
Relaying Protocols

In this paper, we propose and evaluate performance of multihop multipath underlay cognitive radio networks. In a primary network, an uplink nonorthogonal multiple access method is employed to allow primary transmitters to simultaneously transmit their data to a primary receiver. Using an underlay spectrum-sharing method, secondary source and secondary relays must adjust their transmit power to guarantee quality of service of the primary network. Under the limited transmit power, cochannel interference from the primary transmitters, and hardware noises caused by impairments, we propose best-path selection methods to improve the end-to-end performance for the secondary network. Moreover, both multihop decode-and-forward and amplify-and-forward relaying protocols are considered in this paper. We derive expressions of outage probability for the primary and secondary networks and propose an efficient method to calculate the transmit power of the secondary transmitters. Then, computer simulations employing the Monte-Carlo approach are realized to validate the derivations.

scholarly journals Coverage Analysis of Millimeter Wave Decode-and-Forward Networks With Best Relay Selection

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 22670-22683 ◽  
Author(s):  
Khagendra Belbase ◽  
Zhang Zhang ◽  
Hai Jiang ◽  
Chintha Tellambura
Keyword(s):  
Millimeter Wave ◽  
Relay Selection ◽  
Decode And Forward ◽  
Best Relay Selection ◽  
Coverage Analysis
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