Relay Selection-aware Non-orthogonal Multiple Access Networks: Direct and Relaying Mode

2020 ◽  
Vol 13 (3) ◽  
pp. 348-354
Author(s):  
Dinh-Thuan Do ◽  
Minh-Sang V. Nguyen
Keyword(s):  
Relay Selection ◽  
Multiple Access ◽  
Decode And Forward ◽  
Selection Scheme ◽  
Fixed Power ◽  
Transmission Quality ◽  
Improved Performance ◽  
Outage Probabilities ◽  
Future Work ◽  
The Impact

Objective: In this paper, Decode-and-Forward (DF) mode is deployed in the Relay Selection (RS) scheme to provide better performance in cooperative downlink Non-orthogonal Multiple Access (NOMA) networks. In particular, evaluation regarding the impact of the number of multiple relays on outage performance is presented. Methods: As main parameter affecting cooperative NOMA performance, we consider the scenario of the fixed power allocations and the varying number of relays. In addition, the expressions of outage probabilities are the main metric to examine separated NOMA users. By matching related results between simulation and analytical methods, the exactness of derived formula can be verified. Results: The intuitive main results show that in such cooperative NOMA networks, the higher the number of relays equipped, the better the system performance can be achieved. Conclusion: DF mode is confirmed as a reasonable selection scheme to improve the transmission quality in NOMA. In future work, we will introduce new relay selections to achieve improved performance.

scholarly journals Secrecy Performance of Underlay Cooperative Cognitive Network Using Non-Orthogonal Multiple Access with Opportunistic Relay Selection

Symmetry ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 385 ◽  
Author(s):  
Tan-Phuoc Huynh ◽  
Pham Ngoc Son ◽  
Miroslav Voznak
Keyword(s):  
Fading Channels ◽  
Relay Selection ◽  
Multiple Access ◽  
Source Node ◽  
Secrecy Outage Probability ◽  
Decode And Forward ◽  
Cognitive Network ◽  
Best Relay Selection ◽  
Secrecy Outage ◽  
Outage Probabilities

In this paper, an underlay cooperative cognitive network using a non-orthogonal multiple access (UCCN-NOMA) system is investigated, in which the intermediate multiple relays help to decode and forward two signals x 1 and x 2 from a source node to two users D1 and D2, respectively, under wiretapping of an eavesdropper (E). We study the best relay selection strategies by three types of relay selection criteria: the first and second best relay selection is based on the maximum channel gain of the links R i -D 1 , R i -D2, respectively; the third one is to ensure a minimum value of the channel gains from the R i -E link. We analyze and evaluate the secrecy performances of the transmissions x 1 and x 2 from the source node to the destination nodes D1, D2, respectively, in the proposed UCCN-NOMA system in terms of the secrecy outage probabilities (SOPs) over Rayleigh fading channels. Simulation and analysis results are presented as follows. The results of the (sum) secrecy outage probability show that proposed scheme can realize the maximal diversity gain. The security of the system is very good when eavesdropper node E is far from the source and cooperative relay. Finally, the theoretical analyses are verified by performing Monte Carlo simulations.

scholarly journals Rate-Splitting Multiple Access for Intelligent Reflecting Surface aided Multi-User Communications

2021 ◽  
Author(s):  
Ankur Bansal ◽  
Keshav Singh ◽  
Bruno Clerckx ◽  
Chih-Peng Li ◽  
Mohamed-Slim Alouini
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Base Station ◽  
Control Technique ◽  
Decode And Forward ◽  
Cell Edge ◽  
Single Antenna ◽  
Rate Splitting ◽  
Reflecting Surface ◽  
The Impact

Intelligent reflecting surface (IRS) has recently emerged as a promising technology for 6G wireless systems, due to its capability to reconfigure the wireless propagation environment. In this paper, we investigate a Rate-Splitting Multiple Access (RSMA) for IRS-assisted downlink system, where the base station (BS) communicates with single-antenna users with the help of an IRS. RSMA relies on rate-splitting (RS) at the BS and successive interference cancellation (SIC) at the users and provides a generalized multiple access framework. We derive a new architecture called IRS-RS that leverages the interplay between RS and IRS. For performance analysis, we utilize an \textit{on-off control technique} to control the passive beamforming vector of the IRS-RS and derive the closed-form expressions for outage probability of cell-edge users and near users. Moreover, we also analyze the outage behavior of cell-edge users for a sufficiently large number of reflecting elements. Additionally, we also analyze the outage performance of cooperative RS based decode-and-forward (DF)-assisted framework called DF-RS. Through simulation results, it is shown that the proposed framework outperforms the corresponding DF-RS, RS without IRS and IRS-assisted conventional non-orthogonal multiple access (NOMA) schemes. Furthermore, the impact of various system's parameters such as the number of IRS reflecting elements and the number of users on the system performance is revealed.

Relay Selection Scheme for Cooperative Communication Systems in Fixed Decode-and-Forward Mode

2014 ◽  
Vol 6 (2) ◽  
pp. 68-77
Author(s):  
Jyh-Horng Wen ◽  
Jheng-Sian Li ◽  
Hsiang-Shan Hou ◽  
Cheng-Ying Yang
Keyword(s):  
Cooperative Communication ◽  
System Performance ◽  
Communication Systems ◽  
Relay Selection ◽  
Spatial Diversity ◽  
Search Method ◽  
Exhaustive Search ◽  
Decode And Forward ◽  
Selection Scheme ◽  
Relay Stations

Cooperative system is a tendency in the future communications because it provides a spatial diversity to improve the system performance. This work considers the cooperative communication systems in Fixed DF Mode. The scenario includes multiple source stations, multiple relay stations and multiple destination stations. For the whole system, the maximum throughput approaching is the major purpose. Hence, to select the relay stations for signal transmission could be the important scheme to achieve the optimal system performance. With the exhaustive search method, easily to realize, the optimal selection scheme could be found with a highly complicated calculation. In order to reduce the computational complexity, a relay selection scheme is proposed. With different situations of the communication systems, the performances evaluations obtained with both the proposed algorithm and the exhaustive search method are given for comparison. It shows the proposed algorithm could provide a solution approaches to the optimal one. It could apply the proposed scheme to the practical without a delay because of long-time calculation.

scholarly journals A Range-Division User Relay Selection Scheme and Performance Analysis in NOMA-based Cooperative Opportunistic Multicast Systems

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 544 ◽  
Author(s):  
Yufang Zhang ◽  
Xiaoxiang Wang ◽  
Dongyu Wang ◽  
Qiang Zhao ◽  
Yibo Zhang
Keyword(s):  
Relay Selection ◽  
Multiple Access ◽  
Base Station ◽  
Selection Scheme ◽  
Selection Ratio ◽  
Coverage Ratio ◽  
Group Cooperation ◽  
Simulation Results ◽  
And Performance ◽  
Multicast Scheme

The original user relay (UR) selection scheme of non-orthogonal multiple access-based cooperative opportunistic multicast scheme, which realizes inter-group cooperation between two multicast groups, ignores the distribution trend of candidate UR in the cell and adopts fixed efficient relay selection range (ERSR) to select UR. It results in high UR selection ratio. Then the coverage efficiency, defined as the ratio of successfully received users to URs, is low. To tackle this problem, a range-division user relay (RDUR) selection scheme is proposed in this paper. Firstly, it divides the circular coverage range of base station into several continuous annular areas (AAs). Secondly, different ERSRs are assigned to unsuccessfully received users in different AAs. Under different ERSR assignments, the performances of UR selection ratio and coverage ratio are analyzed. Lastly, the radius set of ERSR that optimizes system coverage efficiency is used to perform UR selection. From simulation results, with different radius sets, analytical results of UR selection ratio and coverage ratio match well with their simulated ones. It is proved that ERSR allocation affects UR selection ratio and coverage ratio. With RDUR scheme, coverage efficiency increases by at least 14% and capacity efficiency has also been improved.

scholarly journals Rate-Splitting Multiple Access for Intelligent Reflecting Surface aided Multi-User Communications

2021 ◽  
Author(s):  
Ankur Bansal ◽  
Keshav Singh ◽  
Bruno Clerckx ◽  
Chih-Peng Li ◽  
Mohamed-Slim Alouini
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Base Station ◽  
Control Technique ◽  
Decode And Forward ◽  
Cell Edge ◽  
Single Antenna ◽  
Rate Splitting ◽  
Reflecting Surface ◽  
The Impact

Intelligent reflecting surface (IRS) has recently emerged as a promising technology for 6G wireless systems, due to its capability to reconfigure the wireless propagation environment. In this paper, we investigate a Rate-Splitting Multiple Access (RSMA) for IRS-assisted downlink system, where the base station (BS) communicates with single-antenna users with the help of an IRS. RSMA relies on rate-splitting (RS) at the BS and successive interference cancellation (SIC) at the users and provides a generalized multiple access framework. We derive a new architecture called IRS-RS that leverages the interplay between RS and IRS. For performance analysis, we utilize an \textit{on-off control technique} to control the passive beamforming vector of the IRS-RS and derive the closed-form expressions for outage probability of cell-edge users and near users. Moreover, we also analyze the outage behavior of cell-edge users for a sufficiently large number of reflecting elements. Additionally, we also analyze the outage performance of cooperative RS based decode-and-forward (DF)-assisted framework called DF-RS. Through simulation results, it is shown that the proposed framework outperforms the corresponding DF-RS, RS without IRS and IRS-assisted conventional non-orthogonal multiple access (NOMA) schemes. Furthermore, the impact of various system's parameters such as the number of IRS reflecting elements and the number of users on the system performance is revealed.

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