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.

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 Non-Orthogonal Multiple Access Assisted Device-to-Device Communication: Best Helping Base Station Approach

2018 ◽  
Vol 12 (2) ◽  
pp. 803
Author(s):  
Huu-Phuc Dang ◽  
Minh-Sang Nguyen ◽  
Dinh-Thuan Do
Keyword(s):  
Data Transmission ◽  
System Performance ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Selection Scheme ◽  
Channel Condition ◽  
Expected Performance ◽  
Realistic Assumption ◽  
Device To Device

<span>It can be studied in this paper that a cooperative non-orthogonal multiple access (NOMA) helps device-to-device (D2D) communication system through base station (BS). In particular, we investigate BS selection scheme as a best channel condition for dedicated devices where a different data transmission demand on each device is resolved. The analysis on amplifying-and forward (AF) relay is proposed to evaluate system performance of the conventional cooperative NOMA scheme. Under the realistic assumption of perfect channel estimation, the achievable outage probability of both devices is investigated, and several impacts on system performance are presented. The mathematical formula in closed form related to probability has also been found. By implementing Monte-Carlo simulation, the simulation results confirm the accuracy of the derived analytical results. Also, the proposed D2D cooperative NOMA system introduces expected performance on reasonable selected parameters in the moderate signal to noise ratio (SNR) regime.</span>

scholarly journals Performance Analysis of Power-Splitting Relaying Protocol in SWIPT Based Cooperative NOMA Systems

2021 ◽  
Author(s):  
Quy-Huu Tran ◽  
Ca V Phan ◽  
Quoc-Tuan Vien
Keyword(s):  
Energy Efficiency ◽  
Outage Probability ◽  
Multiple Access ◽  
Base Station ◽  
Cellular Systems ◽  
Power Splitting ◽  
Direct Link ◽  
Maximum Ratio Combining ◽  
Source Data ◽  
Simulation Results

Abstract This paper investigates a relay assisted simultaneous wireless information and power transfer (SWIPT) for downlink in cellular systems. Cooperative non-orthogonal multiple access (C-NOMA) is employed along with power splitting (PS) protocol to enable both energy harvesting (EH) and information processing (IP). A downlink model consists of a base station (BS) and two users is considered, in which the near user (NU) is selected as a relay to forward the received signal from the BS to the far user (FU). Maximum ratio combining is then employed at the FU to combine both the signals received from the BS and NU. Closed form expressions of outage propability (OP), throughput, ergodic rate and energy efficiency (EE) are firstly derived for the SWIPT based C-NOMA considering both scenarios of with and without direct link between the BS and FU. The impacts of EH time, EH efficiency, power-splitting ratio, source data rate and distance between different nodes on the performance are then investigated. The simulation results show that the C-NOMA with direct link achieves an outperformed performance over C-NOMA without direct link. Moreover, the performance of C-NOMA with direct link is also higher than that for OMA. Specifically, (i) the outage probability for C-NOMA in both direct and relaying link cases is always lower than that for OMA. (ii) the outage probability, throughput and ergodic rate vary according to β , (iii) the EE of both users can obtain in SNR range of from -10 to 5 dB and it decreases linearly as SNR increases. Numerical results are provided to verify the findings.

scholarly journals A Framed Slotted ALOHA-Based MAC for Eliminating Vain Wireless Power Transfer in Wireless Powered IoT Networks

Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 9
Author(s):  
Ying-Jen Lin ◽  
Show-Shiow Tzeng
Keyword(s):  
Multiple Access ◽  
Time Slot ◽  
Base Station ◽  
Full Duplex ◽  
Wireless Power ◽  
Slotted Aloha ◽  
Data Packets ◽  
Half Duplex ◽  
Framed Slotted Aloha ◽  
Simulation Results

Multiple access control (MAC) is crucial for devices to send data packets and harvest wireless energy in wireless powered Internet of Things (IoT) networks. A framed slotted ALOHA (FSA) protocol is employed in several practical networks. This paper studies an FSA-based MAC in a centralized wireless powered IoT network, including half-duplex devices and a full-duplex base station transmitting wireless energy in an intended direction. Under such a network, it is possible that a half-duplex device contends for a time slot to transmit a packet while the base station transmits wireless energy to the device in the same time slot, which causes vain charging and wastes the opportunity to charge other devices. To eliminate the vain charging, this paper designs a MAC in which a base station utilizes the information conveyed from devices in advance to arrange the charging order of devices. The novelty is to develop an algorithm to find a charging order of half-duplex devices instead of using full-duplex devices to eliminate the vain charging. Event-driven simulations are conducted to study the performance of the proposed MAC. Simulation results show that the proposed MAC produces better system performances than the system not eliminating the vain charging. In summary, the application of the proposed MAC yields the benefits of higher throughput and lower packet loss.

scholarly journals Content popularity prediction for cache-enabled wireless B5G networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shiwei Lai ◽  
Rui Zhao ◽  
Yulin Wang ◽  
Fusheng Zhu ◽  
Junjuan Xia
Keyword(s):  
Relay Selection ◽  
Base Station ◽  
Mobile Edge Computing ◽  
Prediction Problem ◽  
Hit Rate ◽  
Content Popularity ◽  
Multiple Relays ◽  
Simulation Results ◽  
Popularity Prediction ◽  
Edge Networks

AbstractIn this paper, we study the cache prediction problem for mobile edge networks where there exist one base station (BS) and multiple relays. For the proposed mobile edge computing (MEC) network, we propose a cache prediction framework to solve the problem of contents prediction and caching based on neural networks and relay selection, by exploiting users’ history request data and channels between the relays and users. The proposed framework is then trained to learn users’ preferences by using the users’ history requested data, and several caching policies are proposed based on the channel conditions. The cache hit rate and latency are used to measure the performance of the proposed framework. Simulation results demonstrate the effectiveness of the proposed framework, which can maximize the cache hit rate and meanwhile minimize the latency for the considered MEC networks.

scholarly journals Low Power Allocation Based Error Improvements in wireless 5G

2019 ◽  
Vol 8 (4) ◽  
pp. 11049-11052
Keyword(s):  
Multiple Access ◽  
Antenna Selection ◽  
Base Station ◽  
Time Varying ◽  
Transmit Antenna Selection ◽  
User Experiences ◽  
Common Technique ◽  
Sum Rate ◽  
Simulation Results ◽  
Time Varying Channel

Transmit antenna selection is very common technique to reduce system complexity and power consumption at transmitter side while maintaining nearly the same performance of multiple antennas. In this paper, we introduce a transmit antenna selection (TAS) scheme for non orthogonal multiple access (NOMA) to improve the performance in terms of total sum rate. Therefore different antenna elements added at the base station experiences different fading conditions (A channel is a time varying channel).Experiences different SNR values adding more number of antennas at the base station. Increases the complaxicity as well as the performance with respect to the sum rate Non linear the user experiences the Bit error rate at the receiver simulation results shows that the BER is verified for different antenna error consideration (MIMO).

scholarly journals NOMA-Assisted Multiple Access Scheme for IoT Deployment: Relay Selection Model and Secrecy Performance Improvement

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 736 ◽  
Author(s):  
Dinh-Thuan Do ◽  
Minh-Sang Van Nguyen ◽  
Thi-Anh Hoang ◽  
Miroslav Voznak
Keyword(s):  
Performance Improvement ◽  
Relay Selection ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Master Node ◽  
Access Scheme ◽  
Setting Parameters ◽  
Different Levels ◽  
Relaying System

In this paper, an Internet-of-Things (IoT) system containing a relay selection is studied as employing an emerging multiple access scheme, namely non-orthogonal multiple access (NOMA). This paper proposes a new scheme to consider secure performance, to be called relay selection NOMA (RS-NOMA). In particular, we consider metrics to evaluate secure performance in such an RS-NOMA system where a base station (master node in IoT) sends confidential messages to two main sensors (so-called NOMA users) under the influence of an external eavesdropper. In the proposed IoT scheme, both two NOMA sensors and an illegal sensor are served with different levels of allocated power at the base station. It is noticed that such RS-NOMA operates in two hop transmission of the relaying system. We formulate the closed-form expressions of secure outage probability (SOP) and the strictly positive secure capacity (SPSC) to examine the secrecy performance under controlling setting parameters such as transmit signal-to-noise ratio (SNR), the number of selected relays, channel gains, and threshold rates. The different performance is illustrated as performing comparisons between NOMA and orthogonal multiple access (OMA). Finally, the advantage of NOMA in secure performance over orthogonal multiple access (OMA) is confirmed both analytically and numerically.

Cross–Layer Relay Selection For Cooperative Relay System In IEEE 802.16j Network

2012 ◽  
Author(s):  
Anis Izzati Ahmad Zamani ◽  
Nurul Nazirah Mohd Imam Ma’AROF ◽  
Farah Buthainah Nor Yusof ◽  
Nurulashikin Satiman ◽  
Sharifah Kamilah Syed Yusof ◽  
...  
Keyword(s):  
Relay Selection ◽  
Base Station ◽  
Cooperative Relaying ◽  
Cooperative Relay ◽  
Cross Layer ◽  
Communication Link ◽  
Mac Layer ◽  
Relay System ◽  
Selection Scheme ◽  
Ieee 802.16J

The IEEE 802.16j amendment has been developed to improve the performance of the IEEE 802.16e standard in terms of its network capacity and coverage area via employment of relay stations. An optional feature of cooperative relay has been initiated to fully utilize multihop network environment. This work focuses on the selection of cooperative relay path/paths through cross–layer approach to forward data from source to destination. The selection scheme jointly considers the signal–to–noise ratio (SNR) from physical (PHY) layer and buffer status from medium access control (MAC) layer. The SNR of the communication link between the base–station and the mobile station has to be compared to a certain threshold before making decision on the optimal cooperative relaying mode. Numerical and simulation results show that cooperative relaying improves the throughput and delay of the IEEE 802.16j system. In addition, the average transmission time of cooperative relay system decreases when the parameter from the MAC layer is considered in the relay selection scheme. Key words: Cooperative relay, IEEE 802.16j, relay selection, cross–layer design

Energy-Efficient Joint Power Allocation and Relay Selection in Bit Error Rate Constrained Two-Way Relay Network

2015 ◽  
Vol 7 (4) ◽  
pp. 1-14
Author(s):  
Rashi Mehrotra ◽  
Ranjan Bose
Keyword(s):  
Power Consumption ◽  
Power Allocation ◽  
Bit Error Rate ◽  
Error Rate ◽  
Energy Efficient ◽  
Relay Selection ◽  
Relay Network ◽  
Transmit Power ◽  
Selection Scheme ◽  
Simulation Results

In this paper, the authors have proposed energy efficient power allocation and relay selection scheme in a two-way amplify-and-forward (AF) relay under bit error rate (BER) constrained network. They have derived an expression for the overall BER for Rayleigh fading channel. Based on minimum power consumption in the network, the authors have addressed the problem of power allocation by converting geometric programming to a convex optimization problem. A closed form solution of power allocation is found, which aims at minimizing total transmit power for the overall BER constrained network. The authors have evaluated minimum total transmit power for two-way AF relay network. Based on minimum total transmit power, a novel relay selection scheme has been proposed. Simulation results demonstrate that the proposed two-way power allocation and relay selection scheme can significantly minimize power consumption under BER constrained network as compared to the existing relay transmission. The proposed power allocation scheme gives 3 dBW gain than one-way relay transmission. The proposed relay selection method also outperforms the random relay selection by 24 dBW. The simulation results are corroborated with the analytical result

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