scholarly journals Performance Analysis of Cooperative NOMA Networks with Imperfect CSI over Nakagami-m Fading Channels

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 424 ◽  
Author(s):  
Xianli Gong ◽  
Xinwei Yue ◽  
Feng Liu
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Multiple Access ◽  
Base Station ◽  
High Signal ◽  
Direct Link ◽  
Decode And Forward ◽  
Estimation Errors ◽  
Channel Estimation Errors ◽  
Outage Performance

In this paper, we investigate a downlink cooperative non-orthogonal multiple access (NOMA) network with decode-and-forward relaying, where two scenarios of user relaying with direct link and user relaying without direct link are discussed in detail. More particularly, the performance of cooperative NOMA system under the assumption of imperfect channel state information (ipCSI) is studied over Nakagami-m fading channels. To evaluate the outage performance of the above discussed two scenarios, the closed-form expressions of outage probability for a pair of users are derived carefully. The diversity orders of users are achieved in the high signal-to-noise region. An error floor appears in the outage probability owing to the existence of channel estimation errors under ipCSI conditions. Simulation results verify the validity of our analysis and show that: (1) NOMA is superior to conventional orthogonal multiple access; (2) The best user relaying location for cooperative NOMA networks should be near to the base station; and (3) The outage performance of distant user with direct link significantly outperforms distant user without direct link by comparing the two scenarios.

scholarly journals I/Q Imbalance and Imperfect SIC on Two-Way Relay NOMA Systems

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 249 ◽  
Author(s):  
Xinji Tian ◽  
Qianqian Li ◽  
Xingwang Li ◽  
Hongxing Peng ◽  
Changsen Zhang ◽  
...  
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Interference Cancellation ◽  
Signal To Noise Ratio ◽  
High Reliability ◽  
System Throughput ◽  
Rician Fading ◽  
High Signal ◽  
Decode And Forward ◽  
Outage Performance

Non-orthogonal multiple access (NOMA) system can meet the demands of ultra-high data rate, ultra-low latency, ultra-high reliability and massive connectivity of user devices (UE). However, the performance of the NOMA system may be deteriorated by the hardware impairments. In this paper, the joint effects of in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) on the performance of two-way relay cooperative NOMA (TWR C-NOMA) networks over the Rician fading channels are studied, where two users exchange information via a decode-and-forward (DF) relay. In order to evaluate the performance of the considered network, analytical expressions for the outage probability of the two users, as well as the overall system throughput are derived. To obtain more insights, the asymptotic outage performance in the high signal-to-noise ratio (SNR) region and the diversity order are analysed and discussed. Throughout the paper, Monte Carlo simulations are provided to verify the accuracy of our analysis. The results show that IQI and ipSIC have significant deleterious effects on the outage performance. It is also demonstrated that the outage behaviours of the conventional OMA approach are worse than those of NOMA. In addition, it is found that residual interference signals (IS) can result in error floors for the outage probability and zero diversity orders. Finally, the system throughput can be limited by IQI and ipSIC, and the system throughput converges to a fixed constant in the high SNR region.

scholarly journals Uplink Non-Orthogonal Multiple Access with Channel Estimation Errors for Internet of Things Applications

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 912
Author(s):  
Minjoong Rim ◽  
Chung Kang
Keyword(s):  
Internet Of Things ◽  
Channel Estimation ◽  
Communication Systems ◽  
Multiple Access ◽  
Base Station ◽  
Shared Resources ◽  
Estimation Errors ◽  
Channel Estimation Errors ◽  
Pilot Symbols ◽  
Shift Keying

One of the key requirements for next generation wireless or cellular communication systems is to efficiently support a large number of connections for Internet of Things (IoT) applications, and uplink non-orthogonal multiple access (NOMA) schemes can be used for this purpose. In uplink NOMA systems, pilot symbols, as well as data symbols can be superimposed onto shared resources. The error rate performance can be severely degraded due to channel estimation errors, especially when the number of superimposed packets is large. In this paper, we discuss uplink NOMA schemes with channel estimation errors, assuming that quadrature phase shift keying (QPSK) modulation is used. When pilot signals are superimposed onto the shared resources and a large number of devices perform random accesses concurrently to a single resource of the base station, the channels might not be accurately estimated even in high SNR environments. In this paper, we propose an uplink NOMA scheme, which can alleviate the performance degradation due to channel estimation errors.

Outage Performance of Multiuser AF Two-Way Relaying with Asymmetric Traffic Requirements over Nakagami-m Fading

2014 ◽  
Vol 556-562 ◽  
pp. 4530-4535
Author(s):  
Shi He ◽  
Bing Gao ◽  
Zhang Jun Fan
Keyword(s):  
Monte Carlo ◽  
Outage Probability ◽  
Fading Channels ◽  
Base Station ◽  
Diversity Order ◽  
Amplify And Forward ◽  
Relay System ◽  
Outage Performance ◽  
Shed Light ◽  
Relaying System

In this paper, we investigate the outage performance of a multiuser two-way relaying system over Nakagami-m fading channels. In particular, we consider the amplify-and-forward (AF) relay system with beamforming at the base station. Furthermore, the base station and mobile users have asymmetric traffic requirements. We fist derive a tight lower bound for the outage probability (OP). Moreover, the asymptotic outage probability expression is derived to shed light on the system's diversity order. Finally, Monte Carlo simulations are conducted to verify the analytical results.

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 System Performance of Cooperative NOMA with Full-Duplex Relay over Nakagami-m Fading Channels

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xuan-Xinh Nguyen ◽  
Dinh-Thuan Do
Keyword(s):  
Fading Channels ◽  
System Performance ◽  
Multiple Access ◽  
Base Station ◽  
Full Duplex ◽  
Decode And Forward ◽  
Relay Systems ◽  
Channel Environment ◽  
Analytical Expressions ◽  
Dual User

In this paper, we consider a dual-user nonorthogonal multiple access (NOMA) with the help of full-duplex decode-and-forward (DF) relay systems with respect to Nakagami-m fading channel environment. Especially, we derive the analytical expressions to evaluate system performance in terms of outage probability, achievable throughput, and energy efficiency. The main investigation is on considering how the fading parameters and transmitting power at the base station make crucial impacts on system performance in the various scenarios. Finally, simulations are conducted to confirm the validity of the analysis and show the system performance of NOMA under different fading parameters of Nakagami-m fading channels.

scholarly journals Exact secure outage probability performance of uplinkdownlink multiple access network under imperfect CSI

2021 ◽  
Vol 10 (6) ◽  
pp. 3274-3281
Author(s):  
Dinh-Thuan Do ◽  
Minh-Sang Van Nguyen
Keyword(s):  
Outage Probability ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Access Network ◽  
Base Station ◽  
High Signal ◽  
Secrecy Outage Probability ◽  
Factors Affecting ◽  
Secrecy Outage ◽  
The Right

In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.

scholarly journals Performance Analysis of Cooperative NOMA Systems with Incremental Relaying

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Zhenling Wang ◽  
Zhangyou Peng ◽  
Yongsheng Pei ◽  
Haojia Wang
Keyword(s):  
Performance Analysis ◽  
Outage Probability ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Amplify And Forward ◽  
Signal To Noise ◽  
Decode And Forward ◽  
Outage Performance ◽  
Low Snr ◽  
Incremental Relaying

In this paper, we investigate the performance of the non-orthogonal multiple access (NOMA) system with incremental relaying, where the relay is employed with amplify-and-forward (AF) or decode-and-forward (DF) protocols. To characterize the outage behaviors of the incremental cooperative NOMA (ICN) system, new closed-form expressions of both exact and asymptotic outage probability for two users are derived. In addition, the performance of the conventional cooperative NOMA (CCN) system is analyzed as a benchmark for the the purpose of comparison. We confirm that the outage performance of the distant user is enhanced when ICN system is employed. Numerical results are presented to demonstrate that (1) the near user of the ICN system achieves better outage behavior than that of the CCN system in the low signal-to-noise ratio (SNR) region; (2) the outage performance of distant user for the DF-based ICN system is superior to that of the AF-based ICN system when the system works in cooperative NOMA transmission mode; and (3) in the low SNR, the throughput of the ICN system is higher than that of the CCN system.

scholarly journals Sum Rate DL/UL Performance of Co-operative NOMA Systems Over Weibull Fading Channel

2021 ◽  
Author(s):  
Rampravesh Kumar ◽  
Sanjay Kumar
Keyword(s):  
Fading Channels ◽  
Fading Channel ◽  
Base Station ◽  
Full Duplex ◽  
Rate Performance ◽  
Direct Link ◽  
Decode And Forward ◽  
Weibull Fading ◽  
Mobile Cellular ◽  
Sum Rate

This work evaluates the sum rate performance for dual user with full duplex co-operative non-orthogonal multiple access (FD-CNOMA) over Weibull fading channel environment. For this, we derived closed form expressions for sum-rate in various scenario in downlink and uplink both. One user always acts as decode and forward full duplex relay to help far users in each scenario. In the first scenario, no direct link exists between base station (BS) and far user. In second scenario, direct link exists between BS and far user. The main investigation is to study the effect of fading parameters in different channel condition on sum-rate performance. Since, Weibull Distribution (WD) has an advantage to model different fading condition using varying parameter it is more suitable to study impact of fading condition on different wireless techniques for next generation mobile cellular communication. Therefore, WD is used in this study for sum rate performance evaluation with derived expressions. Finally, simulations were conducted on MATLAB to evaluate the system performance under different fading parameters of Weibull fading channels .

scholarly journals Outage performance users located outside D2D coverage area in downlink cellular network

2021 ◽  
Vol 10 (3) ◽  
pp. 1380-1387
Author(s):  
Thanh-Luan Nguyen ◽  
Dinh-Thuan Do
Keyword(s):  
Outage Probability ◽  
Cellular Network ◽  
Spatial Separation ◽  
Base Station ◽  
Geometric Probability ◽  
High Signal ◽  
Spectrum Utilization ◽  
Coverage Area ◽  
Outage Performance ◽  
Measurement Results

Device-to-device (D2D) communication has been proposed to employ the proximity between two devices to enhance the overall spectrum utilization of a crowded cellular network. With the help of geometric probability tools, this framework considers the performance of cellular users under spatial separation with the D2D pair is investigated. The measurement results and analytical expression of outage probability show that the proposed frameworks improve the outage performance at a high signal-tonoise ratio (SNR) at the base station. Results also interpret that the distances between nodes in the D2D-assisted network make slight impacts on the performance of the cellular user.

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