• Title/Summary/Keyword: NOMA

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On Power Splitting under User-Fairness for Correlated Superposition Coding NOMA in 5G System

  • Chung, Kyuhyuk
    • International journal of advanced smart convergence
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    • v.9 no.2
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    • pp.68-75
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    • 2020
  • Non-orthogonal multiple access (NOMA) has gained the significant attention in the fifth generation (5G) mobile communication, which enables the advanced smart convergence of the artificial intelligence (AI), the internet of things (IoT), and many of the state-of-the-art technologies. Recently, correlated superposition coding (SC) has been proposed in NOMA, to achieve the near-perfect successive interference cancellation (SIC) bit-error rate (BER) performance for the stronger channel users, and to mitigate the severe BER performance degradation for the weaker channel users. In the correlated SC NOMA scheme, the stronger channel user BER performance is even better than the perfect SIC BER performance, for some range of the power allocation factor. However, such excessively good BER performance is not good for the user-fairness, i.e., the more power to the weaker channel user and the less power to the stronger channel user, because the excessively good BER performance of the stronger channel user results in the worse BER performance of the weaker channel user. Therefore, in this paper, we propose the power splitting to establish the user-fairness between both users. First, we derive a closed-form expression for the power splitting factor. Then it is shown that in terms of BER performance, the user-fairness is established between the two users. In result, the power splitting scheme could be considered in correlated SC NOMA for the user-fairness.

Performance analysis of SWIPT-assisted adaptive NOMA/OMA system with hardware impairments and imperfect CSI

  • Jing Guo;Jin Lu;Xianghui Wang;Lili Zhou
    • ETRI Journal
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    • v.45 no.2
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    • pp.254-266
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    • 2023
  • This paper investigates the effect of hardware impairments (HIs) and imperfect channel state information (ICSI) on a SWIPT-assisted adaptive nonorthogonal multiple access (NOMA)/orthogonal multiple access (OMA) system over independent and nonidentical Rayleigh fading channels. In the NOMA mode, the energy-constrained near users act as a relay to improve the performance for the far users. The OMA transmission mode is adopted to avoid a complete outage when NOMA is infeasible. The best user selection scheme is considered to maximize the energy harvested and avoid error propagation. To characterize the performance of the proposed systems, closed-form and asymptotic expressions of the outage probability for both near and far users are studied. Moreover, exact and approximate expressions of the ergodic rate for near and far users are investigated. Simulation results are provided to verify our theoretical analysis and confirm the superiority of the proposed NOMA/OMA scheme in comparison with the conventional NOMA and OMA protocol with/without HIs and ICSI.

On Larger Rate Volume of non-SIC NOMA over SIC NOMA for 3-user Correlated Information Sources (삼중 상관 정보원에서 SIC 대한 non-SIC 비직교 다중 접속의 확장 전송률 용적에 관해)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.3
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    • pp.457-464
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    • 2021
  • This paper investigates the achievable rate volumes for non-successive interference cancellation(SIC) non-orthogonal multiple access(NOMA) schemes, especially for 3-user correlated information sources(CIS). First, the closed-form expressions for the achievable rate volumes of non-SIC 3-user CIS NOMA are derived. Then it is numerically shown that the large correlation coefficients, as the achievable rate volumes of non-SIC 3-user CIS NOMA is larger than that of conventional SIC 3-user independent information sources(IIS) NOMA. We also demonstrate by various comparisons that the impact of the correlation coefficients of weaker channel gain users on achievable rate volume is more significant than those of stronger channel gain users.

NOMA Transmission Scheme using MU-MIMO and STBC (MU-MIMO와 STBC를 적용한 NOMA 전송 기법)

  • Bangwon, Seo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.23 no.1
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    • pp.45-50
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    • 2023
  • In order to improve a total system throughput when a base station (BS) transmits data to user equipments (UEs), we propose a scheme to apply multiuser multiple-input multiple-output (MU-MIMO), space-time block coding (STBC), and non-orthogonal multiple access (NOMA) together. An MU-MIMO is applied to two UEs near the BS and STBC is applied to a UE far from the BS because of the difficulty of obtaining the channel information. Also NOMA is applied to differentiate the data from the near UE and the far UE. Two orthognal precoding vectors are used for the MU-MIMO UEs and it causes no interference between them. The STBC technique with the two procoding vectors are also used for the far UEs. Through performance analysis and simulation, we show that the proposed scheme has higher total system throughput than the conventional ones.

On Additive Signal Dependent Gaussian Noise Channel Capacity for NOMA in 5G Mobile Communication

  • Chung, Kyuhyuk
    • International Journal of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.37-44
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    • 2020
  • The fifth generation (5G) mobile communication has been commercialized and the 5G applications, such as the artificial intelligence (AI) and the internet of things (IoT), are deployed all over the world. The 5G new radio (NR) wireless networks are characterized by 100 times more traffic, 1000 times higher system capacity, and 1 ms latency. One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In order for the NOMA performance to be improved, sometimes the additive signal-dependent Gaussian noise (ASDGN) channel model is required. However, the channel capacity calculation of such channels is so difficult, that only lower and upper bounds on the capacity of ASDGN channels have been presented. Such difficulties are due to the specific constraints on the dependency. Herein, we provide the capacity of ASDGN channels, by removing the constraints except the dependency. Then we obtain the ASDGN channel capacity, not lower and upper bounds, so that the clear impact of ASDGN can be clarified, compared to additive white Gaussian noise (AWGN). It is shown that the ASDGN channel capacity is greater than the AWGN channel capacity, for the high signal-to-noise ratio (SNR). We also apply the analytical results to the NOMA scheme to verify the superiority of ASDGN channels.

Optimal Detection for NOMA Systems with Correlated Information Sources of Interactive Mobile Users (상호작용 이동통신 사용자의 상관 정보원을 가진 비직교 다중접속 시스템에서의 최적 검출)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.15 no.4
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    • pp.651-658
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    • 2020
  • In the fifth generation (5G) mobile networks, the interactive mobile game users have increased tremendously, which induces correlated information sources (CIS). One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In NOMA, the users share the channel resources, so that CIS affect each user's bit-error rate (BER) performance, which is not the case for orthogonal multiple access (OMA). In this paper, we derive the optimal receiver for NOMA with CIS, and then investigate the impact of CIS on each user's BER performance.

Power allocation for full-duplex NOMA relaying based underlay D2D communications

  • Li, Song;Li, Shuo;Sun, Yanjing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.1
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    • pp.16-33
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    • 2019
  • In this paper, a full-duplex NOMA relaying based underlay device-to-device (D2D) communication scheme is proposed, in which D2D transmitter assists cellular downlink transmission as a full-duplex relay. Specifically, D2D transmitter receives signals from base station and transmits the superposition signals to D2D receiver and cellular user in NOMA scheme simultaneously. Furthermore, we investigate the power allocation under the proposed scheme, aiming to maximize D2D link's achievable transmit rate under cellular link's transmit rate constraint and total power constraint. To tackle the power allocation problem, we first propose a power allocation method based on linear fractional programming. In addition, we derive closed-form expressions of the optimal transmit power for base station and D2D transmitter. Simulation results show that the performance of two solutions matches well and the proposed full-duplex NOMA relaying based underlay D2D communication scheme outperforms existing full-duplex relaying based D2D communication scheme.

Higher Spectral Efficiency of 3-User Cross CSC NOMA in 5G Systems

  • Chung, Kyuhyuk
    • International journal of advanced smart convergence
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    • v.10 no.3
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    • pp.17-25
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    • 2021
  • As a new paradigm in non-orthogonal multiple access (NOMA), correlated superposition coding (CSC) has gained an attention in the literature of NOMA, in contrast to standard independent superposition coding (ISC). In the conventional 3-user CSC scheme, it has been reported that the average allocated power can be reduced, owing to an introduced correlation between transmitted signals. Thus, this paper proposes a 3-user cross CSC scheme with purely-imaginary correlation coefficients. First, we derive the achievable data rates of the proposed 3-user cross CSC scheme, for each of the three users. Then, simulations demonstrate that for the proposed 3-user cross CSC scheme, the achievable data rates of the first and second users increase greatly and slightly, respectively, whereas the achievable data rate of the third user decreases little, compared to those of the conventional 3-user CSC scheme. In addition, we also show that the sum rate of the three users of the proposed 3-user cross CSC scheme is much larger than that of the three users of the conventional 3-user CSC scheme. As a result, the proposed 3-user cross CSC scheme could be a solution to the problem of the reduction of the average allocated total power in the conventional 3-user CSC scheme toward the fifth-generation (5G) NOMA mobile networks.

Lossless Non-SIC NOMA Implementation (Part II): 3-user Scheme Study (무손실 Non-SIC 비직교 다중 접속 구현 (II 편): 삼중 사용자 기법 연구)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.6
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    • pp.1029-1036
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    • 2021
  • Recently it has been proposed that lossless 2-user non-orthogonal multiple access (NOMA) can be implemented without successive interference cancellation (SIC) via correlated superposition coding (CSC). However only the 2-user case was considered. Thus this paper proposes a lossless 3-user non-SIC NOMA scheme. This can be achieved via the 3-user CSC scheme. Simulations show that the lossless 3-user non-SIC NOMA scheme can be implemented over power allocation ranges of user-fairness.

Energy-efficient semi-supervised learning framework for subchannel allocation in non-orthogonal multiple access systems

  • S. Devipriya;J. Martin Leo Manickam;B. Victoria Jancee
    • ETRI Journal
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    • v.45 no.6
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    • pp.963-973
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    • 2023
  • Non-orthogonal multiple access (NOMA) is considered a key candidate technology for next-generation wireless communication systems due to its high spectral efficiency and massive connectivity. Incorporating the concepts of multiple-input-multiple-output (MIMO) into NOMA can further improve the system efficiency, but the hardware complexity increases. This study develops an energy-efficient (EE) subchannel assignment framework for MIMO-NOMA systems under the quality-of-service and interference constraints. This framework handles an energy-efficient co-training-based semi-supervised learning (EE-CSL) algorithm, which utilizes a small portion of existing labeled data generated by numerical iterative algorithms for training. To improve the learning performance of the proposed EE-CSL, initial assignment is performed by a many-to-one matching (MOM) algorithm. The MOM algorithm helps achieve a low complex solution. Simulation results illustrate that a lower computational complexity of the EE-CSL algorithm helps significantly minimize the energy consumption in a network. Furthermore, the sum rate of NOMA outperforms conventional orthogonal multiple access.