• Title/Summary/Keyword: NOMA for multiple users

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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.

On the block error rate performance of cooperative non-orthogonal multiple access short-packet communications with full-duplex relay and partial relay selection

  • Ha Duy Hung;Hoang Van Toan;Tran Trung Duy;Le The Dung;Quang Sy Vu
    • ETRI Journal
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    • v.46 no.3
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    • pp.446-460
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    • 2024
  • In this paper, we mathematically investigate a downlink non-orthogonal multiple access (NOMA) system for short-packet communications (SPC) in which the near users are used as full-duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed-form asymptotic expressions of the average BLERs at the near and far users in high signal-to-noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results.

Joint Detection Method for Non-orthogonal Multiple Access System Based on Linear Precoding and Serial Interference Cancellation

  • Li, Jianpo;Wang, Qiwei
    • Journal of Information Processing Systems
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    • v.17 no.5
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    • pp.933-946
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    • 2021
  • In the non-orthogonal multiple access (NOMA) system, multiple user signals on the single carrier are superimposed in a non-orthogonal manner, which results in the interference between non-orthogonal users and noise interference in the channel. To solve this problem, an improved algorithm combining regularized zero-forcing (RZF) precoding with minimum mean square error-serial interference cancellation (MMSE-SIC) detection is proposed. The algorithm uses RZF precoding combined with successive over-relaxation (SOR) method at the base station to preprocess the source signal, which can balance the effects of non-orthogonal inter-user interference and noise interference, and generate a precoded signal suitable for transmission in the channel. At the receiver, the MMSE-SIC detection algorithm is used to further eliminate the interference in the signal for the received superimposed signal, and reduce the calculation complexity through the QR decomposition of the matrix. The simulation results show that the proposed joint detection algorithm has good applicability to eliminate the interference of non-orthogonal users, and it has low complexity and fast convergence speed. Compared with other traditional method, the improved method has lower error rate under different signal-to-interference and noise ratio (SINR).

Analysis of Achievable Data Rate under BPSK Modulation: CIS NOMA Perspective (BPSK 변조의 최대 전송률 분석: 상관 정보원의 비직교 다중 접속 관점에서)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.15 no.6
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    • pp.995-1002
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    • 2020
  • This paper investigates the achievable data rate for non-orthogonal multiple access(NOMA) with correlated information sources(CIS), under the binary phase shift keying(BPSK) modulation, in contrast to most of the existing NOMA designs using continuous Gaussian input modulations. First, the closed-form expression for the achievable data rate of NOMA with CIS and BPSK is derived, for both users. Then it is shown by numerical results that for the stronger channel user, the achievable data rate of CIS reduces, compared with that of independent information sources( IIS). We also demonstrate that for the weaker channel user, the achievable data rate of CIS increases, compared with that of IIS. In addition, the intensive analyses of the probability density function(PDF) of the observation and the inter-user interferennce(IUI) are provided to verify our theoretical results.

Resource Allocation and EE-SE Tradeoff for H-CRAN with NOMA-Based D2D Communications

  • Wang, Jingpu;Song, Xin;Dong, Li
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.4
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    • pp.1837-1860
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    • 2020
  • We propose a general framework for studying resource allocation problem and the tradeoff between spectral efficiency (SE) and energy efficiency (EE) for downlink traffic in power domain-non-orthogonal multiple access (PD-NOMA) and device to device (D2D) based heterogeneous cloud radio access networks (H-CRANs) under imperfect channel state information (CSI). The aim is jointly optimize radio remote head (RRH) selection, spectrum allocation and power control, which is formulated as a multi-objective optimization (MOO) problem that can be solved with weighted Tchebycheff method. We propose a low-complexity algorithm to solve user association, spectrum allocation and power coordination separately. We first compute the CSI for RRHs. Then we study allocating the cell users (CUs) and D2D groups to different subchannels by constructing a bipartite graph and Hungrarian algorithm. To solve the power control and EE-SE tradeoff problems, we decompose the target function into two subproblems. Then, we utilize successive convex program approach to lower the computational complexity. Moreover, we use Lagrangian method and KKT conditions to find the global optimum with low complexity, and get a fast convergence by subgradient method. Numerical simulation results demonstrate that by using PD-NOMA technique and H-CRAN with D2D communications, the system gets good EE-SE tradeoff performance.

On Calculation of Total Power and Allocation for Achieving Near 1+1 Capacity Region of 2PAM NOMA in 5G Networks (5G 네트워크에서 비직교 다중 접속 2PAM의 근접 1+1 용량 영역 달성을 위한 총 전력과 할당의 계산)

  • Chung, Kyuhyuk
    • Journal of Convergence for Information Technology
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    • v.11 no.5
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    • pp.9-16
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    • 2021
  • In binary-modulation non-orthogonal multiple access (NOMA), there has been rare researches for the 1+1 capacity region to be achieved; how much total power is required and what power allocation is assigned for this total power. In this paper, the average total transmitted power to achieve 1+1 capacity region of binary pulse amplitude modulation (2PAM) NOMA is investigated, with a tolerable loss. Then, based on the sufficient average total transmitted power, we calculate the power allocation coefficient to achieve 1+1 capacity region. Furthermore, it is shown by numerical results that with the tolerable loss less than 0.008, near 1+1 capacity region is achieved. We also calculate numerically the power allocation coefficient for both users to achieve near 1+1 capacity region. As a result, for 2PAM NOMA to operate near 1+1 capacity region, proper total power with appropriate power allocation could be calculated in design of NOMA systems.

On Negative Correlation Bit-to-Symbol(: B2S) Mapping for NOMA with Correlated Information Sources in 5G Systems (5G 시스템에서 상관 정보원의 비직교 다중접속을 위한 음수의 상관관계 계수 B2S 사상)

  • Chung, Kyu-Hyuk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.15 no.5
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    • pp.881-888
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    • 2020
  • In this paper, in order to improve the degraded BER performance of the stronger channel user in non-orthogonal multiple access(: NOMA) with interactive mobile users, we propose the negative correlation bit-to-symbol(: B2S) mapping. First, the closed-form expression for the BER of the negative correlation B2S mapping receiver is derived, and then it is shown that the BER of the negative correlation B2S mapping receiver is improved, compared with those of the ideal perfect successive interference cancellation(: SIC) receiver and positive correlation receiver. Additionally, based on the analytical expression, signal-to-noise(: SNR) gain is calculated, and the superiority of the negative correlation B2S mapping receiver is validated.

Energy-efficient Power Allocation based on worst-case performance optimization under channel uncertainties

  • Song, Xin;Dong, Li;Huang, Xue;Qin, Lei;Han, Xiuwei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.11
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    • pp.4595-4610
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    • 2020
  • In the practical communication environment, the accurate channel state information (CSI) is difficult to obtain, which will cause the mismatch of resource and degrade the system performance. In this paper, to account for the channel uncertainties, a robust power allocation scheme for a downlink Non-orthogonal multiple access (NOMA) heterogeneous network (HetNet) is designed to maximize energy efficiency (EE), which can ensure the quality of service (QoS) of users. We conduct the robust optimization model based on worse-case method, in which the channel gains belong to certain ellipsoid sets. To solve the non-convex non-liner optimization, we transform the optimization problem via Dinkelbach method and sequential convex programming, and the power allocation of small cell users (SCUs) is achieved by Lagrange dual approach. Finally, we analysis the convergence performance of proposed scheme. The simulation results demonstrate that the proposed algorithm can improve total EE of SCUs, and has a fast convergence performance.