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⛄ 内容介绍
4G关键技术——正交频分复用多址(Orthogonal Frequency Division Multiplexing,OFDM)技术通过将宽带的频率选择性信道分为多个正交的平衰落的子载波信道,从而具备了良好的抵抗频率选择性衰落的能力,并能够利用信道的频率选择性获得频率和多用户的分集增益,因而已得到广泛的应用.在此基础上,为了应对当前通信数据量爆发性的增长,提出5G关键技术——非正交多址接入(Non-Orthogonal Multiplexing Acess),与正交多址技术相比,NOMA技术通过非正交资源的分配允许更多的用户同时接入,与OFDMA相比,NOMA支持大规模数据的连接,减小了传输时延和信令的开销,提高了频谱效率,增强了用户之间的公平性.
⛄ 部分代码
function [ seq_ofdma ] = ofdma_enc( seq_u1, seq_u2, N_u1, N_u2 )
% [ seq_ofdma ] = ofdma_co( seq_u1, seq_u2, N_u1, N_u2, p1, p2 )
% 将用户1和用户2的数据分别按照N_u1和N_u2的子载波数合成OFDMA序列，只保留部分序列。
sym_total = length(seq_u1);
sym_u1 = sym_total * (N_u1/(N_u1+N_u2));
sym_u2 = sym_total * (N_u2/(N_u1+N_u2));
seq_u1_r = seq_u1(1:sym_u1);
seq_u2_r = seq_u2(1:sym_u2);
% 截取用户1和用户2的部分序列，保证序列总长度和NOMA的一致
mat_u1_r = reshape(seq_u1_r, N_u1, numel(seq_u1_r)/N_u1);
mat_u2_r = reshape(seq_u2_r, N_u2, numel(seq_u1_r)/N_u2);
mat_ofdma = [mat_u1_r; mat_u2_r];
seq_ofdma = reshape(mat_ofdma, numel(mat_ofdma), 1);
end
⛄ 运行结果
⛄ 参考文献
[1] Salameh H B , Tashtoush R , Al-Obiedollah H , et al. Power allocation technique with soft performance guarantees in hybrid OFDMA-NOMA cognitive radio systems: Modeling and simulation[J]. Simulation modelling practice and theory: International journal of the Federation of European Simulation Societies, 2021(112-):112.
[2] Taskou S K , Rasti M , Nardelli P , et al. Distributed Joint Power and Rate Control for NOMA/OFDMA in 5G and Beyond[J]. 2021.
[3] Lin B , Ye W , Xuan T , et al. Experimental demonstration of bidirectional NOMA-OFDMA visible light communications[J]. Optics Express, 2017, 25(4):4348-.
[4] Abdel-Razeq S , Al-Obiedollah H , Bany Salameh H . Efficient user-channel pairing with power-domain sum-rate maximization in opportunistic hybrid OFDMA-NOMA IoT systems[J]. Cluster Computing, 2021:1-14.
[5] Tseng S M , Tsai W D , Suo H S . Cross‐layer 1 and 5 user grouping/power allocation/subcarrier allocations for downlink OFDMA/NOMA video communications[J]. International Journal of Communication Systems, 2019, 32(14):e4084.1-e4084.12.
[6] Zhang X , Wang F . Resource Allocation for Wireless Power Transmission Over Full-Duplex OFDMA/NOMA Mobile Wireless Networks[J]. IEEE Journal on Selected Areas in Communications, 2019, 37(2):327-344.
