Delta-orthogonal multiple access (D-OMA) has been recently investigated as a potential technique to enhance the spectral efficiency in 6G networks. D-OMA enables partial overlapping of the adjacent sub-channels that are assigned to different clusters of users served by non-orthogonal multiple access (NOMA), at the expense of additional interference. In this paper, we analyze the performance of D-OMA in the uplink and develop a multi-objective optimization framework to maximize the uplink energy efficiency in a multi-cell network enabled by D-OMA. Specifically, we optimize the subchannel and transmit power allocations of the users as well as the overlapping percentage of the spectrum between the adjacent sub-channels. The formulated problem is a mixed binary non-linear programming problem; therefore, we first transform the problem into a single-objective problem using Tchebyshev method. Then, we apply the monotonic optimization (MO) to explore the hidden monotonicity of the objective function and constraints, and reformulate the problem into a standard MO in canonical form. The re-formulated problem is then solved by applying the outer polyblock approximation method. Our numerical results show that D-OMA outperforms the conventional non-orthogonal multiple access (NOMA) and orthogonal frequency division multiple access (OFDMA) when the adjacent sub-channel overlap and scheduling is optimized jointly.

中文翻译：

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上行Delta-OMA网络中的能源效率最大化

三角正交多址（D-OMA）最近已被研究为增强6G网络频谱效率的一种潜在技术。D-OMA使相邻子信道的部分重叠成为可能，这些子信道被分配给由非正交多址（NOMA）服务的不同用户集群。在本文中，我们分析了D-OMA在上行链路中的性能，并开发了一个多目标优化框架，以在D-OMA支持的多小区网络中最大化上行链路能量效率。具体来说，我们优化子信道和用户的发射功率分配，以及相邻子信道之间频谱的重叠百分比。拟定的问题是混合二进制非线性规划问题。所以，我们首先使用Tchebyshev方法将问题转换为单目标问题。然后，我们应用单调优化（MO）来探索目标函数和约束的隐藏单调性，并将问题重新规范化为标准形式的标准MO。然后通过应用外部多块近似方法解决重新制定的问题。我们的数值结果表明，当相邻子信道重叠和调度共同优化时，D-OMA优于传统的非正交多址（NOMA）和正交频分多址（OFDMA）。然后通过应用外部多块近似方法解决重新制定的问题。我们的数值结果表明，当相邻子信道重叠和调度共同优化时，D-OMA优于传统的非正交多址（NOMA）和正交频分多址（OFDMA）。然后通过应用外部多块近似方法解决重新制定的问题。我们的数值结果表明，当相邻子信道重叠和调度共同优化时，D-OMA优于传统的非正交多址（NOMA）和正交频分多址（OFDMA）。