In this paper, we investigate the dynamic power allocation for a visible light communication (VLC) cellular system consisting of two coordinating attocells, each equipped with one access-point (AP). The coordinated multipoint (CoMP) between the two cells is introduced to assist users experiencing high inter-cell-interference (ICI). Specifically, the coordinated zero-forcing (ZF) precoding is used to cancel the ICI at the users located near the centers of the cells, whereas the joint transmission (JT) is employed to eliminate the ICI at the users located at the edge of both cells and to improve their receptions as well. Furthermore, two multiple access techniques are invoked within each cell, namely, non-orthogonal-multiple-access (NOMA) and cooperative non-orthogonal-multiple-access (C-NOMA). Hence, two multiple access techniques are proposed for the considered multi-user multi-cell system, namely, the CoMP-assisted NOMA scheme and the CoMP-assisted C-NOMA scheme. For each scheme, two power allocation frameworks are formulated each as an optimization problem, where the objective of the former is maximizing the network sum data rate while guaranteeing a certain quality-of-service (QoS) for each user, whereas the goal of the latter is to maximize the minimum data rate among all coexisting users. The formulated optimization problems are not convex, and hence, difficult to be solved directly unless using heuristic methods, which comes at the expense of high computational complexity. To overcome this issue, optimal and low complexity power allocation schemes are derived. In the simulation results, the performance of the proposed CoMP-assisted NOMA and CoMP-assisted C-NOMA schemes are compared with those of the CoMP-assisted orthogonal-multiple-access (OMA) scheme, the C-NOMA scheme and the NOMA scheme, where the superiority of the proposed schemes are demonstrated. Finally, the performance of the proposed schemes and the considered baselines is evaluated while varying various system parameters.

中文翻译：

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室内 VLC 蜂窝系统中的 CoMP 辅助 NOMA 和协作 NOMA


在本文中，我们研究了可见光通信 (VLC) 蜂窝系统的动态功率分配，该系统由两个协调 attocell 组成，每个 attocell 配备一个接入点 (AP)。两个小区之间引入协作多点（CoMP）是为了帮助用户体验高小区间干扰（ICI）。具体来说，协调迫零（ZF）预编码用于消除位于小区中心附近的用户的ICI，而联合传输（JT）用于消除位于小区边缘的用户的ICI。细胞并改善其接收情况。此外，每个小区内调用两种多址技术，即非正交多址(NOMA)和协作非正交多址(C-NOMA)。因此，针对所考虑的多用户多小区系统提出了两种多址技术，即CoMP辅助的NOMA方案和CoMP辅助的C-NOMA方案。对于每个方案，两个功率分配框架被制定为一个优化问题，其中前者的目标是最大化网络总数据速率，同时保证每个用户一定的服务质量（QoS），而后者的目标是最大化网络数据速率。后者是最大化所有共存用户之间的最小数据速率。公式化的优化问题不是凸的，因此很难直接解决，除非使用启发式方法，而这是以高计算复杂度为代价的。为了克服这个问题，导出了最优且低复杂度的功率分配方案。 在仿真结果中，将所提出的CoMP辅助NOMA和CoMP辅助C-NOMA方案的性能与CoMP辅助正交多址(OMA)方案、C-NOMA方案和NOMA方案的性能进行了比较，其中证明了所提出方案的优越性。最后，在改变各种系统参数的同时评估所提出的方案和所考虑的基线的性能。