隨著科技進步，電子設備的需求也日益增加，傳統的無線射頻頻段開始不敷使用，所以科學家開始尋找其他可使用的頻段，最終找到了可見光，可見光的頻段大小約是無線射頻的 1300 倍，而且這些頻段是可以免費做使用的，相較於無線射頻通訊(RF)，可見光通訊(VLC)有一些優勢，同時也有一些限制。受益於可見光無法穿越不透明物體的物理特性，可見光有極高的安全性，同時也限制於可見光的物理特性，當傳輸端與接收端之間有障礙物出現，則會對訊號造成大幅度的干擾，可見光通訊的傳輸速率較快，但是其覆蓋範圍較小，大約只有數公尺，而無線射頻通訊的覆蓋範圍則能達到數十公尺，最後因為可見光通訊能從基礎照明設備上進行擴展，使成本大幅降低，成為日後室內通訊具有發展潛力的一門技術。
在可見光通訊的相關研究中，功率分配是不可忽視的重點，需要在有限的能源下進行多方面的考量，而目前相關研究中大多只基於用戶的通道狀況進行分配，欠缺考慮了用戶各自的需求，時常造成功率分配的不公平性發生，使用戶中斷機率提升，而少數考慮到用戶需求的研究則未考慮到剩餘資源的利用，造成不必要的浪費。本篇論文採用在可見光通訊系統中使用非正交多重存取的傳輸技術，旨在滿足用戶需求的前提下，最大化功率分配的公平性，使所有用戶都能公平的提升自身的傳輸速率，並盡可能的分配能源給所有用戶，對於剩餘能源分配及中斷機率的降低也在我們的考量之下。

With the advancement of technology, the demand for electronic devices has been increasing, rendering the traditional radio frequency (RF) spectrum crunch. Consequently, scientists have begun to explore alternative spectrums and have ultimately identified visible light. The visible light spectrum is approximately 1300 times larger than the RF spectrum and is available for use without cost. Compared to RF communication, visible light communication (VLC) offers several advantages as well as some limitations. Due to the physical property that visible light cannot penetrate opaque objects; VLC provides very high security. However, this characteristic also means that any obstacles between the transmitter and receiver can cause significant signal interference. While VLC offers higher transmission rates, its coverage is relatively limited, typically extending only a few meters, whereas RF communication can cover tens of meters. Additionally, VLC can be expanded from basic lighting equipment, significantly reducing costs and positioning it as a promising technology for future indoor communication.
Among VLC-related research topics, power allocation is a critical one that demonstrates the significance of utilizing limited resources intelligently. Most current studies allocate power primarily based on users' channel conditions, instead of individual user requirements and hence it might cause unfairness and unnecessary outage. Furthermore, some studies considering users’ requirement fail to exploit remaining resources effectively, resulting in unnecessary waste. In this thesis, we employ non-orthogonal multiple access (NOMA) in VLC systems to maximize the user fairness of power allocation while meeting user requirements. The objective is to ensure that all users can fairly enhance their transmission rates and to allocate power as efficiently as possible. Additionally, we address the residual power allocation and the reduction of outage probability.

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