## 1 Introduction
In the series of studies [12; 10; 13; 14; 15], the fractional transmit power allocation (FTPA) was introduced to dynamically adjust the power allocation and reduce the computational complexity compared to full search power allocation. Furthermore, FTPA adopts a fractional power-counting form based on sorted channel gains, which is different from the power counting in PLS. In research by [PERSON] and [PERSON] et al. [16; 17], when the transmit signal to interference plus noise ratio is not low, the expected NOMA capacity increase following GRPA is greater than the OMA capacity with the same resource allocation conditions, which can be regarded as the guaranteed-QoS data rate. In research by [PERSON] et al. [18], comprehensive numerical results verified the superiority of NOMA-VLC in achieving a satisfactory QoS target rate by random receiver orientation. Vertical angle information can compensate for loss in user rates by incorporating suitable power allocation coefficients, which are inversely proportional to the channel quality of the respective NOMA user. In summary, the trade-off [19] between reduced user fairness and improved system throughput exists in the user priority and data rate. The aforementioned QoS guarantee methods in VLC networks form at least three types. First, PLS preferentially guarantees high priority users a maximization of throughput which is regarded as the representative method and uses disequilibrium allocation and fixed priority. Second, FTPA weakens the unbalance maximization of throughput which is regarded as the representative method and uses equilibrium allocation and fixed priority. Finally, orthogonal frequency division multiple access (OFDMA) exchanges independent resources for interference mitigation and dynamic priority. However, in current GRPA studies, several challenges remain in regard to resource allocation with a QoS guarantee for NOMA-VLC networks. First, the user priority of the current GRPA based on the sorted VLC channel gains is static, although power allocation is not static. Second, the evaluation of high user priority depends on QoS requirements alone [5]. Third, VLC channels with NOMA possess a degree of outage vulnerability which is not usually considered in current or recent studies. Finally, when the signal demodulation adopts SIC, it is difficult to coordinate different interference components with each user requirement. Hence, user priority should be dynamically evaluated by the integrated state of user communications. In this paper, we consider the fuzzy logic (FL) method with NOMA for two reasons. For service provisions in VLC networks, FL can handle problems involving knowledge representation or definition which are difficult to quantify, such as user priority. On the other hand, [PERSON] et al. [20] indicated that the complexity required to provide full consideration for QoS provision is unaffordable. [PERSON] et al. [21] combined a large amount of user state information to determine a suitable load balancing solution with low complexity. In terms of the scheduling in user-specific VLC cells, FL may flexibly handle the complicated user communication information. In regard to the tradeoff between the user data rate and fairness, this paper presents a QoS-guaranteed GRPA based on FL in indoor NOMA-VLC networks. To model the user priority, we introduce three features based on fuzzy logic--the VLC channel, QoS data rate and the NOMA-VLC outage probability--in order to evaluate user priority. Then, the different interference components in each user are comprehensively scheduled by fuzzy logic to ensure balance between the data rate and QoS fairness enhancements. In addition, we consider the outage probability of NOMA-VLC users to induce a realistic numerical simulation by beta distributions. Compared with dynamic OFDMA and static NOMA GRPA methods, such as PLS and FTPA, our design achieves better user fairness and QoS satisfaction than shown in previous studies, while the system throughput of our method is asymptotically optimal under UDN conditions.