## 1 Introduction  
In the context of burgeoning applications such as the Internet of Things (IoT), cloud computing, and data centers, mobile communication networks are experiencing exponential growth in data volume and capacity demands. Consequently, the forthcoming sixth-generation mobile network (6G) is envisioned to not only enhance overall communication capacity, speed, and coverage, but also tackle the scarcity of spectrum resources encountered via conventional radio frequency communication (RF) techniques. Visible light communication (VLC) offers several notable advantages, including immunity to electromagnetic interference, non-interference with authorized spectrum resources, high confidentiality, low networking costs, and minimal resource consumption. As a result, VLC can serve as a crucial supplementary approach in current communication systems [1]. The convergence of VLC with RF and other conventional wireless communication methods presents a promising opportunity to expand coverage, increase communication rates, and enhance network service capacity. This integration effectively addresses the challenge of limited spectrum resources, effectively catering to the communication requirements of specific indoor scenarios, as outlined in Table 1, while establishing a foundation for the development of environmentally friendly and sustainable networks [2]. In VLC-RF heterogeneous networks, two primary challenges impacting communication quality necessitate attention: the vulnerability of VLC line-of-sight links to blockage, and the CCI encountered by mobile terminals (MTs). In the event of a blocked or interrupted VLC link, MTs must perform a vertical handover (VHO) to an alternative communication method to maintain both communication quality and user quality of user experience (QoE). Effective VHO scheme design plays a crucial role in preserving high link quality and user QoE in indoor VLC heterogeneous networks. In 2022, [PERSON] et al. introduced a pioneering application-aware VHO scheme for indoor VLC-WiFi heterogeneous networks, specifically tailored to multi-user access scenarios. Their approach involved establishing a lower threshold to assess the duration of MT residency for VHO when confronted with an active real-time application (RTA) [3]. The hybrid application-aware VHO scheme (HA-VHO) they designed combines a dynamic time-dwelling scheme [4] and two fundamental VHO schemes: immediate VHO (I-VHO) and static time-dwelling VHO (D-VHO) [5]. In [3], video-based RTAs are taken into account as the main target for active RTAs. HA-VHO determines the dwell time for handover by considering the main factors of VLC link blockage and performance degradation, as well as the activity of the video-based RTA. Active RTAs in MT are an important factor affecting QoE. HA-VHO uses the activity of video RTAs as a benchmark for determining the activity of RTAs and sets the VHO dwelling time on this basis. However, we believe that using only a video-based RTA as a benchmark does not meet the actual needs of user terminals. Therefore, our study not only considers the main factors that cause blockage and performance degradation in VLC links, as in [3], but also focuses on the three main types of MT alternate activity RTA: video, VoIP, and web. We assume that the time-dwelling VHO algorithm combines various factors to determine an optimal timing for handover. In the case of multiple RTAs, different users have different levels of tolerance for RTAs delays. So, it is necessary to incorporate different psychological tolerance times into the design. We combine these VLC LoS link influencing factors with different RTA types to calculate the best tradeoff for dwell time during handover. Our simulation results show that our proposed Ac-VHO scheme significantly reduces the signaling cost of frequent handover in an indoor VLC heterogeneous network environment compared with the traditional time-dwelling VHO scheme and time-dwelling VHO without RTA classification.