## 1 Introduction
In particular, prevalent message exchanges during handover execution can increase handover delay, leading to handover timeouts. * Unlike terrestrial environments, where the location of a BS is stationary, buoys floating on the water surface can have variable positions over time. The phenomenon of a floating BS exhibiting mobility is referred to as \"BS motion\" and is caused by maritime environmental factors, including winds, waves, and currents [34; 35], as well as the methods employed for maintaining its position, such as mooring or anchoring [36; 37]. The change in the position of a BS over time due to BS motion is referred to as \"BS motion response\". It is expected that the BS motion response can have a substantial impact on the triggering of handovers. The first two factors are often considered to be intrinsic limitations of underwater acoustic communication; it can be intuitively predicted that prevalent communication failures and long propagation delays during handovers can impair the performance of overall handover operations [38]. However, there is a lack of research investigating how the BS motion can affect underwater handovers. Thus, our focus in this paper is directed towards examining the influence of BS motion on underwater handovers. As depicted in Figure 1, the BS motion can also introduce variability in the overlapping regions of cells. This randomness in the overlapping regions can influence the network connectivity status between the current BS-AUV pair and the target BS-AUV pair. From a handover perspective, frequent triggering events can lead to a handover ping-pong effect. This situation consumes limited resources in underwater acoustic communication, thereby causing network inefficiency and prolonged service disruptions. To the best of our knowledge, no research has been conducted to investigate the impact of BS motion on underwater handovers; this paper aims to explore the influence of BS motion responses on handover decisions. To do this, we consider the AUV-BS distance as a handover decision criterion [39; 40]. This is because the variability in the BS's location directly leads to fluctuations in the distance between the AUV and BS. Consequently, this variation affects the strength of the signals received from either the AUV or the BS over time, as signal strength decreases with increasing distance [41]. In addition, fluctuations in signal strength induced by varying AUV-BS distance impact the network connectivity of the AUV to the BS. This unstable network connectivity could ultimately induce errors in deciding whether to execute a handover, potentially resulting in frequent handover triggering. Therefore, the analysis of the handover decision errors caused by the BS motion considering the AUV-BS distance is necessary to develop handover strategies for B-UWANs. This study investigates handover decision errors caused by BS motion, and the assessment is conducted on the basis of the following BS numerical modeling and simulation approaches:  
* BS numerical modeling: Generally, BS motion can be calculated via numerical modeling of the buoy and mooring systems in environmental conditions [42]. Rather than considering environmental conditions at a specific location, BS motion is targeted for broad applications under general conditions. To do this, we assume that the BS motion is induced by wave loads with respect to World Meteorological Organization (WMO) sea state codes, as specified in Section 3[43; 44]. * Simulation methods: We analyze the AUV-BS distance by varying the direction of BS motion. This is because the likelihood of the AUV making an incorrect handover decision can increase or decrease depending on the combination of the movement direction of the AUV and the motion direction of the current and target BSs. Furthermore, we check how the WMO sea state code implying the magnitude of BS motion and the BS network radius associated with the overlapping region may result in handover decision errors.