# Handover Scheme in LEO Satellite Networks Based on QoE for Streaming Media Services
## 3 Simulation System Design for Handover and Access of Streaming
### Power Occupation Handover Scheme Design Based on Streaming Services  
When satellite handover fails multiple times and persistent streaming service consumption causes the buffer data to fall below the power occupation threshold \(H_{oc}\), the system enters the power occupation handover module. This module allocates a portion of another user's power to the current user in this module to meet the minimum power requirement of this user. On one hand, when the satellite moves from a low-elevation position to a high-elevation position, channel loss decreases substantially, leading to significantly increased channel capacity that far exceeds current streaming bitrate requirements. On the other hand, users with abundant buffer data can avoid rebuffering by ceding partial power to other users whose buffers are nearly depleted. For instance, when user \(u_{1}\) exhausts its buffer due to repeated handover failures and enters rebuffering, the system allocates a portion of power from another user \(u_{2}\)'s link to \(u_{1}\), preventing playback interruption. After obtaining sufficient power, \(u_{1}\) can continue replenishing its buffer data, while \(u_{2}\) may experience buffer depletion due to the power cession. In essence, this allows user \(u_{2}\) to bear the negative impact of high satellite network load on behalf of \(u_{1}\). However, as revealed by the MOS scoring mechanism in Section 3, the user QoE remains unaffected as long as playback continues without rebuffering, even if the current channel capacity fails to meet service demands. Therefore, the QoE of \(u_{2}\) will not degrade in the short term as long as its buffer is not exhausted.  
When the user \(U_{oc}\) repeatedly fails to handover and enters the power occupation module, the user \(U_{oc}\) first uses all satellites \(S_{oc}=\{S_{oc,1},S_{oc,2},...,S_{oc,j},...\}\) in the rising stage as candidates. Each candidate satellite \(S_{oc,j}\) is used by other users \(\{u_{1,j},u_{2,j},...,u_{i,j},...\}\) occupying the power resources \(\{P_{1,j},P_{2,j},...,P_{i,j},...\}\). Eliminate the users in \(\{u_{1,j},u_{2,j},...,u_{i,j},...\}\)with channel capacity below the streaming bitrate. The minimum power required for user \(U_{oc}\) to access each candidate satellite \(S_{oc,j}\) is calculated, and this minimum power \(\{P_{oc,1},P_{oc,2},...,P_{oc,j},...\}\) calculation scheme is referred to the handover scheme in Section 3.1. In our scheme, only one satellite cedes power resources. Calculate the proportion \(\gamma_{voc}\) of power being used by each user served by each candidate satellite that needs to be ceded by each of them. The user link with the smallest proportion of power is selected to yield power to the user \(U_{oc}\) who is currently in the power occupation handover state.  
\[\gamma_{voc}^{i,j}=\frac{P_{oc,j}-P_{rem,j}}{P_{i,j}} \tag{30}\]  
\[P_{rem,j}=P_{tot}-\sum_{i=1}^{N_{j}}\left(P_{i,j}\right) \tag{31}\]  
where \(\gamma_{voc}^{i,j}\in\gamma_{occ}=\{\gamma_{occ}^{1,1},\gamma_{occ}^{2,1},.., \gamma_{occ}^{1,2},...\}\) denotes the ratio of power ceded by user \(u_{i,j}\) (served by satellite \(S_{oc,j}\)) to \(U_{oc}\), which is defined as the ceded power divided by the user's own consumed power \(P_{i,j}\). The user link with the smallest \(\gamma_{occ}\) is selected for power transfer. \(P_{oc,j}\) denotes the power required for \(U_{oc}\) to access \(S_{oc,j}\), while \(P_{rem,j}\) (Equation (31)) is the residual power of \(S_{oc,j}\), which is calculated by subtracting the total occupied power from the satellite's total power \(P_{tot}\). Users whose channel capacity falls below service requirements after power cession are excluded. Finally, the user \(u_{i,j}\) with the smallest \(\gamma_{occ}\) cedes power to \(U_{oc}\), which connects to the selected satellite \(S_{oc,j}\). The power occupation handover algorithm flowchart is shown in Figure 7.  
Figure 7: Structure of the algorithm for power occupation handover.