# Handover Scheme in LEO Satellite Networks Based on QoE for Streaming Media Services
## 3 Simulation System Design for Handover and Access of Streaming
### Handover Scheme Design Based on Streaming Services
Therefore, Equation (13) can be simplified using the following equivalent infinitesimal formula:  
\[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]0  
where \(a\) and \(b\) are constants. According to the equivalent infinitesimal property, when \(x\) approaches 0 in Equation (15), we have \((1+ax)^{b}-1=abx\), i.e., \((1+ax)^{b}=1+abx\). Letting \(ax=G_{tot}\cdot P_{0}/(L_{t}(t_{acc}+(k-1)\Delta t)\cdot N)\) and \(b=d\), we obtain  
\[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]1Substituting Equation (16) into the right-hand side of Equation (14), we find that when \(P_{Rv1}\) satisfies \(d\cdot P_{0}=P_{Rv1}\), Equation (14) holds. Thus, we establish an indirect method to estimate \(P_{Rv1}\) as follows:  
\[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]2  
The indirect calculation method in Equation (17) for estimating the minimum power \(P_{Rv1}\) satisfying the first condition is an approximation. Although it provides \(P_{Rv1}\) values close to the true minimum power that strictly satisfies \(\overline{C_{Rv1}}=R_{v}\), a small discrepancy remains. In the implementation of the algorithm, the algorithm can be iterated several times to bring the calculated user access power, \(P_{i,j}\), closer to the required minimum power. Specifically, after estimating \(P_{Rv1}\) using the preset reference power \(P_{0}\) through the aforementioned scheme, this estimated value is set as the updated reference power \(P_{0}\) to recalculate the new reference average channel capacity \(\overline{C_{0}}\). The updated \(P_{Rv1}\) is then re-estimated using Equation (17). So far, we have used the above method to find the power threshold \(P_{Rv1}\) to satisfy the first condition. In other words, the power of the user \(u_{i}\), in conjunction with the satellites \(S_{i,j}\), cannot be less than \(P_{Rv1}\). The algorithm flow chart of \(P_{Rv1}\) is shown in \[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]3  
\[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]4 Structure of the algorithm for minimum power \(P_{Rv1}\) satisfying the first condition. In order to satisfy the second condition, we need to analyze the changes in the streaming buffer on the user's terminal. As shown in Figure 5, the channel capacity is the input rate of the streaming data in the buffer, and the playback bitrate of the stream is the output rate of the streaming data in the buffer. We assume that the user accesses the satellite at the time \(t_{acc}\) and the channel capacity of the user is equal to the streaming bitrate \(R_{v}\) at the time \(t_{R}\). Because the channel capacity increases as the satellite elevation angle increases, the channel capacity may be less than the streaming bitrate when the user terminal first accesses. So that, from \(t_{acc}\) to \(t_{R}\), the amount of data in the user's buffer will decrease. When the satellite is operating at the time \(t_{R}\), the reduction of data in the buffer will reach the maximum value, which is the integral value of the yellow area in \[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]5 The remaining data in the user's buffer \(H_{rem}\) must therefore exceed the maximum buffer data reduction to satisfy the second condition. It is expressed in the following mathematical formula:  
\[C(t,P_{i,j})=B\text{log}_{2}(1+\frac{G_{tot}}{N}\cdot\frac{P_{i,j}}{L_{t}(t)}), \tag{6}\]6  
A similar approach in the previous condition can be used to find the target power. In simple terms, first the power \(P_{0}\) is preset, then the value of \(t_{R0}\) is calculated, and then the preset power \(P_{0}\) is brought into Equation (6) to compute equation \(C_{0}(t)\) as a function of time t for the reference channel capacity.