# Handover Decision-Making Algorithm for 5G Heterogeneous Networks
## 5 Results and Discussion
Assuming the MT moves from left to right in the scenario, as shown in Figure 5, the \(i\)th network dwelling time, \(t_{i}\), can be calculated using Equation (19). \[t_{i}=\frac{l_{i}}{v} \tag{19}\]  
where \(l_{i}\) is the trajectory distance in the \(i\)th network. The \(i\)th network connection cost, \(C_{i}\), can be determined by  
\[C_{i}=t_{i}\times C_{iM}\times U+C_{handover} \tag{20}\]  
where \(C_{iM}\) is the \(i\)th network cost per Mb, \(U\) is the service data rate requirement in Mb and \(C_{handover}\) is the handover cost. The total connection cost (\(C_{total}\)) is the sum of all types of network connection costs. It is given as  
\[C_{total}=C_{LTE}+C_{WLAN}+C_{5G} \tag{21}\]  
Figure 10: Handover performed based on QoS preference at the speed of 40 km/h: (**a**) TOPSIS-based handover algorithm (circle shows unnecessary handover) and (**b**) proposed handover algorithm. The throughput in Mb (_Tput_) can be computed based on network dwelling time, \(t_{i}\), the \(i\)th network data rate in Mbps, \(N_{i}\), and loss of the network data rate for each unnecessary handover, \(T_{iloss}\), as expressed in Equation (22). \(T_{iloss}\) is expressed in Equation (23), where \(t_{immecessary\;ho}\) is unnecessary handover time. The total throughput (\(Tput_{total}\)) is the sum of the throughput for all types of access points, as expressed in Equation (24). \[Tput_{i}=t_{i}\;\times\;N_{i}\;-T_{iloss} \tag{22}\]  
Figure 7:0  
Figure 7:1  
The network connection period is inversely proportional to MT speed. The higher the MT speed, the shorter the network connection period. Therefore, the total connection cost and throughput reduce while the MT moves at higher speeds. Figure 12a,b show the total connection cost and throughput obtained by the MT when it opted for cost preference, respectively. Figure 7:2 Handover performed based on QoS preference at the speed of 70 km/h: (**a**) TOPSIS-based handover algorithm (circle shows unnecessary handover), (**b**) proposed handover algorithm. Referring to Table 5, the algorithms give the highest priority to WLAN, which has the lowest network connection cost, and then continue to LTE and 5G. Figure 11(a) shows that the proposed algorithm reduces the total connection cost up to 27.51% compared with the TOPSIS-based handover algorithm. In terms of throughput, the proposed algorithm is 3.06% higher than the TOPSIS-based handover algorithm, as shown in Figure 11(b). At the lower speed (40 to 60 km/h), there is a small throughput difference between the two algorithms, as fewer unnecessary handovers occur at low speeds. More unnecessary handovers induced at higher speeds (70 to 100 km/h) caused the throughput to decrease significantly for the TOPSIS-based handover algorithm. The unnecessary handovers are a waste of network resources. Figure 13 shows the total connection cost and throughput achieved by the proposed handover algorithm and TOPSIS-based handover algorithm based on the QoS preference. In this case, the MT is biased toward the 5G network, which offers high service quality. The TOPSIS-based handover algorithm connects to the 5G network wherever it is available. Figure 12(a) shows that the total connection cost of the proposed algorithm is 40.81% lower than that of the TOPSIS-based handover algorithm. In terms of throughput, the proposed algorithm is 5.12% better than the TOPSIS-based handover algorithm. For example, the  
Figure 7:3 Performance of cost preference in terms of (**a**) total connection cost and (**b**) throughput. unnecessary handover to network 5G#3 (as shown in Figures 10a and 11a) performed by the TOPSIS-based handover algorithm is a waste of cost and network resources. The total connection cost and throughput of the QoS-preference-based handover are much higher than the cost-preference-based handover because the 5G network cost is more expensive and offers better service quality. If no wireless network meets the user requirements, the proposed algorithm connects to the best network among the available networks based on user preference.