# Handover Decision-Making Algorithm for 5G Heterogeneous Networks
## 5 Results and Discussion  
The performance of the proposed handover algorithm is here benchmarked against the TOPSIS-based handover algorithm [11]. The main difference between the two algorithms is that the TOPSIS-based handover algorithm has no dwell time prediction technique. It always selects the network with the highest score. As shown in Table 5, the cost preference \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameter** & **Cost** & **Data Rate** & **Delay** & **BER** & **SINR** & **PLR** \\ \hline Cost preference & 0.95 & 0.01 & 0.01 & 0.01 & 0.01 \\ QoS preference & 0.1 & 0.3 & 0.15 & 0.15 & 0.15 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: TOPSIS weightage allocation for cost and QoS preferences. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Network** & **LTE** & **WLAN** & **5G** \\ \hline Cost preference & 0.975 & 0.977 & 0.951 \\ QoS preference & 0.358 & 0.376 & 0.991 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: TOPSIS scoring for each network under different user preferences. Figure 7: Distance threshold (\(l_{th}\)) for different speeds. prioritizes the low network connection cost of WLAN, followed by LTE and 5G networks. In this case, the TOPSIS-based handover algorithm will select WLAN whenever it is available. Figures 8 and 9 show the handover performed by the TOPSIS-based handover algorithm and the proposed handover algorithm at the speed of 40 km/h and 70 km/h, respectively. The TOPSIS-based handover algorithm induces a number of unnecessary handovers as it is biased toward WLAN even though the connection time to WLAN is very limited and does not contribute any benefit to the MT. In contrast, the proposed method has no unnecessary handovers because the dwelling time prediction technique implemented in the proposed handover algorithm rejects the network with an estimated dwelling time of fewer than two seconds. The handover to WLAN#1 is considered an unnecessary handover (circled in red in Figure 8a) at the speed of 40 km/h and above. Referring to Figure 7, WLAN#1 has a trajectory of 10 m, and the dwelling time at the speed of 40 km/h was 0.9 s which is less than the predefined threshold of two seconds. With the dwelling time prediction technique, the proposed handover algorithm avoids unnecessary handover to WLAN#1, as shown in Figure 8b. It rejects all the networks with an estimated dwelling time less than two seconds. At 70 km/h and above, the dwelling time for WLAN#1 and WLAN#2 drops below two seconds. Figure 9b shows that the proposed handover algorithm rejected these networks. Figure 8: Handover performed based on cost preference at the speed of 40 km/h: (**a**) TOPSIS-based handover (circle shows unnecessary handover) and (**b**) proposed handover algorithm. However, the TOPSIS-based handover algorithm performed unnecessary handover to these networks (Figure 9a). The handover performed by the TOPSIS-based handover algorithm and proposed handover algorithm for the QoS preference at 40 km/h and 70 km/h is shown in Figures 10 and 11, respectively. In this case, the 5G network is highly preferred. As shown in Table 5, the 5G network scores the highest points under QoS preference. At the speed of 40 km/h, an MT should avoid connection to 5G#3 because the trajectory in 5G#3 coverage is short and is 18 m, as indicated in Table 3. The travelling time, \(t\), equals 1.62 s, which is less than two seconds. However, the TOPSIS-based handover algorithm performed handover to 5G#3. The unnecessary handovers are marked with a red circle, as shown in Figure 10a. A similar result for the speed of 70 km/h, the TOPSIS-based handover algorithm is connected to the 5G network whenever it is detected where the unnecessary handover occurs at 5G#3. Figure 9: Handover performed based on cost preference at the speed of 70 km/h (**a**) TOPSIS-based handover (circles show unnecessary handover) and (**b**) proposed handover algorithm. The performance of the proposed method is also compared with the TOPSIS-based handover algorithm in terms of total connection cost and throughput.