# QoS-Aware Downlink Traffic Scheduling for Cellular Networks with Dual Connectivity
## 5 Proposed QoS eNB Scheduling (QED) Method
We also see that when the moving speeds of UEs become faster, the GBR traffic throughput decreases accordingly. This is because when UEs move farther away from the SeNB, their downlink data (stored in the SeNB) may not be disseminated to the corresponding UEs in time. Since both QDD and QED consider traffic delay constraints, the throughput of GBR traffic can still be higher than the others. Similar to the above discussions, DTS+DFS can perform better than our scheme on CBR throughput (as shown in Figure 5(c)), but according to Figure 5(d), the proposed scheme can still outperform other schemes on system throughput. Figure 4: Simulation results on (**a**) voice, (**b**) video, (**c**) CBR, and (**d**) system throughput when varying number of UEs. Finally, we simulate the scenario that the network has \(l\) SeNBs, where \(l=1\ldots 4\), and in the network, there are \(l\times 55\) UEs. Figure 7 shows the simulation results. When there are more SeNBs in this network, the throughput values will increase accord

Figure 5: Simulation results on (**a**) video and (**b**) CBR (**c**) system packet drop ratios when varying number of UEs. Figure 6: Simulation results on (**a**) voice, (**b**) video, (**c**) CBR, and (**d**) system throughput when varying velocities of UEs. ingly due to the increased number of UEs. From the results, we can see that the proposed scheme can still outperform the others when traffics are GBR type. Similar to the above simulations results, the DTS+DFS can be slightly better than our scheme in CBR throughput. However, the proposed scheme can perform better than the others on system throughput. Furthermore, recall that the formulation of QDD considers the capability of SeNBs. These simulation results demonstrate that the proposed formulation can be adopted for the network with multiple SeNBs. ## 7 Conclusions

In this paper, we propose QDD and QED schemes to make dispatching decisions and to schedule radio resources, respectively. In QDD, the MeNB solves the designed linear programming formulation to obtain the dispatching decision. After dispatching traffics, the MeNB and SeNBs will then adopt the QED method to arrange the transmission of downlink data. The simulation results indicate that, compared to the other four combinations (mentioned in the simulation section), the proposed scheme can increase system throughput from 9% to 32% and decrease the packet drop ratio from 3% to 25%. In addition, the simulation results also verify that the proposed scheme can indeed preserve the QoS requirements of GBR traffics and increase overall system throughput. Since UEs are mobile in the real network, the proposed scheme does not consider how to effectively relay downlink data between the MeNB and SeNBs according to UEs' movements. Thus, in the future, we plan to design a handover prediction scheme to facilitate data dispatching. Conceptualization, M.-S.P. ; methodology, M.-S.P. and H.-W.M. ; software, H.-W.M. ; investigation, H.S. ; writing--review and editing, M.-S.P. All authors have read and agreed to the published version of the manuscript. This work is sponsored by MOST 111-2628-E-027-002 and NTUT-BJUT Joint Research Program NTUT-BJUT-111-05. Figure 7: Simulation results on (**a**) voice, (**b**) video, (**c**) CBR, and (**d**) system throughput when varying the number of SeNBs. ## References

* (1) [PERSON]; [PERSON] AI-enabled framework for fog computing driven e-healthcare applications. _Sensors_**2021**, _21_, 8039. [CrossRef] [PubMed]
* (2) [PERSON]; [PERSON]; [PERSON]; [PERSON] Edge caching and computing in 5G for mobile AR/VR and tactile internet. _IEEE Multimed._**2018**, _26_, 21-30. [CrossRef]
* (3) LTE; E-UTRA and E-UTRAN; Overall Description (36.300). _3 GPP Technical Specification (TS)_; 3 GPP Specifications: Valbonne, France, 2017. * (4) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]. User-assisted bearer split control for dual connectivity in multi-RAT 5G networks. _Wirel. Netw._**2020**, _26_, 3675-3685.