Real-Time Inspired Hybrid Scheduler for 5G New Radio

Abstract: As an increasing position of the world’s communication moves towards the cloud and wireless solutions the requirement for good throughput and low delay increases. One step towards meeting higher requirements is the move from 4G Long Term Evolution (LTE) to 5G New Radio (NR). In order to utilize the potential of 5G NR, software needs to be improved. With the goal to lower the delay for delay critical applications and services when using 5G NR this thesis studies a new scheduler inspired by Earliest Deadline First (EDF) as a soft real-time system scheduler. This new scheduler called Real-Time Inspired Hybrid Scheduler (RTIHS) is proposed where two different schedulers are used depending on if the network traffic is delay critical or not. Delay critical traffic is served by the new Deadline Inspired Scheduler (DIS) scheduler and other traffic by a traditional Round Robin (RR) scheduler. The transmissions that are delay critical are prioritized differently with the use of a constant that has two functions. To determine if the transmission is in time or not, and how close the transmission is to the fixed deadline. Up until the deadline the priority of that transmission is increased with a factor that is affected by how close the current time is to the deadline. If the deadline has been missed the priority is, however, decreased with respect to how much it missed the deadline.RTIHS is implemented and tested in a state-of-the-art system simulator where services such as;Cloud Gaming (CG), Video on Demand (VoD), and web browsing are evaluated. An already existing technology named Low Latency Low Loss Scalable Throughput (L4S) is included in the evaluations to investigate how RTIHS scales. The performance of RTIHS is then compared to a Delay Scheduler(DS) and a RR scheduler that act as the baseline. The results show that RTIHS performs better for CG in terms of delay and nominal rate than the baseline, especially when the network is under high load. Using RTIHS compared to a DS shows an average increase of nominal rate by roughly 6 % and an average decrease of delay by 16 % for the average users. At the same time RTIHS does show higher delay and lower throughput for services such as VoD and web browsing, making its performance for those service worse than the baseline, especially when the network load is high. With the same comparison as before, RTIHS shows an average 17 % higher delay for web browsing and 1 % lower requested video rate than the DS for the average users. This is due to how the evaluated services are prioritized with the limited resources available. Since RTIHS prioritizes CG more, less resources remain for the other services. The baseline is not as biased towards CG and therefore has a lower nominal rate and higher delay for said service but better for the other services in comparison. Activating L4S mitigates the underwhelming performance of RTIHS for VoD and web browsing further improves the performance for CG. This is also true for the baseline which increases performance for CG and further increases the performance for other services with a small amount. With L4S activated the average increase of nominal rate in CG for RTIHS compared to the DS is 13 % for the average users and the average delay decrease is 9 %. Meanwhile the average requested video rate for RTIHS is less than 1 % lower than that of the DS for the average users and the delay for web browsing is 10 % higher than the DS for the average users.