Performance Evaluation of Scheduling Scheme in O-RAN 5G Network using NS-3

The integration of Open Radio Access Network (O-RAN) principles into 5G networks introduces a paradigm shift in how radio resources are managed and optimized. O-RAN's open architecture enables the deployment of intelligent applications (xApps) that can dynamically adapt to varying network conditions and user demands. In this paper, we present radio resource scheduling schemes -- a possible O-RAN-compliant xApp can be designed. This xApp facilitates the implementation of customized scheduling strategies, tailored to meet the diverse Quality-of-Service (QoS) requirements of emerging 5G use cases, such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). We have tested the implemented scheduling schemes within an ns-3 simulation environment, integrated with the O-RAN framework. The evaluation includes the implementation of the Max-Throughput (MT) scheduling policy -- which prioritizes resource allocation based on optimal channel conditions, the Proportional-Fair (PF) scheduling policy -- which balances fairness with throughput, and compared with the default Round Robin (RR) scheduler. In addition, the implemented scheduling schemes support dynamic Time Division Duplex (TDD), allowing flexible configuration of Downlink (DL) and Uplink (UL) switching for bidirectional transmissions, ensuring efficient resource utilization across various scenarios. The results demonstrate resource allocation's effectiveness under MT and PF scheduling policies. To assess the efficiency of this resource allocation, we analyzed the Modulation Coding Scheme (MCS), the number of symbols, and Transmission Time Intervals (TTIs) allocated per user, and compared them with the throughput achieved. The analysis revealed a consistent relationship between these factors and the observed throughput.