[Paper Review] Performance Evaluation of Different Scheduling Algorithms in WiMAX

Ala'a Z. Al-Howaide, Ahmad Doulat+1 more|arXiv (Cornell University)|Nov 13, 2011

Advanced Wireless Network Optimization5 references21 citations

TL;DR

This paper evaluates six scheduling algorithms—Strict Priority, Round Robin, Weighted Round Robin, Weighted Fair Queuing, Self-Clocked Fair, and Diff-Serv—in WiMAX networks using ns-3 simulations. It finds that Weighted Fair Queuing and Self-Clocked Fair provide the best balance of fairness, throughput, and delay, significantly outperforming simpler algorithms like Strict Priority and Round Robin in multi-class traffic scenarios with diverse QoS requirements.

ABSTRACT

Worldwide Interoperability for Microwave Access (WiMAX) networks were expected to be the main Broadband Wireless Access (BWA) technology that provided several services such as data, voice, and video services including different classes of Quality of Services (QoS), which in turn were defined by IEEE 802.16 standard. Scheduling in WiMAX became one of the most challenging issues, since it was responsible for distributing available resources of the network among all users; this leaded to the demand of constructing and designing high efficient scheduling algorithms in order to improve the network utilization, to increase the network throughput, and to minimize the end-to-end delay. In this study, we presenedt a simulation study to measure the performance of several scheduling algorithms in WiMAX, which were Strict Priority algorithm, Round-Robin (RR), Weighted Round Robin (WRR), Weighted Fair Queuing (WFQ), Self-Clocked Fair (SCF), and Diff-Serv Algorithm.

Motivation & Objective

• To evaluate the performance of multiple scheduling algorithms in WiMAX networks under diverse Quality of Service (QoS) requirements.
• To identify the most efficient scheduling algorithm that optimizes network utilization, throughput, and end-to-end delay.
• To analyze the trade-offs between fairness, delay, and throughput across different scheduling strategies in broadband wireless access.
• To provide a benchmark for selecting optimal scheduling algorithms in IEEE 802.16-based WiMAX deployments.

Proposed method

• The study employs ns-3 network simulator to model a WiMAX network with multiple users and traffic classes.
• Six scheduling algorithms—Strict Priority, Round Robin, Weighted Round Robin, Weighted Fair Queuing, Self-Clocked Fair, and Differentiated Services—are implemented and compared.
• Performance metrics include throughput, end-to-end delay, jitter, and fairness index across various traffic loads and service classes.
• Simulations are conducted under controlled conditions with fixed network topologies and varying traffic sources to ensure reproducibility.
• The simulation results are analyzed using statistical evaluation to compare the performance of each algorithm across all metrics.
• The evaluation focuses on real-time and non-real-time traffic flows to reflect practical QoS requirements in BWA systems.

Experimental results

Research questions

• RQ1 How do different scheduling algorithms impact end-to-end delay in WiMAX networks with mixed traffic types?
• RQ2 Which scheduling algorithm achieves the highest network throughput while maintaining fairness among users?
• RQ3 What is the trade-off between fairness and delay in scheduling algorithms like WFQ and SCF compared to simpler schemes like RR and SP?
• RQ4 How does the Weighted Fair Queuing algorithm perform relative to Self-Clocked Fair in terms of jitter and delay variation?
• RQ5 Which algorithm provides the best overall QoS performance across multiple metrics including throughput, delay, and fairness?

Key findings

• Weighted Fair Queuing (WFQ) achieved the highest fairness index, ensuring equitable bandwidth distribution among users with different traffic classes.
• Self-Clocked Fair (SCF) scheduling demonstrated superior performance in minimizing end-to-end delay and jitter, especially under high load conditions.
• Strict Priority (SP) scheduling led to high throughput for high-priority traffic but caused significant unfairness and starvation for lower-priority flows.
• Round Robin (RR) and Weighted Round Robin (WRR) showed moderate performance, with WRR offering better fairness than RR but still underperforming compared to WFQ and SCF.
• Differentiated Services (Diff-Serv) performed poorly in fairness and delay metrics, especially when handling real-time traffic under congestion.
• The combination of high throughput and low delay was best achieved by WFQ and SCF, making them optimal choices for QoS-sensitive WiMAX deployments.