Dynamic Bandwidth Borrowing and Adjustment for VBR Traffic in WiMAX Network

by Chen, Chun-Chu

Abstract (Summary)
In a WiMAX network, four traffic types with different priorities are defined. They are Unsolicited Grant Service (UGS), real-time Polling Service (rtPS), non-real-time Polling Service (nrtPS), and Best Effort (BE). In this thesis, we propose a Dynamic Bandwidth Allocation (DBA) scheme for BS to schedule the four above-mentioned traffic types. By adopting Deficit Round Robin (DRR) scheduling, DBA first assigns minimum quantum to each traffic type for transmission. When rtPS packets exceed their delay constraints, without sacrificing the minimum requirements of nrtPS and BE traffic, DBA borrows some quantum from nrtPS and BE to satisfy the delay requirements of rtPS traffic. When nrtPS packets can not reach the minimum transmission rate, without starving the BE traffic, DBA borrows some quantum from BE to support the required throughput of nrtPS traffic. According to the history record of borrowed quantum, DBA dynamically adjusts the assigned quantum for the three traffic types. For the purpose of evaluation, we use NS-2 to simulate the proposed DBA. We adjust the traffic load to analyze the performance in terms of average packet delay, average throughput, and average packet loss ratio. The simulation results show that the DBA, in comparison to a previous work, can promise the delay constraints of rtPS, maintain the average throughput of nrtPS, and avoid the starvation of BE, when the traffic load is high.
Bibliographical Information:

Advisor:Rung-Hung Gau; Tsung-Chuan Huang; Sheau-Ru Tong; Tsang-Ling Sheu; Wen-Shyang Hwang

School:National Sun Yat-Sen University

School Location:China - Taiwan

Source Type:Master's Thesis

Keywords:packet delay vbr quality of service dynamic bandwidth allocation wimax throughput


Date of Publication:09/04/2008

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