IEEE 802.16無線寬頻網路下行通道封包排程機制之設計
Design of a Packet Scheduling Scheme for Downlink Channel in IEEE 802.16 BWA Systems
Date Issued
2007
Date
2007
Author(s)
Tsai, Tsung-Yu
DOI
en-US
Abstract
IEEE 802.16 wireless MAN is expected to be a revolutionary wireless broadband access technology. Five service types supporting different Quality of Service are defined in the latest release of the standard (IEEE 802.16-2005) to satisfy a variety of applications supported in nowadays or in the future. However, the standard does not specify the packet-level scheduling in IEEE 802.16, which is one of the crucial technologies to provide the guarantee of QoS of the system level.
In this study, a packet scheduling scheme in the downlink channel for IEEE 802.16 is proposed. The scheme can be implemented in the base station and compatible to the MAC protocol of IEEE 802.16. Consider the properties of location-dependent and burst error of wireless channel, we design a novel packet scheduling algorithm named the Credit-Based Algorithm to guarantee QoS for both real-time and non-real-time services. The guarantee includes the packet loss rate due to delay violation for real-time services and the average effective throughput for non-real-time services. The Credit-Based Algorithm introduces the concept of credits to represent protected capacity of a flow in the system. We then employ a debt allocation procedure to re-allocate the overspent credits consumed by flows suffering temporary burst error to other flows. Simulation experiments are conducted to evaluate the performance of our proposed scheme. Based on the simulation results, our packet scheduling scheme is shown to improve the efficiency of the usage of system capacity significantly, and guarantee the packet delay for real-time services while allocating the remained capacity to non-real-time services more fairly and efficiently. Thus, the goal for satisfying different QoS requirements for real-time and non-real-time services simultaneously is achieved.
Subjects
封包排程
無線寬頻網路
下行通道
packet scheduling
802.16
WiMAX
downlink
QoS
Type
thesis
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