Performance Analysis of ARQ Scheme in IEEE 802.16

IEEE 802.16, also known as WiMax (Worldwide Interoperability for Microwave Access), introduces the Automatic Repeat reQuest with Selective Acknowledgement (ARQ-SA) scheme to improve the reliability of the wireless link. For ARQ-SA, packets or Protocol Data Units (PDUs), several of which compose one Service Data Unit (SDU) from the upper layer, are transmitted orderly, but only those negatively acknowledged packets are retransmitted. We analyze the delay performance of SDU under ARQ-SA in a multiuser network environment. Our analysis shows that the SDU delay is mainly determined by the first transmission of all its PDUs. Further more, we propose a simple scheme to reduce the delivery delay of SDU. Simulation results are given to demonstrate the accuracy of the analytical one.