802.16 M System The Arq Mechanism In The Mac Layer

IEEE802.16m standard occured in the background of mobile broadbandaccess.The standard includes physical layer and medium access control layer. As animportant component in802.16m standards, MAC layer contains three sub-layers torealize reliable data transmission on unreliable physical link.As a QoS-related function in the MAC layer, ARQ (Auto Repeat Request) is one ofthe important technologies to garantee communication quality.This thesis studies on the ARQ in the MAC of802.16m, having main work andachievements as:1) Three types of basic ARQ are introduced. The throughput efficiency of the threetypes of ARQ is analyzed and simulated. Pointed out the defect when the traditionalARQ direct used in802.16m system, this thesis proposed improvement methods.2) This thesis describes the MAC layer‘s workflow of the802.16m system. Thedetailed summary of the ARQ in802.16m includes parameters, state machines and dataframe format.3) In order to accommodate different channel conditions, four types of feedback isgiven in the802.16m. This article first describes the detail format and structureprocesses of the four types of feedback, then analyses the advantages and disadvantagesof each type. This thesis proposes a selection algorithm of feedback type, which candynamically select the most efficient type of feedback under the current situation. Thisalgorithm is proved to be correct by Simulation analysis.4) For wireless channel error of sudden and relevance, this thesis introduces athree-State Markov channel model. Build a standards-compliant ARQ system simulationplatform. A standards-compliant ARQ system simulation platform is designed. On thisplatform, the different effect of parameters to the ARQ’s throughput efficiency isanalyzed.Compared with the traditional way of ARQ feedback, while FER is more than10-4,the presented algorithms can reduce the amount feedback data of33.8%at least. Thisalgorithm of ARQ feedback can provide a reference meaning for high speed wirelessnetwork.Considering the performance and complexity, and combined with simulationresults, this thesis analyses the system performance influenced by different parametersof ARQ. Proposals of some parameter ranges are given too. These can providereferences for the practical application of the802.16m system.