Band-AMC Scheme with Hybrid ARQ in Downlink OFDMA Systems
Date Issued
2008
Date
2008
Author(s)
Wang, Wei-Han
Abstract
Orthogonal Frequency Division Multiple Access (OFDMA) technique wasdopted for the broadband wireless access (BWA) system because of its in-erent immunity to multipath interference and flexible resource allocation inoth the time and frequency domains to obtain the multiuser diversity gain.daptive modulation and coding (AMC) technique in single-carrier sys-em has been studied to do the adaptive transmission with the modulationnd coding scheme (MCS) adjusted according to the instantaneous chan-el condition for throughout maximization. Exploiting AMC technique inFDMA system can be more flexible due to the ability to track the channelariation in both the time and frequency domain. In time-varying channels,he performance degradation of adaptive transmission caused by delayed ornaccurate channel condition feedback can be mitigated with the use of hy-rid automatic repeat request (HARQ).o far, few studies focus on dynamical adjustment of the MCS switchinghresholds tracking the time-varying wireless channel in OFDMA system.n this thesis, we will propose a framework of downlink OFDMA systemmploying band-AMC scheme with HARQ. And the numerical result showshat our work outperforms the traditional method which is adopting fixed-hreshold scheme with a target frame error rate (FER).
Subjects
OFDMA
multiuser diversity
band-AMC
HARQ
FER
Type
thesis
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