Combined mechanism using both ARQ and scheduling for efficient transmission in OFDMAsystem

Orthogonal Frequency Division Multiple Access (OFDMA) has been discussed as one of major next generation multiple access techniques. Its basic concept is to assign different subcarriers into various users at the same time. Recently, many researches have identified ACK or NACK in automatic repeated request (ARQ) and their information have been transmitted to users in the downlink. However this paper considers each user's state with the scheduling in OFDMA system. The user's status can be considered for the user scheduler through either Channel Quality Indicator (CQI) module or ARQ module. The simulation results show that channel information transmission through ARQ has better throughput and increases the fairness than channels information transmission through CQI in terms of throughput and fairness.