ASB-AM/OFDMA with FSS and TPC for Reducing Packet Overhead

Recently, orthogonal frequency division multiple access (OFDMA) has been used as a multiple access method. OFDMA with adaptive modulation can provide superior system performance. However feedback information (FBI) is needed at the transmitter side to efficiently allocate subcarriers to users and to control the modulation level of each subcarrier. Since FBI is a packet overhead, it must be reduced to mitigate the system complexity. FBI consists of channel state information (CSI) and SNR information. Therefore, in an AM-OFDMA system, a large amount of control information is required to achieve high frequency utilization efficiency and high data rates. Furthermore at the receiver side, modulation level information (MLI) is also needed to demodulate the received packets. Since MLIs are transmitted as data symbols, throughput degradation is a problem in AM-OFDMA systems, where MLIs are required on every subcarrier. To reduce FBI and MLI as a packet overhead, in this paper, we propose an adaptive subcarrier block assignment for AM-OFDMA with FSS and TPC.