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This paper presents two channel aggregation schemes for wideband cognitive radio networks: a constant channel aggregation scheme and a variable channel aggregation scheme. In the variable channel aggregation scheme, the bandwidth of the cognitive user is aggregated with a probability distribution or aggregated on the basis of the number of the residual(More)
Most existing studies on broadcast services in orthogonal frequency division multiplexing (OFDM) systems have focused on how to allocate the transmission power to the subcarriers. However, because a broadcasting system must guarantee quality of service to all users, the performance of the broadcast service dominantly depends on the channel state of the user(More)
This paper proposes two algorithms for automatic repeat request (ARQ) feedback message transmission in IEEE 802.16m systems. The proposed algorithms determine the transmission interval of an ARQ feedback message on the basis of the number of transmitted ARQ blocks or the number of received ARQ blocks. If the receiver frequently transmits ARQ feedback(More)