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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)
  • Jaewoo So
  • 2012
This paper analyzes the performance of voice-over-Internet protocol (VoIP) services in terms of the system throughput, the packet delay, and the signaling overhead in a mobile WiMAX system with a hybrid automatic repeat request (HARQ) mechanism. Furthermore, a queueing analytical model is developed with due consideration of adaptive modulation and coding,(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)