Date Added: Jan 2012
In this paper, the authors study the resource allocation in OFDM-based Cognitive Radio (CR) networks, under the consideration of many practical limitations such as imperfect spectrum sensing, limited transmission power, different traffic demands of secondary users, etc. They formulated this general problem as a mixed integer programming task. Considering that this optimization task is computationally intractable, they propose to address it in two steps. For the first step, they perform sub-channel allocation to satisfy heterogeneous users' rate requirement roughly and remove the integer constraints of the optimization problem. For the second step, they perform power allocation among the sub-channels.