A novel sub-carrier and power joint allocation algorithm for multi-user cognitive OFDM

Mathematical model of multi-user power control and resource allocation in cognitive OFDM system is investigated. Multi-user resource allocation with the target of maximizing the cognitive user´s transmission rate and satisfying the proportional rate constraint between cognitive users is proposed in the condition of primary user´s interference constraint. The paper supposes that cognitive transmitter obtains all cognitive users´ instantaneous transmission channel and interference channel state information by the channel side information and cognitive users´ cooperation. Hence, cognitive transmitters utilize these channel information to implement sub-carrier and power joint allocation. Sub-carrier allocation is implemented by sub-carrier efficiency function, while linear water-filling scheme is used in power allocation. Meanwhile, an average interference algorithm that do not need iterate is also proposed, which earns the approximate optimal gains and has some real-time features.