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.