Outage performance analysis of underlay cognitive cooperative NOMA network

In this thesis, we study the cognitive cooperative non-orthogonal multiple access network with interference power constraint in underlay mode, where a primary receiver is situated at the communication range of the secondary network. In the cognitive secondary network, the secondary originating node transmits information with the cognitive close user directly and with the cognitive remote user by the aid of multiple relays under cognitive radio constraint. Secondary originating node sends the mixed message to the cognitive close user and to multiple relays via NOMA principle. Through the signal to interference plus noise ratio between secondary originating node and multiple relays, the best relay is opted to forward the decode signal to the cognitive remote user. In order to gauge the performance of the system accurately, the exact closed form formulas for the outage probabilities of the cognitive close user and the cognitive remote user are deduced respectively over Rayleigh fading channels. Experiment results indicate that power allocation has a great influence on the performance of system for NOMA network and it is an effective way for improving the performance of cognitive cooperative NOMA network that increasing the quantity of relays.