Spectrum sharing based on Frobenius norm in cognitive radio networks

Aiming at the problem of spectrum sharing in multiuser multi-input multi-output cognitive radio networks, a spectrum sharing method based on Frobenius norm is proposed, which is designed to maximize the throughput of cognitive radio (CR) users as well as guarantee the quality of service of primary (PR) users. Multiuser diversity of the cognitive radio network is obtained by user selection, which is according to the Frobenius norm of channel matrices, while twice selection is adopted to reduce the complexity of our method, and then the interference from CR users to PR users is canceled by null-space projection. At last, the singular value decomposition method is employed to derive the parallel spatial sub-channels for each user while the waterfilling power allocation method is used to enhance system capacity. Compared with the existing spectrum sharing strategies, the proposed method can acquire larger ergordic capacity of CR system and reduce the outage probability of PR users. Simulation results show that when the total transmitting power of the CR system is 100w, the proposed method has 13% ergordic capacity gain of the cognitive network over the existing methods.