Research On Joint Selection Of Relay And Cooperation Mode In Spectrum Sharing Framework

With the fast development of wireless communication and the promotion of the extent people relying on the wireless resources,a growing shortage of the spectrum resources become a serious problem.As one of the key technologies for 5G wireless mobile communication network,spectrum sharing can raise the utilization rate of spectrum efficiently.On the other hand,MIMO technology can transfer the shortcoming of multi path fading to advantages so that improve the quality of received signals as well as the transmission data rate and thus satisfy the higher experience data rate for 5G users.In this thesis,we will discuss the scenario combining spectrum sharing with MIMO technology.Under the premise that guaranteeing the outage probability threshold of the primary user,we use different types of cooperative modes to enhance both the spectrum sharing between the primary users and the secondary users,and the promotion of the transmission data rate for the secondary users.First of all,we introduce the development,vision and clarification of spectrum sharing technologies in 5G wireless communication systems.Then,we briefly talk about the different modes of cooperative communicaions and theoretical knowledge of MIMO technology,and compare two disparate cooperative modes and three different types of precoding algorithms through MATLAB simulation.Next,in the only one pair of priamary users existing scenatio,we study the joint optimization of time-slot factor and bandwidth factor based on the assumption that the relay selection process has finished.Guaranteeing the primary user's outage probability restraints,the proposed algorithm can find the optimal time-slot factor and bandwidth factor to maximize the transmission data rate of secondary users.Then,when the transmitter of secondary user equipped with multiple antennas,we propose another power allocation algorithm using multiuser MIMO technology.The revised algorithm is to maximize the transmission data rate of secondary suer while satisfying the primary user's outage probability threshold.Compared with the existing power allocation strategies,our algorithm outperforms them and with the number of antennas and receivers increase,the transmission data rate of secondary user can also be improved.Finally,considering the mobility of secondary users in the cellular network,we discuss the relay selection strategy in cooperative spectrum sharing.During the relay selection process,each alternative secondary user can have different hardware resources,such as different numbers of antennas,velocities,moving directions and the cooperative modes.Under the outage probability of primary user can be satisfied,our proposed relay selection strategy set the product of relay activation duration and the predictive average transmission data rate of secondary user as the object function.The simulation results indicate that no matter how different resources the secondary user may have,we can always find an optimal relay node to both assist primary user to communicate normally and transmit more data of its own.With the number of alternative relay nodes increasing,the transmission data rate of the secondary user and the relay activation duration can both be promoted.