Resource Allocation Algorithms Based On Cognitive Radio In D2D Communication

In new mobile communication networks,D2D(Device-to-Device)communication represents a new communication paradigm that facilitates more efficient data exchange between physically proximate devices.It is particularly important for the current tight and limited spectrum resources to be allocated properly and efficiently.The unique advantage of cognitive radio technology is that it can mitigate the problem of spectrum shortage and greatly enhance the spectrum efficiency in system.The D2 D communication with cognitive radio techniques to form a cognitive D2 D communication has many advantages.The cognitive D2 D communication has become a key technology in the future mobile communication system.In this paper,the optimal resource allocation algorithms in cognitive D2 D communication in radio network are studied.The main works of this thesis are as follows:The D2 D users who reuse the same spectrum resources of cellular users with underlay mode in the uplink will cause a lot of complex interference in cognitive D2 D communication.This paper aiming at the complex interference problem presents a power allocation scheme to maximize the transmission rate in cognitive D2 D full-duplex communication system.Firstly,the interferences of base station and D2 D users in the uplink are analyzed in this paper,and the mathematic expressions of link transmission rate corresponding to each link are given.Secondly,a power allocation algorithm based on the maximum transmission rate of full-duplex D2 D communication in cognitive radio system is proposed,and the optimal transmission power of D2 D terminals under current condition is obtained by the lower boundary relaxation method and Lagrangian multiplication method.Furthermore,the simulation results show that the proposed power allocation scheme in D2 D full-duplex communication not only improves the signal-to-noise ratio(SINR)of cognitive D2 D users but also enhances the spectrum efficiency in the uplink and the total transmission rate in the system.For the problem that multiple D2 D users reusing the spectrum resource of multiple cellular users are prone to be interrupted when the power consumption of the D2 D terminals are too large,a resource allocation algorithm to maximize users' energy efficiency(EE)based on game theory in the cognitive D2 D communication network is proposed in this paper.Firstly,the game model of D2 D communication with underlay mode is established.The D2 D users are regarded as the followers for reusing the spectrum resource of cellular users in the uplink,so the resource allocation problem is considered as a non-cooperative game problem.Secondly,under the constraint condition of interference threshold,the utility functions are constructed according to the energy efficiency of D2 D users and cellular users.Moreover,the optimal transmission powers and the optimal link rate control scheme are obtained by using game theory and Lagrangian dual method when the interference does not exceed a predefined threshold.Finally,it is verified by the simulation results that the algorithm can improve the users' energy efficiency and the average links' energy efficiency,and this algorithm can enhance the performance of the total power consumption and capacity in system.