Resource Allocation Algorithm For Device-to-Device Communication In Cellular Networks

D2D communication underlaying cellular system can improve the capacity of the cell,reduce the energy loss of the end user and base station,raise the spectral efficiency of the system,reduce the burden of the base station,which can alleviate the problem of spectral resource shortage to a certain extent.However,D2 D users transmit data by multiplexing the spectrum resources of the cellular network,which inevitably causes interference between the cellular users and D2 D users.Therefore,how to coordinate the resources allocation between cellular and D2 D users to reduce the interference is one of the key problems of the cellular heterogeneous network.The resource allocation problems of D2 D communication in cellular network system are studied in this thesis,which analyzes the cause of interference between cellular and D2 D users and proposes interference management algorithms.The concrete contents are as followed:(1)In order to improve the probability of users choosing D2 D communication mode,it is necessary to optimize the transmit power of D2 D user to ensure reliable D2 D transmission and to ensure the link quality of cellular users.A communication mode selection method based on power optimization of D2 D user is proposed in this paper,which analyzes the conditions of the user using the D2 D mode based on the distance ratio between the D2 D user and the cellular user with the base station,and increasing the probability of the user selecting the D2 D communication mode by optimizing the transmit power of D2 D user.Simulation results verify the users' communication conditions for using the D2 D mode and show that the probability of selecting D2 D communication mode is improved through power optimization.(2)A QoS-based channel allocation and power control algorithm is proposed.Firstly,the algorithm obtains the candidate set of D2 D users by the minimum SINR requirement of the D2 D users.Secondly,the objective function of maximizing the capacity of the D2 D users is constructed under the condition that the users' QoS and limited transmit power.Lastly,the Lagrangian multiplier method is used to solve the optimal transmit power of the cellular users and D2 D users,and the capacity of D2 D users is calculated according to the optimal power and the channel is assigned to the D2 D user with the largest capacity value.However,the complexity of the algorithm is large,so another sub-optimal algorithm for channel allocation and power control is proposed.Simulation results show that the proposed algorithm can improve the capacity of D2 D users,and the sub-optimal algorithm has the performance of approximation optimization algorithm,but also greatly reduces the complexity.(3)A subcarrier allocation and power control algorithm based on energy efficiency is proposed to maximizing the energy efficiency of D2 D users with different communication modes under the conditions of ensuring QoS for cellular users and D2 D users and the maximum transmit power constraint for the D2 D users.D2 D users can select either mode A(direct communication)or mode B(relayed communication via relay).We assume that different communication modes are selected for the D2 D user based on the relationship between the outage probability of the D2 D user and the active cellular user whose subcarrier is reused and the preset threshold.And then,the Hungarian algorithm is used to allocate subcarriers for D2 D users.Finally,the dichotomy algorithm is used to optimize the transmit power of D2 D users.Simulation results show that the proposed algorithm has better performance in terms of D2 D users' capacity and energy efficiency.