Research On Interference Suppression Of D2D Communication For 5G

With the increasing communication device for massive access and the shortage of cellular spectrum resources,huge volumes of traffic and higher data rate standards will face enormous challenges.Against such backgrounds,technologies such as short-range communications and multiple-input multiple-output have emerged.As a short-range communication technology,D2D communication technology can bring unlimited potential to the utilization of spectrum efficiency by introducing cellular networks,which can obtain more throughput in limited spectrum resources.And in order to deal with larger data exchange tasks and more user access,there is a promising research field in which the combination of D2D and other technologies,such as the combination of D2D and MIMO can utilize the spatial multiplexing and diversity gain of multiple antennas to bring about greater performance gains for future communications systems.Meanwhile,many problems arise in the introduction of D2D technology into traditional networks and the combination of MIMO and D2D,such as user pairing,resource allocation,and interference management issues.This paper focuses on analyzing the co-frequency interference in heterogeneous networks.Firstly,how D2D users can reuse resources in a cellular network was studied,and co-frequency interference coordination between D2D and cellular users was resolved.Secondly,the D2D technology and MIMO technology are combined,and in the combined MIMO-D2D system,the resource multiplexing problem of D2D users under multi-antenna configuration was introduced,and the precoding algorithm was used in the MIMO-D2D heterogeneous network to coordinate and manage the co-frequency interference.The main work of the dissertation is as follows:For D2D users to reuse co-channel interference caused by cellular users' uplink resources,the resource allocation in the system is optimized to reduce the interference between cellular and D2D users.Considering the situation that the uplink resources are sufficient,this paper mainly aims to ensure the communication quality of D2D users.In the resource-abundant uplink,a D2D user multiplexes the lightest uplink resource block of the cellular users while guaranteeing the cellular user's normal communication.Then the system throughput was used as a utility function and a Lagrangian duality function was constructed.According to the convex optimizationtheory,the transmission power of the D2D transmitter was continuously iterated and optimized so that the optimal allocation of D2D user power was achieved.When introducing the MIMO technology into the MIMO-D2D system based on D2D cellular network,the link interference between the cellular and D2D communication will be more complicated due to the equipment terminal and the base station are configured with multiple antennas.For downlink with relatively heavy loads,a method is proposed in which multiple D2D users multiplex a downlink resource of a cellular user by selecting a D2D user group that maximizes the SINR ratio and a cellular user to be multiplexed by the user group.Then,in combination with this multiplexing mode,a maximum signal-to-interference-noise-ratio(SLNR)precoding algorithm was designed to reduce the power leaking to the D2D user group while maximizing the signal power from the base station to the cellular user.