Research On Throughput Improvement Of Centralized Dual Band D2D Wireless Network

As intra-cell traffic becomes increasingly important in wireless communication systems,the traditional base station(BS)forwarding mode suffers from low data transmission efficiency.Device-to-device(D2D)communication has emerged as a solution to offload intra-cell data traffic and improve energy and spectrum efficiency by enabling direct communication between neighboring user equipment(UE)and providing proximity-based services.In a non-standalone architecture,UE can choose to operate in either the sub-6 GHz or millimeter wave(mmWave)bands to adapt to different channel environments and meet the demands for reliable coverage and high data rates.The introduction of D2D technology in dual band networks can increase communication flexibility,while UE suffer from more complex communication mode selection,neighbor discovery and interference management,which are difficult to solve locally due to limited power consumption.Therefore,this thesis focuses on the dual band D2D network and adopts a centralized control method to study the transmission mode selection and the coordinated optimization of dense mm Wave D2D and picocellular interference to improve the network throughput.The main work is as follows:1.Transmission mode selection for dual band D2D network.The process of UE transmission mode selection involves two fundamental steps,namely communication mode selection and neighbor discovery.With respect to the communication mode selection,this thesis analyzes the establishment probability of mm Wave relaying links and D2D links based on the dual band channel and mm Wave antenna models,and assigns communication modes to UE based on appropriate priorities.This thesis further investigates neighbor discovery oriented towards mm Wave D2D mode,models the interference of mm Wave D2D links based on prior dual band channel information,and proposes a neighbor discovery guidance method based on the greedy algorithm.Simulation results confirm that the proposed scheme can reduce useless neighbor discovery and beam training overhead,and effectively improve network throughput.2.Interference coordination optimization for dense mmWave D2D and picocell.To ensure the interruption probability of mm Wave D2D links while maximizing the throughput of device-to-base station(D2B)links,this thesis proposes a two-stage scheduling scheme for D2B links and D2D links based on genetic and greedy algorithms.The power allocation is carried out using optimization theory taking into account that D2B links have the same and different transmit power to multiplex intra-cell resources.Simulation results show the effectiveness of the proposed algorithm in improving the access rate of D2D links and network throughput.