Cross-Layer Joint Scheduling For D2D Communication In Cellular Systems

The introduction of device-to-device(D2D)communication technology into cellular system can improve system spectrum utilization efficiency,save transmission power,and reduce traffic load of the core network.But bringing D2 D communication into cellular system also increases the scheduling complexity at the base station(BS)side.Hence,designing efficient scheduling algorithms has become a hot research topic for developing D2 D communications in cellular systems.However,most existing works commonly assumed that all channel state information(CSI)are known by the BS,i.e.,the BS can obtain all the CSI that it needs to perform scheduling.The scheduling algorithms designed based on such assumptions usually correspond to very high signaling overhead on channel measurement when they are implemented into actual systems.With this background,this thesis focuses on the joint scheduling algorithm designs for D2 D communications in cellular systems under the condition that the CSI are partly known by the BS.Based on the established system models for cellular D2 D communications,scheduling algorithms that can jointly perform power coordination,channel allocation,and communication mode selection for D2D-capable users by taking into account both the transmission rate criteria of physical layer and the transmission delay criteria of link layer are proposed.In particular,the end-to-end transmission delay estimation schemes for reuse direct D2 D mode and reuse relay-assisted D2 D mode are presented when only the statistical characteristics for the interference channels are known.First,the differences of the uplink channel or downlink channel that the D2 D users reuse the cellular users and the reason why choose the modes of the D2 D to research are detailed analyzed.Second,the joint scheduling issue for the situation that only includes reuse direct D2 D communication mode in the cellular system is researched.The corresponding system model is constructed,and the supported D2 D mode for D2D-capable users is only the reuse direct D2 D mode.Based on such a system model,aiming to improve the cellwise end-to-end transmission rate,we present cross-layer joint scheduling scheme that considers both the link quality of service and transmission delay under the situation that the CSI are partly known at the BS side.According to the channel probability and statistical characteristics for the interference channels,the end-to-end transmission delay estimation method for the reuse direct D2 D mode is presented.By solving the established mathematical model of the joint scheduling issue,the power coordination and channel allocation problems are solved.When finishing the design,the effectiveness of the joint scheduling scheme and the increase of the system performance brought in by considering reuse direct D2 D mode are validated by simulations.Meanwhile,the influences of major system parameters on the performance of the joint scheduling scheme are analyzed.Finally,the joint scheduling issue for the cellular system that involving relay-assisted D2 D mode are researched,i.e.,when establishing the system model,the reuse relayassisted D2 D communication mode is further taken into account besides of the above mentioned reuse direct D2 D mode.Taking relay-assisted D2 D mode into account can improve the degree of freedom on performing D2 D communications for the cellular systems.With such a system model,aiming to improve the cell-wise transmission rate,we present cross-layer joint scheduling scheme that considers both the link quality of service and transmission delay under the situation that the CSI are partly known.We demonstrate an end-to-end transmission delay estimation approach for the reused relayassisted D2 D mode when the CSI are partly known by the BS.The power coordination,channel allocation,and communication mode selection issues for D2D-capable users are solved under the framework of joint scheduling.Finally,the effectiveness of the joint scheduling scheme and the increase of the system performance brought in by considering reuse relay-assisted D2 D mode are validated by simulations,and the influences of major system parameters on the performance of the joint scheduling scheme are also analyzed.