Research On QoS Guaranteed Energy Efficiency Optimization In Ultra-Dense Networks

With the continuous evolution of application requirements and the rapid development of communication technology,the sixth generation mobile communication system(6G)has begun extensive research.A key to the realization of 6G related technologies lies in sufficient network capacity.Ultra dense networks(UDNs)can effectively improve network capacity through intensive deployment of base stations.However,due to the increasing deployment density of base stations and the exponential growth of mobile traffic,the energy consumption also surges.On the other hand,the serious and complex inter cell interference also has a significant impact on the quality of service.Many key technologies of 6G,such as further enhanced mobile broadband(further eMBB)and enhanced ultra reliable and low latency communications(enhanced uRLLC),need to meet diversified quality of service(QoS),especially delay related QoS.To solve the above problems,this thesis focuses on the QoS guaranteed energy efficiency optimization UDNs.Firstly,the multi-base station single-user UDN with cell density greater than active user density and its inter cell interference are modeled,and the effective energy efficiency(EEE)considering delay QoS is derived by using the effective capacity(EC)model.Finally,an QoS guaranteed EEE optimized power control mechanism is proposed by using non cooperative game.Then,the thesis further studies the QoS guaranteed EEE optimized power control mechanism in the multi-cell multi-user UDN scenario with the increase of users and the multi-cell single-user UDN scenario with the increase of base stations.The main research contents of this thesis are as follows:1.In the scenario of multi-cell single-user UDN,a QoS guaranteed non-cooperative EEE optimization power control mechanism is proposed.The inter-cell interference model is modeled,and the base station to user point-to-point communication system is modeled as a queuing system.The EEE expression of the base station is derived with the help of EC model,which is taken as the optimization goal of power control.The noncooperative game is used to propose the QoS guaranteed EEE optimization power control mechanism,and the gradient rise method is used to solve the nash equilibrium(NE),which is taken as the power control result.The simulation results prove the feasibility and effectiveness of this power control mechanism.2.In the scenario of multi-cell multi-user UDN,a QoS-guaranteed non-cooperative EEE optimization power control mechanism is proposed.The research scenario is extended to the multi-cell multi-user UDN based on orthogonal frequency division multiple access(OFDMA).The EEE expression in the multi-cell multi-user UDN is derived with the help of EC model,which is taken as the optimization goal of power control.The QoS guaranteed EEE optimization power control mechanism is proposed by using non-cooperative game:Since each user in OFDMA based cell is allocated K orthogonal subchannels,The system is modeled as K independent non-cooperative games,and the Nash equilibrium of all games is solved at the same time.The base station allocates transmission power for each subchannel according to the Nash equilibrium solution.The simulation results prove the feasibility and effectiveness of multiuser power control mechanism.3.In the multi-cell single-user UDN,an QoS-guaranteed mean field game(MFG)based EEE optimized power control mechanism is proposed.The research scenario is extended to multi-cell single-user UDN with dense deployment of a large number of base stations.The inter-cell interference is upgraded to complex interference,which cannot be calculated by simple summation.Therefore,the QoS guaranteed energy efficiency optimization problem is first modeled as a dynamic stochastic game(DSG),and then transformed into MFG.Without dealing with the complex interference of dynamic coupling,the Nash equilibrium of MFG can be obtained only by iteratively solving the FPK and HJB equations,which greatly reduces the computational cost and signaling overhead.The simulation results are compared with the non-cooperative game results,and the data prove the feasibility and effectiveness of the power control mechanism based on MFG.