Research On Microcell Planning And Deployment Methods In 5G Heterogeneous Dense Network

To meet the exponential growth of mobile data services,there will be overlay deployment of microcell in the traditional macrocell coverage area in the fifth generation mobile communication system.Macrocells and microcells will form heterogeneous dense network,as well as enhance the system capacity.However,the increases of energy consumption and cost caused by a large number of microcell deployment have become a problem which the mobile communications technology need to solve in its development process right now.From the aspect of energy efficiency,proper planning and deployment of microcells can reduce system energy consumption and electricity cost,thereby reducing the operator's operating expense.The existing microcell planning and deployment methods mainly center on microcell deployment,microcell sleeping and microcell caching to enhance energy efficiency.However,due to the growth of user data services,the temporal and spatial volatility of services,the microcell caching and so on,there are problems such as: the user service rate is difficult to guarantee by using the existing microcell deployment methods,the energy efficiency of microcell sleeping methods is not high enough,the backhaul cost is too large in cacheable microcell networks and so on.In order to solve the above problems,this paper introduces the networking structure,energy efficiency metrics and modeling methods of heterogeneous dense networks firstly.Aiming at the problem that the microcell deployment method is difficult to guarantee the user's service rate,an energy efficient microcell deployment method with service quality constraint is proposed.In order to solve the problem of low energy efficiency of microcell sleeping methods,an energy efficient microcell sleeping method is proposed.To solve the problem that the backhaul overhead of sleeping method of cacheable microcells is too large,a distributed cell sleeping method is proposed.The details are as follows:1.In order to meet the user data service growth and user's service rate requirements,a quality of service constrained energy efficient microcell deployment method is proposed.Firstly,the feasibility of microcell positions was considered to mitigate the effects of environmental conditions.Then the optimization target value was weighed under different user distribution probability to enhance adaptability for different user distribution scenarios.Finally,an energy efficient deployment algorithm for microcells was proposed by jointly optimizing the number,deployment position and power configuration of microcells.Simulation results show that the proposed method can improve the energy efficiency of the system compared with the method of optimizing the number of microcells and the location of the deployment under the condition of guaranteeing the user QoS,and also verify the influence of the microcell power on the energy efficiency of the heterogeneous network.2.In order to adapt to the dynamic change of mobile service demand so as to fully realize energy saving in heterogeneous dense network,an energy efficient microcell sleeping method is put forward.In this method,the long duration approach was combined with the short duration approach.The long duration approach controlled the activation or sleeping state of the cell,and most of the elements of the cell were closed based on the traffic load.The short duration approach controlled the transmission or non-transmission mode of the cell.In non-transmission mode,only a small number of components such as power amplifier were turned off to ensure the delay and blocking rate and other performance,thereby enhancing the adaptability to dynamic services and reducing system energy consumption.The simulation results show that the proposed method can reduce the energy consumption of the system compared with the traditional long duration approach and short duration approach.3.To improve energy efficiency and reduce the backhaul signaling overhead and latency,a distributed cell sleeping method which considers caching is proposed.Firstly,all the cells periodically transmitted the reference signal and broadcast their own available frequency resource information and cache file information;secondly,the users of each cell reported the received signal strength and the resource information of cells to the connected cell;finally,each cell established the active cell information table and the sleeping cell information table to store the network status information reported by the service users,and executed the distributed activation or deactivation operation based on the network state information.The results show that the proposed method can maintain the throughput of the system and reduce the energy consume of the system,and verify the influence of the caching characteristics of the cell on the energy efficiency of the system.