Optimal Configuration Of Wireless Heterogeneous Network Resources Based On System And Cell Level

Heterogeneous cellular networks(HCN)have became the primary structure of 5G,because they can reduce transmission path loss and improve quality of service(Qo S)of user equipment(UE).Grid model and stochastic geometric model are proposed to model HCNs.Grid model premises fixed network topology—unchanged location and number of UE and base station(BS).The assumption is appropriate in single tier Macro BS network but cannot be applied in HCNs.Stochastic geometric model assumes varied network topology.Compared to grid model,stochastic geometric model can capture HCN randomness and formulate network accurately.However,stochastic geometric model produces complicated formulations which impose challenges to resource allocation.On the other hand,stochastic geometric model cannot provide specific operation details.In this paper,a HCN energy consumption problem is analyzed from system and cell level respectively.At system level,the stochastic geometric model is selected.Overall performances are discussed,such as UE energy consumption in uplink and network energy efficiency in downlink.At cell level,specific operations are analyzed,such as BS switching strategy to restrict energy consumption.The primary contents are detailed as follows.(1)Energy consumption at system level: The BS deployment cost and UE energy consumption are decresed by controlling the BS deployment density and UE transmit power.Aiming to decrease the amount of deployment BS and saving UEs' energy consumption.The PPP(poisson point process)is used to model the uplink of a two-tier heterogeneous network.A truncated outage probability(UE cannot connect the network due to insufficient power)and SINR outage probability(UE cannot connect the network due to poor SINR)are derived.A loss function combining BS deployment cost and UE energy consumption is developed.A optimization problem is finally constructed by combing the loss function and the outage constraints.Genetic algorithm is introduced to solve this problem.Simulation results show that the vast majority of UEs can enjoy service,when deploying BS and allocating UE power with obtained results.(2)Energy efficiency at system level: A energy efficiency problem is further proposed,which aims at improving the low bound of energy efficiency.Aiming at improving the low bound of energy efficiency.The PPP is used to model the downlink of a multi-tier heterogeneous network.Network coverage probability and averaged UE transmission rate are derived.A polynomial comprising BS density and BS transmission power is proposed.The monotonicity between coverage probability,averaged UE transmission rate and the polynomial is determined.A problem of maximizing the low bound of energy efficiency respect to the polynomial is formulated.Through convex approximation method,the low bound of energy efficiency problem can be relaxed to a geometric programming problem.And geometric programming problems can be converted into convex problems and effectively solved by interior point method.Simulation results show that the method is efficient and energy efficiency is largely improved.(3)Energy consumption at cell level: A cell level problem is discussed in the end.Aiming to balance the UE service and energy consumption by switching BS ON/OFF state.A heuristic algorithm is proposed: with lots of UEs,OFF Micro BSs are switched on and UE service is improved;with few UEs,underused Micro BSs are switched off and energy consumption is reduced.Simulation results show that the algorithm is flexibility and can reduce considerable energy consumption.