Research On Energy Efficient Coordinated Multi-points Transimission In Dense Small Cell Deployment

Nowadays the wider take-up of smart phones and other advanced mobile device prompts the rapid growth of user data rate requirement.Dense deployment of small cell,called Ultra-Deployment Networks(UDN),is an effective way to enhance coverage.However,the number of cell-edge user will increase in UDN scenario,and these users experience severe interference.Coordinated Multi-Points(CoMP)transmission,which is considered to be an effective way to protect cell-edge users,allows geographically separated base station to service users cooperatively.Applying CoMP transmission technology in UDN scenario can improve throughput and EE of networks.The main contents of the research are concluded as follows:In order to improve EE and protect cell-edge users in UDN senario,we propose two CoMP transmission algorithms:one is based on interference source recognition,which takes advantage of both Joint Transmission(JT)and Dynamic Point Blanking(DPB)CoMP technologies.Considering the capacity of backhaul link and the characteristics of these two categories of cooperation,JT scheme is used between macro base stations and small cells,and DPB technology is used among small cells.Simulation results shows our algorithm achieves better EE and edge user Spectrum Efficiency(SE)than JT transmission at the cost of little decrease in average SE per sector if proper parameter is set.The gain ratio obtained in UDN senario is more obvious than in sparse deployment.The other one is based on greedy resource allocation under the constraint of integer bit.We bring in greedy resource allocation to assign power and spectrum resource in resource block level.This resource allocation based on bit loading strategy will enable more energy to be allocated to the users with good channel state.Howerver,this allocation will result in poor cell-edge users channel condition.To future optimize the algorithm,we apply CoMP transmission technology that is based on interference source recognition to the severely interfered cell-edge users,which applys JT-CoMP transmission for users that interfered by macro base station and DPB-CoMP transmission for users interfered by small cells.The result show that EE of total system and cell-edge user throughput can be promoted apparently by the proposed strategy when compared to conventional resource allocation counterpart.