Capacity Optimization And Deployment Design For Macrocell/femtocell Tiered Networks

The insufficient indoor coverage problem and network capacity bottleneck have become the important issues that restrict the development of next generation network.Therefore,femtocell network,which is considered as a good solution to solve the indoor coverage problem,becomes one of the major issues for 4G.At the same time,indoor coverage enhancement technology in public areas,such as large-scale commercial center,office building,exhibition center,airport and railway station,has also attract peple's attention.However,femtocell network also brings new technical challenges,including interference coordination and elimination,network resources management.Femtocell networks have the attributes of user deployment.Therefore,it is hard to control and manage them in a unified way.Besides,with the popularization and promotion of public femtocell network,femtocell networks are facing more challenges due to the more complicate indoor wireless environment and much shorter distance between femtocell basestations.This thesis studies the typical multi-cell public femtocell scenario solutions,with main focus on the tired network capacity optimization and interference suppression.Specifically,we mainly study the application of new technologies in femtocell networks.To sum up,this study mainly includes the following aspects:The first part begins with a brief introduction of the mobile communication network,pointing out that femtocell,as the key technology to enhance indoor coverage and network capacity,is becoming the emerging research focus.Furthermore,we focus on key challenge related to current results,in particular with the lack of basic theoretical model and the application of new technologies.Finally,we come up with the conclusion that the focus of this study is the key methods and techniques enhance the tired network capacity.In the second part,setting the maximization of tiered network capacity as the final goal,we solve inter-tier and inter-femtocell interference by using the joint antenna selections and power control.Firstly,to optimize the sum of the tiered network capacity,a mathematic model is built;secondly,based on the target problem,taking into account of the compromise between capacity and complexity of algorithms,two different solutions are proposed.They are:(1)the optimal exhaustive search algorithm,which is at high degree of complexity;(2)the sub-optimal solution based on graph theory,simulation result shows that this method can not only greatly reduce complexity of algorithms,but also mitigate the interference between femtocells and reach a rather good performance in network capacity optimization;The third part explores the application of coordinated multi-point transmission technology in femtocell network to solve the interference problem between diffident femtocells in dense scenario.In this part,a novel Joint Processing(CoMP-JP)is proposed to solve the inter-femtocell interference:firstly,the coordinated femtocells do not have to share user data information.Since only users' CSI information is needed,the inter-cell signaling overhead can be greatly reduced.Secondly,by providing multi-point joint treatment enhanced services with little user data shared,the utilization of radio resources is much higher than the traditional CoMP-JP solution.Thirdly,through joint pre-coding,downlink interference at the cell edge users can be effectively eliminated,which can effectively increase the capacity of the whole femtocell network.Finally,a conclusion is summarized,and the future directions are pointed out.