Research Of The Feasibility Of Interference Alignment For MIMO Heterogeneous Network With Finite Channel Extensions

Multiple input multiple output(MIMO)networks and heterogenous networks(Het Nets)have played an important role in wireless communication system to improve the throughput.However,fading and interference are always two important challenges.On the one hand,as path loss and shadow fading,practical communication systems are partially connected.On the other hand,the inter-cell interference(ICI)and intra-user interference(IUI)may significantly degrade the performance of the multiple users communication system.Hence,the interference management problem in partially connected networks is of great significance.The main work of this paper is to investigate the feasibility of interference alignment(IA)for partially connected downlink MIMO Het Net.Firstly,this paper investigate the feasibility of IA for fully connected MIMO interference channel(IC)and MIMO interfering broadcast channel(IBC),and obtain some sufficient conditions and necessary conditions for IA conditions to be feasible based on algebraic geometry theory and graph theory.Secondly,this paper investigate the feasibility of IA for partially connected MIMO IC and partially connected MIMO interfering multiple access channel(IMAC),and obtain some necessary conditions for IA conditions to be feasible based on algebraic geometry theory.However,all research aforementioned are based on no channel extension.As we know,channel extensions can significantly improve the maximum achievable degrees of freedom(Do F)for the wireless communication system,this paper apply IA into partially connected downlink MIMO Het Net with no channel extensions,T independent channel extensions and T dependent channel extensions,respectively.We first analyze the challenges that the further research may face.Then investigating the feasibility of IA conditions for the considered system with no channel extensions,T independent channel extensions and T dependent channel extensions,respectively.We present three theorems to characterize some necessary conditions when IA conditions are feasible.These necessary conditions are aimed at describing the constraints among system configurations,which not only implicitly imposing the constraints on the maximum achievable Do F with different channel extensions,but also playing an important role in checking the unfeasibility of IA conditions.Moreover,these necessary conditions can guide the design of parameter configurations for practical communication system.