Intereference Management in LTE-Advanced Heteogeneous Network

Abstract

In this thesis, we consider the problem of interference management in heterogeneous networks which is one of the main features proposed in long term evolution advanced (LTE-Advanced)communications standard. The network architecture of heterogeneous network consists of a main cell coexisting with different types of smaller cells. Heterogeneous networks are one cost effective way of handling the unrelenting data traffic demand. The major technical challenge associated with this type of network architecture is the interference experienced between coexisting cells. Interference can be either between similar type of cells or between different types of cells within the network area. In this thesis, we consider a heterogeneous network with a macro cell coexisting with a femto cell. The interference between the cells will lower system performance and eventually result in poor macro user experience. Among the various enhanced intercell interference coordination (eICIC) techniques proposed in the third generation partnership project (3GPP), we focus on power control and time domain schemes using almost blank subframes (ABS). However,these interference management schemes reduce the throughput of femto cell users. This necessitates the need to optimize the resources of power and ABS transmission so that interference experienced by macro user is low and throughput of femto user is high simultaneously. Hence, we consider a joint optimization problem to find the optimal value of power and number of ABS transmission required at the femto cell. In previous work, these optimal parameters were obtained for a system with a macro base station (MBS) serving only one macro user in downlink. We extend the analysis to determine optimal parameters when MBS serves multiple macro users. Specifically, we show that the optimal parameters of power and number of ABS transmissions obtained for the macro user closest to the femto base station (FBS)guarantees maximum throughput for the femto user and minimal interference for all other macro users.