Downlink Femto-to-Macro Control Channel Interference for LTE

Femto-cells promise substantial gains in system spectral efficiency due to an enhanced reuse of radio resources. Femto-cells may be employed in a co-channel fashion such that the bandwidth used by the macro-cell is reused by the femto-cell. Femto-cells maintain an exclusive list of user equipments (UEs) that they serve. In this case, a foreign macro UE trapped inside a femto-cell experiences heavy interference from this femto-cell. As per the current 3(rd) Generation Partnership Project (3GPP) discussions for Rel-10, this paper investigates the issue of femto-to-macro interference on the control channel. The control channel is very crucial because if it is incorrectly decoded, the following data region is completely lost. In line with the 3GPP discussions on the inter-cell interference coordination (ICIC) topic, interference-reducing techniques that are backward compatible with Rel-8/9 UEs are introduced in this paper. Employing these techniques results in a significant improvement of control channel performance for trapped macro UEs.