Alleviating control channel interference in femto-overlaid LTE-advanced networks

Long Term Evolution ¿ Advanced (LTEAdvanced) is a prominent cellular network technology designed to meet the International Mobile Telecommunications ¿ Advanced (IMTAdvanced) requirements for enhanced wireless communications, offering high data rates under an all-Internet Protocol (IP) packet network. The dominant supporter of this effort is the significant improvement in spatial spectrum utilization and indoor coverage expected to be achieved through the penetration of femtocells inside the conventional macrocell areas. However, taking into account that femtocells will spatially reuse the spectrum assigned to macrocells in an unplanned deployment manner, the mitigation of the generated interferences becomes a major challenge. The problem is more severe in the case of closed subscriber group (CSG) femtocells, which serve only a limited set of subscribed users, and interfere with both data and control channels of non-subscribed users. Since deteriorated control channels can lead victim users to radio link or access failure, this article studies the problem of control channel interference in LTE-Advanced networks overlaid by CSG femtocells. Focusing on the downlink interference perceived by macrocell users, a categorization and a performance comparison of the fundamental and emerging control channel interference management schemes are provided.