In-band and out-band relaying configurations for dual-carrier LTE-advanced system

For multi-hop transmission two basic relaying modes are available: in-band and out-band. The in-band mode is the main solution considered in most state-of-the-art studies and it is the focus of the 3GPP LTE-Advanced specification. This is because the solution requires only one frequency carrier for relay node operation. However, with evolution of cellular systems, multi-carrier operation is commonly considered. This enables implementation of the out-band operation mode in an operator controlled spectrum. In this paper we discuss and compare the two operation modes with consideration of real world factors. Furthermore, we propose several resource allocation schemes, that are evaluated in a dual-carrier system, to assess applicability of the relaying modes. As a result we identify the most promising configurations for advanced relay enhanced networks.