Advanced carrier aggregation techniques for multi-carrier ultra-dense networks

An emerging scenario to be considered for further evolution of Long-Term Evolution and beyond is a multi-carrier ultra-dense network (MC-UDN). Advanced carrier aggregation (ACA) techniques, such as carrier switching, lightweight carriers, opportunistic transmissions, and adaptive resource optimization schemes, provide important means for the MC-UDN to allocate carrier-level resources properly and efficiently according to traffic load, channel, and interference conditions across the network. In this article, the general background, motivations, high-level design, and performance benefits of ACA techniques for the MC-UDN are described.