Enabling technologies for 5G air-interface with emphasis on spectral efficiency in the presence of very large number of links

The spectral efficiency enhancement for 5G air interface represents a technical challenge. In addition to the higher capacity requirement, 5G system will also address massive connectivity demand for 5G applications, such as IoT. A straightforward re-design of OFDM based LTE by using different radio parameter set cannot meet the challenges from the diverse 5G usage scenarios. In this paper, we present 5G radio access technologies by exploiting inter-block non-orthogonality and Intra-block non-orthogonality. The interblock non-orthogonality is achieved by block filtering of OFDM sub-block, and the Intra-block non-orthogonality is achieved by Sparse Code Multiple Access based on optimized sequence design. Such a framework can unify the large numbers of radio links for very diverse services and also provides increased spectral efficiency. In particular, when combined with emerging polar codes, we can further increase the spectral efficiency for smaller packets and support excessive number of connection links. Several design details for this novel air-interface will be presented.