MODULATION FORMATS AND WAVEFORMS FOR THE PHYSICAL LAYER OF 5G WIRELESS NETWORKS: WHO WILL BE THE HEIR OF OFDM?

5G cellular communications promise to deliver the giga-bit experience to mobile users, with a capacity increase of up to three orders of magnitude with respect to current LTE systems. There is widespread agreement that such an am-bitious goal will be realized through a combination of inno-vative techniques involving different network layers. At the physical layer, the OFDM modulation format, along with its multiple-access strategy OFDMA, is not taken for granted, and several alternatives promising larger values of spectral ef-ficiency are being considered. This paper provides a review of some modulation formats suited for 5G, enriched by a com-parative analysis of their performance in a cellular environ-ment, and by a discussion on their interactions with specific 5G ingredients. The interaction with a massive MIMO system is also discussed by employing real channel measurements