Multicarrier-Division Duplex: A Duplexing Technique for the Shift to 6G Wireless Communications

In band full duplex (IBFD) has the potential to not only double spectral efficiency (SE) but also greatly reduce transmission latency. However, the immaturity of existing self-interference cancellation (SIC) techniques renders IBFD impractical for near-future wireless applications. To inherit the merits of FD but with practical SIC requirements, multicarrier-division duplex (MDD) was recently proposed and studied. In this article, we demonstrate the advantages of MDD over the IBFD mode and the conventional half-duplex (HD) modes of frequency-division duplex (FDD) and time-division duplex (TDD) from several essential aspects, including SIC capability, resource integration, and the support for high-mobility communications. Several numerical results are included to show that MDD outperforms IBFD in terms of energy efficiency (EE) and SIC. Compared with the HD modes, MDD is capable of efficiently integrating DL/UL resources to achieve higher SE and significantly outperforms TDD when communicating over fast time-varying channels. Finally, some implementation challenges of MDD systems are discussed.