Cellular and Wi-Fi in Unlicensed Spectrum: Competition leading to Convergence

In order to look into the future, it is essential to review the history. Traditionally, the unlicensed spectrum has been widely dominated by Wi-Fi (IEEE 802.11-based) technologies. However, in current deployments, due to the recent cellular (3GPP LTE and NR-based) technologies operation expansion to the unlicensed spectrum, IEEE and 3GPP technologies compete for the access. In this paper, we review the history of IEEE and 3GPP technologies operation in the unlicensed spectrum and highlight future trends. We will show that, as a result of the competition, both technologies are converging to use similar features in the radio access, such as large bandwidth operations and efficient designs. Then, we will expose options for their future convergence, including cellular and Wi-Fi interworking, as well as the combination of cellular and Wi-Fi connections in unlicensed bands. Finally, based on current competition-based deployments, we present a system-level evaluation of NR-U and Wi - Fi coexistence in the 60 GHz unlicensed spectrum bands.