  Non-terrestrial networks (NTNs), including low Earth orbit (LEO) satellites,
are expected to play a pivotal role in achieving global coverage for
Internet-of-Things (IoT) applications in sixth-generation (6G) systems.
Although specific frequency bands have been identified for satellite use in
NTNs, persistent challenges arise due to the limited availability of spectrum
resources. The coexistence of multiple systems, including terrestrial networks
(TNs), sharing these frequencies, presents a technically challenging yet
feasible solution. Furthermore, the effective management and regulation of such
coexistence should be under the purview of regional authorities. To facilitate
efficient spectrum sharing among various systems, including NTNs and TNs,
adopting open architectures is desirable, allowing for the seamless exchange of
key information for spectrum sharing. Therefore, it is essential to consider
open radio access networks (O-RAN) for future NTNs and TNs. In addition to
O-RAN, the establishment of spectrum marketplaces, enabling different operators
to trade their spectrum and dynamic resource allocation information, is
necessary. In this article, we highlight the role of spectrum marketplaces and
discuss a few examples.
