There has been much recent interest in allowing
commercial providers to utilize federal spectrum on a shared
basis. In such scenarios, the use of secondary licenses has been
proposed as a way to provide service providers with greater
predictability about the service that can be offered and thus
help encourage investment. However, since the spectrum is
shared, such a license would differ from traditional exclusive use
licenses in that the given spectrum may only be intermittently
available. In this work we discuss several issues related to
such intermittent spectrum and in particular consider different
market structures for allocating such secondary licenses to
different service providers.