Abstract: Shared spectrum access is disclosed in which multiple tiers of users are allowed to access a set of shared spectrum resources. Second tier users, which receive priority access from the first spectrum tier, transmit reserving signals over the available shared channels during clear channel assessment (CCA) periods associated with the shared channels. Third tier users, which access the shared spectrum at a lower priority than the second tier users, attempt to synchronize timing with second tier users when second tier user presence is detected. Third tier users will be blocked from transmission on the shared channels when the third tier users detect the reserving signals. Second tier users, thus, transmit on the shared channels with a lower likelihood of interference from third tier users, and third tier users will be able to transmit on any of the shared channels when the third tier user detects a clear CCA.

Abstract: Shared spectrum access is disclosed in which multiple tiers of users are allowed to access a set of shared spectrum resources. Second tier users, which receive priority access from the first spectrum tier, transmit reserving signals over the available shared channels during clear channel assessment (CCA) periods associated with the shared channels. Third tier users, which access the shared spectrum at a lower priority than the second tier users, attempt to synchronize timing with second tier users when second tier user presence is detected. Third tier users will be blocked from transmission on the shared channels when the third tier users detect the reserving signals. Second tier users, thus, transmit on the shared channels with a lower likelihood of interference from third tier users, and third tier users will be able to transmit on any of the shared channels when the third tier user detects a clear CCA.