Shared spectrum operation is disclosed for sharing spectrum among multiple wireless deployments. Coordination procedures between and among 2nd and 3rd Tier deployments include the use of beacons transmitted by the 2nd Tier for clearing access to spectrum occupied by 3rd Tier users and multiple 3rd Tier deployments sharing resources using a group-listen before talk (LBT) protocol, rather than a per-node LBT protocol. The 2nd Tier beacon signals are transmitted to alert 3rd Tier users of their presence, which, upon detection, will leave the particular spectrum within a predetermined time. For the shared LBT protocol, the 3rd Tier deployments share the channel with each other through an LBT with random backoff, in which the start time of clear channel assessment (CCA) procedure and the random backoff values are synchronized among nodes of the same deployment.