Active Coordination Set for Shared-Spectrum Environments

A method for operating, in a shared-spectrum environment, an active coordination set (ACS) for joint wireless communication between a user equipment and a first base station of multiple base stations included in the ACS, the method comprising:

• performing, by the first base station included in the ACS, a first listen-before-talk (LBT) operation;
• determining, based on an outcome of the first LBT operation, that the first base station included in the ACS is free to begin a downlink (DL) transmission to the user equipment;
• and
• communicating, by the first base station included in the ACS, first transmit-timing information (TTI) to a second base station of the multiple base stations included in the ACS, the communicating performed using an Xn interface or an X2 interface in order to jointly transmit with the second base station the DL transmission to the user equipment.

A first base station included in an active coordination set (ACS) operating, in a shared-spectrum environment, the first base station comprising:

• a radio frequency (RF) transceiver;
• a processor;
• and
• a memory system comprising instructions for a listen-before-talk (LBT) manger application that is configured to, when executed by one or more processors, direct the first base station to:
• perform a first LBT operation;
• determine, based on an outcome of the first LBT operation, that the first base station is free to begin a downlink (DL) transmission;
• and
• communicate first transmit-timing information (TTI) to a second base station included in the ACS, the communicating performed using an Xn interface or an X2 interface in order to jointly transmit with the second base station the DL transmission.