Method and apparatus for transmitting LTE waveforms in shared spectrum by carrier sensing

1. A method of operating a wireless communication system on a shared frequency spectrum, comprising:

initializing a user equipment (UE) on a primary serving cell (PCell) on a licensed frequency spectrum;

configuring the UE to communicate with a secondary serving cell (SCell) operating on a carrier in the shared frequency spectrum;

monitoring the shared frequency spectrum by a base station (eNB) to determine if it is BUSY;

transmitting to the UE on the shared frequency spectrum if it is not BUSY;

waiting for a first time period if it is BUSY; and

directing the UE to vacate the carrier in the shared frequency spectrum if it is BUSY after the first time period.

2. The method of claim 1 , wherein the shared frequency spectrum is an unlicensed frequency spectrum.

3. The method of claim 1 , comprising accessing the shared frequency spectrum with carrier sense multiple access with collision avoidance (CSMA/CA).

4. The method of claim 1 , comprising directing the UE to vacate the shared frequency spectrum after the first time period by radio resource control (RRC) signaling.

5. The method of claim 1 , comprising directing the UE to deactivate the SCell after the first time period by Medium Access Control (MAC) signaling.

6. The method of claim 1 , comprising

transmitting to the UE on a first plurality of channels if the shared frequency spectrum is not BUSY; and

excluding a second plurality of channels from the shared frequency spectrum.

7. The method of claim 1 , comprising excluding a physical broadcast channel (PBCH) from transmissions on the shared frequency spectrum.

8. The method of claim 1 , comprising transmitting a discovery reference signal by the eNB on the shared frequency spectrum when it is BUSY.

9. The method of claim 1 , comprising transmitting a tracking reference signal by the eNB on the shared frequency spectrum.