What is claimed is:1. A method of operation by a radio network node in a wireless communication network, the method comprising:transmitting control signaling on a downlink carrier during a Discovery Reference Signal (DRS) occasion, conditioned on first performing a Clear Channel Assessment (CCA) procedure to assess availability of a frequency channel occupied by the downlink carrier; andperforming the CCA procedure as an extended CCA, responsive to the DRS occasion including a transmission of data by the radio network node, wherein the extended CCA is determined by a random number, and wherein the range from which the random number is drawn depends on whether previous transmissions were successful or unsuccessful;wherein the control signaling targets one or more wireless devices served by the radio network node, and, when the DRS occasion includes the transmission of the data, the data targets one or more wireless devices served by the radio network node.2. The method of claim 1, wherein a timing structure used by the radio network node for transmitting on the downlink carrier comprises recurring frames, with each frame comprising a plurality of subframes, and wherein the DRS occasion spans one or more subframes.3. The method of claim 1, wherein transmitting the control signaling comprises transmitting the control signaling along with one or more DRS-related signals associated with the DRS occasion.4. The method of claim 1, wherein the control signaling comprises one or more of: an uplink grant, a downlink grant, a cross carrier grant, a joint grant, and common search-space control signaling.5. The method of claim 1, wherein the extended CCA comprises a Listen-Before-Talk (LBT) procedure that includes a random back-off procedure defining a deferment period and a CCA sensing slot, for use as needed in reassessing channel availability, and wherein the short CCA has a duration corresponding to the deferment period or the CCA sensing slot.6. The method of claim 1, wherein the frequency channel resides in unlicensed radio spectrum and the CCA procedure facilitates coexistence between the radio network node and any other nodes or devices that operate in the unlicensed radio spectrum independent of the wireless communications network.7. The method of claim 1, wherein the frequency channel resides in unlicensed radio spectrum and the downlink carrier is a secondary carrier synchronized with a primary carrier residing in a licensed radio spectrum and used by the radio network node in addition to the primary carrier.8. The method of claim 1, wherein the radio network node comprises a radio base station of the wireless communication network.9. A radio network node configured for operation in a wireless communication network, the radio network node comprising:transceiver circuitry configured for wirelessly transmitting on a downlink carrier; andprocessing circuitry operatively associated with the communication circuitry and configured to:transmit control signaling on the downlink carrier during a Discovery Reference Signal (DRS) occasion, conditioned on first performing a Clear Channel Assessment (CCA) procedure to assess availability of a frequency channel occupied by the downlink carrier; andperform the CCA procedure as an extended CCA, responsive to the DRS occasion including a transmission of data by the radio network node, wherein the extended CCA is determined by a random number, and wherein the range from which the random number is drawn depends on whether previous transmissions were successful or unsuccessful;wherein the control signaling targets one or more wireless devices served by the radio network node, and, when the DRS occasion includes the transmission of the data, the data targets the one or more wireless devices served by the radio network node.10. The radio network node of claim 9, wherein a timing structure used by the radio network node for transmitting on the downlink carrier comprises recurring frames, with each frame comprising a plurality of subframes, and wherein the DRS occasion spans one or more subframes.11. The radio network node of claim 9, wherein the processing circuitry is configured to transmit the control signaling along with one or more DRS-related signals associated with the DRS occasion.12. The radio network node of claim 9, wherein the control signaling comprises one or more of: an uplink grant, a downlink grant, a cross carrier grant, a joint grant, and common search-space control signaling.13. The radio network node of claim 9, wherein the extended CCA comprises a Listen-Before-Talk (LBT) procedure that includes a random back-off procedure defining a deferment period and a CCA sensing slot, for use as needed in reassessing channel availability, and wherein the short CCA has a duration corresponding to the deferment period or the CCA sensing slot.14. The radio network node of claim 9, wherein the frequency channel resides in unlicensed radio spectrum and the CCA procedure facilitates coexistence between the radio network node and any other nodes or devices that operate in the unlicensed radio spectrum independent of the wireless communications network.15. The radio network node of claim 9, wherein the frequency channel resides in unlicensed radio spectrum and the downlink carrier is a secondary carrier synchronized with a primary carrier residing in a licensed radio spectrum and used by the radio network node in addition to the primary carrier.16. The radio network node of claim 9, wherein the radio network node comprises a radio base station of the wireless communication network.