A beamforming method is disclosed of a multi-antenna transmitter configured for operation in a listen-before-talk (LBT) environment.
The method comprises transmitting—in transmission resources of a collection of one or more transmission resources corresponding to an LBT sensing event—according to a primary emission pattern (e.g., a primary beam) having a main lobe in a primary angular direction associated with a channel path towards an intended receiver, and transmitting according to one or more secondary emission patterns. The one or more secondary emission patterns—when accumulated over the collection of transmission resources corresponding to the LBT sensing event—are configured to indicate channel occupancy in angular directions other than the primary angular direction.
In some embodiments, the one or more secondary emission patterns comprises a plurality of secondary emission patterns (e.g., a plurality of secondary beams). Transmitting according to the one or more secondary emission patterns may comprise executing a sweep of the respective secondary beams over the collection of transmission resources corresponding to the LBT sensing event.
In some embodiments, the one or more secondary emission patterns consists of a single secondary emission pattern (e.g., an omni-directional emission pattern).
Corresponding apparatus, transmitter, network node, wireless communication device, and computer program product are also disclosed.