Listen Before Talk for LTE Direct over unlicensed radio frequency spectrum band

摘要

Methods, systems, and devices are described for direct device-to-device (D2D) communications in a subframe on a channel in an unlicensed radio frequency spectrum band. A user equipment (UE) may perform a listen-before-talk (LBT) procedure on the channel in the unlicensed radio frequency spectrum band. The UE may identify a time period between a completion of the LBT procedure and a boundary of a second subframe. The UE may transmit a Wi-Fi preamble and a variable length message on the channel during the identified timer period. The variable length message may include a duration that is time aligned with the boundary of the second subframe.