Question: In a Type 2A SL (Sidelnk) channel access procedure, under what condition is the channel considered idle, allowing a UE (User Equipment) to transmit immediately after sensing?
Option 1: If at least one of the two sensing slots senses the channel as idle.
Option 2: If the channel is idle for a duration equal to one sensing interval without any sensing slot.
Option 3: If the UE transmits a probe signal and receives no response.
Option 4: If both sensing slots (one at the start and one immediately after a specified duration) sense the channel as idle.
Explanation: This is correct because, according to the Type 2A SL channel access procedure, the channel is deemed idle (and thus ready for immediate transmission by the UE) only if both sensing slots - the one at the start of the interval and the one following a specified duration - are sensed as being idle. This dual-slot sensing ensures a more reliable assessment of channel idleness, reducing potential collisions in shared spectrum environments.