Subchannel-based listen before talk for unlicensed channel access

A method for wireless communications performed by a user equipment (UE), the method comprising:

• receiving one or more transmissions indicating one or more allocated subchannels of a frequency band that are allocated during a first time period, the frequency band comprising the one or more allocated subchannels and one or more unallocated subchannels during the first time period;
• sensing only the one or more unallocated subchannels for at least a portion of the first time period prior to a second time period;
• and
• transmitting a signal within the frequency band during the second time period based on energy sensed for the one or more unallocated subchannels being less than a threshold.

An apparatus for wireless communications, the apparatus comprising:

• means for receiving one or more transmissions indicating one or more allocated subchannels of a frequency band that are allocated during a first time period, the frequency band comprising the one or more allocated subchannels and one or more unallocated subchannels during the first time period;
• means for sensing only the one or more unallocated subchannels for at least a portion of the first time period prior to a second time period;
• and
• means for transmitting a signal within the frequency band during the second time period based on energy sensed for the one or more unallocated subchannels being less than a threshold.

A non-transitory computer-readable storage medium having instructions stored thereon that, when executed by an apparatus, cause the apparatus to perform operations including:

• receiving one or more transmissions indicating one or more allocated subchannels of a frequency band that are allocated during a first time period, the frequency band comprising the one or more allocated subchannels and one or more unallocated subchannels during the first time period;
• sensing only the one or more unallocated subchannels for at least a portion of the first time period prior to a second time period;
• and
• transmitting a signal within the frequency band during the second time period based on energy sensed for the one or more unallocated subchannels being less than a threshold.