Which feature of 802.11ax improves efficiency in dense environments by dividing channels into smaller subcarriers?

• A. MU-MIMO.
• B. Beamforming.
• C. Spatial multiplexing.
• D. OFDMA.

Answer: (D)

Dividing channels into smaller subcarriers is what OFDMA does in 802.11ax. By splitting a wireless channel into many small Resource Units, the access point can assign different subcarriers to different devices at the same time. This lets multiple users transmit or receive simultaneously within the same channel, which greatly reduces contention and improves overall efficiency in crowded environments with lots of devices vying for airtime.

Other options operate in different ways. MU-MIMO uses multiple antennas to send separate streams to multiple users in the spatial dimension, not by breaking the spectrum into subcarriers. Beamforming focuses energy toward specific devices to improve signal quality rather than dividing the channel. Spatial multiplexing refers to sending multiple data streams over antennas but still centers on spatial paths rather than partitioning the channel into subcarriers.