In the 802.11ax (High Efficiency, HE) amendment, one of the key features introduced is BSS (Basic Service Set) Coloring. This feature is designed to mitigate issues arising from overlapping BSSs (OBSS), which can lead to contention and interference in dense wireless environments. BSS Coloring works by:
Assigning a "color" (a small number) to each BSS: This helps devices differentiate between frames from their own BSS and those from neighboring BSSs.
Reducing Inter-BSS Interference: Devices can ignore frames from different BSSs (with a different "color") under certain conditions, reducing the impact of OBSS interference.
Improving Spatial Reuse: By distinguishing between transmissions from different BSSs, devices can make more informed decisions about when to transmit, improving the efficiency of spatial reuse and reducing unnecessary contention.
This feature directly impacts design decisions related to AP placement and the spacing between same-channel BSS cells, as it allows for closer placement of APs on the same channel without significantly increasing interference, thus improving overall network capacity and efficiency.
The other options, while features of 802.11ax, do not directly pertain to reducing overlapping BSS contention in the same manner:
TWT (Target Wake Time)optimizes device sleep schedules to conserve power.
Uplink MU-MIMOenhances uplink data transmission capabilities but doesn't specifically address OBSS contention.
6 GHz Band Supportintroduces new spectrum for Wi-Fi use but is not a feature aimed at reducing OBSS contention within the 802.11ax framework.
Therefore, the correct answer is B, BSS Color.
References:
IEEE 802.11ax-2021: Enhancements for High Efficiency WLAN.
CWNA Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109, by David D. Coleman and David A. Westcott.
