In the 5 GHz band, all Wi-Fi traffic (802.11a/n/ac/ax) uses OFDM or OFDMA modulation. If multiple APs use overlapping or identical channels, this results in Co-Channel Interference (CCI). Legacy technologies like HR/DSSS and ERP operate in 2.4 GHz and do not contribute to CCI in 5 GHz.
From CWDP-305:
"CCI occurs when multiple devices share the same channel. In 5 GHz, all compliant Wi-Fi traffic uses OFDM- based PHYs, so other nearby OFDM networks are a primary source of CCI."
- Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting

Comprehensive and Detailed Explanation:
Increasing capacity in a coverage-based wireless network involves optimizing the network to handle more clients and traffic efficiently. The recommended techniques include:
A: Maximize airtime usage by disabling lower data rates:Disabling lower data rates (e.g., 1 Mbps, 2 Mbps) reduces the time the medium is occupied by slower transmissions, thereby increasing overall network efficiency and capacity.
B: Add additional APs and use directional antennas:Deploying more access points (APs) with directional antennas helps in segmenting the coverage area, reducing co-channel interference, and increasing capacity by allowing more simultaneous transmissions in different directions.
D: Lower power on the access points and, after careful planning, add more APs:Reducing the transmit power of APs minimizes overlap and interference between cells. After careful planning, adding more APs ensures coverage continuity and increases capacity by distributing the load among more APs.
C: Turn up power on the access points:Increasing the transmit power can lead to excessive overlap between cells, causing interference and reducing overall network capacity. Therefore, this is not a recommended practice for increasing capacity.
Reference:CWDP-305 Study Guide, Chapter on Infrastructure Design - Capacity Planning Techniques.

When conducting a site survey, accurately determining ceiling heights is crucial for proper AP placement and coverage prediction.If ladder use is restricted, utilizing a laser distance meter provides a precise and cost- effective solution.Laser measures can quickly and safely determine vertical distances without the need for physical elevation.#### ###### # ###### ### The CWDP-305 Official Study and Reference Guide emphasizes:
"Laser distance meters are valuable tools during site surveys, allowing for accurate measurements of ceiling heights and other distances without the need for ladders or lifts." Reference: CWDP-305 Official Study and Reference Guide, Chapter on Advanced Site Surveys