When a wireless network is set to a high dBm or "Always use 100% power" under Wireless > Configure > Radio settings > Radio power, all Access Points in the network will set their radios to the set value or highest allowed transmit power (whichever is lower). The actual maximum power may vary between APs due to regulatory limitations or environmental factors.
Some factors that may limit a given AP's max transmit power include:
- Regulatory Domain
Wherever an AP is deployed, it will be subject to the requirements of its regulatory domain. Different regulatory domains may have different rules regarding maximum transmit power, so APs set to high power may have their actual maximum power limited based on their location. Note that these regulations may also differ between indoor and outdoor APs.
- Channel Selection/Band Edge
Certain channels, due to their adjacency to non-802.11 channels, may require a lower transmit power to prevent transmissions from extending into these non-802.11 channels. If an AP uses one of these band-edge channels, its maximum power may be limited.
- Bit Rate
Transmissions with a fast bit rate have a higher chance of being distorted due to the additional complexities involved in transmitting wireless data at high speeds. To reduce the potential for distortion, radios set for a higher bit rate will need to reduce their transmit power. This can further limit the maximum transmit power of a given radio.
Setting a wireless network to use 100% power will cause its APs to negotiate and use the highest possible transmit power. However, keep in mind that due to the factors outlined above, the transmit power observed may be lower than anticipated.