Hello, here is some information that may help:
- The EIRP limits are going to be different between an AP and SM (higher EIRP for SM, except for DFS channels)
- The EIRP limits are going to be different based off of channel size (higher channels = lower EIRP, except for DFS channels)
- Some bands have different EIRP limits depending on the proximity to the upper/lower edges of the frequency band (i.e. 5.1GHz)
- Integrated radio/antenna devices will go up to maximum EIRP for the frequency band and configuration
The recommended configuration for an AP (assuming connectorized radio) is to enter the frequency, channel size and other RF parameters. Then enter in the antenna gain of the attached antenna. This will limit the configurable maximum TX power to the EIRP limit for the band and configuration. Not entering an antenna gain (or using a lower value than the actual gain) may cause the radio to transmit higher than FCC EIRP for the band/configuration. This is especially important to follow in DFS bands (5.2GHz and 5.4GHz).
On the SM side, for a connectorized radio, you should also enter in the attached antenna gain (integrated will have a hard set value). This will limit the maximum TX power to the EIRP limit for the band and configuration. The SM is going to automatically adjust it's TX power. However, since the SM typically has a higher EIRP maximum, there is another parameter that comes into play: the SM Receive Target Level (on the AP Radio Configuration page). This is the desired uplink signal connection into the AP; the SM is going to automatically adjust it's power to meet (or best attempt to meet) this signal level. The SM's ability to meet this value is dependent on the maximum EIRP for the frequency band and maximum TX power of the SM hardware. A SM that is close to the AP will, typically, lower it's power to meet this signal level and, a SM that is far away from the AP will increase it's TX power (up to the hardware maximum) to meet this signal level.
Determining the value to be used for the SM Receive Target Level depends on whether you are doing frequency reuse or not. If not, then the value can be set as high as desired (typically ~25dB above the noise level). If using frequency reuse, it should be lower (e.g. -60 - -65dBm) to prevent SM uplink transmissions from overshooting the intended AP and cause interference on the back sector.
Here are some reference links:
http://community.cambiumnetworks.com/t5/ePMP-Synchronization/ePMP-GPS-Synchronization/m-p/37884#M1
http://community.cambiumnetworks.com/t5/ePMP-3000-MU-MIMO/ePMP-3000-MU-MIMO-indication/m-p/102887#M7