The AP's radio parameter Downlink Max Rate may be configured to fix the MCS (Modulation and Coding Scheme) to a rate which the scheduler will not exceed when transmitting data traffic on the downlink.
Similarly, the SM's radio paramterUplilnk Max Rate may be configured to fix the MCS to a rate which the scheduler will not exceed when transmitting data on the uplink.
If an ePMP deployment is exhibiting packet loss due to downlink or uplink interference, modifying these parameters to limit the device maximum MCS rate may result in more reliable packet delivery. This is especially true in deployments among changing and unpredicatble interference.
While the ePMP system uses adaptive modulation to constantly monitor the quality of the received signal and determine the optimum modulation mode, in a radio environment with high variance of interference higher modulations may result in less reliable transmissions. Consider monitoring device RSSI and SNR at various times of day in high interference environments and comparing these readings to the ePMP system thresholds for 2.4 GHz and 5 GHz (for up-to-date threshold data, please refer to the ePMP Capacity Planner Tool). Transmission reliability may be increased by reducing the AP's Downlink Max Rate or SM's Uplink Max Rate parameter to an MCS rate (and corresponding system thresholds) that closer match the average RSSI and SNR of the ePMP link.
Please note, by reducing the rate configured Downlink Max Rate or Uplink Max Rate, the overall throughput capacity of the link is reduced according to the configured maximum MCS.