Receiver Start of Packet Detection Threshold

Receiver Start of Packet Detection Threshold (RX-SOP) determines the Wi-Fi signal level in dBm at which an AP radio will demodulate and decode a packet. The higher the RX-SOP level, the less sensitive the radio is and the smaller the receiver cell size will be. By reducing the cell size, we ensure that the clients are connected to the nearest access point using the highest possible data rates. This is ideal for high density environments such as stadiums and large auditoriums where there are a large number of client devices connected per AP. In a high density environment, the smaller the cell size, the better.

As the RX-SOP value increase, only packets of a higher RSSI value are decoded by the AP’s radio. This decreases the cell size as shown in the figure above, but ensures that all clients are connected with a good RSSI value.

The following is an example of an AP receiving 802.11 packets. All frames received with weaker RSSI than configured RS-SOP will be classified as non-WiFi frames and will not get decoded by the radio, only packets with acceptable RSSI values are decoded. Packets that are not decoded are treated as non-WiFi interference and detected at the AP as noise.

In this example, the RX-SOP threshold is set to low, so authentication requests sent at -84 dBm are not decoded, but when the same message is sent at -36 dBm, it is decoded.

Table 1 RX-SOP Template Thresholds

802.11 Band	High Threshold	Medium Threshold	Low Threshold	Auto
5 GHz	-76 dBm	-78 dBm	-80 dBm	Use radio default
2.4 GHz	-79 dBm	-82 dBm	-85 dBm	Use radio default

The RX-SOP default threshold value is Auto, which means that the RX-SOP threshold is set to the radio’s default value.Existing RF profiles can be modified to include an RX-SOP Threshold. You need not create a new profile solely for RX-SOP.