Receiver Start of Packet detection threshold

Rx-SOP

Rx-SOP (Receiver Start of Packet detection threshold) - Rx-SOP determines the wireless signal level in dBm from the clients and as per the threshold limit, client packets may be processed or dropped.

For e.g.:- If the threshold is set to -70 dBm and the wireless signals from the clients are up to -70 dBm, then packets will be accepted and processed (i.e., demodulated and decoded at the access point radio). If signal strength from clients are of less than -70 dBm, then clients packets will be dropped.

-- At the low threshold, the radio will be more sensitive and hence larger the cell size.

-- At the high threshold, the radio will be less sensitive and hence smaller the cell size; which will ensure that the clients are connected to nearby access point (this will result in enhanced user experience in the form of high speed and high throughput at the user side).

In case, Rx SOP is set to high threshold value –

a. Cell overlapping will be less between the access points

b. Air time transmission will be less for clients (and thus more airtime will be available for clients)

All the frames received with low RSSI than the configured threshold will not be decoded by the access point and dump into the bin as the noise.

Fig-1 - Global configuration of Rx-Sop for 2.4GHz & 5GHz 

To Configure the Rx-SOP globally for both the 2.4GHz and 5GHz band --

Go to Wireless>Advanced>Rx-Sop Threshold>Rx-Sop Threshold 802.11a or Rx-Sop Threshold 802.11b >>> High; Medium; Low or Auto as per requirements.

	High	Medium	Low	Auto
2.4 GHz	-79dBm	-82dBm	-85dBm	Radio Default
5 GHz	-76dBm	-78dBm	-80dBm	Radio Default

Fig-2

Note: Rx-Sop is only supported on the following models of access points:

• 1552
• 1570
•  1600
•  1700
•  2600
•  2700
• 2800
• 3500
• 3600
•  3700
• 3800

Creating Custom RF-Profiles and configuring Rx-SOP per profile

By creating custom RF-profiles, we can configure one set of access points of large cell size and another set of access points which are of small cell size.

Cisco wireless controller comes with the some pre-configured RF-Profiles that is low client density, typical client density and High Client Density or we can create our new RF-Profile as per our requirement and put it on the AP group.

Fig-3

To Create new RF-Profile, Go to Wireless>RF-Profile and Click New

Give Profile name and select the band 802.11a or 802.11b/g

Fig-4

Fig-5

Go to High Density tab and select Rx-Sop threshold parameters as shown in Fig-6.

Fig-6

Go to WLANs>Advanced>AP Groups>Select the AP group on which RF-Profile to be put.

Fig-7

This way we can apply the different RF-Profiles to different AP groups as per our design.

I hope this is being informative to you and I would like to thank you for viewing.

References:

[1]http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-0/hdx_final/b_hdx_dg_final/high_density_experience_features_added_in_release_8_0.html

http://www.revolutionwifi.net/revolutionwifi/2014/08/optimized-roaming-rssi-low-check-rx-sop.html