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Cisco RRM TCPv1 Formula

Calculating TPCv1 Values

Radio Resource Management (RRM) can be incredibly useful if you have a deployment where a single AP is able to hear at least 3 other APs within the configurable power threshold.

All 4 APs in this scenario need to be a member of the same RF Group.  This is different to an RF Profile, an RF Group is a group of APs and Wireless Controllers that exist within the same mobility group.

What is Transmit Power Control v1

Transmit Power Control (TPC)v1 uses transmit and receive neighbour lists from NDP to calculate the ideal transmit power of each access point.

TPCv1 is the coverage optimal mode, and is usually the most common deployment I´ve come across.  The formula consists of a user defined power threshold, and the third loudest transmit neighbour.

The RRM TPCv1 Formula

The ideal power level for an AP is determined by 3 values.

  • –  Maximum power of an AP, in dBm
  • –  The user defined TCP threshold, in dBm
  • –  The third loudest tx AP, in dBm

TCPv1 Formula Examples

RF Groups

RF groups add a layer of complexity to RRM, and potential some issues.  Once the value is defined using the TPCv1 formula above, it then has to make sure the value meets the requirements set out by the RF Group.

An RF group sets the minimum & maximum values for a group of APs.  Imagine TPCv1 defines the ideal power level as 20dBm (100mW) for a specific AP.  This AP is a member of a high density RF group, which states the maximum power level for any AP in its group is 14dB (25mW).  The AP will be set to 25mW.

This may be the desired outcome for the specific environment, but it also has the potential to introduce coverage holes.

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