There is no power control (PC) in OFDMA DL. The only PC is in the OFDMA UL and it is implemented following the description from TR36.942 [10].
Figure 445: Extract from the 3GPP TR 36.942 [10]
The coupling loss (CL) is the effective path loss (Section 7.6.1) and is proportional to the cell size. Figure 446 illustrates an OFDMA UL for a single cell:
Figure 446: Illustration of the CL for a single cell
For one event, SEAMCAT calculates the CL for all the active UEs which are uniformly distributed over cells and the network. SEAMCAT gathers all the CL value and generate a CDF of it. The CL_xile value is taken out of this CDF for a certain percentile (xile = “power scaling threshold”) and then fed into the equation. The power scaling threshold can be interpreted as the percentage of UEs Transmitting with less than the maximum power.
Figure 447 illustrates the CDF of the CL and the meaning of the X-ile with some illustrative numbers.
Figure 447: Illustration of the CDF of the CL and the meaning of the X-ile (with illustrative numbers)
The default value of 90% was taken while calibrating the tool with respect to the TR36.942 [10] example