Reply To: Power allocation in NOMA

#12586
Bashar Tahir
Participant

Hello,

The power allocation follows the LTE Rel. 14 specs: http://www.3gpp.org/ftp//Specs/archive/36_series/36.211/36211-eb0.zip
On page 147 “7 Generic functions”. For each QAM mapping of the cell-center user, three power ratios are defined. Each is controlled by the two parameters ‘c’ and ‘d’. The superposition is defined as follows:

x = exp(j*phi0*pi)*c*(I-d) + exp(j*(phi1+0.5)*pi)*c*(Q-d), where

– phi0 is the inphase component of the QPSK symbol of the cell-edge user,
– phi1 is the quadrature component of the QPSK symbol of the cell-edge user,
– I is the inphase component of the M-QAM symbol of the cell-center user,
– Q is the quadrature component of the M-QAM symbol of the cell-center user.

The resultant composite constellation is Gray-coded.

Based on that, we can deduce that the power allocation to the cell-center user is c^2; it follows that the cell-edge user has a power allocation of 1-c^2. This is assuming that the total power is 1.

In the simulator, you find those parameters in +Modulation\SignalConstellation.m @ line 37, and @ line 97 you see how they are applied. If you want to change which power ratio is chosen during the simulation, you can do so in +Elements/Link.m @ line 261.

Best regards,
Bashar