Editing Channel capacity (section)

===Frequency-selective AWGN channel===

The capacity of the [[fading|frequency-selective]] channel is given by so-called [[Water filling algorithm|water filling]] power allocation,

:<math>C_{N_c}=\sum_{n=0}^{N_c-1} \log_2 \left(1+\frac{P_n^* |\bar{h}_n|^2}{N_0} \right),</math>

where <math>P_n^*=\max \left\{ \left(\frac{1}{\lambda}-\frac{N_0}{|\bar{h}_n|^2} \right),0 \right\}</math> and <math>|\bar{h}_n|^2</math> is the gain of subchannel <math>n</math>, with <math>\lambda</math> chosen to meet the power constraint.