Parallel Gaussian channels. Consider two parallel complex Gaussian channels with channel gains h1 = 1 + j, h2 = −3j and noise covariances N1 = 1, N2 = 2. Assume that the transmitter knows the channel characteristics.

(a) At “low” SNR, which of the two channels would you use?

(b) For what values of net input power P would you start using both channels?

(c) Plot the capacity as a function of net input power P using the waterfilling power allocation. Also plot for comparison the capacity attained if the transmitter does not know the channel characteristics, and splits power evenly across the two channels.

Answer rating: 100% (QA)

In the two capacity curves youll see that the waterfilling power allocation optimally distributes power and achieves higher capacity values compared to the evenly split power scenario at higher net in... View the full answer