Multi-cluster massive MIMO

Ideas 

• [12/3/2015] It might be worthwhile to look into the design of the transmit unitary matrix.

Challenges

• When interfering channel is present, any use of the interfering channel will add to the noise temperature of the environment.

Key Concepts

• Successive decoding achieves the capacity region of degraded broadcast channel.  
• Scalar broadcast channel is a degraded broadcast channel.

• MISO channel: With only covariance feedback, water filling along the eigenvectors of the channel covariance achieve capacity.  Specifically independent complex circular Gaussian inputs along the eigenvectors of $\Sigma$ is optimal.