Hierarchical Precoding in a Realistic Ultradense Heterogeneous Environment Exceeding the Degrees of Freedom

Table 1

Comparison of computational complexity.

Operation	BDIA	BDIA uncord.	BDIA MMSE JTR
Coordinated interference	✓	✓	✓
Eigenvalue decomposition	✓	✓	✓
Intracluster interference		✓	✓
Intercluster interference		✓	✓
Objective function	✓	✓	✓
Matrix inversion			✓