Coherent, non-coherent, and mixed-CSIR broadcast channels: Multiuser degrees of freedom

The degrees of freedom (DoF) of the MIMO broadcast channel under various conditions remains an important open problem. This paper makes contributions towards completing the picture of the DoF of broadcast channels in the absence of CSIT (Channel State Information at Transmitter). First, the DoF of the quasi-static coherent broadcast channel (with CSIR) is established. Second, the DoF of the two-user asymmetric MIMO broadcast channel without CSIR is established, and is extended to multiple users with arbitrary antenna configurations. Third, an achievable DoF for mixed-CSIR multiuser broadcast channel, which was only known for certain antenna configurations, is extended to other antenna configurations.