Figure 7

The behavior of${\mathit{G}}_{\mathit{R}}\mathbf{\left(}\mathit{\theta }\mathbf{\right)}\mathbf{,}{\mathit{N}}_{\mathit{t}}^{\mathit{m}}\mathbf{=}{\mathit{N}}_{\mathit{t}}^{\mathit{r}}\mathbf{=}\mathbf{4}\mathbf{,}{\mathit{D}}_{\mathit{m}\mathbf{\_}\mathbf{r}}\mathbf{=}\mathbf{200}\mathbf{m}$. (A) Codebook size is 32. (B) Codebook size is 64.