is made known to the users via a single bit of feedback. For the rest of the paper, we assume that the ratio $\frac{h_2}{h_1}$ is calculated at the destination. However, the results obtained still hold when the ratio calculated is $\frac{h_1}{h_2}$, by interchanging the roles of User-1 and User-2. For the rest of the paper a $M$-PSK constellation refers to a symmetric PSK signal set, with $ M=2^\lambda $, $ \lambda $ being a positive integer. The points in the $ M $-PSK signal set are of the form $ e^{j\frac{(k-1)2\pi}{M}} $, where $ 1\leq k \leq M $. We assume that $ \mathcal{S}_1 = \mathcal{S}_2= \mathcal{S}$, where $\mathcal{S}$ is an $M$-PSK constellation. We refer to the pair $ (\gamma , \theta)$ to represent $\gamma e^{j \theta}$ and call it the fade state throughout the paper. We refer to the complex plane that represents $ \gamma e^{j \theta } $ with $ \gamma \geq 1 $ as the $ (\Gamma, \Theta) $ plane.

Perfect channel state information (CSI) is available at the destination only, which quantizes the $ (\Gamma , \Theta) $ plane into finite number of regions. The quantization obtained is similar to the one used for physical layer 