## 2 System Model
### MISO-NOMA Environment  
The fundamental idea of NOMA is to achieve non-orthogonal resource allocation between users while increasing the processing at the receiver side [19]. With non-orthogonal resource allocation, NOMA can attain massive connectivity and accomplish higher spectral efficiency. Existing research on the NOMA system mainly focuses on the code domain and power domain. In the code domain NOMA, distinct spread-spectrum codes are designated to different users and then multiplexed over the same time-frequency resource block. In the power domain NOMA (PD-NOMA) [19], the transmitter superimposes signals with different power levels to be sent to several users on the shared spectrum. At the receiver, each user can decode his own desired signal by means of successive interference cancellation (SIC). In this subsection, the downlink MISO-NOMA system is explored where user devices and BS are linked by different fading channels. NOMA cell is assumed where one BS with two antennas is implemented to assist user devices (UDs), and each device terminal has one antenna. In PD-NOMA [19], user devices receive the superimposed signal sent from BS which involves target and interfering signals sent through the same resources. Thus, combining different signals supported by unique power portions is critical to distinguish signals and strengthen the successive interference cancellation (SIC) technique. The system structure for the basic components implemented in the examined MISO-NOMA system is shown in Figure 1.  
In our observed MISO-NOMA cell, three user devices are considered in the cell, and the examined user devices are identified corresponding to their fading channels and the distances from BS. Fading channels with Rayleigh distribution are adopted to characterize the channel model for every user. The user terminal at the boundary of the cell is realized as a far user, while the nearest user equipment is designated as a near user terminal. The examined cell contains three user devices and the fading path can be distinguished for every user as follows [3]: \(\mathbf{\emph{h}}_{n}\sim\left(0,d_{n}^{-k}\right)\) for near users, \(h_{m}\sim\left(0,d_{m}^{-k}\right)\) for the middle user, and \(\mathbf{\emph{h}}_{f}\sim\left(0,d_{f}^{-k}\right)\) for the user at the edge of the cell, where \(\mathbf{\emph{h}}_{i}\) implies a vector represents the fading path coefficients among BS and user \(i\). Path loss exponent is represented by \(k\), and AWGN is considered with noise power indicated as \(\sigma^{2}\). In terms of channel gains, the relation between user devices can be indicated as \(\left|\mathbf{\emph{h}}_{n}\right|^{2}>\left|\mathbf{\emph{h}}_{m}\right|^{2} >\left|\mathbf{\emph{h}}_{f}\right|^{2}\)[20] and overall power transmitted from BS to all users in the cell is labelled as \(P_{l}\). Every user device contains a receiving element that can activate the SIC process to get rid of signals related to other devices with bad channel environments. In contrast, signals related to user devices  
Figure 1: MISO-NOMA system basic Structure based RL channel prediction. with good link conditions may not be separated and regarded as interference. According to the aforementioned assumptions, the superposition-coded signal \(\mathbf{x}\) sent from BS can be stated as follows [3; 17]:  
\[\mathbf{x}=\sqrt{P_{t}}\Big{(}\sqrt{\eta_{t}}\mathbf{x}_{n}+\sqrt{\eta_{m}}\mathbf{x}_{m}+ \sqrt{\eta_{f}}\mathbf{x}_{f}\Big{)} \tag{10}\]  
where \(\eta_{f}\), \(\eta_{m}\) and \(\eta_{n}\) represent power factors given for a far device, middle device, and near device separately. Furthermore, \(\mathbf{x}_{f}\), \(\mathbf{x}_{m}\) and \(\mathbf{x}_{n}\) refer to the signal vectors related to far, middle, and near users respectively.