## 2 System Model  
The effectiveness of the proposed method is demonstrated on a 5G downlink data-transmission infrastructure. For this purpose, the process steps shown in Figure 1 are implemented in MATLAB [43] by considering the 3 GPP standards [44; 45; 46; 47; 48]. Figure 1: 5G Downlink Data Transmission. First, the data bits are generated at the gNB (base station); they are then subjected to \"cyclic redundancy check\" insertion and \"low-density parity-check\" coding [44] at the downlink shared channel (DLSCH) step [45]. This permits the UE to detect and correct bit errors. The obtained code words are then transferred to the physical downlink shared channel (PDSCH) stage. In the PDSCH stage [46], the code words are first scrambled so that the broadcast cannot be decoded by unautorized devices. IQ modulation is then performed, providing one of the QPSK, 16-QAM, 64-QAM or 256-QAM options [47]. The obtained IQ symbols are mapped to the MIMO transmitter antennas in the layer-mapping phase. In addition, demodulation reference signals (DM-RS) [47], which are reference IQ symbols required for channel estimation in the UE side, are also included in the data symbols. The IQ symbols are modulated into the RF band using OFDM. The smallest frequency grid required for downlink transmission is called a resource element, which corresponds to one OFDM subcarrier frequency. A group of 12 consecutive subcarriers (resource elements) in the frequency domain form a resource block (RB). The total bandwidth allocated to a UE is expressed in the number of RBs, and the concept of RB is used throughout the rest of the paper. Finally, the obtained RF signal is transmitted via MIMO antennas. The mentioned MIMO-OFDM system is detailed in Figure 2. There are \(N_{T}\) transmitter and \(N_{R}\) receiver antennas in the system. The CDL (Clustered Delay Line) channel model, specified by 3 GPP [48] for 5G and beyond communication systems, represents a realistic channel structure with clustered multipath components, each exhibiting Rayleigh fading characteristics. This model aligns with industry standards and is well-suited for the simulation of wireless communication systems, allowing us realistic capture of the effects of multipath propagation and fading in our study. Hence, the overall multipath channel can be expressed by an \(\mathbf{H}\) matrix with each element following a Rayleigh distribution. \[\mathbf{H}=\left[ \begin{array}{ccc}\mathbf{h}_{1,1}&\ldots&\mathbf{h}_{1,N_ {T}}\\ \vdots&\ddots&\vdots\\ \mathbf{h}_{N_{R},1}&\ldots&\mathbf{h}_{N_{R},N_{T}}\end{array} \right], \tag{1}\]  
where \(\mathbf{h}_{i,j}=\left[h_{i,j}[L-1]\ldots h_{i,j}[0]\right]\) is the channel between the \(i\)th receiver and \(j\)th transmitter antennas, and \(L\) is the maximum channel length of all \(N_{R}\times N_{T}\) links. The statistical properties of \(h_{i,j}[l](l=0,\ldots,L-1)\) and \(\mathbf{h}_{i,j}\) can be summarized as follows:  
\[\mathbb{E}\{h_{i,j}[l]\}=0, \tag{2}\]  
Figure 2: MIMO-OFDM Transmit–Receive Model. \[\mathbb{E}\{|h_{i,j}[l]|^{2}\}=1, \tag{3}\]  
\[\mathbb{E}\{h_{i,j}[l]h_{m,n}^{*}[l]\}=0\text{ if }i\
eq m\text{ or }j\
eq n,\text{ and so} \tag{4}\]  
\[\mathbb{E}\{\mathbf{h}_{i,j}\mathbf{h}_{i,j}^{H}\}=L. \tag{5}\]  
The received signal samples at time instant \(k\) are expressed as follows:  
\[\mathbf{y}[k]=\sqrt{\frac{P_{T}}{N_{T}}} \begin{bmatrix}\mathbf{h}_{1,1}& \ldots&\mathbf{h}_{1,N_{T}}\\ \vdots&\vdots&\vdots\\ \mathbf{h}_{N_{R},1}&\ldots&\mathbf{h}_{N_{R},N_{T}}\end{bmatrix}\begin{bmatrix} \mathbf{x}_{1}[k]\\ \vdots\\ \mathbf{x}_{N_{T}}[k]\end{bmatrix} +\mathbf{v}[k], \tag{6}\]  
where \(P_{T}\) represents the average transmitted symbol power, \(\mathbf{v}[k]=\mathbf{j}[k]+\mathbf{n}[k]\) represents the sum of the received jamming and noise vectors, and  
\[\mathbf{x}_{j}[k]= \begin{bmatrix}x_{j}[k-L+1]\\ \vdots\\ x_{j}[k]\end{bmatrix}  \tag{7}\]  
is the vector of the transmitted symbols, each with an average power of one unit, that is, \(\sigma_{x}^{2}=1\).