## 3 Network Model of the mmWave MIMO NR-Relay Node (RN) Cooperative System  
In this section, the mmWave MIMO New Radio RN cooperative network is presented. The scenario is situated in an urban environment, specifically, outdoor-to-indoor, as is shown in Figure 4. A&F and D&F NR-RNs have been designed, where MIMO and out-band operation, i.e., the two links (backhaul and access links) have different work frequencies, are considered. Hence, the backhaul link works in the FR1 band. On the other hand, the access link operates in mmWave bands (FR2), which is achieved through the RF mmWave transmission chain and will be presented in the Section 3.2. The 5G network scenario in Figure 4 is composed of one gNodeB, which will serve the one NR-UE through the NR-RN (A&F or D&F). We have assumed that the backhaul link is given by a Line-of-Sight (LOS) scenario, and the distance between gNodeB and NR-RN is approximately 67.0 m. In Reference [18], a large 5G NR number of propagation channel model that support frequency bands over the range 0.5-100 GHz, which can simulate environments as urban microcell street canyon, urban macrocell, indoor office, rural macrocell, and mobility, also including, a geometry-based  
Figure 4: Outdoor-to-Indoor environment scenario with mmWave MIMO NR-RN. are presented. Specifically, for the simulations of the considered scenario, the Clustered Delay Line (CDL) model was implemented, as it is defined in Reference [18]. The CDL-D channel model is considered for the backhaul link, which is modeled according to the specification of the 3 GPP. The 3 GPP Urban Macrocell (Uma) pathloss model is used to represent the LOS backhaul link, whose expressions are given by  
\[\mathrm{PL}_{\mathrm{BL}}(\mathrm{dB})= \begin{cases}\mathrm{PL}_{1}+\sigma_{ \mathrm{BL}}&10\mathrm{m}\leq\mathrm{d}_{\mathrm{BL}}^{1}\leq\mathrm{d}_{ \mathrm{BL}}^{\dagger},\\ \mathrm{PL}_{2}+\sigma_{\mathrm{BL}}&\mathrm{d}_{\mathrm{BL}}^{\dagger}\leq \mathrm{d}_{\mathrm{BL}}^{1}\leq 5\mathrm{km}\end{cases} , \tag{10}\]  
where \(\mathrm{d}_{\mathrm{BL}}^{1}(m)\) is the distance from gNodeB to the NR-RN, as shown in Figure 4. Besides, \(\mathrm{d}_{\mathrm{BL}}^{\dagger}\) (m) is the breakpoint distance, which can be calculated as Reference [18]; on the other hand, \(\mathrm{PL}_{1}(\mathrm{dB})\) and \(\mathrm{PL}_{2}(\mathrm{dB})\) are the path losses that can be given by  
\[\mathrm{PL}_{1}(\mathrm{dB})=28.0+22\log_{10}(\mathrm{d}_{\mathrm{BL}}^{2})+2 0\log_{10}(\mathrm{f}_{\mathrm{c}}), \tag{11}\]  
and  
\[\mathrm{PL}_{2}(\mathrm{dB})=28.0+40\log_{10}(\mathrm{d}_{\mathrm{BL}}^{2})+2 0\log_{10}(\mathrm{f}_{\mathrm{c}})-9\log_{10}((\mathrm{d}_{\mathrm{BL}}^{ \dagger})^{2}+(\mathrm{h}_{\mathrm{SN}}-\mathrm{h}_{\mathrm{RN}})^{2}), \tag{12}\]  
where \(\mathrm{d}_{\mathrm{BL}}^{2}(\mathrm{m})\) is the distance from the gNodeB antennas to the NR-RN Antennas, and \(\mathrm{h}_{\mathrm{SN}}\) and \(\mathrm{h}_{\mathrm{RN}}\) are the height of the gNodeB and NR-RN both in (m), respectively. \(\sigma_{\mathrm{BL}}\) represents the shadowing term with zero mean and standard deviation of 6 dB, and fc is the carrier frequency in GHz. The NR-RN process the received signals and they are then translated from FR1 bands to FR2 bands. The CDL-D channel model [18] and a LOS scenario indoor-to-indoor environment were considered in the Access Link. The 3 GPP Indoor Office path loss model is employed to simulate the mmWave LOS Access Link, which is capable to capture various typical indoor deployment scenarios. The mmWave indoor path loss model can be expressed as  
\[\mathrm{PL}_{\mathrm{AL}}=32.4+17.3\log_{10}(\mathrm{d}_{\mathrm{AL}}^{1})+2 0\log_{10}(\mathrm{f}_{\mathrm{c}})+\sigma_{\mathrm{AL}}\hskip 14.226378 pt(1 \mathrm{m}\leq\mathrm{d}_{\mathrm{AL}}^{1}\leq 100\mathrm{\ m}), \tag{13}\]  
where \(\mathrm{d}_{\mathrm{AL}}^{1}\) (m) represents the distance between NR-RN and NR-UE, and \(\sigma_{\mathrm{AL}}\) denotes the shadowing term with zero mean and standard deviation of 3 dB.