## 3 Link Level Simulation Model for Interference Evaluation in 5G UDN with LAB
### Transition from the Link to System Level Simulation Model of 5G UDN with LAB  
According to the project \"Location aware beamforming in mm-wave band ultra-dense radio access networks\" [55], considered above link level simulation model of two links is a basis for ongoing research and system level simulation model development on the further  
Figure 4: Dependence of SIR on angular separation at a given range.  
levels of abstraction with a set of links of one cell and a set of UDN cells with account of interference, coming from the neighboring cells.  
In contrast to known private scenarios of LAB [28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54], proposed methodology for LAB in mmWave UDN for 5G and B5G, should take into account a set of conditions for networks development and scenarios for the device operation, including: (a) combining various primary measurements of a heterogeneous radio access network, as well as the accuracy of VUE location estimation and the speed of VUE motion; (b) configuration of antenna arrays of stationary gNB and mobile VUE devices; (c) the accuracy and speed of BF and determining the angle of arrival/departure (AOA/AOD); (d) geographical extent and density of gNB and UE. Consider briefly a set of conditions for networks development and scenarios for the device operation, mentioned above, with references to recent author investigations. Simulation model for vehicles tracking in 5G UDN, using combining range and bearing measurements in [23], shows the relationship between the accuracy of VUE location estimation, the speed of VUE motion, primary measurement accuracy and time interval. An open-source simulator for configuration of antenna arrays for gNB, tracking mobile VUE with location-aware beamforming for the case of two links, described above, is available at [76]. Correspondence between the accuracy and speed of BF and AOA/AOD estimation, is investigated in [24] and [27] respectively. Grid model for simulation of geographical extent and density of gNB and UE is proposed in [18].  
On the link level the relationship between the speed of VUE motion \(v\) and primary measurement time interval \(T\) for VUE location estimation is defined by the discrete step \(\Delta x\) of VUE linear trajectory, parallel to x-axis, in the createScenario function inside LAB link level simulator [76] in following order:  
\[\Delta x=v\cdot T. \tag{22}\]  
During this discrete step developed simulation model performs SIR calculation according to Formulas (1)-(21). The vector, specifying gNB\(\rightarrow\)UE direction in the global CS, is calculated according to (1) and accounts UE coordinates \(\mathbf{x}_{UE}\) during further location-aware beamforming procedures. VUE positioning inaccuracy in the simulation model can be accounted by adding some random error to \(\mathbf{x}_{UE}\) on each discrete step \(\Delta x\) during VUE motion according to its trajectory. For example, 3 m VUE location estimation accuracy is achieved for 60 km/h VUE if at least two gNB combine range and bearing measurements with 10 ns and 12\({}^{\circ}\) error respectively every 0.01 s or one NR radio frame [23]; to achieve sub-meter positioning accuracy additional measurements must be collected. Thus, proposed methodology for LAB in 5G UDN takes into account mentioned above set of conditions for networks development and scenarios for the device operation on the link level.  
On the system level to expand the proposed method for scenarios of more links we can utilize dense urban grid model [18], according to which base stations are placed with predefined ISD between neighboring gNB. System level simulation model development with a set of links of one gNB and a set of gNBs is the object of future research.