I want to simulate the movement of UEs in a dynamic fashion for modeling scenarios involving UE moving to the cell edge, handover between cells, ping-pong handovers, etc. How can I set up these mobility trajectories in NetSim?
NetSim provides options to configure the run-time mobility of UEs in a 5G simulation. With this you can model different scenarios involving UE moving the cell edge, handovers between cells, and ping-pong handovers.
The typical steps would be:
- Design the 5G scenario with gNBs and UEs and configure their RAN parameters.
- Then configure the parameters related to the handover process such as the Handover Interruption Time, Handover Margin, and time-to-trigger parameters present in the Datalink Layer of gNB properties.
- Define the mobility models for each UE in the simulation. To do this, go to the "General" tab in the UE properties and select the desired mobility model from the drop-down menu.
- Configure the parameters of the selected mobility model to match the specific movement pattern you want to simulate. Use a File-based mobility model where you can specify the UE position over time with the format time(s), Device/UE ID, X, Y, Z. The unit of X, Y, and Z is meters.
- Run the simulation and monitor the UE movement trajectories in NetSim Animation/Logs.
Ping pong handover occurs when a mobile device frequently switches between two base stations. This happens when the signal strength from both base stations is similar.
This needs careful configuration. You would need to place the UE close to the boundary between the two base stations. Then set the mobility path of the UE such that the UE repeatedly connects to Base Station 1 (BS1), then Base Station 2 (BS2), back to BS1, and so on.
To check that the UE is near the boundary between base stations, enable radio measurements and examine the SINR received by the UE from both BS1 and BS2. You might need to perform a few iterations to accurately determine the initial position and mobility path.
Setting up user-defined trajectories to model handovers between cells, ping-pong handovers, etc, can be achieved using the File-Based Mobility model that NetSim supports. You can configure a specific movement trajectory by providing the appropriate coordinates for the devices in an excel file. What makes this powerful is the convenience it offers in using Excel’s feature set to the input values. Let’s say you want the UE to go from left to right. You can set the initial two coordinates in excel and then use the drag-and-pull functionality in excel to generate the rest.
For more details see the Mobility model help and a simple example involving handover in 5G from the below links: https://tetcos.com/help/v13.3/Technology-Libraries/MANETs.html#file_based_mobility_model https://tetcos.com/help/v13.3/Experiments-Manual.html#simulate_and_study_5g_handover_procedure_level_2
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