GSM Handover

You simulate GSM handover to understand how an ongoing call is transferred from one channel to another.

The network you model from the example configuration file meets the following specifications:

  • A network with 2 BTSes, 1 MSC, and 2 mobile stations and a unicast application running on one of the mobile stations.
  • The mobile stations are placed within the range of the BTSes. NetSim uses the following defaults for this example:
  • BTSes and mobile stations stationed on present locations in the grid.
  • Mobile_Station_4 moves with a random walk model set at 20 meters/second.

To simulate GSM handover in NetSim: Open NetSim and click Examples > Cellular Networks > GSM Handover then click on the tile in the middle panel to load the example as shown in below.

Figure3-1

The following network diagram illustrates, what the NetSim UI displays when you open the example configuration file see below Figure

Figure3-2

  1. See that by default NetSim has placed 2 BTSes: Base_Station_2 at (300, 200) and the Base_Station_3 at (500, 200).
  2. See that by default NetSim has placed 2 mobile stations: Mobile_Station_4 at (420, 400) and the Mobile_Station_5 at (500, 300).
  3. See that by default NetSim has assigned a mobility model and velocity of movement to both mobile stations. To do so:
    a. Right-click Mobile_Station_4 and click Properties.
        The Mobile_Station_gsm pop-up window appears.
    b. NetSim has set the Mobility_Model to RANDNOM_WALK and the Velocity(m/s) to 20 meters/second.
    c. Click OK.
    d. Repeat steps (a), (b), and (c) for Mobile_Station_5. In step (b) change the velocity to 0 meters/second.
  4. See that by default NetSim has configured the unicast application. To do so:
    a. Click Application on the toolbar.
        The Configure Application pop-up window appears.
    b. NetSim has specified 4 in Source_ID field.
    c. NetSim has specified 5 in Destination_ID field.
    d. NetSim has specified 1 (second) in the Inter_Arrival_Time (in the CALL area) field.
    e. NetSim has specified 1000 (seconds) in the Duration field (in the CALL area).
    f. Click OK.

The following figure illustrates step (d) and (e) as shown Figure 3-3

Figure3-3 5. Simulate GSM handover. To do so:
    a. In NetSim GUI Plots are Enabled.
    b. Click the Run icon located on the toolbar.
        The Run Simulation pop-up window appears.
    c. Retain the default settings in the Simulation Configuration tab (Simulation Time = 250).
    d. Click OK.
        After NetSim simulates GSM Handover, NetSim displays the Simulation Results window.
6. Interpret the results. To do so:
    a. Click View Animation on the toolbar and view the packet animation.
        You will see Mobile_Station_4 undergoing the handover process from Base_Station_2 to Base_Station_3.
    b. Click Cellular metrics > MS Metrics in the left area and check the Detailed View check box in the MS Metrics_Table as shown in below Figure

See the Handover Request the Mobile_Station_4 sent.
The following figure illustrates step (b).

Figure4-3

Note: GSM handover happens by distance from the BTS, that is, hard handover. LTE handover happens by the signal-to-noise ratio (SNR), that is, soft handover.