# Call Model and Test-Verification Methods for PS-LTE Core Equipment
## 3 Field Test Scenarios for MCPTT and eMBMS
### eMBMS Field Test Scenarios  
The core component of eMBMS is multicast-broadcast single frequency network (MBSFN) transmission technology, which can simultaneously transmit the same data from different base stations. Multiple cells can be operated as one large cell using MBSFN technology by simultaneously transmitting the same data across multiple cells adjacent to each other. The set of cells that transmit the same data through the MBSFN transmission technology is called an MBSFN area, and several MBSFN areas are gathered to form an eMBMS service area. MBSFN areas can be configured up to 256, and each cell can be a component of up to 8 different MBSFN areas. Unicast-based MCPTT group calls should allocate as many bearer resources as the number of terminals, but eMBMS-based MCPTT group calls should allocate as many bearer resources as the number of groups [19; 20]. The resource allocation of base stations for eMBMS services can freely switch between unicast and multicast methods, and DSCNs in the format of frequency division duplex can be allocated up to 60% of the resources. For group video and voice services per temporal mobile group identity (TMGI), 600 and 80 Kbps of resources are allocated, respectively, and TMGI has unique values for each eMBMS bearer, i.e., by group. Tests are performed on a total of 50 terminals: 15 from manufacturer A, 15 from manufacturer B, 10 from manufacturer C, and 10 from manufacturer D. For organizing MCPTT groups in command devices, unicast group (50 terminals) and multicast group (50 terminals) are organized, and the area code for MBMS is set. For setting the eMBMS service area, the MBSFN area (1 cell) is configured with a single unit of radio unit for the National Information Society Agency  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Manufacturer** & **Service** & **KPI 1 (ms)** & **KPI 2 (ms)** & **KPI 3 (ms)** \\ \hline A & & 23 & 271 & 170 \\ B & Group voice & 29 & 331 & 247 \\ C & & 27 & 331 & 263 \\ D & & 42 & 402 & 248 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Test results of MCPTT for KPI 1/2/3.  
Figure 6: Test composition for KPI.  
(NIA) testbed, and for the MBSFN area, it is configured with a separate MBMS service area and an MBSFN sync area. For the call group in which the terminals are organized, the service area is set up in the BM-SC, and the MBSFN and synchronization areas are set in the MCE and digital unit. The configuration diagram of the service networks for the eMBMS test is shown in Figure 7.  
As shown in Figure 8, when MBMS service packets are analyzed, the MCPTT server that receives the message of MBMS listening status report should check the message (1-4 in Figure 8), which instructs the MCPTT client to use MBMS for receiving downlink data from the corresponding MCPTT service. Checking whether normal traffic is transmitted to multicast groups rather than unicast IP addresses is essential through the packet analysis of MBMS.  
For the eMBMS, as the networks are established and the terminals are released without testing the service networks and terminal, user-based testing should be performed in an area receiving electric waves from DSCNs. Moreover, handover testing between the DSCNs and commercial networks should be performed to check whether unicast and multicast traffics are received normally. The multicast channel scheduling period of the terminals and service networks should also be checked in advance to prevent the situation of replacing hardware due to nonsupporting functions in the future.  
Figure 8: Logs of eMBMS.  
Figure 7: Configuration diagram of eMBMS-based service network.