## 5 VoLTE Network Experimental Implementation
### Experimental Platform Configuration and Test Tools  
This section presents the configuration, preparation, and test tools that we have used in our experimental platform. OAI Public License V2.1. software can combine all the relevant functions of the structural elements of SGW and PGW into the same executable program, while HSS and MME are separate entities. The above elements have been installed on the EPC host PC. The only physical connection made during our experimental stage was the connection between the EPC and the eNB. The HSS serves as the database containing subscriber and UICC connection information for network access. MySQL local and PhpMyAdmin (apache2) databases were installed on the EPC for \"HSS.PhpMyAdmin's\" graphical user interface for ease of use. After defining the user and password for database access, installation was completed, and accessibility to the database was checked at \"[[http://127.0.0.1/phpmyadmin/](http://127.0.0.1/phpmyadmin/)]([http://127.0.0.1/phpmyadmin/](http://127.0.0.1/phpmyadmin/))\". A new database named \"oai_db\" was created, and its data were imported from the HSS path (openair-cn\src\)\(\oai\_hsss\)\(\db\)\(\oai\_db.sql\)) into PhpMyAdmin. The \"mme_identity\" component facilitates connection and mobility management for LTE networks while supporting subscriber identity control. Before the UICC card programming, a user was registered for network access. Operational entities of the EPC (MME, HSS, SPGW) were configured for the network, and necessary certificates were ensured to be active before starting tests.  
The three terminal windows correspond to HSS, MME, and S-PGW, providing us with information about the status of our network and the stations connected to it, including the connection between eNB with the USRP and eNB with the UEs. The Asterisk server provides a console that displays the necessary Session Invitation Protocol (SIP) peers of the network's registered and connected UEs. Also, it presents the traffic of the UE's listening port. Moreover, it reports the UE's status (online/offline). The Asterisk console is one of the most essential tools for monitoring calls and real-time issues, as it enables the detection and resolution of any problems that may arise. During the experimental procedure, we used Asterisk to make VoIP calls over the LTE network, leveraging VoLTE technology. Through Asterisk's console, we gained a comprehensive view of the call's duration and timestamp per call when they were made, as well as any errors that occurred.  
After the successful UE network registration, we ensure the monitoring of LTE packets on our private network by using the WireShark application, a useful LTE network analysis tool. In this experimental part, we monitored the packets exchanged between LTE layers, confirming the established network QoS. Additionally, using the WireShark open-source V3.6.22 software, we can prevent many security issues by monitoring the network traffic and packet losses. To provide internet services to the UEs, we had to connect the EPC to a public internet provider, as seen in Figure 13.  
To conduct a study on the network's speed, both in terms of download and upload, as well as losses, we used the free SpeedTest application installed on each device. Table 14 depicts the SpeedTest results for two UEs, while other parametrizations should be tested to reduce the ping time.  
Figure 13: Public Internet provider diagram.  
Finally, we used the OAI Soft Scope, a tool provided by OAI, to analyze and visualize the functionality of wireless communication systems. To test the above network tools and perform tests, an SDR base station, two smartphones, and a local host PC were used. The registered smartphones were separated 4 m from each other and 2 m from the base station, inside an RF laboratory.