Network Monitoring Challenges and Solutions Regarding the VoLTE Service

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Dr. Varga Pál
Department of Telecommunications and Media Informatics

With the spread of the fourth generation mobile network deployments, there is a general demand for further developments to expand and enhance the capabilities of mobile telephony. Nowadays, the increase of bandwidth, the extension of ultra-broadband services and the improvement of sound quality are the desired drivers for progression trends. Voice transmission over LTE (VoLTE) provides many benefits for its users. We can benefit from the advantages of LTE only in the field of data services in Hungary. We can access to the intended data to download with significantly higher speed than before. On the other hand, since the voice services over 4G have not been made available at the time of the present paper, the incoming calls make the device to switch down to 3G or 2G networks.

When the user’s device is operating in LTE (data connection) mode and a call comes in, the LTE network pages the device. It falls back to 2G/3G to accept the incoming call, because voice over 4G service is not publicly available during the writing of this paper. The use of the so called CS fallback (Circuit Switched fallback) requires more time and intensive battery use by the searching of new network.

The actual implementation of the VoLTE service generates new elements and perspectives in the signalling network, as well. Between mobile entities, new connections are generated, and thus the messages contain new parameters through the monitoring of previously unknown communication interfaces. During a call over VoLTE, the signals and messages are travelling from the LTE core network to the IP Multimedia Subsystem. We can follow the call flow through different protocols with the help of a proper signalling monitoring system. In a more complex system the troubleshooting is an even more difficult task. Service providers intend to find a fast and simple way for the identification of potential failures. Those monitoring system suppliers who best understand the requirements and obstacles are able to provide the best solutions.

The current paper shows and explores the different troubleshooting and analysis methods across a monitoring system through test calls over VoLTE. This is shown through utilizing monitoring systems that proved their feasibility for the current network structure. Furthermore, this paper also provides a recommendation for automating the workflow, in order to avoid the unknown errors caused by initial problems before the technology gets widely used and public.


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