VoLTE – Ensuring High Performance and Quick Troubleshooting

VoLTE – Ensuring High Performance and Quick Troubleshooting


The deployment of LTE and LTE-Advanced mobile networks – also known as 4G wireless networks – is expanding rapidly. While data and video are consuming a growing portion of the network resources, voice is still the most critical service of a mobile subscriber, and one for which customers will not tolerate interruptions and service degradation. The IMS architecture is changing the way voice services are delivered to mobile customers, with VoLTE taking over the traditional voice technologies.

To verify adequate VoLTE performance and troubleshoot its issues whenever they occur, it is essential for the mobile service provider to have visibility into the voice traffic and its control signals throughout the whole network, from the voice server, through the different segments of the core network, and through the access network up to the customer's handset. As various service providers have told us, one of the most critical areas where this visibility is needed is the air interface, commonly known as the Uu interface, because it is the only measurement point that clearly allows them to isolate if the source of a problem is in the handset itself or elsewhere in the network. The importance of this visibility is enhanced by the fact that the air interface is often the source of the service-related issues, resulting from factors like radio interference, marginal SNR values in some locations, performance differences between different UE models etc.

Furthermore, disconnections and performance degradation in voice calls may only be the symptom of deeper underlying problems. Marginal performance at the physical layer, frequent RRC re-establishment attempts or delays in network accessibility are additional symptoms, which on their own may have a smaller direct impact on the customer, but are very valuable for the service provider as indications about the underlying cause for the voice call problems.

Thus, a measurement tool that looks into the air interface and provides an unbiased view into the full LTE protocol stack, from the physical layer through the MAC, RLC, PDCP, RRC and NAS messages and up to the IP layer and the VoLTE control messages is essential to ensure adequate VoLTE performance and quick troubleshooting of issues when they occur. If such a tool would not only present the information, but also analyze it and point out potential failures, then it could significantly ease the troubleshooting process, shorten the troubleshooting time and ensure that the real root cause of the problem is identified. You can check our partners online slots.


Troubleshooting of VoLTE and ensuring its performance are one of the areas that we at TraceSpan are addressing with our LTE-Advanced Xpert analyzer. The approach we took is exactly the one mentioned above – passive sniffing of the signals directly from the air interface and analysis of the full protocol stack from the physical layer, through the MAC and control layers and all the way to the user data, and all this in a single comprehensive and unbiased tool.

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