How to solve VoLTE quality problems

Users expect high-quality voice from VoLTE.
Users expect high-quality voice from VoLTE.

Welcome to the Mobile Voice Optimization blog, which will be published monthly.

OTT VoIP may be the mobile network operators’ (MNOs) biggest challenge ever, threatening to change the landscape of the mobile industry forever. Voice services have been the cash cow of the industry, not only generating over half the revenue but more importantly the lion’s share of earnings. In addition, since voice quality and coverage are the leading causes of churn, VoLTE quality will impact churn.

Another major MNO challenge is the requirement to offer high enough service quality to VoLTE early adopters to gain acceptance and convince these early adopters to recommend VoLTE to their friends and colleagues. Therefore, if VoLTE is going to succeed and be used by MNOs to combat the threat of OTT VoIP these VoLTE early adopters need to be treated as VIPs.

LTE is significantly more efficient than previous technologies, but since it’s based on an all-IP network, it requires voice calls to traverse the network utilizing VoIP. As everyone knows, VoIP calls struggle to guarantee service levels, but that’s exactly what’s required if MNOs are going to match the service quality level of existing circuit switched calls. VoLTE quality problems fall into 3 categories as follows:

  1. Call set-up failures – VoLTE utilizes IMS (to set-up the VoIP sessions), which is extremely complex.
  2. End to End QoS – Congested cells cause havoc with VoIP calls; therefore, the dedicated bearer to deliver guaranteed bandwidth even when the rest of the cell is congested must be monitored.
  3. Cell Edge Issues – LTE networks are still wireless networks and have the same RF issues as other wireless networks. Therefore when a VoLTE user is on the edge of the cell interference and noise increases often times above acceptable thresholds.

MNOs have automated LTE call trace and bandwidth verification tools to manage the first two categories above, but RF optimization is still very much a manual task. Today, VoLTE is optimized in the same manner voice calls have been optimized for years, but VoIP calls are much more susceptible to higher levels of bit errors caused by noise and interference that change constantly on the edge of LTE cells. Existing optimization methods such as drive testing and walk arounds are just not sufficient to meet the quality threshold required for VoLTE calls. The problem is VoLTE users on the edge of the cell can experience a worse user experience than VoLTE users in the rest of the cell.

A new optimization solution is required in order to automatically monitor VoLTE call quality for every user in real time. The platform needs to provide real-time incremental network adjustments to resolve these issues with a real-time feedback mechanism that verifies results.

Only with such a platform will MNOs resolve the problems associated with the third and most challenging VoLTE quality problem category and harness its ability to combat the OTT VoIP and churn challenge. At Optulink, we’re working to make sure MNOs get what they need to be successful in the VoLTE transition.


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