VoLTE is a new technology and is causing operators more problems than initially expected. One of the most common issues is Call Drop Rate when using VoLTE. Here are some main points to verify when tackling the VoLTE Call Drop problem in your network.
To reduce VoLTE drop rate it is important to assure LTE coverage and quality:
- In poor 4G RF coverage areas, such as tunnels, garages, basements or indoor areas operator should adjust SRVCC threshold to guarantee acceptable HO performance to 3G.
- Check if new sites are needed in specific areas or if radio conditions can be improved by adjusting tilt or azimuth.
- Consider activating features that will improve VoLTE retainability: TTI- Bundling, RRC connection re-establishment.
- Check parameter inconsistences associated with DRX settings, ROHC parametrisation, inactivity timers, etc.
- Check specific mobility parameterisation for QCI=1
- Check other frequency definitions as well as external cell definitions in case you are optimising a shared network.
- Check if MSS supports SRVCC request when VoLTE UE is in alerting phase. This feature will help to improve call drop rate in the network.
- Interference also affects VoLTE performance. Optimise the radio network to minimise or completely avoid internal and external interference.
- If none of the above works, contact 3dB consult. We have the experience to tackle any problems in your radio network: http://3dbconsult.com/en/contact.html