Test Solution for VoLTE

09 March 2012 – At the Mobile World Congress 2012, Rohde & Schwarz demonstrated a new VoLTE (voice over LTE) signaling and audio quality test solution for network operators and user equipment manufacturers. The latest Rohde & Schwarz test solution for LTE is based on the R&S CMW500 wideband radio communication tester with new options and the R&S UPV audio analyzer.

The R&S CMW500 emulates an LTE network and the R&S UPV assesses the voice transmission and voice quality of the LTE user equipment according to an objective set of test criteria. The analyzer uses a state-of-the-art perceptual objective listening quality analysis (POLQA) measurement algorithm to perform this task. The solution also tests whether the LTE user equipment can signal a voice call and how it performs under realistic network conditions.

The R&S CMW-KAF10 option is particularly aimed at equipment developers who deal with the relevant R&D scenarios for VoLTE. The R&S CMW-KAC10 option is designed for carrying out conformance tests. Rohde & Schwarz offers test cases for text messaging (SMS) services over LTE as well.

Along with the new options on exhibit at the Mobile World Congress trade fair, Rohde & Schwarz will be presenting another milestone for the implementation of VoLTE. For the first time, the R&S CMW500 makes it possible to verify the handover of a VoLTE voice channel from LTE to WCDMA in line with the single radio voice call continuity (SRVCC) standard. The SRVCC standard specified by 3GPP describes how user equipment can perform the handover from the LTE packet switched bearer to a WCDMA circuit switched bearer during an active VoLTE voice connection. This ensures that the connection does not drop when changing bearer services, even if there is insufficient LTE network coverage.

Because LTE is an IP-based network, it did not originally support voice and SMS services. The focus was instead on mobile data services due to LTE’s high transmission rates and large capacity. Until very recently, LTE-compatible user equipment handled voice calls by switching automatically to other mobile radio standards such as GSM or WCDMA. VoLTE now provides for LTE voice services that are based on IP multimedia subsystems (IMS). Network operators and manufacturers of mobile user equipment are using this technology in order to fully utilize the LTE infrastructure in the future.

In 2008, Rohde & Schwarz became the first supplier to validate test cases for the IMS call control feature developed by GCF and PTCRB, making the solutions for voice and SMS over LTE a logical step toward expanding the range of IMS products. One additional benefit of the new test solution is that it is based on the R&S CMW500 multistandard platform. As a result, manufacturers, network operators and test houses can use a single device to conduct RF, protocol, performance and application tests, which allows them to utilize their test equipment resources in optimal fashion.

The R&S CMW-KAF10 and R&S CMW-KAC10 options are now available from Rohde & Schwarz.