VoLTE device manufacturers' challenge
Modem chipset designers and cellular device manufacturers need to characterize the performance of their products. Not just under ‘ideal’ network conditions, but also in the ‘real world’ of packet loss and jitter.
Network Operators too need to satisfy themselves about the voice quality delivered by new devices. And this is not only when the network has plenty of capacity, but also at times of peak traffic and cell loading.
In all cases, organizations must take control of the process by making detailed assessments to understand and optimize the performance of the products. And all this has to be done at the right time, before the costs and commercial implications reach unacceptable levels.
The RTP packet stream from the network to the VoLTE device may be subject to impairments including loss, jitter and mis-sequencing. The impairments have the potential to degrade the listening quality of the speech heard by the user. For this reason, QA engineers must quantify this for many combinations of impairment, codecs, bitrates and operating modes.
To be certain of separating cause from effect, your tests need to be 100% repeatable. Using a standard packet impairment generator does not achieve this, since it generates random impairment patterns.
Why is this important?
Codecs respond to and handle short durations of the sound elements in the speech signal. The characteristics of the human voice are such that the effect on listening quality of loss or other distortion depends on when it occurs in relation to the speech signal. The performance of the codec implementation must be assessed under diverse packet propagation conditions. If an issue is found or suspected, the ability to maintain precise impairment patterns is key: if any unfavorable behavior ‘escapes’ the QA process the consequences for product and brand reputation may be severe.
- 100% repeatability
- as many combinations as are required
- no need for a separate packet impairment generator
You may launch tests from the GUI or through the advanced API supporting TCP/IP, Python, Perl and TCL.
The MultiDSLA test system supports both SIP/VoIP and analog domains and makes test calls directly to a device under test (DUT), generating a clean or precisely impaired RTP stream. The analog interface collects the speech signal received at the DUT and the test system generates POLQA scores which accurately predict the Mean Opinion Score (MOS) for listening quality.
MultiDSLA works in conjunction with a base station simulator or lab base station with IMS server, as shown here:
Contact us to learn how Opale’s test systems can bring repeatability and precision to your VoLTE modem or device testing.