QoS and QoE in VoIP

QoS is mainly oriented to analyze the performance of the network and the media involved. On the other side, Quality of Experience (QoE) examines the point of view of the end user and how he perceives the value of the service. Though these two concepts are related, they have a substantial difference. In short, they refer to the perspective from which we measure quality in each case.

The transmission of Voice over IP networks (VoIP) has a significant role in the telecommunications world. Its use is increasing day by day. But VoIP still lacks the quality of traditional telephone systems. Is a crucial key business to understand that the end user’s quality expectations need to be accomplished, regardless of the technology.

Enabling the transformation to a Digital Service Provider is a complex undergoing. To learn what is needed, check out Intraway’s Vision for 2020 and beyond.

What do we Consider Quality in VoIP?

Quality in VoIP is the ability to listen and speak with a clear and fluid voice, without noise or unwanted delays. The big issue is that quality is often inherent in the use of the network (speed and bandwidth). It may be solved in the future but, in the meantime, we need to focus on understanding the issues.

As VoIP faces problems inherent to the networks, the end user perceives this network degradations as a poor Quality of Experience (QoE). The causes of these degradations can be due to delays, jitter and packet loss, among others. It’s essential to ensure good quality for VoIP to monetize this technology massively.

How to Measure Quality in VoIP?

We can divide the developed methods into two groups:

Objective Method

This method is for QoS. Its objective is to analyze and quantify the quality from the network performance perspective. The voice services should be delivered with the appropriate quality. The measures of performance and quality used are objective parameters such as the percentage of lost packets, the delay (latency) and the variation of the delay (Jitter).

Subjective Method

This method is for QoE. Its objective is to analyze and quantify the degradation of the service from the end user’s point of view. It aims to make the service meets its expectations. The measure of performance and quality used is MOS (Mean Opinion Score). The MOS is expressed as a single rational number in the range 1-5. Here, 1 is lowest perceived quality and 5 is the highest.

As you see, it seems only a syntactic difference that refers to the same. In reality, they have a different conceptual approach, which is essential to know and apply. Intraway’s QX suite provides a tool that automates all the tests to have a clear vision of the network’s behavior. The experience of the end user is also contemplated to allow telecommunication companies to provide the best quality in their services.

VoIP Quality Tests

Intraway’s QX Suite VoIP Quality Tests are based on E-model (computational model for use in transmission planning). The ITU-T standard proposed this model. It provides a repeatable way to evaluate whether a network is ready to carry out a VoIP call with acceptable quality.

This model is suitable to ensure that users will be satisfied with end-to-end transmission performance. The primary output of the model is a scalar rating of quality named “Theoretical Range of Transmission Performance Rating Factor.” The R Factor contemplates the transmission degradation factors presented in the modern networks.

The R value goes from 0 to 100, where R=0 represents the worst quality and R=100 the best one. The value is finally transformed to the MOS score, reflecting the user’s level of satisfaction.

However, studies have shown that the E-model is complicated to apply for monitoring purposes. For this reason, we engineered a simplified version of this model. With the objective of generating a more practical, simple to deploy, and oriented to real quality monitoring scenarios, the Intraway QX Suite measures the following metrics:

• Latency

• Jitter

• Effective Latency

• Packet Loss

• R Factor

• MOS

This tool is used to simplify complex equations while maintaining the accuracy in the results of the values of the different indicators. It allows working with a valid, accurate and reliable tool to measure the QoS and QoE of the VoIP service.

In the next few years, IoT, 5G, dynamic services, autonomous networks, edge computing, AI-based operations and dynamic provisioning will all be part of our reality. Find out more about what the future holds for the telecom industry in Intraway’s Vision for 2020 and beyond.