Assessing QoE: Another Solution to Network Optimization

With the development of mobile networks, customer needs and behaviors have changed. Mobile communications means so much more than simple voice communication; there is now mobile Internet with web surfing, video phone, streaming media, and microblogging. Traditional KPIs are no longer adequate for measuring the quality of mobile services. The objective of network optimization has gradually shifted from enhancing network performance to improving quality of experience (QoE). Therefore, assessing and optimizing QoE is the trend for optimizing future mobile networks.

QoE is the quality of network and services that a customer actually experiences. It encompasses the technical performance of the network as well as customer behavior features, service provider brand image, service quality, and prices.

In the case of coexisting 2G and 3G standards, network assessment and optimization are often independent, making it impossible to accurately assess customer experience. Therefore, it is vital to develop a comprehensive and scientific means of assessing and optimizing QoE.

Assessing QoE in a Multinetwork Environment   

In a mobile network, where multiple networks coexist, most users of dual-mode terminals experience trouble with multinetwork convergence. They do not know how to operate between networks nor do they care about what standard the network uses. Their only concern is whether the network signal is strong enough and whether they can access network quickly.

After years of in-depth research into QoE, ZTE has worked out an innovative system for measuring and assessing customer QoE in a multinetwork environment (Fig. 1).

The QoE assessment system is a mapping system comprising KPI, KQI, sub-QoE, and QoE layers. It supports data from multistandard networks and combines multiple networks on the KQI layer. 

Assessing QoE with NetMAX

ZTE's NetMAX solution is designed to assess the QoE of a radio access network (RAN). The solution is low cost but cannot distinguish specific packet-switched services. It is mainly used in small and medium-sized networks and is currently being implemented by China Mobile in Hunan. The solution has the following functions:

• overall QoE assessment. Customer QoE can be rated excellent, good, fair, poor, or bad (Fig. 2). Detailed statistics can be shown for each customer's KQI and sub-QoE and for overall network QoE. Optimization staff can determine each customer's QoE and optimize the network with poor QoE.
• QoE correlation analysis. If a customer has poor QoE, optimization staff can use correlation analysis to view a customer's QoE in each cell. They can quickly locate the cell where the customer has poor QoE and determine the causes, which may be poor coverage, poor accessibility, call drop, or poor call quality.
• KQI trend analysis. It may be necessary to analyze the point at which customer KQI begins to drop. By analyzing KQI trends, optimization staff can clearly see the changes in customer KQI over time and optimize the network using a definite target. After optimizing the network, they can determine whether customer QoE is improved by observing the changes in customer KQI.

CEMC End-to-End QoE Assessment

ZTE’s customer experience management center (CEMC) is a QoE assessment platform for multistandard networks and multiple data sources. It provides end-to-end monitoring for RAN, CN and VAS. It is mainly used in large-scale carrier networks.

CEMC uses self-adaptive linear-weighted fitting algorithm to minimize the mean-square error between the QoE model and customer questionnaires. The CEMC system is highly automatic:

• It can be used in independent 2G and 3G networks as well as hybrid 2G/3G networks. In the future, CEMC QoE assessment will also be used for CDMA, LTE and other network standards.
• Performance, signaling, MR/CDT, and UBAS data can be imported.
• It supports voice, VP, SMS, HTTP, WAP, FTP, streaming and MMS. It also supports customized services.
• It assesses customer QoE using the four-layer QoE/Sub, QoE/KQI/KPI mapping system. Through innovative computer fitting of customer questionnaires, a mathematical QoE model closest to actual customer experience can be obtained.

CEMC can be used to assess QoE from a whole-network level down to a region, cell, or customer level. In some carrier networks, it can also provide

• real-time QoE monitoring for the whole network. This allows optimization staff to easily obtain the real-time QoE assessments in order to promptly identify where QoE is deteriorating.
• QoE assessment for VIP customers. CEMC can define VIP customers, assess and monitor their QoE in real-time, perform end-to-end assessment of eight basic services, and display the results in graphs.
• real-time alarm. When QoE is deteriorating, alarms are sent via email or SMS to optimization staff so that they can check and optimize the network in real-time.

Drawing on years of experience in network optimization, ZTE has developed a QoE assessment system for a multinetwork environment. The NetMAX solution is designed to assess and optimize QoE in small and medium-sized networks. It is also low cost. The CEMC end-to-end QoE assessment solution is used in large-scale carrier networks. ZTE is dedicated to providing innovative technologies that make QoE measurable and assessable and improve customer experience.