LTE KPI's (Key Performance Indicators)

Key Performance Indicators of KPI's are indicators for if a device or equipment meets a certain reliability criteria for being ready for deployment.

In [1] the following KPI's are defined

• Accessibility
• Retainability
• Integrity
• Availability
• Mobility

[2] gives the requirements related to the above KPI's. Take for instance Accessibility, [2] defines the requirements as follows:

Business level requirements: If an end user cannot access a service it is hard to charge for the service. Also, if it happens often that an end-user cannot access the provided service, the end-user might change wireless subscription provider, i.e. loss of income for the network operator. Hence, to have a good accessibility of the services is important from a business point of view. This measurement assists the network operator with information about the accessibility provided to their customers.

Specification level requirements: The accessibility of an end-user application covers a wider area than just the E-UTRAN part. Hence it is important to realize that a KPI for this in E-UTRAN shall be limited to the parts that E-UTRAN has control of, i.e. the E-UTRAN KPI shall be defined so that it indicates the E-UTRAN contribution to the end-user impact, NOT attempt to take responsibility of the whole end-to-end part of service accessibility.

The service provided by E-UTRAN for this KPI shall be E-RAB. It shall be possible to measure the accessibility of E-RABs in E-UTRAN. Accessibility measurement should be available as a success rate for the attempts. 

As for defining an attempt, it shall be considered an attempt first when the eNodeB can be certain that is a request for an E-RAB. As for defining a success, it shall be considered a success when the eNodeB have completed its task to setup resources and the result of the E-RAB establishment can be informed to the requester of the E-RAB. The KPI shall be available per QoS group.

Use case description: In providing end-user services to wireless end-users, the first step is to get access to the wireless service. First after access to the service has been performed, the service can be used. If an accessibility measurement is not considered OK, then the network operator can investigate which steps that are required to improve the accessibility towards their customers. This measurement should be used for observing the impact of E-UTRAN on end-users service accessibility.

From the above, we can create certain tests to test the Accessibility KPI. Example cases as follows:

1. RRC Connection Setup for Registration success rates

2. RRC Connection Setup for Services success rates

3. Initial E-RAB Setup Success rates

4. Successive E-RAB Setup Success rates

5. Call (VoIP) setup success rates

[1] 3GPP TS 32.450: Key Performance Indicators (KPI) for Evolved Universal Terrestrial Radio Access Network (E-UTRAN): Definitions

[2] 3GPP TS 32.451: Key Performance Indicators (KPI) for Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Requirements