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

RSRQ is used to determine the best cell for LTE radio connection

RSRQ is used to determine the best cell for LTE radio connection at a certain geographic
location. However, while RSRP is the absolute strength of the reference radio signals, RSRQ is
the signal-to-noise ratio. Like RSRP, RSRQ can be used as the criterion for initial cell selection
or handover. If a UE changes its location or if radio conditions change due to other reasons and RSRP (i.e., the absolute signal strength of the reference signals) remains stable or becomes even better than before.
Similar to what was described for RSRP, for RSRQ also three quality ranges can be defined, but the
numbers here are still very uncertain since no loaded network environment has yet been monitored,
due to the fact that the number of calls and location of subscribers are limited during field trials. All in
all, it seems that in general RSRQ values higher than−9 dB guarantee the best subscriber experience.
The range between−9and−12 dB can be seen as neutral with a slight degradation of QoS, but
overall customer experience is still at a fair level. Starting with RSRQ values of−13 dB and lower,
things become worse with significant declines of throughput and a high risk of call drop.

RSRP is used to measure the coverage of the LTE cell on the DL

RSRP is used to measure the coverage of the LTE cell on the DL. The UE will send RRC measurement
reports that include RSRP values in a binned format. The reporting range of RSRP is defined from−140 to−44 dBm with 1 dB resolution.
The main purpose of RSRP is to determine the best cell on the DL radio interface and select this
cell as the serving cell for either initial randomaccess or intra-LTE handover. The RRC measurement
reports with RSRP measurement results will be sentby the UE if a predefined event trigger criterion
is met
RSRP measurement results can be categorized in three ranges.
If RSRP>−75 dBm, excellent QoS can be expected as long as not too many subscribers struggle for
the available bandwidth of the cell. In the range between −75 and−95 dBm a slight degradation of
the QoS can be expected, for example, throughput will decline by 30–50% if RSRP goes down from
−75 to−95 dBm. Below−95 dBm the QoS become unacceptable and throughput tends to decline
down to zero at approximately−108 to−100 dBm. Under such radio conditions, call drops must be
expected as the worst case.

LTE KPI Measurement Methodology and Acceptance Procedure

Here I write in simple word on LTE KPI Measurement Methodology and its Acceptance Procedure. As it’s for only at network start up stage and now a day worldwide so many operator starts to launch LTE and so this is the way for them to check of KPI in LTE

LTE KPI Measurement Methodology

The KPIs are formulated to measure the network performance in terms of Accessibility, Integrity, Mobility, Retainability, and Subscriber perceived quality.

LTE KPIs are mainly classified into 5 classes, which are, Accessibility, Retainability, Mobility, Latency, and Integrity. The KPI architecture is shown in the following figure.

The above KPI classification fully considers the customer experience and focuses on the Quality of Experience, providing a wide range of network KPIs to reflect network factors that are relative to the service quality, using industry standards as reference to define network counters and KPIs.

LTE KPI Acceptance Procedure

LTE network KPI acceptance procedure for the two phases, preliminary acceptance and final acceptance, are recommended as shown above.

During the phase of preliminary acceptance before commercial launch, KPIs will be derived from the drive test analysis and stationary measurements, and this analysis and measurement are on the basis of cluster which constitutes a group of sites (20-40 sites).

Statistics KPIs are not proposed and measured at this stage as the traffic is insufficient, statistics will not eligible statistical result without enough samples.

After on-going optimization while the traffic keeps increasing after commercial launch, the final acceptance of the whole network performance on the basis of statistics will be implemented. However, the KPI values of statistics probably might not be same with those in drive test due to different calculations and considerations.

LTE Service KPIs and LTE Network KPIs

The Field Test KPIs into two categories: LTE Service KPIs and LTE Network KPIs.

Service KPIs are the KPIs that are not subject to be effected by cluster tuning and optimization activities, mainly determined by product performance, configuration and parameter setting, e.g. ping delay, throughput, etc. I recommend that only one cluster (named pilot cluster) is selected for the evaluation and acceptance for the Service KPIs, no necessary for repeating the measurement in all clusters Based on the above reasons, the Service KPIs’ test is suggested to be performed by Stationary Test (ST) in the area with good RF conditions and close to the cell in order to eliminate the affect of poor RF or non-equipment factor and the test is proposed to be implemented under the condition of one serving cell.

LTE Network KPIs, such as Call setup success rate, Call Drop Rate, HandoverSuccess Rate, which is determined by the radio network environment, planning and optimization capabilities, should be performed on the Drive Test (DT) routes in rollout clusters.

KPIs for LTE

KPIs for LTE and you might be interested in. 

eRAB Establishment Success Rate (%) 
Abnormal eRAB Release (%) 
Total number of eRABs (per cell) 
RRC establishment Success Rate (%) 
Intra LTE mobility Success Rate (%) 
Connected Users License capacity limit (per RBS) 
Average percentile of Connected Users License utilization (per RBS) 
Connected Users License (CUL) Time Congestion (per cell) 
RRC Failure Rate due to CUL (per cell) 
Peak number of Connected Users (per cell) 
DL Baseband Capacity utilization per RBS (%) 
UL Baseband Capacity utilization per RBS (%) 
Average DUL main Processor Load (%) 
Peak number of UE in RRC_CONNECTED mode 
Number of neighbour relations added by the ANR function 
Number of neighbour relations removed by the ANR function 
PDCCH utilization per cell (%) 
Average UE DL Throughput (Mbps) 
Average UE UL Throughput (Mbps) 
DL PDCP volume per cell (kilobits) 
UL PDCP volume per cell (kilobits) 
Average cell throughput (PDCP DRB) DL (kbps) 
Average cell throughput (PDCP DRB) UL (kbps) 
Max UE DL Latency (ms) 
Physical Resource Block (PRB) 
DL Physical Resource Block (PRB) utilization (per cell) 
UL Physical Resource Block (PRB) utilization (per cell) 
Average Noise and Interference Power on PUSCH 
Average Noise and Interference Power on PUCCH