Sachidananda Sahu

Introduction

Why SON

SON In LTE

Drivers for LTE SON

LTE SON Features

LTE SON Framework

LTE SON Architecture

Self Configuration Use Case

PCI Planning Use Case

ANR Use Case

MRO Use Case

Other LTE SON Features

Conclusion

References

Processes of self-organization literally create order out of disorder~Francis Heylighen

Self Organizational Network express itself that it organizes the network automatically and reduces the manual intervention.

SON is a collection of procedures or functions for automatic configuration, optimization, diagnostication, and healing of networks.

Things under consideration

Material (Spectrum, Equipment, etc.) - With what things we will do the work.

Human (Engineering time) - Who will do the work.

The NGMN (Next Generation Mobile Networks Association) first published its SON requirements in 2006.

The concepts quickly picked up by 3GPP in 2008 and rolled into the LTE standardization activities.

Starting with Release 8, 3GPP defines interfaces for SON built upon existing management architecture.

Successive 3GPP releases incorporates additional SON features tracking the expected network evolution stages in time.

Specification for SON and its use cases

TS 36.300 : E-UTRAN Overall Description

TR 32.821 : Study of SON related operation and OAM for home eNB.

TR 32.500 : SON Concepts and Requirements

TR 36.902 : Self Configuring and Self Optimizing Network use cases and solutions

Reducing manual intervention or least possible human interaction.

Atomization of repetitive process.

Improve runtime operation/optimization based on real time data analysis.

Improving user experience and network performance.

Reduction of OPEX, CAPEX and complexity.

Network with out SON Capability Network with SON Capability

SON Solution can be divided in to three categories

1 Self Configuration

2 Self Optimization

3 Self Healing

SON Features Proposed by NGMN

LTE SON Features …

1 Self Configuration

Self-configuration mechanism is desirable during the pre-operational phases of network elements such as network planning and deployment.

Self Configuration Use Cases

Plug & Play : IP Address allocation, Authentication, Software and Configuration Download from OAM, Establish connectivity with other nodes

Planning radio parameters of a new eNB: Physical Cell ID automatic configuration, handover & cell selection thresholds, power settings, etc

Planning transport parameters of a new eNB : SGW gateway nodes

Planning connection for all neighbor nodes: Automatic Neighbor Relation (ANR)

Self test

LTE SON Features …

2 Self Optimization

Self-optimization mechanism is desirable during the operational stage so that network operators get benefits of the dynamic optimization.

Self Optimization Use Cases

Neighbor cell list optimization

Evaluation/addition/deletion of existing neighbor cells

Intra/inter frequency and inter system neighbor cell list optimization

Interference control

Handover parameter optimization (MRO)

Load balancing

Energy savings

RACH load optimization

QoS related parameter optimization

LTE SON Features …

3 Self Healing

Detects problem and solve or mitigate those to avoid user impact.

Self Healing Use Cases

cell outage detection and compensation : Antenna tilt and the cell transmit power

self-recovery of network element (NE) software

self-healing of board faults

Self-diagnosis: create a model to diagnose, learning from past experiences.

Self-healing: automatically start the corrective actions to solve the problem.

Significantly reduce maintenance costs.

3GPP Proposed SON Framework

SON can be located as whole functionality block or even split in sub-functionality located in different nodes.

Localization of algorithm and control.

Centralized SON Distributed SON Hybrid SON

Process where newly deployed nodes (eNBs) are configured by automatic installation procedures to get the necessary basic configuration for system operation.

Self Configuration Procedure Flow

Automatically configure the Physical Cell ID of a newly introduced cell and also change the PCI to after detection of problem in PCI planning.

Things to consider :

Collison Free : The PCI of one cell should not be the same as those of his neighbor cells.

Confusion Free : The PCI of the neighbor cells should not be the same.

PCI A PCI BPCI A PCI A

Collision Based Collision Free

PCI A PCI C

PCI B

PCI A PCI A

PCI B

Confusion Based Confusion Free

PCI Planning Approach

Listen on Radio Interface (NLM)

UE assisted PCI detection

X2 Message Based PCI detection

3GPP Messages used for PCI Planning

X2 Set Up Request

X2 Set Up Response

Measurement Report

ENB Configuration Update

A Possible Solution

It aims to set up the neighbor relation automatically as much as possible.

ANR function relies on OAM and UE to report the neighbor cell information.• OAM’s significance

• UE Measurement Report

ANR with help of UE Measurement

A Neighbor cell Relation

• Source cell knows the ECGI/CGI and PCI of the target cell.

• Has an entry in the Neighbor Relation Table for the source cell identifying the target cell.

• Has the attributes in this Neighbor Relation Table entry defined, either by O&M or set to default values.

ANR Architecture Diagram

Problem

Manual setting of HO parameters in current 2G/3G systems is a time consuming task and it is also costly.

Incorrect HO parameter setting negatively affect user experience.

Solution

Automatically adjusting the mobility parameters Trigger thresholds, Time to trigger, Hysteresis, NRT, Antenna Remote Electrical Tilt etc

Detecting the cause of Reduce Radio Link Failures and unnecessary handovers and decrease those counts.

To enable adjustment of HO parameters , HO errors, reported by UE, can be notified to eNBs by backhaul signaling.

Too late handover

Too early handover

Handover to the wrong cell

Too Late Handover

• If the UE mobility is faster than the HO parameter settings allow for.

• RLF in the source cell before the HO was initiated or during HO procedure.

• Terminal re-establishes in a different cell than the source

Too Early handover

• RLF occurs a short time after the HO trigger to the target cell. The HO may or may not be

completely successful, depending on the over-the-air-messaging in the target cell.

• Terminal re-acquires the system in the source cell

Wrong Cell handover

• RLF occurs a short time after the HO trigger to the target cell. The HO may or may not be

completely successful, depending on the over-the-air-messaging in the target cell.

• Terminal re-establishes in a different cell than the source or target.

Mobility Load Balancing

To balance the load between neighbor cells, capacity and handover parameters information are shared between eNBs

MLB Functionality

Load is measured for each cell in its monitoring eNB and information is exchanged over X2.

An algorithm is applied to identify the need to distribute the load between two adjacent cells.

Handover and/or cell reselection parameters are adjusted to enable the load balancing.

Energy Saving & Interference Reduction

Decreasing power consumption of network elements and reduce greenhouse emission.

The ability of ENB to perform cell deactivation and reactivation based on cell load information and maintaining coverage, capacity and quality of service.

Interference reduction based on cell switch on/off which also increases capacity and quality.

Based on load server information SON server takes decision.

3GPP Supported Messages

Inter Cell Interference Coordination

Problem

DL Interference

UL Interference

Solution

Avoid Use of same PRBs

Co-ordinate use of PRBs

RACH Optimization

To reduce possible RACH (Random (Random Access Channel) Channel) resources collisions, so configuration information is shared between eNBs.

PRACH‐Configuration information is delivered by the X2 Setup and eNB Configuration Update messages.

Reduction of human intervention.

Real time optimization of network.

Control in OPEX and CAPEX for operator.

SON are flexible, adaptive, resilient, and scalable.

Merits of SON Operational Efficiency ~ Technology Graph

TS 36.300 - Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Overall description

TR 36.902 : Self Configuring and Self Optimizing Network use cases and solutions

Self-Organizing Networks (SON) in 3GPP LTE Nomor Research

The SOCRATES (Self-Optimisation and self-ConfiguRATion in wirelEss networkS) Project

Benefits of Self-Organizing Networks (SON) for Mobile Operators Journal

https://www.exploregate.com/

https://www.sonlte.com/

http://www.3gpp.org/

THANK YOU!