socrates key results ope... · introduction to socrates key results from ... – reallocate part of...

FP7 ICT-SOCRATES

SOCRATES key results

Presented by Neil Scully Vodafone

NGMN OPE workshop 15 June 2010

WWW.FP7-SOCRATES.EU

2/21

Neil Scully, Vodafone

Outline

  Introduction to SOCRATES   Key results from SOCRATES use cases   Potential SOCRATES input to 3GPP   SON coordinator concepts   SOCRATES focus for 2010

WWW.FP7-SOCRATES.EU

3/21


The SOCRATES project

  Collaborative R&D project with objectives: –  Develop solutions for LTE self-organising radio networks –  Drive standards to support these solutions

  EU-funded research project, started January 2008, and ends December 2010

http://www.fp7-socrates.eu

WWW.FP7-SOCRATES.EU

4/21


SOCRATES phases

Defining use cases, assessment criteria, reference scenarios and the framework

Development phase

Developing solutions for individual use cases

Integration phase

Integrating use cases into an overall solution

4

Requirements phase

This presentation focuses on the results of the development phase

WWW.FP7-SOCRATES.EU

5/21


SOCRATES use case results

Self-optimisation

Handover parameter optimisation

Self-configuration Automatic generation of initial params

Self-healing Cell outage compensation

5

SON enabler X-map estimation

Load balancing

Packet scheduling optimisation

Admission control optimisation

Interference coordination

HeNB handover optimisation

HeNB interference and cov. optimisation

To be presented

Back-up slides

NGMN OPE call 16/3/10

To be presented

To be presented



Back-up slides


Back-up slides

WWW.FP7-SOCRATES.EU

6/21


Handover optimisation: Introduction

  Problem –  Non-optimal handover performance

–  Handover failures –  Ping-pong handovers –  Call dropping

  Objective –  Automatic optimisation of the handover

performance   Approach

–  Analyse the system behaviour –  Develop handover optimisation algorithm

  Control parameters –  Hysteresis –  Time-to-Trigger

Ping-pong

time

HO Drop

X

WWW.FP7-SOCRATES.EU

7/21


Handover optimisation: Analysis of system behaviour

  The above figure is based on using the same parameter settings for all cells

  The developed optimisation algorithm tunes cells individually

WWW.FP7-SOCRATES.EU

8/21


Handover optimisation: Simulation results

  Performance is improved by the optimisation algorithm, relative to static parameter settings

WITHOUT SON WITH SON

WWW.FP7-SOCRATES.EU

9/21


Load balancing: Introduction

  Problem –  Users concentrate in the area served by one

cell –  Unequally load distribution causes overload

  Objective –  Reallocate part of users from overloaded cell to

less loaded neighbour cell   Target

–  TeNB increases overlapped area and takes over part of users previously served by SeNB

–  SeNB is able to serve remaining users with required QoS

  Control parameters –  Hysteresis –  Maximum HO offset –  Load that triggers LB –  Target Load at SeNB –  Target Load at TeNB

WWW.FP7-SOCRATES.EU

10/21


Load balancing: Simulation results downlink

  DL simulations

1) Regular network ISD = 500m

2) Regular network ISD = 1700m

3) Non regular network

WWW.FP7-SOCRATES.EU

11/21


Load balancing: List of target eNodeBs for load balancing

  We propose a decentralised load balancing solution –  All neighbouring eNodeBs are potential targets for load balancing –  The decision depends on the reported load situation from all eNodeBs

  A decision made by one individual eNodeB cannot take the larger network environment into account

  The central load balancing entity can report the cell load of the 2nd neighbours   The central entity provides guidelines on LB priorities

–  Cell 1 can obtain information about its neighbour cells over X2 –  Best target cells for cell #1 seem to be cells #3 and #7 –  Based on the overall load distribution available in

the central SON entity we generate a priority list for the load balancing event:

–  4 –  5, 6 –  3

–  Cell #7 is not on the list (LB to this cell is not allowed) –  Cell #3 has the lowest priority due to the load situation in cell # 2

  The central entity concept has been proposed in SA5 standards: –  S5-093243 –  S5-093922

WWW.FP7-SOCRATES.EU

12/21


X-map estimation: Introduction

  X-maps can be coverage maps, throughput maps etc.   X-maps aim at the interconnection of UE events and measurements with

the estimated UE position, and gather UE reports to build map relating geo reference data and metric of interest

–  X-maps can indicate path loss or interference –  Detection of coverage holes, service quality, traffic density –  Position data is expected to be available, e.g. through UE GPS information,

WCDMA positioning or LTE standard methods   SOCRATES X-map study and simulations aim at modelling the accuracy of

UE positioning techniques and measurements and to find ways to improve the accuracy of models

WWW.FP7-SOCRATES.EU

13/21


X-map estimation: General Concept Proposal

WWW.FP7-SOCRATES.EU

14/21


X-map estimation: Comparison of the different X-maps

Reference X-map X-map based on measurements X-map based on predictions

mean error standard deviation covered pixel

Approach 1 -0.1 2.1 22%

Approach 2 -3.0 6.8 100%

  In approach 1, error is only due to positioning error   In approach 2, error is due to positioning error and prediction model limitations   Based on GPS location

WWW.FP7-SOCRATES.EU

15/21


Use case conclusions

  Handover optimisation –  Handover parameters are chosen for every cell individually –  Using the proposed algorithm, the overall network performance is increased and

the handover failure ratio and ping-pong ratio drop to zero in the considered scenario

  Load balancing –  The proposed algorithm reduces the overload significantly of the cells and

increases the number of satisfied users –  The algorithm works on the measurements, information elements and control

parameters defined in 3GPP Rel. 9 –  UL power limitation is the most limiting factor for load balancing activities –  3GPP SA5 contribution: Central SON entity provide guidelines on LB priorities.

Keep a priority list based on load estimation. Discussion on-going.   Work on X-map estimation is still ongoing

WWW.FP7-SOCRATES.EU

16/21


Key conclusions from stand-alone use cases

  Performance gains from SON have been demonstrated –  E.g. handover optimisation, load balancing

  There are often trade-offs in the gains –  One metric is improved, while another metric is degraded –  Operator policy input is important –  E.g. admission control parameter optimisation

  In some cases, gains are marginal –  E.g. packet scheduler parameter optimisation

WWW.FP7-SOCRATES.EU

17/21


Potential for standardisation from SOCRATES results

  Load balancing –  Contributions on central entity (S5-093243, S5-093922) –  Exchange of open loop power control parameters for estimation of UL load

  Control and monitoring requirements –  For example, cell outage compensation: Specify user degradation at OAM level,

and send over Itf-N   Automatic generation of initial parameters

–  Centralised solution, so information exchange between OAM and eNodeB   X-map estimation

–  Related to RAN2 Minimization of Drive Tests activity   Implementation in eNodeB

–  Use cases such as admission control optimisation will be implemented locally in the eNodeB, and therefore do not require interaction with other eNodeBs

WWW.FP7-SOCRATES.EU

18/21


18

Why a SON coordinator is required

  In a system with multiple optimisation SON functions: –  Possible fights over the same parameters –  Possible fights over the same performance metrics

–  SON coordinator will identify and resolve conflicts

  Operator wants to input high level policy to SON optimisation –  E.g. access, fairness, variation in offered quality

–  SON coordinator will translate this for individual SON functions

  Risk that SON functions "go mad" –  SON coordinator will have a "guard function" to

detect and act upon undesired behaviour

WWW.FP7-SOCRATES.EU

19/21


19

Function blocks within the SON coordinator

  Policy –  Interface to operator –  Translates operator's high-level requirements –  Reports performance

  Autognostics – data source for SON functions –  Common source of OSS and UE performance data, configuration, etc –  Common manipulation, eg sliding window average, min, max, … –  Maintain history of changes

  Alignment –  Receives parameter change requests from SON functions –  Authorises changes and passes them out –  Detects and acts on parameter change conflicts –  Includes guard function to detect and act on undesired behaviour

WWW.FP7-SOCRATES.EU

20/21


Roles in SON Coordination

AUTOGNOSTICS

POLICY

ALIGNMENT Incl. Guard function

NETWORK SUBSYSTEM (e.g., eNB, neighbours, OSS, NMS)

OPERATOR

SON FUNCTIONS

POLICY interface

performance quality metric

change requests

objectives

feedback on performance

SON System

SON FUNCTIONS

SON FUNCTIONS

SON FUNCTION

specify data

requests

objectives & constraints

performance data

configuration changes

performance data

feedback & constraints

control parameter interface

raw measurements & configuration changes

Communication with peers

Note SON system will often be in the

eNB, but could be in any node

WWW.FP7-SOCRATES.EU

21/21


SOCRATES focus for 2010

  Further work on self-configuration and self-healing   Integration use cases: Combinations of two use cases where there is

either a control parameter conflict or an observability dependency. 1.  HO optimisation and load balancing 2.  Interference control and packet scheduling optimisation 3.  Admission control and HO optimisation 4.  Macro HO and Home eNodeB HO optimisation 5.  Automatic Generation of Initial Parameters and HO optimisation

  SON coordinator   Measurements, architecture and interfaces

–  Input to 3GPP standards   Demonstrations   Final public workshop planned for February/March 2011

SOCRATES is keen to continue interaction with NMGN during 2010

WWW.FP7-SOCRATES.EU

22/21


References

  For more details on the use cases, here are some useful links (links work best in presentation mode):

–  Handover optimisation –  Load balancing –  Packet scheduling optimisation –  Admission control optimisation –  HeNB handover optimisation –  HeNB interference and coverage optimisation –  Cell outage compensation –  X-map estimation

  For further information, please contact: Neil Scully Vodafone Group R&D E-mail [email protected] Phone +44 7919 994699

WWW.FP7-SOCRATES.EU

23/21


Back-up slides

WWW.FP7-SOCRATES.EU

24/21


Packet scheduling parameter optimisation: Results

  Use case objective: –  Appropriately tune the parameters of the packet scheduling algorithm, in

response to changes in e.g., traffic load, traffic mix, traffic characteristics, multipath environment, etc.

  Activities: –  Sensitivity analysis of the optimal settings of the scheduling parameters with

respect to changes in traffic load, traffic characteristics, multipath environment and traffic mix and study of the potential gain of self-optimisation

The figure shows the cell capacity versus the coefficient of variation of the file size and the scheduler parameter α.

WWW.FP7-SOCRATES.EU

25/21


Packet scheduling parameter optimisation: Conclusions

 Results sensitivity analysis – Sensitivity of the optimal parameter settings of the scheduler is limited –  In other words the optimal parameter settings are almost the same in

all system conditions  Potential gain of self-optimisation

– The potential gain of self-optimisation observed so far (lower than 5% on average in terms of capacity improvement) does not justify self-optimisation

– A practical implementation of a self-optimised scheduling algorithm would not be able to apply the optimal parameter settings in every situation, therefore the gain would be lower

WWW.FP7-SOCRATES.EU

26/21


c*(t) + creq > ThHO * C(k): fresh calls are blocked

  Admission control algorithm: decides if a call request will be admitted or rejected

  To give priority to handover calls: –  Introduction of ThHO, to be used upon arrival of fresh calls

  Self-optimising AC algorithm: auto-tune ThHO in response to changes in measured performance

–  Might require opposite adaptations, depending on which performance measure is considered (outcome of sensitivity analysis on ThHO)

–  Operator policy to decide on this trade-off

  Evaluation of the SON algorithm under sudden overload (“change”)

Admission control parameter optimisation: Introduction

26

WWW.FP7-SOCRATES.EU

27/21


Admission control parameter optimisation: Simulation results

27

SON no SON: fixed ThHO

defined policy achieved

defined policy achieved, SON results are better

defined policy not achieved

QoS results for non-rt traffic QoS results for rt traffic and HO failure ratio show similar trends

Call blocking ratio results (fresh calls)

WWW.FP7-SOCRATES.EU

28/21


Interference coordination: Soft reuse experiments

For resource fair schedulers 5th percentile throughput increase can be exchanged for a mean throughput decrease.

Monte Carlo soft reuse experiments were executed for a variety of power ratios between reuse three and reuse one.

Gains depend on accurate SINR prediction

WWW.FP7-SOCRATES.EU

29/21


Self-optimisation of Home eNodeB: Handover

  Effectively use open access Home eNodeBs

  Optimise handover parameters to improve reliability and user experience

  Results showed that adjusting handover parameters does significantly impact performance (see figure)

  Rules to determine when handover should be avoided have been defined

–  Cell individual offset (CIO) is the most effective control parameter

–  Use low CIO for fast handover –  Use high CIO to avoid handover

WWW.FP7-SOCRATES.EU

30/21


Self-optimisation of Home eNodeB: Interference and Coverage

  First simulations showed that one problem with closed access Home eNodeBs is dead-zones   Home eNB maximum transmit power is a suitable control parameter   A self-optimisation algorithm should focus on

a)  Providing coverage within the eNB house b)  Minimizing the size of the created dead-zone

  Simulation results (below) show ratio of connected UEs when slowly changing the downlink power from a medium setting to the optimised setting.

  Conclusions –  Dead-zones are the major problem when introducing closed access home eNodeBs –  HeNB Maximum Transmit Power is a suitable parameter for controlling the trade-off between HeNB coverage and the size of the

dead-zone. –  Simulations show that for a HeNB far away from the macro eNB,

the proposed algorithm can set the HeNB power to a level where HeNB coverage is achieved while the dead-zone is smaller than when using a medium power setting.

WWW.FP7-SOCRATES.EU

31/21


Automatic Generation of Initial Parameters (AGP)

  Self-configuration covers the complete process from physical installation of a new (or re-located) node until its transfer to the operational phase

  “Automatic Generation of Initial Parameters for eNodeB Insertion” (AGP) addresses one dedicated use case out of self-configuration

–  Determine “target configuration” of new site and its surrounding using off-line planning methods

–  Communicate “target configuration” to all affected NEs

Preparation for Self-config

OAM Connec-tivity

SW Download & Install

Conf DB Prepa-ration & Install

SW & DB Activation

S1 Interface Setup

DRC / AGP

X2 Interface Setup

Transition to Operational State

WWW.FP7-SOCRATES.EU

32/21


Cell outage compensation: Introduction

Measurements

Goal: Mi0gate coverage hole resul0ng from the cell(s) in outage.

SON approach: Automa0c adjustment of control parameters at neighbor cells

DL control parameters: Tx Power, Antenna Tilt

UL control parameters: Po (open-‐loop power control opera0ng point) , Antenna Tilt

IMPORTANT:

1) Trade-‐off between coverage improvement and quality degrada0on

2) UL control parameters have much higher impact (from sensi0vity studies) so focus on target Rx Power (Po), Antenna Tilt

WWW.FP7-SOCRATES.EU

33/21


Cell outage compensation: Demonstration of results

Compensating cell (blue)

Cell in outage (red)

Compensated coverage hole (grey)

10th-perc DL throughput [Mbps] (averaged over compensating cells)

10th-perc UL throughput [Mbps] (averaged over compensating cells)

Increase in number of served UEs (relative to no compensation)

Control Parameter P0

WWW.FP7-SOCRATES.EU

34/21


Cell outage compensation: Demonstrator – High Load

socrates key results ope... · introduction to socrates key results from ... – reallocate part of...

Documents