04 rn31634en40gla0 ranpar1 loadcontrol v1.1 ru40

1 Nokia Siemens Networks RN31634EN40GLA0

Load Control


Load Control:

Module Objectives

At the end of the module you will be able to:

Describe the basic principles of Load Control

Describe the relationships of Load Control with AC and PS

Identify the parameters influencing BTS load measurements


Load Control

Load Control Functions

Radio Interface Load

Power based Radio Resource Management

Throughput based Radio Resource Management

Planning thresholds for cell loading

BTS Measurements and Reporting

Common Measurements

Dedicated Measurements

Filtering of Measurements

Automatic Access Class Restriction


Load Control Functional Overview

LC is a cell based RRM Function, utilising cell specific:

thresholds set by RNP,

load measurements,

AC, PS & LC algorithms.

LC performs the function of load control in association with AC & PS

LC updates load status using resource measurements & estimations provided by AC & PS

Continuously feeds cell load information to the other RRM functions, e.g. PS & AC

LC

AC

PS RM

RNC


Load Control Functional Overview

RRM in RNC

LC

AC

PS

Load change estimations

Load change estimations

Scheduling period

PRACH load measurement

WBTS NB/RS NBAP-PRIVATE:

RRIndPeriod or

3GPP NBAP :

COMMON MEASUREMENT

REPORT

Dedicated measurement reporting

parameters

parameters

measurements

estimations

when changed Load change info

Load status request

Load status

NRT load

measurements


Load Control







Common Measurements





DL uses Power Measurements and calculations for RRM decisions

UL uses Power & Throughput estimations and calculations for RRM decisions

NSN RRM: Power & Throughput based

=

+ = N

j j UL L i

1

) 1 ( h NR P

P

total rx

noise rx

UL

1 1 1

_

_ - = - = h

max _

_

BTS tx

total tx

DL P

P = h

defining Load

h = 0% 100%

jjbj

j

NE

RWL

1

/

/1

1

0

+

=defining Little i

Slide 9


Load Estimation Methods and other cell interference

Throughput based

threshold

Wideband Power based

threshold

Own cell load factor h (capacity)

i=0.5

i=0

i=1

2 Load estimation

methods:


UL power based load measurement

PRx_Own

PRxTotal = PRx_Own + PRx_Other + PNoise

= PRx_NRT + PRx_RT + PRx_Other + Pnoise

= PRx_NRT + PRx_NC + PRx_SC PRx_Other

iUL = PRx_Other / PRx_Own

PRx_SC The semi-controllable interference power, consists of the powers of PS streaming users (DCH and E-DCH). Before RU10 semi-controllable traffic has not been separated from the non-controllable traffic, so for those releases it is equal to zero.


DL power based load measurement

PTx_Own

PTxTotal = PTx_Own

= PTx_NRT + PTx_RT + PTx_Common

= PTx_NRT + PTx_NC+ PTx_SC

PTx_Common

PRx_Own_DL

PRx_Other_DL

iDL = PRx_Other_DL / PRx_Own_DL

PTx_SC the power caused by the semi-controllable traffic of real-time users (PS streaming). Before RU10 semi-controllable traffic has not been separated from the non-controllable traffic, so for those releases it is equal to zero.



The BTS measures the total received power (PrxTotal) and the total transmitted power

(PtxTotal) on cell basis

The BTS reports PrxTotal & PtxTotal of each cell to the RNC

LC updates

Cell load status for each cell based on RADIO RESOURCE INDICATION

Non-controllable UL (PrxNC) & DL (PtxNC) load in cell

Semi-controllable UL (Prx_SC) & DL (Ptx_SC) load in the cell (related to PS Streaming)

AC and PS algorithms work on the current cell load status provided by LC

Denying call admission (AC) & throttling back NRT traffic (PS) are the overload actions

After scheduling PS provides LC with PrxNRT, PtxNRT & LNRT estimates

After admitting RT RAB, AC provides LC with NC load increase estimate


System Noise & PrxNoise Auto-tuning Algorithm

System noise PrxNoise is the sum of all stationary noises: thermal noise

interference caused by spurious emissions of other systems,

noise caused by additional equipment such as repeaters

PrxNoise can vary place to place & even time to time

PrxNoise setting affects the capacity of cell: PrxNoise too low: overestimation of cell load and can lead to unnecessary call blocking

PrxNoise too high: underestimation of cell load and can lead to overload situation

RNC provides Autotuning-Tool to measure unloaded system noise:

PrxUnloaded; it adjusts PrxNoise parameter based on these measurements

PrxTotal = PrxUnloaded when own cell considered unloaded / very low load;

LRT UnloadedRT & LNRT UnloadedNRT & no EDCH users in the cell

UnloadedRT & UnloadedNRT are RNC parameters (default values for NRT: 1 %, RT: 2 %)

LRT & LNRT: UL load factor for own cell RT (AC estimates) & NRT users (PS estimates)

PrxNoise updated by the autotuning algorithm based on PrxUnloaded

PrxNoise autotuning step size limited by PrxNoiseMaxTuneAbsolute

PrxNoise WCEL: -130..-50; 0.1; -105 dBm

PrxNoiseAutotuning WCEL: 0 (Off) / 1 (On)

PrxNoiseMaxTuneAbsolute WAC: 0..60; 0.5; 255 dB

255 dB: Autotuning is not limited

UnloadedRT RNC: 0..0.1; 0.01; 0.02

UnloadedNRT RNC: 0..0.1; 0.01; 0.01


UL Preventive & Overload Thresholds

Prx Target [dB]

PrxTarget [dB] + PrxOffset [dB]

load factor h

Range [0..1]

N

ois

e R

ise

[d

B]

Overloaded Area

Marginal Load Area

Feasible Load Area

PrxTarget: WCEL; 0 .. 30; 0.1; 4dB

PrxOffset: WCEL; 0 .. 6; 0.1; 1dB

dBLog h-- 110 10PrxTarget =


DL Preventive & Overload Thresholds

Ptx Target [dBm]

Ptx Target [dBm] + PtxOffset [dB]

load factor h

Range [0..1]

To

tal tr

an

sm

itte

d

po

we

r P

tx T

ota

l [d

Bm

]

Overloaded Area

Marginal Load Area

Feasible Load Area

Cell Maximum

PtxTarget: WCEL; -10 .. 50; 0.1; 40 dBm

PtxOffset: WCEL; 0 .. 6; 0.1; 1dB

PtxCellMax WCEL: 050; 0.1; 43dBm


Load Control







Common Measurements





Common measurements taken & reported by WBTS

PtxTotal Transmitted Carrier Power

Nokia Private NBAP

PtxNonHSPATransmitted Code Power of all codes not used for HSDPA

Nokia Private NBAP

PrxTotal Received Total Wideband Power

Nokia Private NBAP

REPS Received E-DCH Power Share

Nokia Private NBAP

Acknowledged PRACH preambles

Nokia Private NBAP

Provided HSDPA Bitrate

Provided HSUPA Bitrate

Required Power

RRM in RNC needs this information for Streaming mapped on HSPA

(NST Non Scheduled Transmission)

Nokia Private part is protocol extension specified in 3GPP


WBTS Common Measurements sent to CRNC

WBTS sends measurements periodically according setting of RRM parameter:

(Nokia Private part)

RADIO RESOURCE MEASUREMENT REPORT

RRIndPeriod

Radio Resource Indication Period

WBTS; 200 .. 2000; 100; 400 ms

RACHloadIndicationPeriod

WBTS; 0 (Off); 1 .. 20; 1; 1 RRI report


Measurement filtering

The RNC can order BTSs to report cell-based & connection-based measurements only if internal thresholds are exceeded.

However, a report is sent at least once per 10 reporting periods (RNP parameters).

The filtering functionality decreases the amount of measurement messages between the BTS and the RNC and thus decreases the load of RNC computer units.

Internally RNC repeats the cell based measurements every WBTS: RRIndPeriod to provide RRM functions a continuous flow of measurements

BTS Measurements

Reporting period

10 * Reporting period

RRIndPeriod WBTS; 200 .. 2000;

100; 400 ms


WBTS Measurements sent to CRNC

WBTS can filter a measurement report (not sent to RNC)

only inform RNC about important load changes

reduce common NBAP signaling on IuB interface

RNC provides load threshold and value change threshold to WBTS

Measured entity

Max amount of

consecutive filtered

reports

Reporting period

Change threshold

Load Threshold

Report Report Report Report Time ReportReport

Parameter settings for

PtxTotal Measurement

0,5 dB

20 % of Ptx max

non-configurable:

PtxTotalLoadThreshold: 20%

PtxTotalChangeThreshold: 0.5dB

PrxTotalChangeThreshold: 0.2dB


Dedicated Measurements in BTS

Transmitted Code Power

WBTS send periodic measurement reports with code power measurement results from all Radio Links (UEs in Cell_DCH)

Depending on allocated service type WBTS applies different reporting frequency:

CS Services & SRB:

CS Data Services:

PS Data Services:

DedicatedMeasReportPeriod WBTS; 0.5..5; 0.5; 2.5 s

DediMeasRepPeriodCSdata WBTS; 0.5..5; 0.5; 1.5 s

DediMeasRepPeriodPSdata WBTS; 0.5..5; 0.5; 0.5 s


Load Control







Common Measurements






Automatic Access Class Restriction allows limiting access to the network in overload conditions for a number of UE to reduce control plane and user plane

traffic

The access class for every UE is a randomly allocated digit from 0 to 9, stored in the SIM/USIM

The feature sets automatically and dynamically a number of the access classes to a barring state (by default all the UE access classes 0,...,9 are allowed for

accessing the network) if severe overload conditions occur

The number of access classes is automatically increased or decreased as the overload condition continues or respectively relaxes

Barred Access Classes can be cycled to avoid specific subscribers from being barred for long periods of time

Individual Access Classes can be barred by listing them within SIB3

It returns the system to normal state once the overload conditions are over

Access Class 10 is reserved to indicates whether or not network access for Emergency Calls is allowed for UEs with access classes 0 to 9 or an without

IMSI

The feature can be activated by turning on the Long Term ON/OFF license key Automatic Access Class Restriction and RNC level radio network planning

parameter AutoACResEnabled

Public

Subscribers

- PLMN Use

- Security Services

- Public Utilities

- PLMN Staff

- Emergency Calls

- Emergency Services

Barred AC

NEW

SLIDE

AutoACResEnabled RNFC; Bit 0: Received total wideband power ,

Bit 1: NRT scheduling queue length , Bit 2: CN overload , Bit 3: RNC overload; 0



The feature introduces following new parameters:

o RNFC: AutoACResEnabled

o WCEL: AutoACResULOLThr

o WCEL: AutoACDSACRestriction

o RNAC: AutoACRLevelUpdInt

o RNAC: AutoACRestForCellPCH

o RNAC: AutoACRTrigRNCLoad

A smooth, automatic overload control in UTRAN

Avoidance of dramatic overload toggling at the core network

Increasing the successful traffic share in case of core network overload

Management parameters are replaced by an automatic functionality (OPEX savings)

Limitation to minimum of the amount of subscribers affected in case overload condition occurrence

Parameterization

o RNAC: AutoACMaxRestLevel

o RNAC: AutoACIncRestHysRTWP

o RNAC: AutoACDecRestHysRTWP

o RNAC: AutoACIncRestHysNRTQ

o RNAC: AutoACDecRestHysNRTQ

Benefits

NEW

SLIDE

04 rn31634en40gla0 ranpar1 loadcontrol v1.1 ru40

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