01_rn31634en10gla0_loadcontrol

1 © Nokia Siemens Networks RN3007EN06GLN00I insert classification level

Course Content

Radio Resource Management Overview

Parameter Configuration

Common Channels & Power Control

Load Control

Admission Control

Packet Scheduling

Handover Control

Resource Manager

HSPA

2 © Nokia Siemens Networks RN3007EN06GLN00 Soc Classification level

Module Objectives

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

• Describe the difference between controllable and non-controllable loads

• Describe the difference between preventive and overload threshold

• Describe the relationships of Load Control with Admission Control and Packet Scheduler

• Name and describe summarily the main RAN parameters related to load control


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


Load Control Functional Overview

RRM in RNC

LC

AC

PS

Load change estimations

Load change estimations

Scheduling period

PRACH load measurement

WBTS NB/RSNBAP-PRIVATE:RRIndPeriod or3GPP NBAP :COMMONMEASUREMENTREPORT

Dedicated measurement reporting

parameters

parameters

measurements

estimations

when changed Load change info

Load status request

Load status

NRT load

measurements


BTS Measurements sent to CRNC

Common Measurements from Cell

WBTS – RADIO RESOURCE MEASUREMENT REPORT (private part)

NB/RS – COMMON MEASUREMENT REPORT

Dedicated Measurements from active users in Cell_DCH

WBTS – NB/RS DEDICATED MEASUREMENT REPORT

IuB

C - NBAP

D - NBAP


Load Control




• Planning thresholds for cell loading





Load Estimation Methods

• Actual prevailing load in the cell depends on multiple factors

• Number of active connections

• Properties of the connections• Bit rate

• Eb/No requirement• BLER requirement

• Propagation channel conditions (speed, multipath profile etc.)

• SHO condition

• Activity

• Different methods can be applied to measure/estimate prevailing load conditions, e.g.

• Throughput Based Load Estimation

• Power Based Load Estimation


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_Other

iUL = PRx_Other / PRx_Own


DL power based load measurement

PTx_Own

PTxTotal = PTx_Own

= PTx_NRT + PTx_RT + PTx_Common

= PTx_NRT + PTx_NC

PTx_Common

Com

mon

Cha

nnel

s

PRx_Own_DL

PRx_Other_DL

iDL = PRx_Other_DL / PRx_Own_DL


Radio Interface Load

• The BTS measures the total received power (PrxTotal) and the total transmitted power (PtxTotal) on cell basis

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

LC updates

Cell load status for each cell based on RADIO RESOURCE INDICATION

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

Semi-controllable UL (Prx_SC) and 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) and 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

• System noise (WCEL: 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 and even time to time

• PrxNoise is a RNP parameter whose 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 calculates averaged PrxUnloaded values using a mean filter to remove temporary interference peaks

PrxNoise is updated by the autotuning algorithm based on PrxUnloaded


PrxNoise Autotuning Algorithm

• RNC provides tools to measure unloaded system noise, PrxUnloaded, and tools to adjust PrxNoise parameter based on these measurements

• PrxTotal = PrxUnloaded when own cell is considered unloaded (or very low load);

Own Cell;

LRT UnloadedRT and

LNRT UnloadedNRT and no EDCH users in the cell

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

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

• RNC calculates averaged PrxUnloaded values using a mean filter to remove temporary interference peaks

• PrxNoise is updated by the autotuning algorithm based on PrxUnloaded

• PrxNoise autotuning step size is limited by PrxNoiseMaxTuneAbsolute parameter


UL Preventive & Overload Thresholds

Prx Target [dB]

PrxTarget [dB] + PrxOffset [dB]

load factor

Range [0..1]

Nois

e R

ise [

dB

]

Overloaded AreaOverload threshold = PrxTarget + PrxOffset

Overload Threshold defines the limit when the cell is considered to be overloaded

If load in the cell exceeds these limits then AC & PS move to OVERLOAD STATE function

New calls are blocked, and PS starts to decrease NRT bit rates in the cell

Marginal Load Area

Feasible Load Area

WCEL:PrxTarget (0…30dB)(0.1dB)(4dB)

WCEL:PrxOffset (0…6dB)(0.1dB)(1dB)

dBLog 110 10PrxTarget =


DL Preventive & Overload Thresholds

Ptx Target [dBm]

Ptx Target [dBm] + PtxOffset [dB]

load factor

tota

l tr

an

sm

itte

d

pow

er

Ptx T

ota

l [d

Bm

]

Overloaded Area

Marginal Load Area

Feasible Load Area

Cell Maximum

WCEL:PtxTarget (-10…PtxCellMax)(0.1dBm)(40dBm)

WCEL:PtxOffset (0…6dB)(0.1dB)(1dB)

WCEL:PtxCellMax(0…50dBm)(0.1dB)(43dBm)


Load Control








NB/RS situation

• Selected by WBTS:NBAPCommMode(0,1)(-)(-)

• 0=Nokia

• 1=Siemens


Measurements taken and reported by NB/RSxxx

• Periodical reporting every 800ms or slower

• TCP – Transmitted Carrier Power

• Periodic and Event E reporting for non HSDPA cells

• Periodic for HSDPA cells

• Transmitted Code Power of all codes not used for HSDPA

• Periodic and Event E reporting for non HSDPA cells

• RTWP – Received Wideband Wideband Power

• Periodic and Event E reporting for non HSDPA cells for non-HSUPA cells

• Event E reporting for HSUPA cells

• RSEPS – Received Scheduled E-DCH Power Share

• Periodic and Event E reporting for HSUPA cells

• Acknowledged PRACH preambles

• Periodic reporting is used


WBTS situation

• Selected by WBTS:NBAPCommMode(0,1)(-)(-)

• 0=Nokia

• 1=Siemens


Common measurements taken and reported by WBTS

• PtxTotal – Transmitted Carrier Power

• Nokia Private NBAP

• PtxNonHSPATransmitted Code Power of all codes not used for HSDPA


• PrxTotal – Received Wideband Wideband Power


• REPS – Received E-DCH Power Share


• Acknowledged PRACH preambles


• 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


BTS measurements in RNC

NBAP-c in CRNC

RRM

Iub

Repetitions (dedicated measurements not repeated)


Dedicated Measurements in BTS

• Transmitted Code Power• WBTS and NB/RSxxx 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 and SRBWBTS: DedicatedMeasRepPeriod Range and Step [0.5..5 s, step 0.5 s], step 0,5 sec

Default = 2.5 sec

• CS Data Services WBTS: DediMeasRepPeriodCSdata Range and Step [0.5..5 s, step 0.5 s], step 0,5 sec

Default = 1.5 sec

• PS Data ServicesWBTS: DediMeasRepPeriodPSdata Range and Step [0.5..5 s, step 0.5 s], step 0,5 sec

Default = 0.5 sec


Dedicated Measurements in BTS

• Uplink SIR Error

• HSPA Serving cell change feature makes use of UL SIR quality measurements to check the quality for HS-DPCCH reception

UE has RRC connection establishedHS-DSCH channel type is selected

AS>1

NBAP: Dedicated Measurement Initiation

NBAP: Dedicated Measurement Report




Reporting frequency can be controlled:

RNC: HSDPASIRErrorReportPeriod

Range and Step: 0..10 sec, step 1 sec

Value “0” means “switched off”

Default: 0.5 sec

Measurement Filtering can be controlled:

RNC: HSDPASIRErrorFilterCoefficient

Range and Step: 0 (100 %), 1 (71 %), 2 (50 %), 3 (35 %),

4 (25 %), 5 (18 %), 6 (13 %), 7 (9 %), 8 (6 %), 9 (4 %), 11 (2 %)

Default: 5 (18%)

01_rn31634en10gla0_loadcontrol

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