Top 25 RAN Parameters

8/13/2019 Top 25 RAN Parameters

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1 NOKIA E-Plus E-Max Project / 22.04.2004 / THa Company Confidential

Nokia Radio Resource Management

3G System Fundamentals

Top 25 RAN Parameters


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Radio Resource Management

RRM is responsible for optimal utilisation of the radio resources: Transmission power

Logical codes

Bandwith

The trade-off between capacity, coverage and quality is done all the time: asmany users as possible will get the resources in such a way, that the minimum

required quality is meet (nothing less and nothing more)

By means of several RRM functionalities, the radio resources are continuously

monitored and optimise.

service

quality

cell coverage cell capacity

Optimization

and Tailoring


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Radio Resource Management

RRM must be able to:

Predict the impact on interference (power) ofthe admitting a new user for UL & DL

Perform appropriate actions (e.g. new calladmissions, bitrate increase/decrease etc.) inaccordance with prevailing load conditions

Provide different quality of service for real time(RT) and non-real time (NRT) users

Take appropriate corrective action when thedifferent cell load thresholds are exceeded in

order to maintain cell stability (i.e. load control)

Overload

Load Target

Overload Margin

Power

Time

Estimated capacity forNRT traffic

Measured load causedby non-controllable load(RT)

RT services must have higher quality assurance than NRT


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RRM Functionalities

AC Admission Control LC Load Control

PS Packet Scheduler

RM Resource Manager

PC Power Control

HC HO ControlPC

HCConnection based functions

LC

AC

Network based functions

PS

RM



Admission Control



Admission Control Checks that admitting a new user will not sacrifice planned coverage or quality of

existing connections

Determines whether or not a new RT RAB can be admitted to the RAN

With PS decides whether to admit NRT RABs (PS handles all NRT connections)

Also sets

UL/DL BLER, Eb/No targets

SIR target for outer loop power control

Initial DL transmission power for the channel Radio Link Control parameters, e.g. transmission mode

Transport Channel (TrCH) parameters, e.g. TFS

Provides RLC parameters to PS for NRT users;

Bearer class

Traffic handling priority

Transport Formats

MS capabilities



Admission Control

Radio Access Bearerson the air interface

UuInterf

aceBa

ndwid

th

AC Procedure

...

Allowed Range



Admission Control

Planned uplink interference margin;defines the optimum operating poit upto which the AC can operate.

Defines the limit (the first UL overload

threshold) for the UL interferencemargin, after which the BS starts itsload control actions to preventoverload.

In

terference

Margin(dB

)

Offset

25

20

15

10

5

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Load


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Impact of Inaccurate Parameter Setting

NR = PrxNoise / Prxtotal(Interference floor increase)

ActualNoise Floor

Calc.Interf.floor

increase

PrxTotal

PrxNoise

PrxNoise settoo high

PrxTarget

PrxNoise set too high

Actualinterf.floorincrease

AC likely to admit more capacity requests than it should(higher actualinterference floor increase than calculated)

used in ACUplink Load


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Estimation of DL Ptx_nc

The maximum DL transmission power per connection is determined by theparameter CPICHToRefRABOffsetand the scaling factor

scaling factor is the mapping of the max power to the actual bearer based onthe wanted service bitrate and downlink Eb/No compared to the referenceservice bitrate and Eb/No (12.2 kbps AMR)

== max,txtx PP P_CPICH-CPICHtorefRABoffset+scaling factor

The maximum link power is defined so that the CPICH coverage and theservice coverage are ALWAYS the same

CPICH coverage=

Service Coverage


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Admission Control Parameters

MaxBitRateDLPSNRTand MaxBitRateULPSNRTdefine the maximum allowed bit

rates in a cell

range: [8, 16, 32, 64, 128, 256, 320, 384] kbps,default: 384 kbps

System noise (PrxNoise) is the sum of all stationary noises; thermal noise interference caused by spurious emissions of other systems, noise cause by additional equipment such as repeaters

PrxNoisecan vary place to place and even time to time PrxNoiseis a RNP parameter whose setting affects the capacity of cell

PrxNoise too low: overestimation of cell load and can lead to unnecessary callblocking

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


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Load Control Cell load is defined as a function of interference main criterion in WCDMA

The load control function within RRM can be divided into:

Preventive load control (e.g. congestion)

Overload control (e.g. dropping of calls in worst case)

The load control functionality is done by measuring both UL (receivedinterference) and DL (transmit power) periodically on a cell basis

Load control is performed for UL and DL separately (asymmetric traffic)

Preventive actions are performed before the cell is overloaded (threshold y)

Overload actions are performed after cell is overloaded (threshold x)

RNP parameters define the thresholds for the RRM functionalities

The thresholds define a stable functionality within a cell and with surroundingcells


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Load Control

Estimated capacity for NRT traffic.

Overloadthreshold x

Load Targetthreshold y

Power

Time

Preventive Load Control

Overload Control

Measured load caused by non-controllable load (RT)

d C l


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Load Control

LC performs the function of load control in association with AC & PS (LC works asglue between these two functions)

Updates load status using measurements & estimations provided by AC and PS

Continuously feeds cell load information to PS and AC;

Interference levels

BTS power levels

Non-controllable load

LC

AC

PS

Load change info

Load status

NRT load


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Prx Target [dB]

PrxTarget [dB] + PrxOffset [dB]

totalrece

ivedpower

Prx

Tot

al[dBm]

Overloaded Area

Marginal Load Area

Feasible Load Area

UL Preventive & Overload Thresholds

load factor


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l d h h ld


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UL Overload Thresholds

Overload 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 STATEfunction

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

PrxOffsetrange: 0...6 dB, step 0.1 dBdefault: 1 dB


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Ptx Target [dBm]

Ptx Target [dBm] + PtxOffset [dB]

totaltransmitted

po

wer

Ptx

Tot

al[dBm]

Overloaded Area

Marginal Load Area

Feasible Load Area

Cell Maximum

DL Preventive & Overload Thresholds

load factor

DL P ti Th h ld


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DL Preventive Thresholds

Preventive threshold = PtxTarget Target threshold defines the optimal operating point of the cell load, up to which PS

& AC can operate normally

If cell load exceeds these limits then AC & PS move to PREVENTIVE STATE function

New RT RABs are blocked, and PS can't schedule more NRT bit rates in the cell

PtxTarget

range: -10...50 dBm, step 0.1 dBdefault: 40 dBm

Default value depends on the cell max TX power: in case the cell max power is 43dBm, the PtxTarget should be 40 dBm (3 dB below max)

DL O l d Th h ld


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DL Overload Thresholds

Overload threshold = PtxTarget+ PtxOffset 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

PtxOffsetrange: 0...6 dB, step 0.1 dB

default: 1 dB

The default value is given for 20W WPA!


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Radio Resource Indication Period

BTS Measurements

RRI PeriodRRIndPeriod

The parameter defines the reporting period of the RADIO RESOURCE INDICATIONmessages, which are used for cell based load measurements.

range: 0...2000 ms, step 100 msdefault: 200ms

The BTS informs the RNC about the current load at the radio interface from the radioresource point of view and the load of every RACH in each cell.


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Packet Scheduler

P k t S h d l


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Packet Scheduler A non-real time call constitutes of a bursty sequence of packets.

In the downlink, the Packet Scheduler decides which channel to use, DCH or FACH.

The load target can be reached by scheduling the transmission of NRT packets .

time

packet service session

packet call

reading time

packet size packet arrival interval

NRT bit t ll ti th d


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NRT bit rate allocation method

The traffic volume measurement reports are classified into thefollowing three types:

1. Initial request for low bit rate (UL/DL); when

The NRT RB in question has no previous DCH allocation RLC buffer payload < TrafVolThresholdDLHigh orTrafVolThresholdULHigh

Low bitrate means minimum bitrate

2. Initial request for high bit rate (UL/DL); when The NRT RB in question has no previous DCH allocation RLC buffer payload => TrafVolThresholdDLHigh or

TrafVolThresholdULHigh

3. Upgrade request for high bit rate (DL); when The NRT RB in question has a low bit rate DCH allocation RLC buffer payload => TrafVolThresholdDLHigh or

TrafVolThresholdULHigh

P k t S h d l


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Packet Scheduler

PS allocation times need to be fast to accommodate changing conditions & accurate(up-to-date load info)

Capacity requests sent via traffic volume measurement reports (governed by RNPparameters)

PS comprises two parts: MS specific & Cell specific

power

time

non-controllable load

controllable load

Total Load

Target threshold

Overload threshold

Responsible for scheduling radio resourcesfor both UL and DL NRT RABs

Scheduling period defined by RNP

parameters PS relies on up-to-date information from

AC and PS

Capacity allocated on a needs basis usingbest effort approach

RRC M d ith P t


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RRC Modes with Parameters

Release RRCConnection


URA_PCH

CELL_DCH CELL_FACH

CELL_PCH

Establish RRCConnection

UTRA RRC Connected Mode

Idle Mode

(UE camps on UTRAN cell)

Available inRAN1.5.2ED2

Available inRAN04

cellUpdate, UL Tx

UL_DL_activation_timer

#cellUpdates

UL Tx

UL_DL_activation_timer(workaround)

DRX DRX

Tx/Rx

inactivityTimer

Tx/Rx FACH/RACH

trafficVolume



URA_PCH

CELL_DCH CELL_FACH

CELL_PCH

Establish RRCConnection

UTRA RRC Connected Mode

Idle Mode

(UE camps on UTRAN cell)

Available inRAN1.5.2ED2

Available inthe future

cellUpdate, UL Tx


#cellUpdates

UL Tx


(workaround, in RAN1.5.2 ED)

DRX DRX

Tx/Rx

inactivityTimer

Tx/Rx FACH/RACH

trafficVolume

Supported Radio Bearers in RAN


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Supported Radio Bearers in RAN

RAN1.5.1AN1.5.1AN1.5.1 RAN1.5.2ED2AN1.5.2ED2AN1.5.2ED2 RAN04AN04AN04 RAN05AN05AN05 RAN06AN06AN06AMR 12.2MR 12.2Transparent CS data 64ransparent CS data 64Non-transparent CS data 57.6on-transparent CS data 57.6NRT PS data UL:64, DL 64,128,384)RT PS data UL:64, DL 64,128,384)

Non-transparent CS data 14.4on-transparent CS data 14.4AMR 10.2, 7.95, 7.40, 6.70, 5.90. 5.15, 4.75MR 10.2, 7.95, 7.40, 6.70, 5.90. 5.15, 4.75Transparent CS data 33.6, 32, 28.8ransparent CS data 33.6, 32, 28.8NRT PS data 8, 16, 32RT PS data 8, 16, 32Streaming PS data UL/DL 8, 16, 32, 64, 128), DL:256treaming PS data UL/DL 8, 16, 32, 64, 128), DL:256AMR = Conversational CS speech

Transparent CS data = Conversational CS dataNon-transparent CS data = Streaming CS dataNRT PS data = Interactive/Background PS data

Implementation of Nokia RAN shall supportasymmetric combinations with all bit rates. Thecombinations supported by terminals are verified insystem verification and inter-operability testingbetween Nokia RAN and Nokia & third partyterminals.

NRT PS data 256RT PS data 256Conversational PSQoS is a study itemin RAN06Conversational PSQoS is a study itemin RAN06

Packet Scheduler


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Packet Scheduler

Radio network planningparameters

Periodical cell measurements

Periodical radio linkmeasurements

RBsetup/reconfiguration/release

information

Traffic volumemeasurements (triggers for

DCH allocation)

Updated powerestimations

Control of traffic

volume measurements

DCH allocations for NRT RB

PacketPacketschedulerscheduler

Parameters for Packet Scheduling


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InactivityTimerUplinkDCH

The time indicating how long the radio and transmission resources are reserved after

silence detection on uplink DCH before release procedures

range: 8 kbps: 5 s, 16 kbps: 5 s, 32 kbps: 5 s, 64 kbps: 3 s, 128 kbps: 2 s, 256 kbps: 2 s,

320 kbps: 2 s, 384 kbps: 2 s

InactivityTimerDownlinkDCH

The time indicating how long the radio and transmission resources are reserved aftersilence detection on downlink DCH before release procedures

range: 8 kbps: 5 s, 16 kbps: 5 s, 32 kbps: 5 s, 64 kbps: 3 s, 128 kbps: 2 s, 256 kbps: 2 s,

320 kbps: 2 s, 384 kbps: 2 s

Recommendation is to use 20 s for all services


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UL/DL activation timer

This timer is set when the MS is transferred to CELL_FACH state due to inactivity, orMS inactivity is detected in CELL_FACH state (CELL_FACH-> IDLE)

default value: : 2s; Recommendation is to set this to 10srange:50 ... 10000 ms; step 50 ms


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Resource Manager

Resource Manager


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Resource Manager

Responsible for managing the logical radio resources of the RNC in co-operationwith AC and PS

On request for resources, from either AC(RT) or PS(NRT), RM allocates:

DL spreading code

UL srambling code

Also looks after code tree management (to maintain orthogonality);

Initial code selection codes concentrated to the same branch

Code re-fragmentation dynamic reallocation of codes as users enter/leave the system

Code Type Uplink Downlink

Scrambling codes

Spreading codes

User separation Cell separation

Data & control channels from same UE Users within one cell

Resource Manager Parameters


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Resource Manager ParametersPriScrCode

Identifies the downlink scrambling code of the Primary CPICH (Common Pilot Channel) of the Cell

range: 0 ... 511, step 1default: No default

ULScrCodeMax

Defines the maximum value of the uplink scrambling code. The uplink scrambling code isunique for each MS, and it is used continuously even if the frequency is changed. The first0...8191 scrambling codes are reserved for future use.

range: 8192 ... 16.777.215, step 1default: 2.000.000

ULScrCodeMin

Defines the minimum value of uplink scrambling code. The uplink scrambling code is unique foreach MS.

range: 8192 ... 16.777.215, step 1default:1.000.000


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Power Control

Power Control (PC)


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Open Loop Power Control (Initial Access)

(Fast) Closed Loop Power Control

Power Control (PC)

RNC

MS

BS

Outer Loop Power Control


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Open loop power control


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Open loop power control

Purpose: To set the initial transmitted power of PRACH & DPCCH in the UL. UE determines the uplink preamble power of PRACH

UE PRACH First Preamble Power =

Transmission power of CPICH (Broadcast on BCH, SIB 5)) -Downlink RSCP measurement from active cell on CPICH (Measured by UE) +

Total received wideband interference power at WCDMA BTS (Broadcast on BCH, SIB 7)

+

Required received SIR at the WCDMA BTS (Broadcast on BCH, SIB 5)

Open loop PC is a part of the random access procedure for PRACH channel

Example:PtxCPICH=33dBm (Parameter per Node-B)

DL RSCP = -80dBm (Measured by UE)UL_IF = 80 dBm

UL_Required_SIR = -25 dB (Parameter per Node-B)

UE PRACH First Preamble Power = 33 dBm (-80 dBm) + (-80 dBm) + (-25 dB) = 8 dBm


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Closed Loop Power Control


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Closed Loop Power Control

Adjusts the SIR for every user based on BER/FER observation. Initial, max. and min.SIR values are set by AC

Needed to track changes in radio environment

Aims to provide required quality

UL quality evaluation is made after MDC

RNP parameters control the threshold comparison process for SIR target and thereporting of these results

If SIR target reaches its maximum (I.e. radio conditions deteriorate even thoughSIR target is inceased, system has to take action;

inter-frequency / inter-system handover RRC connnection release

Power Control Parameters


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Transmitted powerPtxPrimaryCPICHshould be 5%-10% of the total Tx Power for a 20W sector

Value = [-10 50] dBm, step 0.1 dBm

The default value is 33dBm (2W) for 20W sector

PtxPrimaryCCPCH: (BCCH info broadcast)

P-CCPCH power relative to the CPICH power

Range [-35 15] dB, step 0.1dB

default -5dB

Power Control Parameters


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Primary Synchronisation Channel is used for DL slot (10ms/15) synchronisationPtxPrimarySCH

transmission power of primary SCH (Synchronisation channel) relative to CPICH.

Range: [-35 15] dB, step 0.1dB,

Default -3 dB

Comments: optimal value allows decoding of the channel at the cell edge

Secondary Synchronisation Channel is used for DL Frame (10ms) synchronisation

PtxSecSCH

the transmission power of the secondary SCH channel relative to CPICH.

Range: [-35 15] dB, step 0.1dB, Default -3 dB

Comments: optimal value allows decoding of the channel at the cell edge


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Handover Control

Handover Control


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Intra-layerInter-layer

Intra-System

Soft(er) Handover

Hard HandoverInter-frequency

Intra-frequency

Intra-frequency

Inter-System(Inter-RAT)

Hard HandoverInter-frequency

WCDMA to GSM

WCDMA to GPRSGSM to WCDMAGPRS to WCDMA

WCDMA to WCDMA




RequiresCompressed

Mode

Handover Control


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HC is responsible for:

Managing the mobility aspects of an RRC connection as UE moves around thenetwork

Maintaining high capacity by ensuring UE is always served by strongest cell

Hard handover: MS handover between different frequencies or between WCDMAand GSM

Soft handover: MS handover between different base stationsSofter handover: MS handover within one base station but between different sectors

Soft handover keeps simultaneous connection to different base stations thusproviding a way to improve call quality during handover. However, this feature has adirect impact on network capacity and therefore is a trade-off between quality andcapacity. It has also an effect to coverage due cell breathing.

Optimisation has an important role in controlling the handover performance duringthe pre-launch optimisation (initial setting). This role is especially essential incontinuous optimisation when traffic increases and levelling of traffic between basestations becomes more important.

1A: A Primary CPICH Enters the Reporting Range


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4

Strongest CPICH in AS

time

Ec/Io

P CPICH 3

P CPICH 1

P CPICH 2

1

2

3

AdditionWindow

AdditionTimeAdditionReportingInterval

RNC

MeasurementReport

Add to

the AS?

no

ActiveSetWeightingCoefficient

1B: A Primary CPICH Leaves the Reporting Range


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Strongest CPICH in AS

time

Ec/Io

P CPICH 3

P CPICH 1

P CPICH 2

1

2

3

DropWindow

DropTime

MeasurementReport

Remove the

reported cellfrom the AS


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Handover Control Parameters


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Addition window

Addition Time

Drop Window

Drop Time

Replacement Window

MaxActiveSetSize

References


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Nokia RANPAR Training 2004

Top 25 RAN Parameters

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