05_admissioncontrol_2004

5/28/2018 05_AdmissionControl_2004

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1 N OK IA 1 99 9 31/10/2002 RANPAR Version 1.0

Course Content

Radio Resource Management Overview Parameter Configuration

Common Channels & Power Control

Load Control

Admission Control

Packet Scheduling

Handover Control

Resource Manager


Course ObjectivesAt the end of the course you will be able to:

Describe the admission criteria for uplink and downlink

Describe the decision procedure of the admission control for RT and NRT RABs

Describe the role of the packet scheduler in the admission control

Name the main parameters admission control derives from the RAB parameterset

Name and describe the main parameters admission control delivers to otherRRM entities


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AC Functional Overview UL admission control

Power allocation in UL

DL admission control

Power allocation in DL

Dynamic Link Optimisation (DyLo)

Admission Control


Admission Control Functional Overview

Maximises capacity whilst maintaining stability

Decides if new RAB request is admitted into RAN

AC decision procedure set according to whether;

Request is for RRC connection and RT or NRT RAB Setup

RAB setup can be for call setup or handover

Admission control for RAB setup is different for RT and NRT

For RT RAB admission requests AC;

estimates the non-controllable power (load) increase that would result from admitting the new RAB

checks if the new non-controllable load is below a certain threshold

Bearer is not admitted if the predicted load exceeds defined thresholds in UL or DL

AC is also responsible for determining quality requirements of the RB including;

setting RLC and TrCH parameters

BLER & Eb/No targets

initial SIR target (used in Outer Loop PC) & upper and lower limits for the uplink SIR target

LCLCLC

AC

Network based functions

PSPSPSRMRMRM

RNC


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RABEstablishment

6

Admission Control Functional Overview

RAB attributes (HLR); SDU error ratio traffic class max bit rate

Nokia

RNC

Core

NetworkRAB ASSIGNMENT REQUEST

NRT PScall

ACRABadmitted

RABrequestdenied

QueueRAB

Radio Access BearerService Request

1Quality Requirements

of Radio Bearer2

RB attributes (RNC);

target BLER target Eb/No initial SIRtarget

AdmissionDecision

4

RT CS call

Power IncreaseEstimates

3

UL/DL Load ChangeReport to LC

5

RRC Connection

Establishment0

NRT AdmissionDecision Process (PS)


Radio Access Bearer Service Request

UE RNC MSC HLR

RAB Assignment Response

Setup

RAB Assignment Request

Call Proceeding

Alerting

Connect

Conne

ct Acknowledge

RAB service attribute RAB service attribute value

Traffic Class Conversational

Maximum bit rate 12.2 / 10.2 / 7.95 / 7.4 / 6.7 / 5.9 / 5.15 / 4.75 kbit/s

Guaranteed bit rate 12.2 / 10.2 / 7.95 / 7.4 / 6.7 / 5.9 / 5.15 / 4.75 kbit/s

Delivery Order Yes

Maximum SDU size 244 / 204 / 159 / 148 / 134 / 118 / 103 /95 bits

Traffic Handling Priority Not applicable

Source statistics descriptor Speech

SDU Parameters RAB sub-flow 1

(Class A bits)

RAB sub-flow 2

(Class B bits)

RAB sub-flow 3

(Class C bits)

-

>

SDU error ratio 7 * 10-3 - -

-

>

Residual bit error ratio 10-6 7) 10-3 5 * 10-3

Delivery of erroneous SDUs yes - -

SDU format information 1-9

Sub flow SDU size 1-9

Sub flow SDU size parameters 10

Sub flow SDU size 10 0 0 0

AC maps RAB parameters into RB parameters using UE capability parameters and outputs:

BLER & Eb/No targets

Initial SIR target (with max/min values)

RLC , TrCH parameters

PDCP and physical channel parameters


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Mapping Residual BLER : Target BLER : Eb/Nos

AC uses calculated Residual BLER to obtain the target BLERs via look-up tables

Eb/Nos are obtained from another look-up table using target BLER values

Target BLER and Eb/Nos are obtained for UL and DL separately.

Both dedicated and signalling channels have there own targets

EbNoSetIdentifier specifies

which Eb/No table is used

depending on the type of

antenna configuration used

RAB QoS

Attributes

RAB QoS

Attributes

BLER

Calculated

EbNo

Mapping

EbNo

Mapping

Initial SIR

Max SIRMin SIR

Initial Pwr

Max PwrMin Pwr

Target Eb/Nos are usedin calculating SIRtargets, power/loadincrease estimates, DLpower allocations


BTS measures the SIR from the pilot bits of the DPCCH. So radio link specific initial SIRtarget depends on following elements:

DCH specific planned Eb/No.

DCH coding rate after the error correction coding and the static rate matching.

In UL there is one encoded bit in symbol.

The relative power difference between DPCCH and DPDCH.

The initial UL SIR target of the DPDCH is achieved from the equation:

Initial SIR target

+

=

DPCCHTFC

d

TFC

cC

DCHDCH

C

DCH

RLDCH

DCH

DCH

DCH

bDPCCHULInit SF

NRM

NRM

WR

NESIR

Max

Max2

0

, log10


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The maximum and minimum limits for SIR target are calculated from this initial value;

Initial SIR target

( ) ( ) DPCCHULInitDCHN

E

DCHN

EDPCCHULSIRSIR bb

,min,

min 00+=

( ) ( ) DPCCHULInitDCHN

E

DCHN

EDPCCHULSIRSIR bb

,max,

max 00+=

1 0 N OKI A 1 999 31/10/2002 RANPAR Version 1.0

AC produces the TrCH parameters:

Transport Formats (TF)

Transport Format Combination (TFC)

TFC identifiers

TrCH Parameters

Supported

Bitrates

0

TFCS (SL & RT RB)

TrCh1

TFI0

TFI1

64

128

384

0

TFI2384

128

Peak Bitrate

In Bearer

Parameters

Sheduled

Bitrate

TFS for RT RB

intermediate

Bitrates

64

128

0

TFS subset

For TFCS

construction

64

0

TrCh2

TFI0

TFI1

0

64

0

TFI1

TFI0TFI0


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RLC Transfer Mode

AC determines the UL & DL RLC transfer mode for RNC & UE

RLC transfer mode indicates, whether the RLC entity of a RB shall use an Acknowledged(AM), an Unacknowledged (UM) or a Transparent (Tr) Modedata transfer.

Equal transfer mode is used in UL and DL for a RB.

The transfer mode is determined from the RAB parameters and CN domain information.

NRT trafficT traffic

Conversationalonversational Streamingtreaming Interactiventeractive BackgroundackgroundAMRLCAMRLC

AMRLCAMRLC

TMRLCTMRLCDCHCH

UMRLCUMRLCDCHCH

TMRLCTMRLCDCHCH

UMRLCUMRLCDCHCH

AMRLCAMRLCDCHCH RACH/FACHACH/FACH DCH/DCHCH/DCHCH/HS DSCHCH/HS DSCH

PS domainS domain


AC for NRT RAB For a NRT RAB admission request, AC will first check that the maximum bit rates

requested in the RAB Assignment Requestmessage are lower or equal thanoperator configurable limits for the specific target cell

If there is too much RACH signalling then there will be significant transmissiondelays and collision probability resulting in lower throughputs in the RACH.Furthermore, the uplink interference caused by the RACH transmissions canbecome very significant.

Since after a NRT admission request is granted by AC, PS can decide to setup theNRT RAB on common channels, if the RACH load is deemed excessive the ACwill block any NRT request before it reaches PS.

The instantaneous RACH load (%) in the associated Physical RACH is defined as

100%_______

_______

=

signaturespreambleAllowedframeRACHperSlotsAccessAvailable

frameRACHperpreamblesRACHNumberAvgloadRACH


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Admission decision for NRT RABs

NRT RABs do not cause an increase of the non-controllable load: their bit rate can be

reduced up to 0 if necessary However, when capacity requests are transmitted, common channel signalling is

required, and RACH overload could occur

RACH load is taken into account in NRT RAB admission decision

RACH load is reported by the BTS in Radio Resource Indication messages in averagenumber of RACH received per radio frame

This number of received RACH messages is normalised to the product :

Number of access slots x Number of preamble signature allowed onPRACH

AC produces the TFS for NRT RBs based on RAB requirements

MaxBitRateDLPSNRTandMaxBitRateULPSNRTdefine the maximum allowed bitrates in a cell

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


RACH load for NRT RABs admission

If all RACH load measurement results received during the period WinRachOverloadBSexceedRachOverloadBS, the cell is considered in RACH overload and no NRT RAB is admitted.

If all RACH load measurement results received during the period WinRachNormalLoadBSarebelowRachNormalLoadBS, the cell is considered in normal RACH load and all NRT RABs areadmitted again.

RachOverloadBS: Threshold for RACH overload

range: [0...100]%; step: 1%;

default 100%

RachNormalLoadBS: Threshold for RACH normal load

range: [0...100]%; step: 1%;

default 100%

WinRachOverloadBS: Window for comparison of measurements and threshold in RACH overload

range: [0100] RACH load indication periods; step: 1;

default 1

WinRachNormalLoadBS: Window for comparison of measurements and threshold in RACHnormal load

range: [0100] RACH load indication periods; step: 1;

default 5


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RACH load for NRT RABs admission

RachNormalLoadBS

RachLoadIndicationPeriod

RachOverloadBS

RACH load WinRachOverloadBS

No NRT RAB admission

WinRachNormalLoadBS

NRT RABadmission

RACHLoadIndicationPeriod: defines the reporting period of the PRACHs in a BTS. The BTS mayreport load figures to the RNC in every Nth (N=1-20) NBAP Radio Resource Indicationmessage.range: [020] RRI periods; step: 1; default: 1 (reporting every RRI period)

Example valuesWinRACHOverloadBS = 3WinRACHNormalLoadBS = 3

1 x RACH load ind. period


AMR RAB The number of available AMR modes in each cell can be reduced to a

subset

AMRModeDLandAMRModeUL,

range: [4.75; 5.15; 5.9; 6.7; 7.4; 7.95; 10.2; 12.2] kbps;default: 12.2 kbps (DL); 12.2 kbps (UL)

In RAN1.5 only 12.2 kbps is implemented

In RAN04 also other bitrates will be implemented


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Resources If admission of an emergency call, RT call or pre-emption is unsuccessful due congested logical

(codes, transmission) or hardware (WTR) resources, several attempts are triedRNCcongNumberofReAttemptsdefines the maximum number of re-attempts

range: [010]; step: 1; default 2

Meanwhile, WBTS is set in 'frozen' state.

BTSfrozenMaxTimerdefines the maximum time the WBTS can remain frozen

range: [0 10]s; step: 0.1s; default 3s

If the RRC connection cannot be established, the UE is set a wait time before sending a newRRC Connection Request

WaitTimeRRCdefines this timer, and is set differently for each RRC connection setup cause

(conversational call, streaming call, interactive call, background call, emergency call, highpriority signalling, inter-RAT re-selection, registration, subscribed, unknown, other)range: [0 15]s; step 1; default value for each type e.g.: WaitTimeRRCconversational= 3 s


Mesurement Averaging Window for AC

BTS Measurements

RRI Period

WinACRABsetupDL/UL

=

+=m

j

jntotalrx Totalx

mP

1

_ _Pr1


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DL/UL Mesurement Averaging Window for AC

WinACRABsetupDL/UL This parameter determines the DL/UL load measurement averaging window size in

number of NBAP: Radio Resource Indication message periods. This window is usedin averaging the total transmission power measurement results of a cell that arereceived from the BTS in the NBAP: Radio Resource Indication messages. Slidingtype of window is used: the oldest measurement result is removed when a new oneis received from BTS.

range: 1...20, step 1default: 5


ACRABQueueTime

The parameter determines the period of time that a RAB establishment request can wait forthe admission decisionI

If the RAB has not been admitted during the allowed queuing time, the RAB establishmentrequest is rejected

Especially if the value of the parameter is less than the NBAP: RRIndPeriod, the requesthas to be removed immediately from the queue provided that it cannot be admitted in thefirst estimation

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

note that the default value is smaller than RRIndPeriod which means that the RAB must be removed before newload information has been sent from the BTS to RNC -> basically no queuing -> parameter value should bereconsidered when loading increases to reduce RAB setup failure rate

AC RAB Queuing Time


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Admission Control


Load Based Admission Decision Process To maintain stability, UL and DL loads at each cell must be maintained below defined

thresholds.

Admission decision takes into account 3 main issues;

The measured power quantities (current load status of the cell) Average total wideband UL received power

Average total DL transmit power

Non-controllable UL power Prx_NC = - Prx_NRT

Non-controllable DL power Ptx_NC = - Ptx_NRT

Where the Prx_NRT and Ptx_NRT are the sums of the initial powers allocated to NRT DCH users by

the PS and reported to LC everySchedulingPeriodFor RAN1.5 there is no guaranteed minimum bit rate for NRT DCHs (i.e. 0 kbps) thus all NRT DCHpower is classed as controllable power

Non-controllable power increase estimation associated with new admissions

Comparison against admission criteria thresholds

totalrxP _

totaltxP _

totalrxP _

totaltxP _


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Admission decision is based on cell specific thresholds given by RNP

In UL the total received wideband interference power measured from the widebandchannel indicates the traffic load of the radio resources

Fundamental criterion;

UL Cell Load Admission Decision Process

rx_targetrx_ncrx_nc PPP +

BSettrxtotalrx PP _arg__

or

power

load

max planned load

max planned power

?


The total received wideband interference power can be expressed as the sum of:

the power caused by non-controllabletraffic, Prx_nc,

the power caused by controllabletraffic of non-real-time users, Prx_nrt

The non-controllable interference power, Prx_nc, consists of the powers of real-timeusers, other-cell users, and noise

UL traffic load caused by the NRT RABs for which the Packet Scheduler (or LoadControl) can freely adjust the UL power(i.e., the UL transmission bit rate) according tothe current load, even drop it to zero when necessary(the best effort type of services)

Hence;

nrtrxncrxtotalrx PPP ___ +=

Calculation of UL Prx_nc

nrtrxtotalrxncrx PPP ___ =determined by PSand delivered to ACthrough LC

Measured by Node Band sent to RNC


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Estimation of UL Prx_nc

AC estimates the increase in the total non-controllable UL power of a cell using aproprietary estimation algorithm

Estimation of the load increase, L, for thatRAB is made based on bit rate, Eb/Nos etc.

L is mapped to an estimated value ofPrx_nc using a load vs power curve.

Change in load factor L is calculated by ACbased on the new bearer Eb/No requirement.

The corresponding estimated new receivedNon-Controllable power is calculated by ACusing integral method and using the Load vs.Prx_nc curves maintained by AC for every cell

L

L

Prx_nc

Prx_nc

Load factor


BSettrxtotalrx PP _arg__ or

Current load L andcurrent received Non-Controllable powerPrx_nc are measured


The estimated non-controllable UL interference power and the average measuredtotal UL interference are compared against their thresholds ->

If either or both are satisfied then the RAB can not be admitted

If there is queuing time left for the RAB (parameter AcRabQueueTime) then the RABremains in the queue to wait for the next RADIO RESOURCE INDICATION message,otherwise it is removed from the queue

UL Cell Load Admission Criteria Thresholds

totalrxP _


BSettrxtotalrx PP _arg__

or

Prx_target_BS =PrxNoise + PrxTarget + PrxOffset

Prx_target =PrxNoise + PrxTarget


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Impact of Inaccurate Parameter Setting

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

PrxNoise set too high

NR = PrxNoise / Prxtotal

(Interference floor increase)

used in AC

ActualNoise Floor

Uplink Load

Calc.Interf.floor

increase

PrxTotal

PrxNoise

Actualinterf.floorincrease

PrxNoise settoo high

PrxTarget


Load < PrxTarget

In case the PrxTarget value is set too high (higher than used in dimensioning) then:

the AC will admit new users beyond the planned UL load limit

cell breathing will cause coverage holes

RAB establishment will fail due to not enough power from UE


RAB for newuser admitted


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AC likely to deny more capacity requests than it should(lower actual interference floor increase than calculated)

PrxNoise set too low

NR = PrxNoise / Prxtotal

(Interference floor increase)

used in AC

ActualNoise Floor

Uplink Load

PrxTotal

PrxNoise

Calc.Interf.floor

increase

Actualinterf.floorincrease

PrxNoise settoo low


In case the PrxTarget value is set too low:

UL load threshold exceeded too early.

Admission Control will reject RT RAB establishments even though there is enoughcoverage in UL


Load >= PrxTarget

RAB for newuser denided


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Prx_Target_BS is defined to allow instantaneously the target received power level to

be exceeded due to changes in interference and propagation conditions when UEs aremoving in the network

When the non-controllable part of the cell load exceeds the target limit, AC willreject those RAB establishment requests that would mean immediate UL loadincrease (i.e. RT services)

When the PrxTargetlevel hasbeen exceeded it is stillpossible for the AC/PS to admitNRT services and (AC) andschedule (allocate) bitrate forNRT services

however bitrate (load) increase

for NRT is not possible

Prx_NC[dBm]

PrxTotal[dBm]

PrxNoise [dBm] + PrxTarget [dB]

PrxNoise [dBm] + PrxTarget [dB] + PrxOffset [dB]

Parameters

Note:

PrxTarget_BS is defined as PrxTarget + PrxOffset

PtxTarget_BS is defined as PtxTarget + Ptx Offset


Prx_NCPrxTotal

Prx_NC + Prx_NC Prx_Target

PrxTotal Prx_Target_BS

RT RAB admitted (as well as NRT)

Admission Decisions

Prx_NC

Prx_Target_BS

Prx_Target

Case I Case II

Prx_NCPrxTotal

Prx_NC


Prx_Target PrxTotal Prx_Target_BS

RT RAB admitted


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Prx_NC

PrxTotal

RT RAB denied (as well as NRT)

Admission Decisions

Prx_NC

Prx_Target_BS

Prx_Target

Case III Case IV

Prx_NC

PrxTotal

Prx_NC

RT RAB denied (NRT RAB permitted)

Prx_NC + Prx_NC Prx_TargetPrxTotal Prx_Target_BS


Prx_target PrxTotalPrx_Target_BS


UL Admission Procedure Summary

BTS sends periodically the received UL power to the RNC

Fractional load[0..1]

OVERLOADAREA

MARGINALLOADAREA

FEASIBLELOADAREA

0

Load curve in UL

PrxTotal[dBm]

PrxNoise [dBm]

PrxTarget [dB]

PrxTarget [dB]+PrxOffset [dB]

1

Noise RiseNR [dB]

XX [dB]

RNC compares the measured received power levels against the setthresholds

If measured UL (PrxTotal) load exceeds target thresholds (PrxTarget) ACcan admit NRT RABs to the cell. The NRT RAB bitrate can not beincreased and remains at the same level as after previous schedulingperiod

If measured UL (PrxTotal) load exceeds overload thresholds(PrxTarget+PrxOffset) no RABs can be admitted and NRT bitrates arereduced until PrxTotal reaches again PrxTarget

OverLoad

MarginalLoad

FeasibleLoad

In feasible load area the admission decision is based on the power rise

estimate of the new RT bearer

If the resulting power is still below PrxTraget the RAB is admitted

rx_targetrx_ncrx_nc PPP +In case the RAB can not be admitted it is putinto the queue


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Admission Control


After PRACH procedure the initial UL DPCCH transmit power is set by RRC

When one or more radio links already exist then the current UL transmission poweris used as initial transmission power for new radio link to be established

When establishing the first DPCCH the UE starts the UL inner loop power control ata power level according to:

DPCCH_Initial_power = DPCCH_Power_offset CPICH_RSCP

The value for the CPICH_RSCP, is measured by the UE

DPCCH_Power_offsetis determined by AC/PS of RNC and its value is signaled tothe UE in the UL DPCH power control info IE included in the RRC CONNECTIONSETUP message

DPCCH Initial Power


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The value of the DPCCH_Power_offset is determined by the equation

)log(10 DPCCHDPCCHRSSICPICH SFSIRRxTx ++=DPCCH_POWER_OFFSET

Where:

TxCPICH is the transmission power of Primary CPICH given by the RNP parameterPtxPrimaryCPICH

RxRSSI is the received wide band interference power measured by BTS and offered by LC

SIRDPCCH is the required received SIR for DPCCH; it equals to the initial DPCCH SIR target

SFDPCCH is the spreading factor of the UL DPCCH

DPCCH Power Offset


Max UE Transmission PowerUEtxPowerMaxDPCH

This parameter defines the maximum transmission power level a UE can use onDPCH. It is signaled to UE in the Maximum allowed UL TX power IE of a properRRC message, when a radio link is set up.

range: -50 ... 33 dBm, step 1 dBdefault: 24dBm

UEtxPowerMaxRACH

This parameter defines the maximum transmission power level a UE can use onPRACH. The value of the parameter also effects the cell selection andreselection procedures. The value of the parameter is sent to UE in the Cell

selection and re-selection of System Information Blocks 3 and 4 of the servingcell.

range: -50 ... 33 dBm, step 1 dBdefault: 21dBm


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Admission Control


Admission decision based on cell specific thresholds given by RNP (same as UL)

Each BTS measures the total transmitted DL power (PtxTotal) of each cell, and reports theresults to the RNC by using RADIO RESOURCE INDICATION message

BTS applies same process as UL for calculating averaged Ptx_Total values ( filter)

RNC applies sliding window averaging using WinAcRabSetupDlto obtain av Ptx_Total

Ptx_total can be expressed as the sum of the power caused by the non-controllabletraffic, Ptx_nc, and the power caused by the controllable traffic of non-real-time users,Ptx_nrt:

Ptx_Total can be calculated in the same way as Prx_Total

For each RAB request the admission control has to estimate the increase in the total non-controllable transmission power (caused by the new RAB), Ptx_NC

nrttxnctxtotaltx PPP ___ +=

Estimation of DL Ptx_nc


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Estimation of DL Ptx_NC

No load curve is used to estimate the power increase associated with a new RAB

The increase in non-controllable power due to a new RT RAB, Ptx_nc, is calculated using; Estimation for Tx power increase due to admission of a reference RAB

Estimations due to the increase from other RAB are calculated by multiplying thepower of the reference RAB by an appropriate normalising factor based on the ratiobetween the bit rates and Eb/No targets of the reference RAB and requesting RAB.

The default reference RAB/service is voice AMR 12.2 kbps which is specified using;

DLreferenceBitRate(Riref) = Bit rate of reference RAB/service (12.2 kpbs)

DLreferenceTargetBLER = value for target BLER for reference service (value is 10logBLER)(note: DLreferenceTargetBLER is used to obtain the Eb/No target of the referenceRAB (ref)

CPICHtoRefRABoffset


Together with the DL admission decision equation the maximum allowed DLtransmission power per connection limits the coverage (and capacity) ofcertain user (using certain service)

The current transmission power of an active-set basestation, Ptx_total, is increased by the required maximumpower of the requesting user, Ptx, and by the requiredtotal power of the inactive real-time users, Ptx_rt,inactive(for which the RB is still in the establishment phase)

tx_targettx_nctx_nc PPP +

BSetttxtotaltx PP _arg__ or

nrttxtotaltxnctx PPP ___ =

inactivetxtxnctx PPP ,_ +=



22/33


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

scaling factor is the mapping of the max power to the actual bearer based on thewanted service bitrate and downlink Eb/No compared to the reference servicebitrate and Eb/No (12.2 kbps AMR)

CPICH coverage=Service Coverage

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


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


CPICHtoRefRABoffset

The parameter defines the offset of the primary CPICH transmission power, and themaximum DL transmission power of the reference service channel in DL power allocation

The maximum transmission power of the reference service is calculated (in dBm) bysubtracting the value of the parameter from the transmission power of the primary CPICH

range : -10 ... 17 dB, step 0.5 dBdefault : 2dB

Note that the default value is obtained for AMR 12.2 kbit/s due to that the AMR speech is

probably the most used service

P-CPICH Transmission Power Offset


23/33


DLreferenceBitRate ( )

The parameter defines the downlink bit rate of the reference service. Reference service isused in the determination of the maximum downlink code channel transmission power

The service is considered to be AMR speech, if the bit rate is one of the followings: 12.2,10.2, 7.95, 7.4, 6.7, 5.9, 5.15, 4.75 (kbit/s). Otherwise the service is data service

range : 0.01 ... 16000 kbit/s , step 0.01 kbit/sdefault : 12.2 kbit/s

Note that the default value is obtained for AMR 12.2 kbit/s speech service

refRI

DL Bit Rate of the Reference Service


The power needed by the inactive (still inestablishment phase) RT RBs Ptx_rt,inactivecan be calculated by summing all the RBstogether by using the same formula(s) asbefore


BSetttxtotaltx PP

_arg__ or

nrttxtotaltxnctx PPP ___ =

inactivetxtxnctx PPP ,_ +=

Each time data transfer begins in the DCH the corresponding portion of the inactive RT

RB is removed from the equation above at the time next RRI report (or perhaps afterseveral periods depending on the RAB queuing parameters) is received from the BTS

Therefore MAC has to inform AC,LC and PS when the data transfer is activated in DCHat RL setup


{ }=

inactivertRB

inactivetxP_,

, (P_CPICH-CPICHtorefRABoffset+scaling factor)


24/33


For the RB to be established the increase of the non-controllable load Ptx_nc isestimated on the basis of the measured

Then the estimated non-controllable DL power and the average measured total DLtransmission power are compared against their thresholds

If either or both of them are exceeded then the RAB can not be admitted

totaltxP _

totaltxP _


BSetttxtotaltx PP _arg__

or = + Ptx,inactive

Ptx_nc = Ptx_total Ptx_nrt txPtx_ncP

DL Cell Load Admission Criteria Thresholds


Ptx_NCPtxTotal

Ptx_NC + Ptx_NC Ptx_Target

PtxTotal Ptx_Target_BS

RT RAB admitted (as well as NRT)

DL Admission Decision

Ptx_NC

Ptx_Target_BS

Ptx_Target

Case I Case II

Ptx_NCPtxTotal

Ptx_NC


Ptx_Target PtxTotal Ptx_Target_BS

RT RAB admitted


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Ptx_NC

PtxTotal

RT RAB denied (as well as NRT)

DL Admission Decision

Ptx_NC

Ptx_Target_BS

Ptx_Target

Case III Case IV

Ptx_NC

PtxTotal

Ptx_NC

RT RAB denied (NRT RAB permitted)

Ptx_NC + Ptx_NC Ptx_TargetPtxTotal Ptx_Target_BS


Prx_target PrxTotalPrx_Target_BS


BTS sends periodically the total transmitted DL powerto the RNC

RNC compares the measured transmitted power levelsagainst the thresholds

If measured DL (PtxTotal) transmitted power exceedstarget thresholds (PtxTarget) AC can admit NRT RABsto the cell (no RT RABs can be admitted). The NRTRAB bitrates can not be increased and they remain atthe same level as after previous scheduling period

If measured DL (PTxTotal) transmitted power exceedsoverload thresholds (PtxTarget+PtxOffset) no RABscan be admitted and NRT bitrates are reduced untilPtxTotal reaches again PtxTarget

OverLoad

MarginalLoad

FeasibleLoad

In feasible load area the admission decision is basedon the power rise estimate of the new RT bearer

If the resulting power is still below PtxTraget theRAB is admitted

In case the RAB can not be admitted it is putinto the queue

OVERLOADAREA

MARGINALLOADAREA

FEASIBLELOADAREA

Load curve in DL

PtxTotal[dBm]

PtxTarget [dBm]

PtxTarget [dBm]+PtxOffset [dB]

Cell maximum [dBm]

Load[0...1]

01

tx_targettxtx_total PPP +

DL Admission Procedure Summary


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Admission Control


The determination of the transmission power requires knowledge about severalparameter values:

required Eb/No of the connection ( )

signal-to-interference ratio per chip of the CPICH ( ) measured by the UE

W is the chip rate, R is bit rate, Ptx_total is measured by the base station (andreported back to the RNC in Radio Resource Indication)

Ptx_CPICH is the CPICH power (determined byPtxPrimaryCPICH)

is the orthogonality factor

0NEb=

0IEcc=

Initial DL Power Allocation

= tx_totalCPICHtx,1 PP

W

RP

c

tx


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64 kbit/s service with required DL Eb/No: 4.5dB = 2.82

PtxCPICH: 30dBm = 1 W

= 0.5, Ptx_total= 37dBm (5.011)

measured Ec/Io (by the UE) -10dB = 0.1

Therefore:

Ptx_init = 2.82*64/3840*(1/0.1*1-0.5*5.011) = 352.24mW (25.47dBm)

Initial DL Power AllocationExample


When radio link is established or modified both maximum DL transmission power andminimum DL transmission power has to be determined for it

The average power of transmitted DPDCH symbols over one timeslot must notexceedmaximum DL transmission power, or it can not be below minimum DL transmissionpower

The power control dynamic range of BTS is the difference between the maximum andthe minimum transmit output power of a code channel

Downlink power allocation of a radio link


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Downlink power allocation of a radio link

PTxTotalMax (Max total power of NodeB)

CPICHtoRefRABOffset (def 2 dB)SF_adjustment

+PTxDPCHmin (default -28 dB)

+PTxDPCHMax (default -3 dB)

P_CPICH (Absolute CPICH power of cell)

PCrangeDL (default 15 dB)

The maximum DL power is thelowest of these three values for

NRT and Multirab

The minimum DL power is themaximum of these value

PCrangeDL

In most cases we are operating in thisrange for voice. For PS data thePTxDLabsMax can be lower than theupper limit dictated by this

PtxDLabsMax(Maximum planned DLpower of a radio link) Thisparameter sets themaximum power for anyradio link, only NRT andMultirab..

PCrangeDL


How it is actually done Define maximum radio link power:

RT: Ptx_max_rl=min{P_CPICH-CPICHtorefRABoffset+SF_adjustment, Ptxtotalmax-PTxDPCHmax}

NRT & Multirab: Ptx_max_rl=min{P_CPICH-CPICHtorefRABoffset+SF_adjustment,Ptxtotalmax-PTxDPCHmax, PTxDLabsMax}

Define minimum radio link power:

Ptx_min_rl=max{Ptx_max_rl-PCrangeDL, Ptxmax-PTxDPCHmin}

SF_adjustmentis the mapping of the max power to the actual bearerbased on spreading factor and downlink Eb/No compared to the

reference service (12.2 kbps AMR)

refref

effRI

RIRI

=

maxmax,


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64 kbit/s service with required DL Eb/No: 4.5dB =2.82 Reference service: speech 12.2kbit/s Eb/No 5.5dB = 3.548

CPICHtoRefRabOffset = 2dB (for speech)

PtxCPICH: 30dBm = 1W

SF_Adjustment= 2.82*64/(3.548*12.2) = 4.17

PtxCPICH - CPICHtoRefRabOffset = 30 dBm-2 dB=28 dBm= 0.630 W

Ptx_max_rl=min(4.17*0.630, 10W) = 2.63 W (34.20dBm)

Ptx_DPCH_max = PtxDPCHMax=3dB below the maximum power = 40dBm

Maximum DL Ptx of the Radio LinkExample


Ptx_max = 2.63 W (34.20dBm)

Ptx,range = PCrangeDL =15dB

Ptx_DPCH_min = PtxDPCHMin= 28dB below the maximum power = 15dBm

Ptx_min_rl=max(34.20dBm - 15dB, 15 dBm) = max(19.20dBm, 15dBm)=> Ptx_min_rl = 19.20dBm

Minimum DL Ptx of the Radio LinkExample


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PtxDPCHMax Parameter defines the maximum code channel output power for the power control

dynamic range of BTS. The maximum transmission power is calculated by adding thevalue of the parameter to the BTS maximum output power (Pmax in dBm).

range: -3 ... 0dB , step 0.1dBdefault: -3 dB

PtxDPCHMin

Parameter defines the minimum code channel output power for the power controldynamic range of BTS. Minimum transmission power is calculated by adding the valueof the parameter to the BTS maximum output power (Pmax in dBm).

range: -60 ... 28dB , step 1dBdefault: -28 dB

DL Power Thresholds


PCrangeDL

The parameter defines the downlink power control range in relation to the maximumallocated transmission power of the radio link

The minimum transmission power is achieved by subtracting the value of the parameterfrom the maximum transmission power of the radio link

However, the minimum BTS output power of the code channel defines the absolute lowerlimit for the minimum transmission power

range: 0 ... 25 dB, step 1 dBdefault: 15dB

DL Power Control Dynamic Range


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Planned Maximum DL Ptx of the Radio Link

PtxDLabsMax The planned maximum downlink transmission power of radio link. This parameter is

used in the downlink power allocation when CCTrCH includes one or more DCH's ofinteractive or background traffic class RAB's. The allocated power of a radio linkcannot exceed the value of this parameter. The parameter is set separately for eachcell. This parameter is the planned maximum, not the physical limit.

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

default: 50 dBm


Admission Control in case of Congestion If there are no Iub resources available the admission request will be denied.

The purpose of the pre-emption procedures is to immediately offer aservice of a guaranteed level to the subscribers in a temporary resourcecongestion situation. RT RAB pre-emption is possible.

In case of congestion RT RAB pre-emption procedure is possible for RT oremergency call, when RT RABs which has RAB based indication "vulnerableto pre-emption" are released.

RT over NRT procedure can also be applied

NRT RAB bitrate can go to 0 kbits/s in case of congestion


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Admission Control (AC) Summary

RB information

Resourceinformation

Active setinformation

Load changeinformation

Target BLER,B ER and SIR

Loadinformation

Admission Control

RAB admission decisionLoad change estimationProducing L2 parameters

Producing TFSDL power allocation

Iu

Packet Scheduler

Radio resourcescheduling

Load Control

Producing of loadinformation

Power Control

UL Outer looppower control

Handover Control

Active state mobilitycontrol

Resource Manager

Radio resource informationCode allocation

Transport resource allocation

Resourcerequest

RAB setup/modify/release request

Loadinformation


RRC connection setup

RRC connection setup RAB setup

RAB setup

Admitted if total load is belowoverload threshold

If total load is above overloadthreshold, RRC connection over NRTandRT RAB pre-emption procedures can beapplied


If total load is above overloadthreshold, RRC connection over NRTandRT RAB pre-emption procedures can beapplied

Admitted if non-controllable load isbelow target and total load is belowoverload threshold

If total load is above overloadthreshold, RRC connection over NRTprocedure can be applied


If total load is above overloadthreshold, RRC connection over NRTprocedure can be applied

Emergencycall

Emergencycall

RT

RT

NRT

NRTAdmitted if non-controllable load isbelow target and total load is belowoverload threshold


Admitted if non-controllable loadadded by estimated change is belowtarget and total load is belowoverload threshold

If non-controllable load added byestimated change is above target, RTRAB pre-emption procedure can beapplied

If total load is above overloadthreshold, RT over NRTprocedure can beapplied

Admitted if non-controllable loadadded by estimated change is belowtarget and total load is belowoverload threshold

If non-controllable load added byestimated change is above target, RTRAB pre-emption procedure can beapplied

If total load is above overloadthreshold, RT over NRTprocedure can beapplied



Admission Control for RT and NRT (RAN1.5)

During SHO branch addition is possible in the case when total DL load is less thanthe overload threshold, valid both for RT and NRT traffic


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Chapter 4-Admission Control-

1. What is the admission control needed for?

2. What triggers execution of the admission control?

3. Name main issues taken into account by AC.

4. What condition prevents the RT RAB to be admitted in the UL?

5. What condition prevents the RT RAB to be admitted in the DL?

6. What effect will cause too high/ too low PrxNoise?

05_admissioncontrol_2004

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