WCDMA Optimization

UMTS Optimization Prepared By Legend Technologies

Copy Rights © LEGEND Co. 2010

Course Content • WCDMA Features – Idle Mode Behavior – Radio Link Supervision – Power control – Load sharing – Handover – – Channel switching

• 3G KPIs Monitoring and analysis


Course Content • WCDMA Features – Idle Mode Behavior – Radio Link Supervision – Power control – Load sharing – Handover – – Channel switching

• 3G KPIs Monitoring and analysis


WCDMA Features • Course Ob ective Upon completion of this of this part you be able to of idle mode behavior • Explain the main parts of idle • xp a n w a s e ra o n superv s on an w a are s benefits of power control • Explain the different types of power

under minimum interference • Explain Different Handover types and scenarios

• of channel switching we have • Explain the main types of channel • Explain the Main 3G KPIs and how to analyze them


WCDMA Radio Network Features


Idle Mode Behavior • • • • •

Cell Selection / Reselection Paging Location Update and Routing area update System Information


What is Idle Mode? 1. OFF Mode 2. IDLE MODE 3. CONNECTED MODE

UE in IDLE MODE has the following properties :

•

UE is Powered ON , while it doesn't have connection to the Radio Network

•

UE is synchronized with Radio Network and can read broadcast information Accordin l UE can access the Network re uest services .

•

UE is registered on the network , updating Network with its LAC ,


Services Types in Idle Mode • Normal Service • When the UE select accepted level cell in its HPLMN

• Limited Service • When the UE didn’t find any accepted level cells at its home PLMN it selects any accepted level cell at any ot er

• Operator reserved services • The operator can reserve any cell for testing only and this through two parameters cell reserved and Access classNbarred Copy Rights © LEGEND Co. 2010

PLMN Selection • – What is it ? And When it happens ? What are the • PLMN Selection is the process in which the UE decide which PLMN it should register in and this process happens when the Mobile turned on or when the mobile returned back from limiting service – Automatic PLMN selection – Manual PLMN selection


Automatic PLMN selection • • The mobile uses information about the last registered PLMN (Freq, the stored neighbors before off)

• Mobile search the strongest signal cells and read its system information to get (MCC and MNC)

•

t e c osen ce registration

s accepte t e mo

e try to o t e

• If the last chosen cell not available or there is no stored info in the mobile USIM then the mobile might select any accepted PLMN automatically or manually


• In the automatic selection if no last re ister PLMN exists or available the Mobile will select the PLMN that is available and allowed as follow – – Each PLMN in User controlled PLMNs list in the USIM, in order of priority

– Eac PLMN in operator contro e PLMN ist in t e USIM, in order of priority

– Other PLMNs according to the high quality criteria randomly t e m n mum power s ‐ m – Other PLMNs that don’t fulfill high quality criteria


Manual PLMN Selection • carriers scanning it is allowed or not and ignoring the forbidden


f 1

Strongest cell ) B d ( e 80 d u t i n g 60 a M m40 u r t c e p S 20 r e

f 2

PLMN A PLMN B

•

HPLMN

•

PLMN E

w o 0 P

‐20 ‐40

0.2

0.4

0.6

0.8

1 Frequency

1.2

1.4

1.6

1.8 x 10 7

f n


Roaming • to obtain services from another PLMN – Another country (international roaming)

• very

m nu es home PLMN


e

ry o rese ec

s

Cell Search

Detectin frame s nchronization and rimar scramblin code rou

Detectin

rimar scramblin and read s stem information

End


Broadcast Channels Pilot Channel

P-CCPCH PICH

1 timeslot = 2560 Chips = 10 symbols = 20 bits = 666.667 uSec

Pilot Symbol Data (10 symbols per slot)

P-CCPCH 0 1 2 3 4 1 Frame = 15 slots = 10 mSec

CPICH always take tree


Cell selection procedure •

=

–

– Qqualmeas is CPICH Ec/No –

• Srxlev = Qrxlevmeas ‐ qRxlevMin – Pcompensation or a ce s – Qrxlevmeas is CPICH RSCP – qRxlevMin is minimum required RSCP


–

=

‐

• P is maximum O/P power of the UE accoring to its class • maxTXpowerUL is maximum power used in accessing

• The cell consider as acce ted if – Squal > 0 and – Srxlev > 0



• • When UE is switched on • When UE in idle mode has had a number of failed RRC connection request

• When a UE returns to idle mode from the connection mo e on common c anne ce ‐ a ter a num er of failed cell update

• UE returns to idle mode from connected mode cell‐ DCH)

• When a UE returns to idle mode after an emergency call on any PLMN Copy Rights © LEGEND Co. 2010

Cell reselection procedure • – When cell on which it is camping is no longer – When there is any neighbor with better quality than the selected one

– When the UE in the limited service state on an acce table cell

– When the UE is in cell _FACH state


•

i.

According to the cell reselection criteria. In order to perform cell ranking, the UE measures the serving cell and neighbor cells listed in SIB11 according to the measurement rules . Measurement rules for cell reselection

1. Intra frequency measurements starts when Squal <= Sintrasearch

ntra earc : ontro s w en ntra‐ requency measurements are per orme

(0 dBm)


2. Inter frequency measurements starts when Squa <= S nterSearc Sintersearch : Controls when intra‐frequency measurements are performed (0 dBm)

3. GSM measurements starts when Squal <= sRatSearch OR Srxlev <= SHcsRat sRatSearch : Controls quality Threshold at which GSM measurements are

performed (4 dBm) SHcsRat

: Controls Signal Strength Threshold at which GSM measurements

are performed (3 dBm)



GSM measurements can also be triggered qua meas c , Qrxlevmeas (RSCP, dBm)

-

sRatSearch = 4dB -112

sHcsRat = 3dB (negative values are nterprete as

qQualMin = -18 qRxLevMin+P = -115

WCDMA measurements


WCDMA & GSM measurements

WCDMA & GSM WCDMA measurements measurements

Time s

• procedure it starts ranking for the cell satisfy

‐ ranking will be according R‐criteria – R(serving)= Qmeas(s)+qHyst(s) – R(neighbor)= Qmeas(n)‐qOffset(s,n) Copy Rights © LEGEND Co. 2010

• signal which is derived from • • CPICH RSCP

• system information used to delay the – qHyst1 if the ranking based on CPICH RSCP – Copy Rights © LEGEND Co. 2010

• the neighbor cell also used to shift the cell boarder

– Offset1sn : if the rankin based on RSCP there are 2 qOffset1sn one for WCDMA neighbor and the other one for GSM neighbor.

– qOffset2sn : if the ranking based on Ec/No • qualMeasQuantity is the parameter that determine if we will do the ranking based on RSCP or Ec/No

• The UE reslect the better cell if it stay better for time interval more than Treselection Copy Rights © LEGEND Co. 2010

UMTS to UMTS cell

Qmeas (dBm)

Qmeas(n) R(n) = qHyst2 = 4

R(s)

Cell reselection R(n)>R(s)

treSelection


time

UMTS to GSM cell Reselection Qmeas (dBm) Qmeas(n) qRxLevMin* qOffset1sn qHyst1 R(n) qRxLevMin*+ sHcsRat R(s) Qmeas s WCDMA&GSM measurements

* Pcompensation is assumed to be 0


Ranking

treSelection R(n)>R(s)

time Cell reselection

• FACH‐connected cell reselection – During the FACH‐connected mode the UE use secondary common control physical channel (SCCPCH)

– fachMeasOccaCycLenCoeff and interFreqFddMeasIndicator

– fachMeasOccaCycLenCoeff (K) used to show when the UE has o o s measurmen s va ue s ou e grea er this value send to mobile via system information

an

an

– FACH measurment occasions are defined as being the frame where the following equation is fulfilled SFN= C‐RNTI mod n*2^K Copy Rights © LEGEND Co. 2010

, , ,….

– or False if it set to True the UE will perform the reselection criteria on inter frequency or inter RAT and if it is set false it will not do


Location area Update and • After a UE has found a suitable cell it tries to make PLMN registration.

• has been changed then the UE tries to do RA or LA re istration U date

• During the idle mode when the UE changes its RAU

•

an

manage


y

• Types of Updates – er o c • Occurs periodically after timer T3212 for LAU or T3312 , BCCH in the IMSI attach or in RAU , it is CN parameter, when the UE is in connected mode and the timer exp re en e wa un en er e mo e aga n o perform the periodic LA

– • Occurs when the UE change its LA or RA, the UE discover the changes after comparing the new Cell RAC or LAC with the stored values in the USIM Copy Rights © LEGEND Co. 2010

– IMSI attach and detach •

a ac occurs w en e ac va e n e same LA in which it was before deactivation and the detach occurs when UE deactiated

• This function used to prevent unnecessary paging for the off UEs

•

attac s an opt ona unct on an t s manage cell parameter called ATT sent to UE over BCCH

y

– If ATT set to 1 it means the UE should do IMSI attach and detach

– When the UE is turned on it sent registration request indicate IMSI attach to find out if the LA changed or not if changed it send normal LA update Copy Rights © LEGEND Co. 2010

Paging • Is the process through it the CN inform the UE there is a service request or RAN inform all the UEs that the System information has been updated also to initiate the channel switch from URA‐PCH to Cell‐FACH state

• Paging occurs in the following states – Idle – URA‐PCH – Cell‐FACH – Cell‐DCH Copy Rights © LEGEND Co. 2010

• Paging in Idle mode and URA‐PCH – PICH and S‐CCPCH are used to page the UE • PICH used to tell the UE when to read S‐CCPCH • S‐CCPCH used to carry RRC message type1 which nc u es actua pag ng n o an t e num er o t mes the WCDMA RAN will retransmit the paging (noOfPagingRecordTransm)


• – In the Idle mode the UE should in order to save its predefined times 288 bits for paging indication b0 b1

b287 b288

One radio frame (10 ms)


12 bits (undefined) b299

– related to one paging group and each paging group related to one user

– The number of PIs in a PICH frame is given by parameter named PichMode • If PichMode is 72 that mean we have 72 PIs and each one 4 bits

–

e mon ors one per DRX cycle

n one pag ng occas on *


• cnDRXcycleLengthCS (PS)

• Different DRX cycle for CS, PS and URA‐PCH


•

‐

‐

– When the establish connection between UE and the user it is carried on DCCH so it is only for one user.

• Updated System information –

“ ” idle mode to inform it about the updated SI


System Information


• – Powered on – ‐ – UE informed that change occurred in system ‐ – UE switches from Dedicated mode to Common .

– Timer expires for SIBs with expiration time.



Radio Connection Supervision


Radio Connection Supervision •

‐ URA‐PCH

• Supervision of the UE in Cell‐DCH


• Is the algorithm supervises the radio connection connected states, the reason of this is to check if the s

con ro

e

or no an

o preven

undue charging and increase the efficiency of resources usage. Occurs in both of Uplink and Downlink


Supervision in Cell‐FACH and

‐ • In CELL _FACH state su ervision is rovided b monitorin periodic Cell Update messages sent by the UE. The timer cchWaitCuT is started whenever the UE enters the _ , CONFIRM message to the UE. The timer is stopped if the UE enters CELL_DCH state and is reset to zero (but not stopped) upon receipt of a Cell Update from the UE. Upon expiry of the timer, the overall release of the connection shall be triggered. The time set on cchWaitCuT is longer than the one set on timer t305. The timer t305 indicates how often the UE has to send a Cell Update message.


Cell Update Message will be sent either when t305 expires or In URA PCH state the UE sent URA_Update Message instead of Cell_ Update as in Cell FACH case T305 expires

starts

Cell Update Confirmation

Cell Update Message

CCHWAITCUT Expire

CCHWAITCUT Reset Cell FACH Copy Rights © LEGEND Co. 2010

Overall Connection Release

Timer Should stopped if UE Enters CELL-DCH

Supervision in Cell‐DCH •

_ , Supervision functionality is provided by means Supervision algorithm, located in the RBS, Evaluation algorithms, located in the SRNC


indication send from the 2 RBSs Copy Rights © LEGEND Co. 2010

• Evaluation The Radio Connection Supervision synchronization status of the whole radio .


• Radio Link Set RLS Su ervision The RLS Supervision function supervises the synchronization status of the RLS provided by the RBS to the radio connection, an repor s any c anges o e . en n u ync n number of consecutive frames are out‐of ‐sync a timer rlFailureT is started and at expiry the RLS is considered out‐ of ‐sync and Radio Link Failure is reported to the SRNC. When the RLS is out‐of ‐sync and nInSyncInd number of frames are

‐ is reported to the SRNC.


‐

• Dedicated Physical Data Channel (DPDCH) Slot (0.666 mSec) Coded Data, 10 x 2^k bits, k=0…6

I

(10 to 640 bits)

Dedicated Physical Control Channel (DPCCH) Slot (0.666 mSec) Pilot (FSW: is some of Pilot Bits)

1 Frame = 15 slots = 10 mSec


TFCI

FBI

TPC

Q

• The connection is considered lost by the RCS when the last RLS for the connection has been out‐of ‐s nc for a time given by the parameter dchRcLostT. For a connection that includes HSDPA, the PS part of the connection is considered lost by the RCS when the RLS that contains the Serving HS‐DSCH cell, has been ou ‐o ‐sync or a me g ven y e parame er hsDschRcLostT. This means that when the requested to the PS CN and when the dchRcLostT timer expires, an Iu Release will be requested to all involved CNs. Copy Rights © LEGEND Co. 2010

SRNC

c

Radio Link out of sync sent to SRNC

T.S 1

T.S 15

c os

Radio Link Restore ar s

Number of Bad frames = nOutSyncInd

……………………….

Number of good frames = nInSyncInd Good Frame

Bad Frame #1

What is the BER of this frame (CRC decoding) Time Slot in DPCCH Copy Rights © LEGEND Co. 2010

r a ure starts

rlFailure T Expires

N.B if number of good frame that decoded by NB before rlFailureT timer expiration equal to nInSyncInd then the cons er o an e mer s ou s oppe

Power Control


Power Control types

Uplink

Open Loop Power Control

Closed Loop Power Control


Downlink

settings for Power

Closed loop Power control

Setting Of Of common common Channel

Channel Name

Parameter Name

Default Power Setting

Meaning

CPICH

PrimaryCpichPower

30 0

30dBm

BCH

bchPower

‐31

‐3.1dB

AICH

aichPower

‐6

‐6dB

FACH control

maxFach1Power

18

1.8dB

FACH (Traffic)

maxFach2Power

15

1.5dB

PCH

pchPower

‐4

‐0.4dB

pc

‐

‐ .

ower

P‐SCH

schPower1

‐18

‐1.8dB

S‐SCH

schPower2

‐35

=3.5dB


Open Loop Power Control • – SIR=Ec/No X SF = RSCP‐RTWP + 10log SF

– RSCP=SIR + RTWP – 10log SF as arge va ue epen on serv ce an • • SF has value related to the used service


anne

RACH preamble Power setting •

=

‐

.

– RSCP = SIR+RTWP – 10log SF. _ – _ . – – P_PRACH = SIR_TARGET_RACH + RTWP – 10 log SF _ CPICH_RSCP.

–

–

_ _ – parameter called (constantValueCprach)


, RTWP are sent to the UE through BCCH Now the UE can transmit the Preamble using P_PRACH ca cu ate Va ue


Power Ramping


Parameter

Range

Default

Description

PowerOffsetPO

1 to 8

3

3dB

PowerOffsetPpM

‐5to10

‐4

‐4dB

1 to 64

8

8 step of increase of increase recalculation of P_PRACH

MaxP Ma xPrreamb eamble leCy Cycl cle e

1 to 32


4

4 trials for P_PRACH calculation before giving access failure

RACH Message Power

RACH Data Slot (0.666 mSec)

I

Random Access Message (10, 20, 40, or 80 bits per slot) RACH Message Message Slot Slot (0.666 (0.666 mSec) Pilot (8 bits)

TFCI (2 bits)

Control Part Power = P_PRACH+ PowerOffsetPpm PowerOffsetPpm

1

2

3

4

5

6

7



8

9

10

11

12

13

14

15

Q

= GFc: is stan ar gain actor re ate to contro part GFd: is standard gain factor related to data part the type of carried information


Gain Factor

c

on ro

Range

Default

o

GFd (Control)

0 to 15

15

GFc (Data)

0 to 15

10

aa


o

FACH Power Setting • reserved relative to CPICH power The question Now is that do every part of FACH message as t e same power as t e reserve value 0, 2, or 8 bits

TFCI or DTX


20 to 1256 bits

Data

0, 8, or 16 bits

Pilot

•

_

=

_

– FO1 Default Value is 0 dB

• Pilot_Power = FACH_Power + FO2 – FO2 Default Value is 0 dB


Initial Setting of DL_DPDCH

In case of inter frequency non blind handover cBackoff will be replaced by cNbifho (modified parameter to enhance the performance of IFHO Copy Rights © LEGEND Co. 2010

DPDCH

Data 1

DPCCH

TPC

TFCI

DPDCH

Data 2

Default Values PO1 00 Ste 0.25 Value 0dB PO2 (12) Step 0.25 Value 3dB PO3 (12) Step 0.25 Value 3dB


DPCCH

Pilot

Downlink Power Ramping

P_DL_DPDCH Calculated nd

1st power steps x steps Used only when the NBAP indicates it should be used via parameter first

1st power Ramp

2nd power increase


Lower Power Limit

Inner loop

Setting of initial UL_DPDCH

_

_

_

PrimaryCpichPower + RTWP+uLInitSirTarget ‐ og _ +

–RSCP_PCPICH (dBm) Measured by the UE

DPCCH_power_offset Sent to UE by RBS in RRC connection setup Message

cPO= -30 to 30 in 0.5 dB steps default = 0 (0 dB) PrimaryCpichpower = -100 to 500 in 0.1 dB steps default = 300 (30 dBm) ulInitSirTarget : has different values for different services = = = = = and for RAB with SF= 32 or higher =4.9 Copy Rights © LEGEND Co. 2010

• U link DPDCH DPCCH Dedicated Physical Data Channel (DPDCH) Slot (0.666 mSec) Coded Data, 10 x 2^k bits, k=0…6

I

(10 to 640 bits)

Dedicated Physical Control Channel (DPCCH) Slot (0.666 mSec) Pilot

TFCI



FBI

TPC

Q

P_DPDCH power calculation

DPCCH power/ DPDCH power = Bc/Bd DPCCH power – DPDCH power= 20 log (Bc/Bd) = Bc: DPCCH gain factor Bd: DPDCH gain factor


‐

Radio Bearer

DPCCH gain Factor

DPDCH gain factor

DPDCH power

Signaling

11

15

DPCCH power +2.7

Speech

11

15

DPCCH power + 2.7

CS 64

8

15

DPCCH power + 5.46

PS 64/64

8

15

DPCCH power + 5.46

PS 64/384

8

15

DPCCH power + 5.46


Inner loop power control • DPDCH/DPCCH (pilot + Data +TFCI +TPC + Data)

TPC_Command = (UP) or (Down) DPCCH (Pilot + TFCI + TPC) DPDCH


RBS measure SIR _UL_ RLS of the pilot Data then compare it with Target value

DPCCH TPC_cmd=‐1 (Down) or +1 (UP)

DPCCH change =

TPC X TPC_cmd dB

DPDCH power related to DPCCH power

SIR_UL_RLS>= SIR_TARGET SIR_UL_RLS < SIR_TARGET


TPC command = “down” TPC command = “UP”

UL Power control during

10 mSec Frames (15 slots) Normal Operation 11

12

13

14

15

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15

Compressed-Mode; single-frame method 11

12

13

14

15

1

2

3

4

12

Transmission Gap

confirmation


13

14

15

1

2

3

4

SIR_target in CM

SIR_target + 1dB SIR_target + 0.5dB SIR_target 13

14

15

1

2

3

4

12

Transmission Gap


13

14

15

1

2

3

4

TPC command in CM

TPC = 2 dB TPC = 1 dB

13

14

15

1

2

3

4

12

13

14

15

1

Transmission Gap after the Gap pilot = 10 log (Npilot,prev/Npilot,curr) DPCCH= TPC X TPC_cmd + Copy Rights © LEGEND Co. 2010

Pilot

2

3

4

Down link inner loop power

DPDCH/DPCCH (pilot + Data +TFCI +TPC + Data)

DPCCH (Pilot + TFCI + TPC) DPDCH

SIR_DL_RLS of the pilot Data then compare it with Target value Copy Rights © LEGEND Co. 2010

TPC_Command = (UP) or (Down)

TPC command (UP or Down)

‐ P_TPC(K) = +1 dB if (TPC_CMD is _ SIR_UL_RLS>= SIR_TARGET SIR_UL_RLS < SIR_TARGET


TPC command = “down” TPC command = “UP”

Downlink Power Balancing

Power Drift SRNC

UE RBS 1 Copy Rights © LEGEND Co. 2010

RBS 2

8 frame cycle Frame 1

Frame 2

Frame 3

Frame 4

Frame 5

Frame 6

Frame 7

Frame 8

Reference value SRNC

RBS 1

RBS 2 UE At the beginning of each cycle a reference power, which is the average of all radio link powers is calculated. Over the next 8 frames cycle the power of each RL is adjusted back to this reference value


dlPcMethod

1 no DL power balance and no inner loop power control

2 No balancing only inner loop power control is used

3 Balancing is working

P(K) = P(K-1) + Pbalance Pbal = +1 dB increase the power -1 dB decrease the power Power balancing is configured to work on 8 frame cycle Copy Rights © LEGEND Co. 2010

4 fixed power balancing algorithm is used fixed Dl reference value

Downlink power control in

=

-

+

pc

+

a

Ptpc (K): +1(UP) or -1(down) X

+

sr

m

TPC

PSIR(K) = 3.5dB

PSIR(K) = 4dB TPC(K) = 1 dB 13

14

15

1

2

3

TPC(K) = 2 dB

4

12

13

14

15

1

2

Transmission Gap Recovery Period 7 slots after the Gap Copy Rights © LEGEND Co. 2010

3

4

14

15

Outer Loop Power control • The outer loo

ower control al orithm erformed for DL in the UE and for the UL in the RNC

• The Main idea behind the outer loop power control is to set proper

arge

• SIR target value change according to blerQualitytargetDl • . SIR min ‐82(‐8.2 dB) • UL outer loop power control could be either jump regulator or constant step regulator by ulOuterLoopRegulator parameter 1 Jump Regulator Copy Rights © LEGEND Co. 2010

Jump Regulator

SIRtarget= SIRtarget + ulSirStep(-x/(z*UPDOWNSTEPRATIO)+Y/Z)

Where: •ulSirStep = 0 to 50 in 0.1 step default 10 (1 dB) •X = Number of Transport blocks that have CRC OK •Z= Total Number of received Transport blocks •Y= Number of transport blocks that have CRC NG •UPDOWNSTEPRATIO= (1/blerQualityTargetUL * 0.5) -1 default •blerQualityTargetUL = -63 to 0 default is -2 (0.01)


_ arge = . CRC=OK Will continuo to drop until receive bad CRC

The SRNC will Update the SIR target value for the UL in resolution of 0.1 dB to prevent excessive Iub signaling. ulInitSirTaget = 4.9 SIRTarget= 4.9+1(-0/(199*1) +1/1) = 5.9 …………………………………………………………………………………. NG frame received Copy Rights © LEGEND Co. 2010

Step Regulator If ulOuterLoopRegulator set to 0 the Step regulator will work Idea of step regulator is as following : •The SIR target should increased by “ulSirStep” when one NG CRC have been Received • And decreased b “ulSirSte ” if number of ood CRC e ual to (1/(1.5blerQualityTargetUL) (0.5) Default 133

133 Good CRC

ulSirInitTarget NG CRC Copy Rights © LEGEND Co. 2010

NG CRC

Handover


Handover Type

HO Types

Hard Handover

IRAT handover

Inter Frequency HO


Core Network Hard HO

Soft HO

Softer HO

Soft/ Softer HO RNC

UE DCCH

Perform measurement UE Evaluation

RNC Evaluation RL addition

Active Set Update DCCH

Radio Link Removal

Update Complete

DCCH Copy Rights © LEGEND Co. 2010

Radio Link Add/Remove / Replace

Reported Measurement


Measurements Elaboration


RRC Measurement initial


Handover triggering type • – Measurement to be sent whenever the levels of

• Periodic triggering – easuremen repor s ou the UE periodically


e sen o

e

y

Event Description


Event 1A


Event 1B


Event 1C


Event 1D


Event 1E


Event 1F


Event 2D/2F

2B/2C 3A/3C


Compressed Mode


Compressed mode

• – SF/2 – – Higher layer scheduling



Load Control


PUC


ICAC


Cell Resource Decision


The algorithm Chooses UEs for Pre‐emption


LDR


WCDMA Optimization

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