NSN 2G-3G Parameter Setting

(1)

I insert classification level

Sharing Traffic 2G-3G

• Load Base Handover 2G-3G

• Cell Reselection

3G-2G

2G-3G

(2)

Load based Handover GSM -> WCDMA

100%

80%

Load reason

Handovers

for speech

Load of GSM cell

Packet Data to WCDMA

regardless of GSM load

Packet Data to WCDMA

regardless of GSM load

Speech to WCDMA

only with high GSM load

Speech to WCDMA

only with high GSM load

Higher bit rates

for data users

Higher bit rates

for data users

More capacity

for speech

More capacity

for speech

Packet BCCH parameters can be used

to push GPRS mobiles to WCDMA

Packet BCCH parameters can be used

to push GPRS mobiles to WCDMA

Utran

HoThScTpdc

= 80%

(3)

Soc Classification level

GSM

Load & Coverage Reason Handover

GSM

GSM high

loaded

WCDMA low

loaded

GSM

_GSM

WCDMA

_WCDMA

Load reason

Handover for speech

and for HSCSD

Load reason

Handover for speech

and for HSCSD

WCDMA

GSM

_GSM

Load reason

Handover

Coverage reason

Handover

WCDMA can be used

to relieve GSM overload

GSM can be used to extend

WCDMA coverage area

WCDMA can be used

to relieve GSM overload

GSM can be used to extend

WCDMA coverage area

(4)

Load based Handover Process: GSM-> WCDMA

Handover Triggering Thresholds set in BSC

Inter-RAT measurements starts in case

The RXLEV of the serving cell is above or

below the given threshold Qsearch_C

Inter-RAT measurements starts in case

The RXLEV of the serving cell is above or

below the given threshold Qsearch_C

Handover Decision is done in case of

Load of the serving cell > Load_Threshold

& CPICH Ec/No> min Ec/No Threshold

Handover Decision is done in case of

Load of the serving cell > Load_Threshold

&

CPICH Ec/No> min Ec/No Threshold

MS selects the target UTRAN cell based

on measurement results

MS selects the target UTRAN cell based

on measurement results

Handover command is send to MSC

MS is measuring the UTRAN cells continuously

if they are defined as a neighbor ,

The number of GSM neighbor reported could be 3-6

depending on the set value of parameter

FDD_MULTIRAT_REPORT

(0,1,

2=def

,3).

The load is measured in the cell level by comparing

the occupied TCHs to the available TCHs (20 s

interval used)

Load Threshold for Speech Calls or Transparent

Data inter-RAT Handover:

utranHoThScTpdc

(Min Traffic Load TDHO),

default =

80%

minEcnoThreshold

(Min CPICH EC/NO

Threshold),

default –15 dB

Parameters are sent from the BSC to the mobile

in the Measurement Information message

(5)

ISHO 2G -> 3G Parameters

Parameter

Specification name

NSN parameter

Range

Default value

min traffic load for speech call

LOAD_THRESHOLD_FOR_S

C_IS_HO

utranHoThScTpdc (LTSC)

0-100%

80%

minimum CPICH Ec/Io level

MIN_ECNO_THRESHOLD

minEcnoThreshold

(MET)

-24…0.5 dB

-15 dB

min interval between unsucc ISHO

attempt

MIN_INTERVAL_BETWEEN_

UNSUCC_ISHO_ATTEMPT

minIntUnsuccIsHo (UMIU)

0…255 s

3 s

threshold for multi-RAT MS

Qsearch_C

qSearchC (QSRC)

0…15

15 (never)  rec. 7

(always)

Specification name

Parameter explanation

Value range

Note

FDD_REP_QUANT

Indicates the reporting quantity for UTRAN FDD

cells

0=RSCP,

1=EC/NO

Not tunable, Fixed

value 1

3G_SEARCH_PRIO

Indicates if 3G cells may be searched when

BSIC decoding is required

0 = no,

1 = yes

Not tunable, Fixed

value 1

FDD_MULTIRAT_REPORTING

The number of cells from the access

technology/mode FDD that shall be included in

the measurement report

0…3

Not tunable, Fixed

value 2

Qsearch_C_Initial

Indicates the Qsearch value to be used in

connected mode before Qsearch_C is received

0 = use Qsearch_I,

1 = ∞ (always)

Not tunable, Fixed

value 0

C

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H

id

d

e

n

(6)

Handover Control

• GSM ISHO

• Load Based Handover to WCDMA

(7)

Cell Reselection 3G -> 2G

First ranking of all the cells based on

CPICH RSCP (WCDMA) and RSSI (GSM)

Rs = CPICH RSCP + Qhyst1

Rn= Rxlev(n) - Qoffset1

First ranking of all the cells based on

CPICH RSCP (WCDMA) and RSSI (GSM)

Rs = CPICH RSCP + Qhyst1

Rn= Rxlev(n) - Qoffset1

Rn (GSM) > Rs (WCDMA)

And

Rxlev (GSM) >QrxlevMin

Rn (GSM) > Rs (WCDMA)

And

Rxlev (GSM) >QrxlevMin

Yes

No

Cell re-selection

to GSM

Cell re-selection

to GSM

Neighbour WCDMA or GSM

cell calculation with offset

parameter

Serving WCDMA cell

calculation, with

hysteresis parameter

UE starts GSM measurements if

CPICH Ec/No < qQualMin + sSearchRAT

UE starts GSM measurements if

CPICH Ec/No < qQualMin + sSearchRAT

SintraSearch

SinterSearch

SsearchRAT

CPICH EcNo

qQualMin

Second ranking only for WCDMA

cells based on CPICH Ec/No

Rs = CPICH Ec/No + Qhyst2

Rn=CPICH_Ec/No(n)-Qoffset2

Second ranking only for WCDMA

cells based on CPICH Ec/No

Rs = CPICH Ec/No + Qhyst2

Rn=CPICH_Ec/No(n)-Qoffset2

Cell re-selection to

WCDMA cell of highest

R value

Cell re-selection to

WCDMA cell of highest

(8)

Cell Reselection 3G -> 2G



UE ranks the serving cell and the measured neighboring cells to find out if

reselection should be made



All the measured suitable cells (S-criteria) are included in the ranking.



Criteria for a suitable cell (S-criteria) is defined as



_{WCDMA intra-frequency neighbor cell:}



CPICH Ec/No >

AdjsQqualmin

and CPICH RSCP >

AdjsQrexlevmin



_{WCDMA inter-frequency cell:}



CPICH Ec/No >

AdjiQqualmin

and CPICH RSCP >

AdjiQrexlevmin



GSM cell:



Rxlev >

Qrxlevmin



Ranking is done using Criteria R, and the UE reselects to the cell with highest

R-criteria. R-criteria is defined as:



_{For serving cell: Rs =}

_Qmeas,s

₊

_Qhysts



_{For neighboring cell Rn =}

_Qmeas,n

_–

_Qoffsetts,n



_{Qmeas is CPICH Ec/No for WCDMA cell and RxLev for GSM cell}

(9)

Cell Reselection List

GSM MS starts WCDMA measurements if :

RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7

or

RLA_C> F(Qsearch_I) for 7<Qsearch_I<=15

If, for suitable UMTS cell

& for a period of 5 s:

CPICH RSCP > RLA_C +

FDD_Qoffset

CPICH Ec/No

≥

FDD_Qmin

no priorities

between

WCDMA

neighbors

Measurement Updates:

• RLC_C value of the serving cell

• + least 6 strongest non serving GSM cells

at least every 5 s

check

and

WCDMA cell

reselection

BCCH: FDD_Qmin, FDD_Qoffset

Cell Reselection 2G -> 3G

Qsearch_I:

0..15; 1;

7 (always)

FDD_Qmin

:

-20... –6; 2;

-12 dB

Fdd_Qoffset

:

select always

(value is

-infinity

)

(10)

Cell Re-selection Parameters

• Qsearch_I

and

Qsearch_P

define the threshold for non-GPRS/GPRS (respectively) capable

UEs to measure 3G neighbour cells when a running average of the received downlink

signal level (RLA_C) of the serving cell is below (0-7) or above (8-15) the threshold

Value

0

1 …

6

7

8

9

10 …

14

15 dBm

-98

-94

…

-74

Always

_-78

_-74

_-70

_…

_-54

_Never

• FDD_Qoffset

and

FDD_GPRS_Offset

the non-GPRS/GPRS (respectively) capable UEs

add this offset to the RLA_C of the GSM cells. After that the UE compares the

measured RSCP values of 3G cells with signal levels of the GSM cells

Value

0

1

2

3 …

8 …

14

15 dBm

-always

-28

-24

-20

…

0 …

24

28 If RLA_C < -94 UE

starts 3G

measurements

UE always

measures 3G cells

If RLA_C > -70 UE

starts 3G

measurements

(11)

RLA_C

Cell Re-selection Example: weaker WCDMA

Non GPRS case

t

Serving GSM Cell

Neighbour WCDMA Cell

Ec/No

RSCP/

RLA_C

5 sec.

Cell re-selection to WCDMA

FDD_Qmin=0

-12 dB

FDD_Qoffset = -8 dB

Qsearch_I =

-98 dBm

Measurements starts (serving cell)

Minimum Quality Requirement for WCDMA

Ec/N0

RSCP

GSM -> WCDMA

CPICH RSCP > RLA_C + FDD_Qoffset

&

CPICH Ec/No

≥

FDD_Qmin

Idle Mode

(12)

Cell Re-selection Example: stronger WCDMA

GPRS case

t

Serving GSM Cell (Best)

Neighbour WCDMA Cell

Ec/No

RSCP/

RLA_C

5 sec.

Cell re-selection to WCDMA

FDD_Qmin

= -20 dB

FDD_GPRS_Qoffset

= 8 dB

_{Qsearch_P}

= -98 dBm

RLA_P

Measurements starts (serving cell)

Minimum Quality Requirement for WCDMA

Ec/N0

RSCP

Connected Mode

(13)

How to avoid ping pong ?

• When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of

serving cell is below Ssearch_RAT + QqualMin.

• When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of the

candidate is above FDD_Qmin.

• Therefore, to avoid ping pongs between 3G and GSM the following condition should be

met:

FDD_Qmin >= QqualMin+Ssearch_RAT

QqualMin=-18 dB

Ssearch_RAT=4 dB

CPICH Ec/Io

FDD_Qmin >=

-12 dB

QqualMin +Ssearch_RAT

t

(14)

PUSH AMR

(15)

max. allowed UE Tx Power

(e.g. 21 dBm)

+

GsmUETxPwrThrAMR

:

FMCG; -60..0; 1;

-3 dB

here: - 60 dB !

Forced Handover for AMR Voice Call

• Feature can be used to push

3G AMR calls to 2G

• Extreme parameter setting for ISHO

trigger cause “UE Tx power” (event 6A)

WCDMA

GSM

AMR voice call setup in 3G

forced handover

to GSM

[..]

UE

RNC

RRC: RadioBearerSetup

RRC: RadioBearerSetupComplete

RRC: MeasurementControl

RRC: MeasurementReport (event 6A)

FMCG: GSMcauseTxPwrUL

FMCG: GsmUETxPwrThrAMR

ISHO measurements & HO

to GSM

UE immediately answers

with Measurement Report

„push“ means Handover, not Directed-Retry !

Remember:

6A:

UE Tx power >

absolute threshold

GSMcauseTxPWRUL

FMCG; 0 (no) /

1 (yes)

(16)

Forced Handover for AMR Voice Call

• FMCG:

GSMcauseTxPwrUL

• Range and step: 0 (False), 1 (True)

• Indicates whether a handover to GSM caused by high UE TX power level is enabled. The

handover is enabled when the value of the parameter is "Used“

• To enable feature, setting must be 1 (True)

• FMCG:

GsmUETxPwrThrAMR

• Range and step: -60..0 dB

• This parameter determines the UE TX power threshold for a CS voice connection. If the

handover to GSM caused by high UE TX power level is enabled, the RNC starts inter-RAT

(GSM) measurements when the UE TX power reaches this threshold. The UE TX power

threshold is relative to the maximum TX power level an UE can use on the DPCH in the cell (or

the maximum RF output power capability of the UE, whichever is lower

(17)