s02-1_idlemodes9_1

1 © NOKIA 2000 BSSPAR/ Idlemode.ppt/ January 2002

IDLE MODE OPERATION

BSSPAR


IDLE MODE OPERATIONCONTENTS

1. IDLE Mode tasks overview

2. ID’s and ID Codes , Frequencies

3. PLMN (Public Land Mobile Network) selection

4. Cell selection and cell reselection

C1 Algorithm

C2 Algorithm

5. Location Area Management (as in Radio Resource Management)

Location Updates

Time Periodic Location Update

6. IMSI Attach/Detach


IDLE MODE OPERATION

When the MS is switched ON

When there is no dedicated connection

When?

Why?To camp on the best suitable cell

Why to camp on a specific cell?For MS to receive system info from the NW on DL

For MS to be able to initiate a call whenever needed

For the NW to be able to locate the MS when there is a MT call/SMS


IDLE MODE OPERATIONIdle Mode Tasks

• PLMN selection

• Cell selection and reselection

• Location update


IDLE MODE OPERATION ID's and ID Codes

Parameter Value

locationAreaId

• MCC (Mobile Country Code) 0 … 999• MNC (Mobile Network Code) 0 … 999• LAC (Location Area Code) 0 … 65535

• NCC (Network Colour Code) 0 … 7• BCC (BTS Colour Code) 0 … 7

bsIdentityCode

Cell-ID 0 … 65535

TrainingSequenceCode 0 … 7

Cell Global Identity MCC + MNC + LAC + CI


IDLE MODE OPERATIONIDLE MODE OPERATIONBaseStationBaseStation Identity Code (BSIC)Identity Code (BSIC)

• BSIC is a combination of NCC and BCC

• MS reports the BSIC of the serving cell and neighbors to the BSC.NOTE: Serving BTS does not send the BSIC of the neighbors to MS. Only

the BSIC of the serving cell is sent on idle and dedicated mode.

• Can be listed in Octal or Binary

Octal 27 (2 * 81+7 * 80) = Decimal 23

NMS Mobile


IDLE MODE OPERATIONLocation Area Code & Base Station Color Code bcc = 2

f1f2

f3

f1

f1

bcc = 1Location Area Code

MNC = Operator

MCC = Country e.g USA

LAC 1 LAC 2

LAC 3 LAC 4 BSC

BTS BTS BTS1 2 n

bcc = 3

Neighbour list of f3:f1f2...


IDLE MODE OPERATION Frequencies

Parameter Value

initialFrequency 1 ... ….124 GSM 900512 … 885 GSM 1800512 … 810 GSM 1900

bCCHAllocation-ID 1 ... 255 in GSM

bCCHAllocationList 1 ... 124 in GSM ( max. 32 freq. for all bands)

idleStateBCCHAllocation 0 (BCCH list is taken from the adjacent cell)1 ... 128 (number of the BCCH list used)

measurementBCCHAllocation ADJ (BCCH frequency list taken from adj. cell)IDLE (active MS uses the same list as MSin IDLE mode)


IDLE MODE OPERATIONPLMN Selection

• Two Modes

•Automatic

•Manual

• Three Types of Lists

•Preferred

•Found

•Forbidden

Parameter Value

plmnpermitted 0 ... 7

NOTE This parameter is confusing. It’s not used for network selection. It’s used AFTERa network has been selected so that only measurements from those defined PLMN(s) are reported


IDLE MODE OPERATIONCell Selection in Idle Mode

Two methods:a) Normal cell selectionb) Stored list cell selection (opt)

If no suitable cell found with method b) then a) is tried.


IDLE MODE OPERATION Suitable cell to camp on

• Cell is in the selected PLMN• Cell is not barred• It is not in a forbidden location area for national roaming• C1 >0• If there is no normal priority cell then low priority cell


IDLE MODE OPERATION Cell Barred

GPS-satellite

Example

Existing Layer• Barred, No

New Microcell Layer• Barred, Yes

Measurement System

•Call setup on macro, no SDCCH needed in micro (only BCCH)

cellBarred Y/NcellBarQualify Y cell bar can be overridden(C2) N cell bar can not be overridden


IDLE MODE OPERATIONCell Selection in Idle Mode- Implementation

Averaging 3-5 s.Decision 5s.

• Radio Criteria• C1 = (A - Max(B,0))

• A = Received Level Average - p1

• B = p2 - Maximum RF Output Power of the Mobile Station

• p1 = rxLevelAccessMin Min. received level at the MS required for access to the system

• p2 = msTxPowerMaxCCH Max. Tx power level an MS may use when accessing the system

Parameter Value

rxLevelAccessMin -110 ... –47dBm

msTxPowerMaxCCH 0 … 30 dBm


IDLE MODE OPERATION Cell Selection in Idle Mode, GSM 1800

• The powerOffset parameter is used for class 3 GSM 1800 MSs (P = 36dBm).

• P2 = msTxPowerMaxCCCH + powerOffset• When calculating C1• When accessing the Network

Parameter Value

powerOffset 0 = 0 dB1 = 2 dB2 = 4 dB3 = 6 dB


IDLE MODE OPERATION Cell Re-selection in Idle Mode

MS will calculate the C1 and C2 for the serving cell, every 5 s

MS will calculate the C1 and C2 for the six best neighbor cells, every 5 s

Cell re-selection is needed if

• Path Loss criterion C1 < 0 for cell camped on ,for more than 5 seconds.

•Any of the neighbors have a higher C1 after 5 seconds.

•There is DL signaling failure.

• The cell camped on has become barred.

•There is a better cell in terms of C2 criterion

• A random access attempt is still unsuccessful after " maxNumberRetransmission "

repetitions.


IDLE MODE OPERATION Cell Re-selection with C2

BC C H

BC C H

fast m oving m obile

slow m oving m obile

tim e

m icrocell

m acrocell

cell attractiveness


IDLE MODE OPERATION Cell Re-selection with C2, continues

Parameter Value

cellReselectParamInd Y C2 reselection parameters are broadcastN C2 reselection parameters are not broadcast

C2= C1 + cellReselectOffset - temporaryOffset*H(penaltyTime-T) 20 <= penaltyTime < 11111= C1 - cellReselectOffset …………………………………………..<= penaltyTime = 11111

For the neighbor cell For the serving cell1 when T < = penaltyTime

H(x) = H(x) = 0 when T>penalty time>T0 when T > penaltyTime

In NOKIA BSC penaltyTime = 640s = 11111 !!!!!!

cellReselectOffset 0 ... 126 (dB) 2 dB steppenaltyTime 20 ... 640 (s) 20 s steptemporaryOffset 0 ... 70 (dB) 10 dB step (the value is negative)


IDLE MODE OPERATION Cell Re-selection with C2, continues

C2 when penaltyTime = 640C2 when penaltyTime < 640dB

C2

timepenaltyTime

cellReselectOffset temporaryOffset C1

cellReselectOffset

C2


IDLE MODE OPERATIONCell Re-selection

cellReselectHysteresis (0 … 14 dB)

MS Moving

LA2LA1

A = 4 dB

B = 6 dB

C = 8 dB• A B C •1 2

1

2

A B C


IDLE MODE OPERATION Cell Re-selection

cellReselectHysteresis (0 … 14 dB)cellReselectHysteresis

The nominal LA border

L1

The real LA border

L2


IDLE MODE OPERATIONLocation Update

• MS => MSC / VLR

• Mobile Station switched ON• No IMSI Attach / Detach• Same Location Area => No Location Update• Different Location Area => Location Update

• Change of the Location Area• Location Area under the same MSC / VLR• Location Area under another MSC /VLR => HLR will be updated

• Service is rejected (MS unknown in VLR)

• Time Periodic (MS -> MSC/VLR)

Parameter Value

• timerPeriodicUpdateMS 0.0 ... 25.5 (hours)• allowIMSIAttachDetach Yes/No

s02-1_idlemodes9_1

Documents

idle mode operationwhen

idle mode operationbsspar

idle mode operationcontents1

idle mode operation

dedicated mode

idle mode tasks overview2

serving cell

specific cell