alcatel lucent drive test 1 part 4

Call Flow and Call ProcessingCall Flow and Call Processing

Created byPulok Sinha (Trainer, ALUMS)

All Rights Reserved © Alcatel-Lucent 2009

( , )09320096525

Call Flow and Call Processing

Objectives :

After successful completion of this program, You will be able to Describe

Swap and Types Swap and Types Coverage, Quality and Hand Over issuesInvolvement of Channels in a call ProcessMobile originating Call Flow in GSMMobile terminating Call Flow in GSMIntroduction to Layer 3 –System Info Messagesy y gLocation Updating FlowLayer 3 Messages in Location UpdateSome More Layer 3 Messages


Some More Layer 3 Messages

2

Swap and Types


Swap and Types

Swap : Swap :

Wh th f d bl f th t f it t i t h d it When the feeder cables of the sector of a site gets interchanged it is commonly termed as SWAP.

Basicall can be of 3 t pesBasically can be of 3 types− Sector Swap− Diversity or TX cable Swap between two sectors

Di it bl i t d TX bl i th− Diversity cable swap in one sector and TX cable swap in other.


Swap and Types

Sector SwapSector Swap

• Both the Tx and Rx feeder cableare interchanged between sectors

• Coverage is good.

• Network Parameter are reversed

• Poor Handover


Swap and Types

• BCCH Sec-2 • BCCH Sec-1BCCH Sec 2• Cell ID Sec-2• Poor HOs

BCCH Sec 1• Cell ID Sec-1• Poor HOs


Swap and Types

Diversity cable Swap between two sectorsDiversity cable Swap between two sectors

• Only Rx feeder cable areinterchanged between sectorsg

• Good Coverage near to Site butbad coverage far from the site.g

• Some times lead to poor Quality

• Poor Handover


Swap and Types

• BCCH Sec-1 • BCCH Sec-2BCCH Sec 1• Cell ID Sec-1• Poor Rx Level with dist• Unexpected HOs

BCCH Sec 2• Cell ID Sec-2• Poor Rx Level with dist• Unexpected HOs


Swap and Types

Div cable swap in one sector and TX cable swap in otherDiv cable swap in one sector and TX cable swap in other• Only Tx feeder of one sector and

Rx feeder cable of another sectorare interchanged

• Coverage of both the sector will be• Coverage of both the sector will benearly equal.

• Some times lead to poor Qualityp y

• Level of both the sector is highnear Sector-2 and poor in Sector-1in this casein this case

• Ping pong Handover between thetwo sector and poor handover with


pother cells

Swap and Types

• BCCH Sec-1 & Sec-2• Cell ID Sec-1 & Sec-2

••

• Rx Lev almost equal of both the sec

• Ping Pong HOs betwn the sectors

•


sectors

Coverage, Quality and Handover Issues



Coverage issues: Coverage issues:

L k f D i t S C t h d b t Lack of Dominant Server Causes too many handovers between the same Cells which may lead to poor RxQual as well as drop.

Cur e Formation due to Tunnel also lead to sudden degradation Curve Formation due to Tunnel also lead to sudden degradation of the Signal Level

Effect causing sudden level decrease and Ping Pong Handovers Effect causing sudden level decrease and Ping Pong Handovers sometimes leading to call drops

Levels of 3–4 cells are too closed to each other – This might point Levels of 3 4 cells are too closed to each other This might point overlapping cells. Optimization for dominant server is needed as it leads to quality problems.




L k f D i t S C t h d b t Lack of Dominant Server Causes too many handovers between the same Cells which may lead to poor RxQual as well as drop.

Cur e Formation due to Tunnel also lead to sudden degradation Curve Formation due to Tunnel also lead to sudden degradation of the Signal Level

Effect causing sudden level decrease and Ping Pong Handovers Effect causing sudden level decrease and Ping Pong Handovers sometimes leading to call drops

Levels of 3–4 cells are too closed to each other – This might point Levels of 3 4 cells are too closed to each other This might point overlapping cells. Optimization for dominant server is needed as it leads to quality problems.




Th di t t ll l i th d t t The distant cell always popping up as the second strongest neighbor in the list through a large area might show an overshooting cell the cell need to be physically optimized.

Signal Strength may change fast due to far away server being blocked by obstacles from the terrain.

Even the signal of a cell may be low near the site. This may be due to high VSWR and hardware issue like loose connectors, damaged feeder cable, antenna issue, etc.damaged feeder cable, antenna issue, etc.



Quality issues:Quality issues:

RXQUAL can be poor because of poor RXLEV (coverage), low carrier-to-noise ratio (C/N), co-channel interference, adjacent channel interference or multipathp

If RXQUAL is poor and RXLEV is good, then it is generally assumed that the cause is interference and C/I is verified./

TCH carriers are also reused, and hence can contribute to co-channel interference, although this interference will not always be present; it will only be present when these TCH carriers have call activity.



Quality issues:Quality issues:

The collision of frequencies with neighboring cells MAIO list frequencies become more significant with dropping signal level.

Bad Quality due to Signal Strength – Bad FER. As the signal strength drops down, not only Rx Quality is bad, but also FER is high.g

Bad Quality due to Signal Strength – Good FER. If the Signal strength is poor and FER is fine. The area in this case should most probably be a flat area without any obstacles to create reflection.


Coverage, Quality and Handover IssuesOvershooting ExampleOvershooting Example

30115 is overshooting in the30115 is overshooting in thevicinity of 10333.

May lead to poor quality evenMay lead to poor quality evencall drop in dedicated mode.

The orientation and tilt of30115 need to be checked.


Coverage, Quality and Handover IssuesSwap SuspectedSwap Suspected

Need to check,,

If orientation is proper

If swap is there in the site

If the cell 30056 radiatingproperly

If not then check for H/Wissuesissues.


Coverage, Quality and Handover IssuesIssue with HOIssue with HOThere is issue in HO between 30364 and 20375.

Need to check,

If both the cells defined as neighborIf the cell was radiating.If the cell was in congestion.


gIf there was any H/W issue in the cell.


What's the issue?What's the issue?


Involvement of Channels in a call process


Involvement of Channels in a call processRole of channels as soon as MS is switched on till a call is Role of channels as soon as MS is switched on till a call is

completed.completed.


Mobile Originating Call Flow in GSM


Call Flow Mobile Originating Call


Mobile Terminating Call Flow in GSM


Call Flow Mobile Terminating Call


Introduction To Layer 3 - System Info



System Information System Information

i f i i d b h k h h d iSystem information is data about the network that the MS needs in order to communicate with the network.

ll h fBasically the system information messages are sent on− BCCH in Idle Mode− SACCH in Dedicated Mode

There are different types of System information and are numbered from 1-8

− System information 1, 2, 3, 4, 7 and 8 are sent on BCCH in idle mode − System Information 5 and 6 are sent in dedicated mode on SACCH.− System information 13 is for GPRS



System Info 1 Message



System Info 1System Info 1

The System Info 1 is generally sent if frequency hopping is used TheThe System Info 1 is generally sent if frequency hopping is used. TheMS is informed about Cell Channel Description and RACCH ControlParameters.Cell Channel description gives the frequencies that are used in theCell Channel description gives the frequencies that are used in thecell. In non hopping case may give BCCH and TCH frequencies.

ACCACC

The access control class is described using a bit map with 16bits AllThe access control class is described using a bit map with 16bits. AllMSs are spread out on ACC 0-9. Priority group MSs use ACC 11-15.Bit 10 is used to indicate if emergency calls are permitted.

ECECECEC

EC=0 means that all MSs are allowed to make emergency calls, whileEC=1 means that only MSs belonging to priority classes 11-15 areallowed to make emergency calls


allowed to make emergency calls.


CBCell barred for access is denoted by using one bit only (yes/no).

RECall re-establishment allowed is also denoted by using one bit(yes/no).(yes/no).

MAXRETMaximum retransmission is the maximum number of channel requestqmessage retransmissions allowed when an MS attempts to access thesystem. MAXRET can have the value 1, 2, 4 or 7.

TXTXThis is the number of slots to spread random access retransmissionsover when an MS attempts to access the system. The values TX canhave are 3-12 in increments of one 14 16 20 25 32 and 50


have are 3 12 in increments of one, 14, 16, 20, 25, 32 and 50.


System Info 2System Info 2System information type 2 contains a list of

− Neighbor cells description.− The MS is also receives information about which PLMN permitted.− RACCH Control Parameters.

BA-NOThis is a BCCH allocation number. BA-NO=0 means GSM 900.

BA-INDThis is a BCCH allocation sequence number indication. When theoperator changes the frequency list, the BA-IND changes from 1 to 0p g q y , gor vice versa.

BA ARFCNThese are absolute RF channels of neighbor cells


These are absolute RF channels of neighbor cells


EXT-INDBit indicates whether the information element carries the completeinformation or whether a complementary information element is sentinformation or whether a complementary information element is sentin another message.

− 0 ⇒ this information element carries the complete frequency list− 1 ⇒ this information element carries part of the frequency list only and a 1 ⇒ this information element carries part of the frequency list only and a

complementary information element is located in another message

NCCPERMNCCPERMThe MS gets information about which NCCs of the BCCH carriers it isallowed to monitor for handover purposes.



System Info 3 Message [Cont…]



System Info 3System Info 3Network sends following information in System Info 3

− Cell Identity− Location Area Identification− Control Channel Description− Cell Options− Cell Selection Parameters− RACH Control Parameters

Cell Identity (CI)Two octets (16 bits) identifying a cell within a location area.

Location Area Identification (LAI)Location Area Identification (LAI)MCC Mobile Country Code (3 digits)MNC Mobile Network Code (2-3 digits)LAC L ti A C d (2 t t 0 65535 diff t LAC )


LAC Location Area Code (2 octets: 0-65535 different LACs)


ATTWhether or not the MS is to perform IMSI Attach and IMSI Detachprocedures (ATT=1) or (ATT=0)procedures (ATT=1) or (ATT=0).

CCCH_CONFThis is the number of Basic Physical Channels used for the CCCH. (1-4 BPC h t bi d ith SDCCH 1 BPC if bi d)4 BPCs when not combined with SDCCH, 1 BPC if combined).

AGBLK (BS_AG_BLKS_RES)This is the number of CCCH blocks reserved for the AGCH, CBCH orBCCH Extended. The range of this parameter is 0-2 if CCCH iscombined with SDCCH and 0-7 for non-combined CCCH.

MFRMS (BS_PA_MFRMS)This is the number of 51 multiframe periods for transmission ofPaging Request messages to the same paging group (2-9) i.e. MFRMSis the multiframe period and defines the transmission interval ofpaging messages to the same paging group


paging messages to the same paging group.


T3212This is the time-out value for MS periodic location updating. T3212has values from 0 to 255has values from 0 to 255.

Cell options

DTXDiscontinuous transmission indicator (may, must or must not).

PWRCPWRC = 0 means not setPWRC 0 means not setPWRC = 1 means set.If the PWRC parameter is set, it means that the MS is not to includemeasurements on the BCCH carrier in the calculated average. If themeasurements on the BCCH carrier in the calculated average. If theparameter is not set, the BCCH measurements are included.

RLINKTThis parameter define the maximum value of the radio link counter


This parameter define the maximum value of the radio link counterthat has been defined for the serving cell.


Cell Selection ParametersACCMIN (RXLEV_ACCESS_MIN)

Thi i h i i i d i l l l h MS f hi h i iThis is the minimum received signal level at the MS for which it ispermitted to access the system. Range (0-63): -110 dBm up to -48dBm.

ACCMIN value Signal strength value

0 Below ‐110 dBm0 Below 110 dBm

1 ‐110 dBm to ‐109 dBm

2 ‐109 dBm to ‐108 dBm

.

. .

62 ‐49 dBm to ‐48 dBm

63 G h 48 dB


63 Greater than ‐48 dBm

44


CCHPWR (MS_TXPWR_MAX_CCH)

Th CCHPWR fi ld d fi th i t t MS iThe CCHPWR field defines the maximum output power an MS isallowed to use when accessing the cell. Signal Strength value forcorresponding power level for GSM is shown below:

CCHPWR value Signal strength value

0 ‐ 2 39 dBm

3 37 dBm

4 35 dBm

..

. .

18 7 dBm

19 31 5 dBm


19 ‐ 31 5 dBm


CRH (CELL_RESELECT_HYSTERESIS)This represents cell reselect hysteresis. The measured signal strengthis decreased by CRH (range 0-14 dB) in increments of 2 dB if the cellis decreased by CRH (range 0 14 dB) in increments of 2 dB if the cellbelongs to a new LA.

ACSThis field defines the additional reselect parameters indicator and isThis field defines the additional reselect parameters indicator and isspare in a system information type 3 message.

NECIThis parameter is used for new establishment causes indication (0 orThis parameter is used for new establishment causes indication (0 or1). It indicates whether the phase 2 establishment causes aresupported by the system. The establishment cause is included in thechannel request message on the RACH.

RLINKTThis parameter define the maximum value of the radio link counterthat has been defined for the serving cell.



SI 3 Rest OctetsSystem information type 3 rest octets may contain parameters thatare used by a phase 2 MS for calculating the cell reselection criterionare used by a phase 2 MS for calculating the cell reselection criterionC2.

2TIThis is system information type 2 ter indication (0 or 1) 2TI is used byThis is system information type 2-ter indication (0 or 1). 2TI is used bythe MS to determine, if the network broadcasts system informationtype 2 ter.2TI=0 means that system information type 2 ter is not available.y yp2TI=1 means that system information type 2 ter is available.

ECSCThe setting of the early classmark sending control bit informs MSsThe setting of the early classmark sending control bit informs MSswith the “control early classmark sending” option whether earlysending of additional classmark information is accepted or notaccepted by the system. Early in this case means as soon as possible


after access.


PICell_reselect_param_ind can have the value 0 or 1. PI is used by theMS to determine if the C2 parameters are broadcast by the network inMS to determine if the C2 parameters are broadcast by the network inthis message.PI=0 ⇒ C2 parameters are not presentPI=1 ⇒ C2 parameters are presentPI=1 ⇒ C2 parameters are present

CBQCell bar qualify (values: 0 or 1) is used by the network to control MScell selection and re-selection.

CELL_RESELECT_OFFSETA system information value used by the MS to apply a positive ornegative offset to the value of C2. Range is 0-63, which corresponds to0 126 dB in 2 dB steps


0-126 dB in 2 dB steps.


TEMPORARY_OFFSETA system information value used by the MS to apply a negative offsetto the value of C2 for the duration of PENALTY TIMEto the value of C2 for the duration of PENALTY_TIME.Range : 0 – 7 with increment of 10 dB and & 7 is infinity

PENALTY_TIMEThis parameter defines the length of time for whichTEMPORARY_OFFSET is active.Range: 0-31, with 20 second increments and 31 indicate thatTEMPORARY_OFFSET is to be ignored.



System Info 4 Message [Cont…]



System Info 4System Info 4Network sends following information in System Info 4

L ti A Id tifi ti− Location Area Identification− Cell Selection Parameters− RACH Control Parameters

CBCH Ch l D i ti− CBCH Channel Description− CBCH Mobile Allocation− SI 4 Rest Octets

Cell Selection ParametersCell Selection Parameters

ACSAdditional reselect parameters indicator (0 or 1).0 ⇒ the system information type 4 rest octets, if present, are used toderive the PI value and any existing C2 parameters.1 ⇒ the PI value and any existing C2 parameters in systemi f ti t 7 d 8 t b d


information type 7 and 8 message are to be used.

Introduction To Layer 3 - System InfoCBCH Channel Description (Optional)

CHANNEL TYPEThis is the channel combination and sub-channel used for CBCH ForThis is the channel combination and sub channel used for CBCH. Forexample, SDCCH/4 + SACCH/C4 or CBCH, sub channel 2.

TNThis represents the time slot numberThis represents the time slot number.

TSCThis is the training sequence code. BCC part of BSIC is recommended.

HHThis is the hopping parameter, where H=0 means single RF channeland H=1 means RF hopping channel.

CHANNEL SELECTORCHANNEL SELECTORH=0 ⇒ the channel selector field consists of the absolute RF channelnumberH 1 th h l l t fi ld i t f th bil ll ti


H=1 ⇒ the channel selector field consists of the mobile allocationindex offset, MAIO, and the hopping sequence number HSN

Introduction To Layer 3 - System InfoCBCH Mobile Allocation (Conditional)

This information element must be present if the CBCH channeldescription information element indicates frequency hopping.p q y pp g

SI 4 Rest OctetsSystem information type 4 rest octets may contain the parameters System information type 4 rest octets may contain the parameters needed for C2 calculations as described under SI type 3 rest octets. These are PI, CBQ, CELL_RESELECT_OFFSET, TEMPORARY_OFFSET, and PENALTY_TIME.



System Info 5System Info 5In dedicated mode The network sends the System info 5 in Downlinkand MS send the measurement report in Uplinkand MS send the measurement report in Uplink.In down link the message contains

− Neighbor Cell Description

In Uplink the measurement report “Message type 21” is send by the MSIn Uplink, the measurement report Message type 21 is send by the MSwhich contains:

− DTX USED− BA USED− RxLev Full Serving Cell: The value is given by (RX level – (-111))− RxLev Sub Serving Cell : The value is given by (RX level – (-111))− RxQual Full Serving Cell− RxQual Sub Serving Cell− Neighbor cell measurements− RxLev: The value is given by (RX level – (-111))− BSIC


BSIC− BCCH-INDEX: the value represents the BA index no.


System Info 6System Info 6

S t I f 6 i d t MS i d di t dSystem Info 6 is send to MS in dedicated.In Sys Info 6 consist of

Cell identity (CI) : May also given in HexadecimalMobile country code (MCC)Mobile country code (MCC)Mobile network code (MNC)Location area code (LAC)Power control indicator (PWRC): If the PWRC parameter is set, it means that the MS is not( ) p ,to include measurements on the BCCH carrier in the calculated average. If the parameteris not set, the BCCH measurements are included.DTX indicator: Indicates whether MS “May Use”, “Shall Use” or “Shall Not Use” DTX.RADIO-LINK-TIMEOUTO OUNCC permitted valuesBand indication 1800



Layer 3 Messages in Call OriginationLayer 3 Messages in Call Origination

Channel Request Message



Immediate Assignment Message



CM Service Request Message



Authentication Request Message



Authentication Response Message



Ciphering Mode Command Message



Ciphering Mode Complete Message



Setup Message



Identity request Message



Identity Response Message



Call proceeding Message



Assignment Command Message



Assignment Complete Message



Alerting Message



Connect Message



Connect Acknowledge Message



Layer 3 Messages in Call TerminationLayer 3 Messages in Call Termination

Paging Request Type 1 Message (2 TMSI )



Paging Request Type 1 Message (1 IMSI & 1 TMSI)



Paging Request Type 1 Message (2 IMSI )



Paging Request Type 2 Message (1 IMSI & 2 TMSI)



Paging Request Type 2 Message (3 TMSI)



Paging Request Type 3 Message (4 TMSI)



Paging Response Message



Ciphering Command Message



Ciphering Mode Complete Message



Identity Request Message



Identity Response Message



Setup Message



Call Confirmed Message



Assignment Command Message



Assignment Complete Message



Alerting Message



Connect Message



Connect Acknowledge Message


Location Updating Flow


Location Update Flow

Location UpdatingLocation UpdatingWhen a MS moves from one location area to another location area it

f L ti d t t i f th t k b t it l tiperforms a Location update to inform the network about its location.


Location Update Flow


Layer 3 Messages in Location Update



Location updating Request Message



Authentication Request Message



Authentication Response Message



TMSI Reallocation Command Message



TMSI Reallocation Complete Message



Location Updating Accept Message



DL Disconnect Normal Cause



DL Disconnect Due to No Circuit



Release Message



Release Complete Message



Channel Release Message


Example for Layer 3 MessagesDrop Call Example


Example for Layer 3 MessagesHO Fail Example 1


Example for Layer 3 MessagesHO Fail Example Contd…


Example for Layer 3 MessagesHO Complete Example 1


Example for Layer 3 MessagesHO Fail Example Contd…


QuestionsQuestions


alcatel lucent drive test 1 part 4

Documents