Alcatel Lucent Drive Test 1 Part 4 5h3qy

Call Flow and Call Processing

Created by Pulok Sinha ((Trainer,, ALUMS)) 09320096525 All Rights Reserved © Alcatel-Lucent 2009

Call Flow and Call Processing Objectives : After successful completion of this program, You will be able to Describe ¾Swap and Types ¾Coverage, Quality and Hand Over issues ¾ Involvement of Channels in a call Process ¾ Mobile originating Call Flow in GSM ¾ Mobile terminating Call Flow in GSM ¾ Introduction to Layer y 3 –System y Info Messages g ¾ Location Updating Flow ¾ Layer 3 Messages in Location Update ¾ Some More Layer 3 Messages 2

All Rights Reserved © Alcatel-Lucent 2009

Swap and Types

3


Swap and Types Swap : ¾When th ¾Wh the feeder f d cables bl off the th sector t off a site it gets t interchanged i t h d it is commonly termed as SWAP. ¾Basicall can be of 3 types ¾Basically t pes − Sector Swap − Diversity or TX cable Swap between two sectors − Diversity Di it cable bl swap in i one sector t and d TX cable bl swap in i other. th

4


Swap and Types Sector Swap

•

Both the Tx and Rx feeder cable are interchanged between sectors

•

Coverage is good.

•

Network Parameter are reversed

•

Poor Handover

5


Swap and Types

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

6

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


Swap and Types Diversity cable Swap between two sectors

•

Only Rx feeder cable interchanged g between sectors

•

Good Coverage near to Site but bad coverage g far from the site.

•

Some times lead to poor Quality

•

Poor Handover

7

are


Swap and Types

• • • •

8

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

• • • •

BCCH Sec Sec-2 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 other •

Only Tx feeder of one sector and Rx feeder cable of another sector are interchanged

•

Coverage of both the sector will be nearly equal.

•

Some times lead to p poor Quality y

•

Level of both the sector is high near Sector-2 and poor in Sector-1 in this case

•

Ping pong Handover between the poor handover with two sector and p other cells

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Swap and Types

• • •

10

• 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 All Rights Reserved © Alcatel-Lucent 2009

Coverage, Quality and Handover Issues

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Coverage, Quality and Handover Issues Coverage issues: ¾Lack ¾L k off Dominant D i t Server S Causes C too t many handovers h d between b t the same Cells which may lead to poor RxQual as well as drop. ¾Curve ¾Cur e Formation due to Tunnel also lead to sudden degradation of the Signal Level ¾Effect causing sudden level decrease and Ping Pong Handovers sometimes leading to call drops ¾Levels of 3 3–4 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.

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Coverage, Quality and Handover Issues Coverage issues: ¾Lack ¾L k off Dominant D i t Server S Causes C too t many handovers h d between b t the same Cells which may lead to poor RxQual as well as drop. ¾Curve ¾Cur e Formation due to Tunnel also lead to sudden degradation of the Signal Level ¾Effect causing sudden level decrease and Ping Pong Handovers sometimes leading to call drops ¾Levels of 3 3–4 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.

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Coverage, Quality and Handover Issues Coverage issues: ¾The distant ¾Th di t t cell ll always l popping i up as the th second d strongest t t neighbor in the list through a large area might show an overshooting cell the cell need to be physically optimized. ¾Signal Strength may change fast due to far away server being blocked by obstacles from the terrain. ¾Even 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.

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Coverage, Quality and Handover Issues Quality issues: ¾RXQUAL can be poor because of poor RXLEV (coverage), low carrier-to-noise ratio (C/N), co-channel interference, adjacent channel interference or multipath p ¾If RXQUAL is poor and RXLEV is good, then it is generally assumed that the cause is interference and C/I / is verified. ¾TCH carriers are also reused, and hence can contribute to cochannel interference, although this interference will not always be present; it will only be present when these TCH carriers have call activity.

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Coverage, Quality and Handover Issues Quality issues: ¾The collision of frequencies with neighboring cells MAIO list frequencies become more significant with dropping signal level. ¾Bad 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 ¾Bad 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.

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Coverage, Quality and Handover Issues Overshooting Example ¾ 30115 is overshooting in the vicinity of 10333. ¾ May lead to poor quality even call drop in dedicated mode. ¾ The orientation and tilt 30115 need to be checked.

of


Coverage, Quality and Handover Issues Swap Suspected Need to check,, ¾ If orientation is proper ¾ If swap is there in the site ¾ If the cell properly

30056 radiating

¾ If not then check for H/W issues. issues


Coverage, Quality and Handover Issues Issue with HO There is issue in HO between 30364 and 20375.

Need to check, ¾ If both the cells defined as neighbor ¾ If the cell was radiating. ¾ If the cell was in congestion. g ¾ If there was any H/W issue in the cell. All Rights Reserved © Alcatel-Lucent 2009

Coverage, Quality and Handover Issues What's the issue?


Involvement of Channels in a call process

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Involvement of Channels in a call process Role of channels as soon as MS is switched on till a call is completed.


Mobile Originating Call Flow in GSM

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Mobile Originating Call Flow in GSM


Call Flow Mobile Originating Call


Call Flow Mobile Originating Call


Mobile Terminating Call Flow in GSM

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Call Flow Mobile Terminating Call






Introduction To Layer 3 - System Info

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Introduction To Layer 3 - System Info System Information ¾ System information i f i is i data d about b the h network k that h the h MS needs d iin order to communicate with the network. ¾ Basically ll the h system information f messages are sent on −

BCCH in Idle Mode

−

SACCH in Dedicated Mode

¾ There are different types of System information and are numbered from 1-8

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−

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


Introduction To Layer 3 - System Info System Info 1 Message

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Introduction To Layer 3 - System Info System Info 1 ¾ The System Info 1 is generally sent if frequency hopping is used. used The MS is informed about Cell Channel Description and RACCH Control Parameters. ¾ Cell Channel description gives the frequencies that are used in the cell. In non hopping case may give BCCH and TCH frequencies. ACC ¾ The access control class is described using a bit map with 16bits. 16bits All MSs 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. EC ¾ EC=0 means that all MSs are allowed to make emergency calls, while ¾ EC=1 means that only MSs belonging to priority classes 11-15 are allowed to make emergency calls. calls 34


Introduction To Layer 3 - System Info CB ¾ Cell barred for access is denoted by using one bit only (yes/no). RE ¾ Call re-establishment allowed is also denoted by using one bit (yes/no). MAXRET q ¾ Maximum retransmission is the maximum number of channel request message retransmissions allowed when an MS attempts to access the system. MAXRET can have the value 1, 2, 4 or 7. TX ¾ This is the number of slots to spread random access retransmissions over when an MS attempts to access the system. The values TX can have are 3 3-12 12 in increments of one, one 14, 14 16, 16 20, 20 25, 25 32 and 50. 50

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Introduction To Layer 3 - System Info System Info 2 ¾ System information type 2 contains a list of −

Neighbor cells description.

−

The MS is also receives information about which PLMN permitted.

−

RACCH Control Parameters.

BA-NO ¾ This is a BCCH allocation number. BA-NO=0 means GSM 900. BA-IND ¾ This is a BCCH allocation sequence number indication. When the p changes g the frequency q y list,, the BA-IND changes g from 1 to 0 operator or vice versa. BA ARFCN ¾ These are absolute RF channels of neighbor cells

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Introduction To Layer 3 - System Info EXT-IND ¾ Bit indicates whether the information element carries the complete information or whether a complementary information element is sent in another message. −

0 ⇒ this information element carries the complete frequency list

−

1 ⇒ this information element carries part of the frequency list only and a complementary information element is located in another message

NCERM ¾ The MS gets information about which NCCs of the BCCH carriers it is allowed to monitor for handover purposes.

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Introduction To Layer 3 - System Info System Info 3 Message [Cont…]

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Introduction To Layer 3 - System Info System Info 3 ¾ Network 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) ¾ Two octets (16 bits) identifying a cell within a location area. Location Area Identification (LAI) ¾ MCC Mobile Country Code (3 digits) ¾ MNC Mobile Network Code (2-3 digits) ¾ LAC Location L ti A Area C d (2 octets: Code t t 0-65535 0 65535 different diff t LACs) LAC ) 41


Introduction To Layer 3 - System Info ATT ¾ Whether or not the MS is to perform IMSI Attach and IMSI Detach procedures (ATT=1) or (ATT=0). (ATT=0) CCCH_CONF ¾ This is the number of Basic Physical Channels used for the CCCH. (14 BPCs BPC when h nott combined bi d with ith SDCCH, SDCCH 1 BPC if combined). bi d) AGBLK (BS_AG_BLKS_RES) ¾ This is the number of CCCH blocks reserved for the AGCH, CBCH or BCCH Extended. The range of this parameter is 0-2 if CCCH is combined with SDCCH and 0-7 for non-combined CCCH. MFRMS (BS_PA_MFRMS) ¾ This is the number of 51 multiframe periods for transmission of Paging Request messages to the same paging group (2-9) i.e. MFRMS is the multiframe period and defines the transmission interval of paging messages to the same paging group. group 42


Introduction To Layer 3 - System Info T3212 ¾ This is the time-out value for MS periodic location updating. T3212 has values from 0 to 255. 255 Cell options DTX ¾ Discontinuous transmission indicator (may, must or must not). PWRC ¾ PWRC = 0 means not set ¾ PWRC = 1 means set. ¾ If the PWRC parameter is set, it means that the MS is not to include measurements on the BCCH carrier in the calculated average. If the parameter is not set, the BCCH measurements are included. RLINKT ¾ This parameter define the maximum value of the radio link counter that has been defined for the serving cell. 43


Introduction To Layer 3 - System Info Cell Selection Parameters ACCMIN (RXLEV_ACCESS_MIN) ¾ Thi This is i the h minimum i i received i d signal i l level l l at the h MS for f which hi h it i is i permitted to access the system. Range (0-63): -110 dBm up to -48 dBm.

ACCMIN value

Signal strength value

0

Below ‐110 Below 110 dBm dBm

1

‐110 dBm to ‐109 dBm

2

‐109 dBm to ‐108 dBm . . .

44

62

‐49 dBm to ‐48 dBm

63

G Greater than ‐48 dBm h 48 dB


Introduction To Layer 3 - System Info CCHPWR (MS_TXPWR_MAX_CCH) ¾ Th The CCHPWR field fi ld defines d fi th maximum the i output t t power an MS is i allowed to use when accessing the cell. Signal Strength value for corresponding power level for GSM is shown below:

CCHPWR value

Signal strength value

0 ‐ 2

39 dBm

3

37 dBm

4

35 dBm

. . .

45

18

7 dBm

19 31 19 ‐

5 dBm 5 dBm


Introduction To Layer 3 - System Info CRH (CELL_RESELECT_HYSTERESIS) ¾ This represents cell reselect hysteresis. The measured signal strength is decreased by CRH (range 0 0-14 14 dB) in increments of 2 dB if the cell belongs to a new LA. ACS ¾ This field defines the additional reselect parameters indicator and is spare in a system information type 3 message. NECI ¾ This parameter is used for new establishment causes indication (0 or 1). It indicates whether the phase 2 establishment causes are ed by the system. The establishment cause is included in the channel request message on the RACH. RLINKT ¾ This parameter define the maximum value of the radio link counter that has been defined for the serving cell.

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Introduction To Layer 3 - System Info SI 3 Rest Octets ¾ System information type 3 rest octets may contain parameters that are used by a phase 2 MS for calculating the cell reselection criterion C2. 2TI ¾ This is system information type 2-ter 2 ter indication (0 or 1). 1) 2TI is used by the MS to determine, if the network broadcasts system information type 2 ter. ¾ 2TI=0 means that system y information type yp 2 ter is not available. ¾ 2TI=1 means that system information type 2 ter is available. ECSC ¾ The setting of the early classmark sending control bit informs MSs with the “control early classmark sending” option whether early sending of additional classmark information is accepted or not accepted by the system. Early in this case means as soon as possible after access. 47


Introduction To Layer 3 - System Info PI ¾ Cell_reselect_param_ind can have the value 0 or 1. PI is used by the MS to determine if the C2 parameters are broadcast by the network in this message. ¾ PI=0 ⇒ C2 parameters are not present ¾ PI=1 ⇒ C2 parameters are present CBQ ¾ Cell bar qualify (values: 0 or 1) is used by the network to control MS cell selection and re-selection. CELL_RESELECT_OFFSET ¾ A system information value used by the MS to apply a positive or negative offset to the value of C2. Range is 0-63, which corresponds to 0 126 dB in 2 dB steps. 0-126 steps 48


Introduction To Layer 3 - System Info TEMPORARY_OFFSET ¾ A system information value used by the MS to apply a negative offset to the value of C2 for the duration of PENALTY_TIME. PENALTY TIME Range : 0 – 7 with increment of 10 dB and & 7 is infinity PENALTY_TIME ¾ This parameter defines the TEMPORARY_OFFSET is active.

length

of

time

for

which

Range: 0-31, with 20 second increments and 31 indicate that TEMPORARY_OFFSET is to be ignored.

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50


Introduction To Layer 3 - System Info System Info 4 Message [Cont…]

51


Introduction To Layer 3 - System Info System Info 4 ¾ Network sends following information in System Info 4 −

L Location ti Area A Identification Id tifi ti

−

Cell Selection Parameters

−

RACH Control Parameters

−

CBCH Ch Channell D Description i ti

−

CBCH Mobile Allocation

−

SI 4 Rest Octets

Cell Selection Parameters ACS ¾ Additional reselect parameters indicator (0 or 1). ¾ 0 ⇒ the system information type 4 rest octets, if present, are used to derive the PI value and any existing C2 parameters. ¾ 1 ⇒ the PI value and any existing C2 parameters in system i f information ti t type 7 and d 8 message are to t be b used. d 52


Introduction To Layer 3 - System Info CBCH Channel Description (Optional) CHANNEL TYPE ¾ This is the channel combination and sub sub-channel channel used for CBCH. CBCH For example, SDCCH/4 + SACCH/C4 or CBCH, sub channel 2. TN ¾ This represents the time slot number. number TSC ¾ This is the training sequence code. BCC part of BSIC is recommended. H ¾ This is the hopping parameter, where H=0 means single RF channel and H=1 means RF hopping channel. CHANNEL SELECTOR ¾ H=0 ⇒ the channel selector field consists of the absolute RF channel number ¾ H H=1 1 ⇒ the th channel h l selector l t fi ld consists field i t off the th mobile bil allocation ll ti index offset, MAIO, and the hopping sequence number HSN 53


Introduction To Layer 3 - System Info CBCH Mobile Allocation (Conditional) This information element must be present if the CBCH channel p information element indicates frequency q y hopping. pp g description SI 4 Rest Octets ¾ 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.

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Introduction To Layer 3 - System Info System Info 5 ¾ In dedicated mode The network sends the System info 5 in Downlink and MS send the measurement report in Uplink. Uplink ¾ In down link the message contains −

Neighbor Cell Description

¾ In Uplink, Uplink the measurement report “Message Message type 21 21” is send by the MS which contains:

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−

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

−

BCCH-INDEX: the value represents the BA index no. All Rights Reserved © Alcatel-Lucent 2009


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Introduction To Layer 3 - System Info System Info 6 ¾ System S t I f 6 is Info i send d to t MS in i dedicated. d di t d ¾ In Sys Info 6 consist of

58

¾

Cell identity (CI) : May also given in Hexadecimal

¾

Mobile country code (MCC)

¾

Mobile network code (MNC)

¾

Location area code (LAC)

¾

Power control indicator ((PWRC): ) If the PWRC p parameter is set,, it means that the MS is not to include measurements on the BCCH carrier in the calculated average. If the parameter is not set, the BCCH measurements are included.

¾

DTX indicator: Indicates whether MS “May Use”, “Shall Use” or “Shall Not Use” DTX.

¾

RADIO-LINK-TIMEOUT O OU

¾

NCC permitted values

¾

Band indication 1800


Introduction To Layer 3 - System Info Layer 3 Messages in Call Origination Channel Request Message

59


Introduction To Layer 3 - System Info Immediate Assignment Message

60


Introduction To Layer 3 - System Info CM Service Request Message

61


Introduction To Layer 3 - System Info Authentication Request Message

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Introduction To Layer 3 - System Info Authentication Response Message

63


Introduction To Layer 3 - System Info Ciphering Mode Command Message

64


Introduction To Layer 3 - System Info Ciphering Mode Complete Message

65


Introduction To Layer 3 - System Info Setup Message

66


Introduction To Layer 3 - System Info Identity request Message

67


Introduction To Layer 3 - System Info Identity Response Message

68


Introduction To Layer 3 - System Info Call proceeding Message

69


Introduction To Layer 3 - System Info Assignment Command Message

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Introduction To Layer 3 - System Info Assignment Complete Message

71


Introduction To Layer 3 - System Info Alerting Message

72


Introduction To Layer 3 - System Info Connect Message

73


Introduction To Layer 3 - System Info Connect Acknowledge Message

74


Introduction To Layer 3 - System Info Layer 3 Messages in Call Termination Paging Request Type 1 Message (2 TMSI )

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Introduction To Layer 3 - System Info Paging Request Type 1 Message (1 IMSI & 1 TMSI)

76


Introduction To Layer 3 - System Info Paging Request Type 1 Message (2 IMSI )

77


Introduction To Layer 3 - System Info Paging Request Type 2 Message (1 IMSI & 2 TMSI)

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Introduction To Layer 3 - System Info Paging Request Type 2 Message (3 TMSI)

79


Introduction To Layer 3 - System Info Paging Request Type 3 Message (4 TMSI)

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Introduction To Layer 3 - System Info Channel Request Message

81


Introduction To Layer 3 - System Info Immediate Assignment Message

82


Introduction To Layer 3 - System Info Paging Response Message

83


Introduction To Layer 3 - System Info Ciphering Command Message

84


Introduction To Layer 3 - System Info Ciphering Mode Complete Message

85


Introduction To Layer 3 - System Info Identity Request Message

86


Introduction To Layer 3 - System Info Identity Response Message

87


Introduction To Layer 3 - System Info Setup Message

88


Introduction To Layer 3 - System Info Call Confirmed Message

89


Introduction To Layer 3 - System Info Assignment Command Message

90


Introduction To Layer 3 - System Info Assignment Complete Message

91


Introduction To Layer 3 - System Info Alerting Message

92


Introduction To Layer 3 - System Info Connect Message

93


Introduction To Layer 3 - System Info Connect Acknowledge Message

94


Location Updating Flow

95


Location Update Flow Location Updating When a MS moves from one location area to another location area it performs f a Location L ti update d t to t inform i f the th network t k about b t its it location. l ti

96


Location Update Flow

97


Layer 3 Messages in Location Update

98


Layer 3 Messages in Location Update Channel Request Message

99


Layer 3 Messages in Location Update Immediate Assignment Message

100


Layer 3 Messages in Location Update Location updating Request Message

101


Layer 3 Messages in Location Update Authentication Request Message

102


Layer 3 Messages in Location Update Authentication Response Message

103


Layer 3 Messages in Location Update TMSI Reallocation Command Message

104


Layer 3 Messages in Location Update TMSI Reallocation Complete Message

105


Layer 3 Messages in Location Update Location Updating Accept Message

106


Some More Layer 3 Messages

107


Some More Layer 3 Messages DL Disconnect Normal Cause

108


Some More Layer 3 Messages DL Disconnect Due to No Circuit

109


Some More Layer 3 Messages Release Message

110


Some More Layer 3 Messages Release Complete Message

111


Some More Layer 3 Messages Channel Release Message

112


Example for Layer 3 Messages Drop Call Example

113


Example for Layer 3 Messages HO Fail Example 1

114


Example for Layer 3 Messages HO Fail Example Contd…

115


Example for Layer 3 Messages HO Complete Example 1

116


Example for Layer 3 Messages HO Fail Example Contd…

117


Questions

118


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