Handovers_1

8/3/2019 Handovers_1

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Handovers in BSCHandovers in BSC


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Handover signalling phases in BSCHandover signalling phases in BSC

1.1. Start of HO in BSC:Start of HO in BSC: Measurement resultMeasurement result

HO algorithmHO algorithm

Threshold comparisonThreshold comparison

HO type determination in BSC:HO type determination in BSC:

ExternalExternal

InternalInternal

IntraIntra

Candidate cell determination in BSCCandidate cell determination in BSC

Based on type of HO (intra, internal, external)Based on type of HO (intra, internal, external)


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Contd.Contd.

2.2. Handover Request in BSC:Handover Request in BSC:

After receiving a HANDOVER_REQUIREDmessage from the BSC, theAfter receiving a HANDOVER_REQUIREDmessage from the BSC, the

MSC determines the candidate cell and sends a HANDOVER_REQUESTMSC determines the candidate cell and sends a HANDOVER_REQUEST

message to the target BSC. When the BSC receives this message, themessage to the target BSC. When the BSC receives this message, the

handover attempt is started. The message contains, for example,handover attempt is started. The message contains, for example,

information on the cell identifier of the candidate cell.information on the cell identifier of the candidate cell.

3.3. Handover inquiry in BSC:Handover inquiry in BSC:If the handover is allowed at the current phase of the call, the BSC sendsIf the handover is allowed at the current phase of the call, the BSC sends

the HANDOVER_REQUIREDmessage to the MSC. Otherwise thethe HANDOVER_REQUIREDmessage to the MSC. Otherwise the

handover attempt is terminated and the call continues on the old channel.handover attempt is terminated and the call continues on the old channel.

If the MSC does not allow the handover or, for example, there are no freeIf the MSC does not allow the handover or, for example, there are no free

channels available in the target cell, the MSC sends achannels available in the target cell, the MSC sends aHANDOVER_REQUIRED_REJECT message to the BSC. The handoverHANDOVER_REQUIRED_REJECT message to the BSC. The handover

attempt is terminated and the call continues on the old channel.attempt is terminated and the call continues on the old channel.


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Contd.Contd.4.4. Physical context request in BSCPhysical context request in BSC

The BSC requests the physical context from the BTS by sending aThe BSC requests the physical context from the BTS by sending aPHYSICAL_CONTEXT_REQUEST message to the BTS. If aPHYSICAL_CONTEXT_REQUEST message to the BTS. If aPHYSICAL_CONTEXT_CONFIRMmessage is not received from thePHYSICAL_CONTEXT_CONFIRMmessage is not received from theBTS before time supervision elapses, the handover attempt is terminatedBTS before time supervision elapses, the handover attempt is terminatedand the call continues in the old channel (assignment).and the call continues in the old channel (assignment).

5.5. Channel activation in BSCChannel activation in BSCThe BSC requests the BTS to activate a new channel by sending aThe BSC requests the BTS to activate a new channel by sending a

CHANNEL_ACTIVATIONmessage. If aCHANNEL_ACTIVATIONmessage. If aCHANNEL_ACTIVATION_ACKNOWLEDGE message is receivedCHANNEL_ACTIVATION_ACKNOWLEDGE message is receivedfrom the BTS before time supervision elapses, the handover attemptfrom the BTS before time supervision elapses, the handover attemptcontinues. The HANDOVER_REQUEST_ACKNOWLEDGE message iscontinues. The HANDOVER_REQUEST_ACKNOWLEDGE message issent to the MSC in an external handover.sent to the MSC in an external handover.

If the activation of a channel fails and the BTS sends aIf the activation of a channel fails and the BTS sends aCHANNEL_ACTIVATION_NEGATIVE_ACKNOWLEDGE messageCHANNEL_ACTIVATION_NEGATIVE_ACKNOWLEDGE messageto the BSC, the handover attempt is terminated (in an external handover,to the BSC, the handover attempt is terminated (in an external handover,the BSC sends a HANDOVER_FAILURE message to the MSC) and thethe BSC sends a HANDOVER_FAILURE message to the MSC) and thecall continues on the old channel.call continues on the old channel.


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Contd.Contd.

6.6. Connection of unidirectional speech path in BSCConnection of unidirectional speech path in BSCIf the handover attempt is allowed at the current phase of the call, the BSCIf the handover attempt is allowed at the current phase of the call, the BSCconnects a unidirectional speech path so that the MS is immediately able toconnects a unidirectional speech path so that the MS is immediately able tohear the speech from the MSC. The BSC starts the buffering of messageshear the speech from the MSC. The BSC starts the buffering of messagesfrom the MSC.from the MSC.

Start of message buffering in BSCStart of message buffering in BSC

If the handover attempt is allowed at the current phase of the call, the BSCIf the handover attempt is allowed at the current phase of the call, the BSCstarts the buffering of messages coming from the MSC.starts the buffering of messages coming from the MSC.

In an internal handover, a HANDOVER_COMMAND (inter cell) or anIn an internal handover, a HANDOVER_COMMAND (inter cell) or anASSIGNMENT_COMMAND (intra cell) message is sent to the MS on theASSIGNMENT_COMMAND (intra cell) message is sent to the MS on theold channel.old channel.

7.7. Handover detection in BSCHandover detection in BSCAfter receiving an access burst from the MS, the BTS sends aAfter receiving an access burst from the MS, the BTS sends aHANDOVER_DETECTIONmessage to the BSC. In the case of anHANDOVER_DETECTIONmessage to the BSC. In the case of anexternal handover, the HANDOVER_DETECTIONmessage is sent to theexternal handover, the HANDOVER_DETECTIONmessage is sent to theMSC.MSC.


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Contd.Contd.

8.8. Indication of handover establishment in BSCIndication of handover establishment in BSC After the BTS has received an SABM (Set Asynchronous BalancedMode)After the BTS has received an SABM (Set Asynchronous BalancedMode)

frame, it sends an ESTABLISH_INDICATIONmessage to the BSC.frame, it sends an ESTABLISH_INDICATIONmessage to the BSC.

9.9. Connection of bidirectional speech path in BSCConnection of bidirectional speech path in BSC

In an internal handover, unidirectional and bidirectional speech paths areIn an internal handover, unidirectional and bidirectional speech paths areswitched through. If the connection fails, the handover attempt is terminatedswitched through. If the connection fails, the handover attempt is terminatedand the call is cleared.and the call is cleared.

In an external handover, the bidirectional speech path is connected. TheIn an external handover, the bidirectional speech path is connected. Thetarget BSC sends a HANDOVER_REQUEST_ACKNOWLEDGE messagetarget BSC sends a HANDOVER_REQUEST_ACKNOWLEDGE messageto the MSC. The message contains the handover command informationto the MSC. The message contains the handover command informationwhich the MSC sends to the source BSC. If the connection fails, thewhich the MSC sends to the source BSC. If the connection fails, the

handover attempt is terminated by sending the HANDOVER_FAILUREhandover attempt is terminated by sending the HANDOVER_FAILUREmessage to the BSC and the call continues in the old channel.message to the BSC and the call continues in the old channel.


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Contd.Contd.

10.10. Handover / assignment complete in BSCHandover / assignment complete in BSC

After the MS has established the main signalling link successfully, it sendsAfter the MS has established the main signalling link successfully, it sends

the HANDOVER_COMPLETE (internal interthe HANDOVER_COMPLETE (internal inter--cell) or thecell) or the

ASSIGNMENT_COMPLETE (internal intraASSIGNMENT_COMPLETE (internal intra--cell) message in the newcell) message in the new

channel. In an internal handover, the BSC sends thechannel. In an internal handover, the BSC sends theHANDOVER_PERFORMED to the MSC. In an external handover, theHANDOVER_PERFORMED to the MSC. In an external handover, the

BSC sends the HANDOVER_COMPLETE message to the MSC.BSC sends the HANDOVER_COMPLETE message to the MSC.


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Successful internal intraSuccessful internal intra--cell TCH to TCH handovercell TCH to TCH handover


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Successful internal interSuccessful internal inter--cell TCH to TCH handovercell TCH to TCH handover


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Successful external TCH to TCH handover, source BSCSuccessful external TCH to TCH handover, source BSC


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HO types & priorityHO types & priority

TCH channelTCH channel1.1. Interference (uplink or downlink)Interference (uplink or downlink)

2.2. IntraIntra--segment intersegment inter--band because of downlink level (fromband because of downlink level (from

higher to lower frequency band)higher to lower frequency band)3.3. Uplink qualityUplink quality

4.4. Downlink qualityDownlink quality

5.5. AMR unpacking (uplink level and also uplink unpackingAMR unpacking (uplink level and also uplink unpackingquality triggers)quality triggers)

6.6. Uplink levelUplink level


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Contd.Contd.

7.7. AMR unpacking (downlink level and also downlinkAMR unpacking (downlink level and also downlinkunpacking quality triggers)unpacking quality triggers)

8.8. Downlink levelDownlink level

9.9. MSMS--BS distance (maximum or minimum)BS distance (maximum or minimum)

10.10. TurnTurn--aroundaround--corner MScorner MS-- deep drop edge level (rawdeep drop edge level (rawsample)sample)

11.11. Rapid field dropRapid field drop--ul thrsh for rfd + chained cellul thrsh for rfd + chained cell

12.12. Slow/fastSlow/fast--moving MSmoving MS-- adj cell layer (fast/slow)adj cell layer (fast/slow)

13.13. UmbrellaUmbrella

14.14. Power budget:minimum path lossPower budget:minimum path loss

15.15. BSCBSC--initiated TRHOinitiated TRHO


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Contd.Contd.

16.16. IUOIUO17.17. IntraIntra--segment HO based on loadsegment HO based on load

18.18. AMR packing because of good uplink and downlinkAMR packing because of good uplink and downlinkqualityquality

19.19.

AMR unpacking because of bad uplink or downlinkAMR unpacking because of bad uplink or downlinkqualityquality

20.20. PC because of lower quality thresholds (uplink andPC because of lower quality thresholds (uplink anddownlink)downlink)

21.21. PC because of lower level thresholds (uplink andPC because of lower level thresholds (uplink and

downlink)downlink)22.22. PC because of upper quality thresholds (uplink andPC because of upper quality thresholds (uplink and

downlink)downlink)

23.23. PC because of upper level thresholds (uplink andPC because of upper level thresholds (uplink anddownlink)downlink)


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HOF counters: MSC HOFHOF counters: MSC HOF

MSC O HO NOT ALLOWED (c4037)MSC O HO NOT ALLOWED (c4037) Unsuccessful external TCH to TCH handover because a handover is notUnsuccessful external TCH to TCH handover because a handover is not

allowedallowed Unsuccessful external TCH to TCH handover because the MSC rejects theUnsuccessful external TCH to TCH handover because the MSC rejects the

handover due to various causeshandover due to various causes Description:Number of outgoing HOs, controlled by the MSC, that areDescription:Number of outgoing HOs, controlled by the MSC, that are

unsuccessful because no HOs are allowed.unsuccessful because no HOs are allowed.

UpdatedUpdated a) When HO execution is not allowed in the current phase of the call ina) When HO execution is not allowed in the current phase of the call in

progress.progress. b) When theb) When the DISABLE_INT_HODISABLE_INT_HOparameter is set and an underlay overlay HOparameter is set and an underlay overlay HO

start is attempted.start is attempted. c) When DISABLE_EXT_DR is set and DR is attempted.c) When DISABLE_EXT_DR is set and DR is attempted.

d) When external HO is not possible due to FACCH call setup.d) When external HO is not possible due to FACCH call setup. e) When an external HO is not possible because the neighbouring cell ise) When an external HO is not possible because the neighbouring cell is

defined to be the normal area of an extended cell from another BSC.defined to be the normal area of an extended cell from another BSC. Impact: HO failureImpact: HO failure

Reason for the impact:InternalReason for the impact:Internal


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MSC ctrl ho not allowedMSC ctrl ho not allowed


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Contd.Contd.

MSC O FAIL LACK (c4055):MSC O FAIL LACK (c4055): Unsuccessful external TCH to TCH handover due to a lack of resourcesUnsuccessful external TCH to TCH handover due to a lack of resources

Unsuccessful external TCH to TCH handover because the MSC rejects theUnsuccessful external TCH to TCH handover because the MSC rejects thehandover due to various causeshandover due to various causes

Unsuccessful external TCH or TCH handoverUnsuccessful external TCH or TCH handover Description:Description:

Number of outgoing HOs, controlled by the MSC, that are unsuccessfulNumber of outgoing HOs, controlled by the MSC, that are unsuccessfulbecause there are no radio resources available in the target cell.because there are no radio resources available in the target cell.

Updated:Updated: a) When no SDCCH is available in the target cell for an SDCCH HO.a) When no SDCCH is available in the target cell for an SDCCH HO.

b) When no TCH is available in the target cell for a TCH HO.b) When no TCH is available in the target cell for a TCH HO. c) When no TCH is available in the target cell for an SDCCH to TCH HO.c) When no TCH is available in the target cell for an SDCCH to TCH HO.

d) When no terrestrial channel is available in the target cell.d) When no terrestrial channel is available in the target cell. e) When the GSM timer T7 (Handover required periodicity) expirese) When the GSM timer T7 (Handover required periodicity) expires

Impact:HO failureImpact:HO failure


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MSC HOF due to lack of resourcesMSC HOF due to lack of resources


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Contd.Contd.

MSC O UNSUCCESS HO DUE RETURN (c4006)MSC O UNSUCCESS HO DUE RETURN (c4006)

Unsuccessful external TCH to TCH handover due to MS returning toUnsuccessful external TCH to TCH handover due to MS returning to

the old channelthe old channel

DescriptionNumber of outgoing HOs, controlled by the MSC, that areDescriptionNumber of outgoing HOs, controlled by the MSC, that are

unsuccessful because the MS returns to the source channel.unsuccessful because the MS returns to the source channel. Updated: When the MS returns to the source channel.Updated: When the MS returns to the source channel.

Impact: HO failure.Impact: HO failure.


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MSC HOF due to ROCMSC HOF due to ROC


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Contd.Contd.MSC O END OF HO (c4007)MSC O END OF HO (c4007) Unsuccessful external TCH to TCH handover because the MSC rejects theUnsuccessful external TCH to TCH handover because the MSC rejects the

handover due to various causeshandover due to various causes Unsuccessful external TCH to TCH handover due to GSM timer T8 expiryUnsuccessful external TCH to TCH handover due to GSM timer T8 expiry

Description: Number of the end of handover procedures (outgoing HODescription: Number of the end of handover procedures (outgoing HOcontrolled by the MSC).controlled by the MSC).

Updated:Updated:

a) When the GSM timer T8 expires (thea) When the GSM timer T8 expires (the CLEAR_COMMANDCLEAR_COMMANDmessage notmessage notreceived, Time to receive of Successful HOreceived, Time to receive of Successful HO--Info).Info).

b) When the HO is rejected with another cause than switch_crc_pool,b) When the HO is rejected with another cause than switch_crc_pool,cip_type_mismatch, invalid_cell, no_radio_res_avail, req_terr_res_unava orcip_type_mismatch, invalid_cell, no_radio_res_avail, req_terr_res_unava orT7_expiry.T7_expiry.

c) When the MSC sends ac) When the MSC sends a CLEAR_COMMANDCLEAR_COMMANDmessage with a reason othermessage with a reason otherthan handover successful or call control to the BSC.than handover successful or call control to the BSC.

d) When there is an internal conflict with the A interface.d) When there is an internal conflict with the A interface. Impact:HO failure (b and d)Impact:HO failure (b and d) Possibly call cleared (a and c)Possibly call cleared (a and c)


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MSC HOF due to End of HO (various causes)MSC HOF due to End of HO (various causes)


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MSC HOF due to End of HO (T8 expiry)MSC HOF due to End of HO (T8 expiry)


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Contd.Contd.

MSC O END OF HO DUE BSS (c4008)MSC O END OF HO DUE BSS (c4008)

Unsuccessful external TCH to TCH handover due to aUnsuccessful external TCH to TCH handover due to aradio link failure during handover,radio link failure during handover,

Description:Description:

Number of the end of handover procedures due to BSSNumber of the end of handover procedures due to BSSproblems (outgoing HO controlled by the MSC).problems (outgoing HO controlled by the MSC).

Updated: When the connection between the MS and theUpdated: When the connection between the MS and theBTS is broken (on the source channel), that is, when aBTS is broken (on the source channel), that is, when a

message carrying an indication of a connection failure ismessage carrying an indication of a connection failure isreceived (radio link failure or transcoder failure).received (radio link failure or transcoder failure).

Impact: The call may possibly be cleared.Impact: The call may possibly be cleared.


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MSC HOF due to End of HO BSSMSC HOF due to End of HO BSS


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Contd.Contd.

MSC O CALL CLEAR DURING HO (c4041)MSC O CALL CLEAR DURING HO (c4041) Unsuccessful external TCH to TCH handover due to call clearingUnsuccessful external TCH to TCH handover due to call clearing

during handover, source BSCduring handover, source BSC

Description:Number of outgoing HOs, controlled by the MSC, that areDescription:Number of outgoing HOs, controlled by the MSC, that areunsuccessful because the call is cleared during the HO.unsuccessful because the call is cleared during the HO.

UpdatedUpdated

a) When the subscriber clears the call during the HO.a) When the subscriber clears the call during the HO. b) When channel blocking is started during the HO.b) When channel blocking is started during the HO.

c) When the MS has sent messages concerningc) When the MS has sent messages concerning -- A interface speechA interface speechcircuitscircuits-- state changes of the BSSAP subsystemstate changes of the BSSAP subsystem-- abnormal release ofabnormal release ofthe SCCP connectionthe SCCP connection

d) When the reset of circuits are received from the MSCd) When the reset of circuits are received from the MSC

e) When there is a BCSU restart (if the TCHs related to the HO are ine) When there is a BCSU restart (if the TCHs related to the HO are inthat BCSU).that BCSU).

Impact:Call clearedImpact:Call cleared


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MSC HOF due to call clearMSC HOF due to call clear


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Contd.Contd.

MSC O UNSUCC DUE A IF CRC (c4102)MSC O UNSUCC DUE A IF CRC (c4102) Unsuccessful external TCH to TCH handover because theUnsuccessful external TCH to TCH handover because the

MSC rejects the handover due to various causesMSC rejects the handover due to various causes

Description: Number of HOs that are unsuccessful becauseDescription: Number of HOs that are unsuccessful becauseof a wrong A interface circuit type.of a wrong A interface circuit type.

Updated: When an external HO attempt ends with the AUpdated: When an external HO attempt ends with the Ainterface causes circuit_pool_mismatch or switch_interface causes circuit_pool_mismatch or switch_circuit_pool.This counter is updated also when a HOcircuit_pool.This counter is updated also when a HOattempt initiated by the BSC is interrupted because there isattempt initiated by the BSC is interrupted because there isno proper circuit pool or there is no free A interface circuitno proper circuit pool or there is no free A interface circuitavailable in the proper pool.available in the proper pool.

FeatureBSS5010 Half RateFeatureBSS5010 Half Rate

ImpactHO failureImpactHO failure


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MSC HOF due to wrongAMSC HOF due to wrongA--Intrf circuit typeIntrf circuit type


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Contd.Contd.

MSC O ADJ CELL ID ERR (c4100MSC O ADJ CELL ID ERR (c4100)) Unsuccessful external TCH to TCH handover because the MSC rejectsUnsuccessful external TCH to TCH handover because the MSC rejects

the handover due to various causesthe handover due to various causes

Unsuccessful external TCH to TCH handover due to adjacent cell errorUnsuccessful external TCH to TCH handover due to adjacent cell error


Number of errors in adjacent cell identification.Number of errors in adjacent cell identification.

UpdatedUpdated a) When the BSC notices that the target cell information (BCCHa) When the BSC notices that the target cell information (BCCH

frequency and/or BSIC) received in thefrequency and/or BSIC) received in the HANDOVER_COMMANDHANDOVER_COMMANDmessage from the MSC differs from that in the source BSDATA (BSSmessage from the MSC differs from that in the source BSDATA (BSSRadio Network Configuration Database).Radio Network Configuration Database).

b) When the MSC rejects the HO attempt due to the cause invalid_cellb) When the MSC rejects the HO attempt due to the cause invalid_cell

during a HO from SDCCH to TCH or from TCH to TCH .during a HO from SDCCH to TCH or from TCH to TCH . Reason for the impact: Information on the adjacent cells is incorrect inReason for the impact: Information on the adjacent cells is incorrect in

the BSS Radio Network Configuration Database in the source BSCthe BSS Radio Network Configuration Database in the source BSC


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M

SC HOF

due to adjacent cell errorM

SC HOF

due to adjacent cell error


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Contd.Contd.

MSC O CALL DROP DURING HO (c4107)MSC O CALL DROP DURING HO (c4107) Unsuccessful external TCH to TCH handover due to GSM timer T8Unsuccessful external TCH to TCH handover due to GSM timer T8

expiryexpiry


Number of calls that are dropped during external HOs, afterNumber of calls that are dropped during external HOs, afterHANDOVER_COMMANDHANDOVER_COMMAND is received from the MSC.is received from the MSC.

Updated:Updated: a) When a call is dropped during an external HO and after the BSC hasa) When a call is dropped during an external HO and after the BSC has

received areceived a HANDOVER_COMMANDHANDOVER_COMMANDmessage.message.

b) When either the GSM timer T8 (Time to receive of Successful HOb) When either the GSM timer T8 (Time to receive of Successful HO--Info) expires, or the MSC sends aInfo) expires, or the MSC sends a CLEAR_COMMANDCLEAR_COMMANDmessage to themessage to theBSC with other cause than call control or handover successful.BSC with other cause than call control or handover successful.

Dependencies with other counters/PI(s)Counter 004007 is updatedDependencies with other counters/PI(s)Counter 004007 is updatedalong with this counter.along with this counter.


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HOF counters: BSC HOFHOF counters: BSC HOF

BSC O HO NOT ALLOWED (c4038)BSC O HO NOT ALLOWED (c4038)

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover because acell TCH to TCH handover because ahandover is not allowed at this phase of the callhandover is not allowed at this phase of the call

Description: Number of outgoing HOs, controlled by the BSC, that areDescription: Number of outgoing HOs, controlled by the BSC, that areunsuccessful because no HOs are allowed.unsuccessful because no HOs are allowed.

UpdatedUpdated-- When HO execution is not allowed in the current phase ofWhen HO execution is not allowed in the current phase ofthe call in progress.the call in progress. -- When an HO is interrupted because theWhen an HO is interrupted because theassignment procedure bas been started during a HO but before theassignment procedure bas been started during a HO but before the

BSC has sent aBSC has sent a HANDOVER_COMMANDHANDOVER_COMMANDmessage to themessage to theMS.Dependencies with other counters/PI(s)Counter 004081 is updatedMS.Dependencies with other counters/PI(s)Counter 004081 is updatedalong with this counter.along with this counter.

Impact: HO failureImpact: HO failure


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Contd.Contd.

BSC O FAIL LACK (c4072)BSC O FAIL LACK (c4072)

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover duecell TCH to TCH handover dueto a lack of resourcesto a lack of resources

Updated:Updated:

a) When no SDCCH is available in the target cell for ana) When no SDCCH is available in the target cell for anSDCCH HO.SDCCH HO.

b) When no TCH is available in the target cell for a TCHb) When no TCH is available in the target cell for a TCHHO.HO.

c) When no TCH is available in the target cell for anc) When no TCH is available in the target cell for anSDCCH to TCH HO.SDCCH to TCH HO.



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Contd.Contd.

BSC O UNSUCCESS HO DUE RETURN (c4015)BSC O UNSUCCESS HO DUE RETURN (c4015)

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover duecell TCH to TCH handover dueto MS returning to the old channelto MS returning to the old channel


Number of outgoing HOs, controlled by the BSC, that areNumber of outgoing HOs, controlled by the BSC, that areunsuccessful because the MS returns to the source channel.unsuccessful because the MS returns to the source channel.

Updated: When the MS returns to the source channel.Updated: When the MS returns to the source channel.

Dependencies with other counters/PI(s)Counter 004012 isDependencies with other counters/PI(s)Counter 004012 is

updated along with this counter.updated along with this counter. Impact: HO failureImpact: HO failure


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Contd.Contd.

BSC O END OF HO (c4016):BSC O END OF HO (c4016):

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover due to a failure in thecell TCH to TCH handover due to a failure in theactivation of a new channelactivation of a new channel

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover due to losing the MScell TCH to TCH handover due to losing the MSduring handover. The GSM timer T3103 expiresduring handover. The GSM timer T3103 expires


Number of the end of handover procedures that are related to outgoing HOsNumber of the end of handover procedures that are related to outgoing HOscontrolled by the BSC.controlled by the BSC.

Updated:Updated: a) When the MS is lost (GSM timer T3103 (supervision of ho) expires).a) When the MS is lost (GSM timer T3103 (supervision of ho) expires). b) When radio channel activation fails.b) When radio channel activation fails.

c) When the connection between the MS and the BTS is broken (on the targetc) When the connection between the MS and the BTS is broken (on the targetchannel), that is, when a message carrying an indication of a connection failurechannel), that is, when a message carrying an indication of a connection failureis received (radio link failure or transcoder failure).is received (radio link failure or transcoder failure).

Dependencies with other counters/PI(s)Dependencies with other counters/PI(s) a) Counters 004012, 004083 and 004084 are updated along with this counter.a) Counters 004012, 004083 and 004084 are updated along with this counter. b) Counter 004013 is updated along with this counter.b) Counter 004013 is updated along with this counter.

c) Counter 004012 is updated along with this counter.c) Counter 004012 is updated along with this counter. Impact: a) Call cleared b) and c) HO failureImpact: a) Call cleared b) and c) HO failure


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Contd.Contd.

BSC O END OF HO DUE BSS (c4017):BSC O END OF HO DUE BSS (c4017): Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover due to a radio linkcell TCH to TCH handover due to a radio link

failure during handoverfailure during handover Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover caused by internalcell TCH to TCH handover caused by internal

timer expiry or a failure in the connection of a bitimer expiry or a failure in the connection of a bi--directional speech pathdirectional speech path Description: Number of outgoing HOs, controlled by the BSC, that areDescription: Number of outgoing HOs, controlled by the BSC, that are

unsuccessful due to BSS problems.unsuccessful due to BSS problems.

Updated:Updated: a) When the connection between the MS and the BTS is broken (on the sourcea) When the connection between the MS and the BTS is broken (on the source

channel), that is, when a message carrying an indication of a connection failurechannel), that is, when a message carrying an indication of a connection failureis received (radio link failure or transcoder failure) before theis received (radio link failure or transcoder failure) before the HO_COMMANDHO_COMMANDmessage.message.

b) When switching from a unidirectional to a bib) When switching from a unidirectional to a bi--directional speech path fails.directional speech path fails.

Dependencies with other counters/PI(s): a) Counter 004081 is updated alongDependencies with other counters/PI(s): a) Counter 004081 is updated along

with this counter. b) Counters 004013, 004083 and 004084 are updated alongwith this counter. b) Counters 004013, 004083 and 004084 are updated alongwith this counter.with this counter.

Impact: Call cleared.Impact: Call cleared.


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Contd.Contd.

BSC O CALL CLEAR DURING HO (c4042)BSC O CALL CLEAR DURING HO (c4042)

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handovercell TCH to TCH handoverdue to call clearing during handoverdue to call clearing during handover


Number of outgoing HOs, controlled by the BSC, that areNumber of outgoing HOs, controlled by the BSC, that areunsuccessful because the call is cleared.unsuccessful because the call is cleared.

Updated:Updated:

a) When the subscriber clears the call during the HO.a) When the subscriber clears the call during the HO.

b) When channel blocking is started during the HO.b) When channel blocking is started during the HO.

Dependencies with other counters/PI(s)Counter 004081 isDependencies with other counters/PI(s)Counter 004081 isupdated along with this counter.updated along with this counter.

Impact: Call clearedImpact: Call cleared


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Contd.Contd.

BSC O UNSUCC A INT CIRC TYPE (c4096)BSC O UNSUCC A INT CIRC TYPE (c4096)

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover because nocell TCH to TCH handover because noradio resources are available due to switch_crc_poolradio resources are available due to switch_crc_pool

Successful handover type reselection from an internal interSuccessful handover type reselection from an internal inter--cell TCH tocell TCH toTCH handover to an external handover due to switching the circuitTCH handover to an external handover due to switching the circuitpoolpool

Description:Description: Number of outgoing HOs that are unsuccessful due to a wrong ANumber of outgoing HOs that are unsuccessful due to a wrong A

interface circuit type.interface circuit type.

Updated: When an internal outgoing interUpdated: When an internal outgoing inter--cell HO attempt iscell HO attempt isinterrupted because the BSC wants to change the A interface circuitinterrupted because the BSC wants to change the A interface circuitpool before TCH allocation.pool before TCH allocation.

Dependencies with other counters/PI(s)Counter 004097 is updatedDependencies with other counters/PI(s)Counter 004097 is updatedalong with this counter.FeatureBSS5010 Half RateImpactHO failurealong with this counter.FeatureBSS5010 Half RateImpactHO failure


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Contd.Contd.

BSC O DROP CALLS (c4084):BSC O DROP CALLS (c4084):

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover due to losingcell TCH to TCH handover due to losingthe MS during handover. The GSM timer T3103 expiresthe MS during handover. The GSM timer T3103 expires

Unsuccessful internal interUnsuccessful internal inter--cell TCH to TCH handover caused bycell TCH to TCH handover caused byinternal timer expiry or a failure in the connection of a biinternal timer expiry or a failure in the connection of a bi--directionaldirectionalspeech pathspeech path

Description:Description: Number of calls that are dropped during outgoing HOs controlled byNumber of calls that are dropped during outgoing HOs controlled by

the BSC.the BSC.

Updated:Updated:

a) When the MS is lost (timer T3103 expires).a) When the MS is lost (timer T3103 expires).

b) When switching from a unidirectional to a bib) When switching from a unidirectional to a bi--directional speech pathdirectional speech pathfails.fails.

Dependencies with other counters/PI(s)a) Counters 004012, 004016 andDependencies with other counters/PI(s)a) Counters 004012, 004016 and004083 are updated along with this counter. b) Counters 004013, 004017004083 are updated along with this counter. b) Counters 004013, 004017and 004083 are updated along with this counter.and 004083 are updated along with this counter.


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HOF counters: IntraHOF counters: Intra--cell HOFcell HOF

INT CELL HO NOT ALLOWED (c4036):INT CELL HO NOT ALLOWED (c4036):

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handovercell TCH to TCH handoverbecause a handover is not allowed at this phase of the callbecause a handover is not allowed at this phase of the call

Description:Number of HOs that are unsuccessful becauseDescription:Number of HOs that are unsuccessful because

no HOs are allowed (intrano HOs are allowed (intra--cell HO).cell HO). Updated:Updated:

a) When HO execution is not allowed in the current phasea) When HO execution is not allowed in the current phaseof the call in progress.of the call in progress.

b) When a HO is interrupted because an assignmentb) When a HO is interrupted because an assignment

procedure has been started during a HO but before theprocedure has been started during a HO but before theBSC has sent anBSC has sent an ASSIGNMENT_COMMANDASSIGNMENT_COMMAND ororHANDOVER_COMMANDHANDOVER_COMMANDmessage to the MS.message to the MS.

Impact: HO failureImpact: HO failure


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Contd.Contd.

INT CELL UNSUCCESS HO DUE LACK (c4019)INT CELL UNSUCCESS HO DUE LACK (c4019)

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover duecell TCH to TCH handover dueto lack of resourcesto lack of resources

Description: Number of intraDescription: Number of intra--cell HOs that arecell HOs that are

unsuccessful due to a lack of resources.unsuccessful due to a lack of resources. Updated:Updated:

a) When no SDCCH is available for a SDCCH HO.a) When no SDCCH is available for a SDCCH HO.

b) When no TCH is available for a TCH HO.b) When no TCH is available for a TCH HO.

c) When no TCH is available for an SDCCH to TCH HO.c) When no TCH is available for an SDCCH to TCH HO.



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Contd.Contd.

INT CELL UNSUCCESS HO DUE MOVE (c4020)INT CELL UNSUCCESS HO DUE MOVE (c4020)

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover duecell TCH to TCH handover dueto losing the MS during handover. The GSM timer T3107to losing the MS during handover. The GSM timer T3107expiresexpires

Description: Number of intraDescription: Number of intra--cell HOs that arecell HOs that areunsuccessful because the MS cannot either move to theunsuccessful because the MS cannot either move to thetarget channel or return to the source channel.target channel or return to the source channel.

Updated: When the MS is lost (GSM timer T3107Updated: When the MS is lost (GSM timer T3107(supervision of assgn procedures) expires).(supervision of assgn procedures) expires).

Dependencies with other counters/PI(s)Counter 004085 isDependencies with other counters/PI(s)Counter 004085 isupdated along with this counter.ImpactCall clearedupdated along with this counter.ImpactCall cleared


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Contd.Contd.

INT CELL UNSUCCESS HO DUE BSS PROBLEM (c4021)INT CELL UNSUCCESS HO DUE BSS PROBLEM (c4021) Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover due to a failurecell TCH to TCH handover due to a failure

in the activation of a new channelin the activation of a new channel

Description: Number of unsuccessful intraDescription: Number of unsuccessful intra--cell HOs due to BSScell HOs due to BSSproblems.problems.

UpdatedUpdated

a) When a radio channel activation fails.a) When a radio channel activation fails. b) When the physical context request fails.b) When the physical context request fails.

c) When the connection between the MS and the BTS is broken, that is,c) When the connection between the MS and the BTS is broken, that is,when a message carrying an indication of a connection failure iswhen a message carrying an indication of a connection failure isreceived (radio link failure or transcoder failure).received (radio link failure or transcoder failure).

d) When switching from a unidirectional to a bid) When switching from a unidirectional to a bi--directional speech pathdirectional speech path

fails.fails. Dependencies with other counters/PI(s)d) Counter 004085 is updatedDependencies with other counters/PI(s)d) Counter 004085 is updated

along with this counter.along with this counter.

Impact: a) and b) HO failure c) Possibly call cleared d) Call clearedImpact: a) and b) HO failure c) Possibly call cleared d) Call cleared


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Contd.Contd.

INT CELL UNSUCCESS HO DUE RETURN (c4022):INT CELL UNSUCCESS HO DUE RETURN (c4022): Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover due to MScell TCH to TCH handover due to MS

returning to the old channelreturning to the old channel

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover, caused by ancell TCH to TCH handover, caused by aninternal timer expiry in the BSC or a CONNECTION_FAILURE,internal timer expiry in the BSC or a CONNECTION_FAILURE,ERROR_INDICATION, or ERROR_REPORT message coming toERROR_INDICATION, or ERROR_REPORT message coming to

the target channelthe target channel

Description: Number of unsuccessful intraDescription: Number of unsuccessful intra--cell HOs due to the MS'scell HOs due to the MS'sreturn to the source channel.return to the source channel.

Updated: When the MS returns to the source channel.Updated: When the MS returns to the source channel.



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Contd.Contd.

INT CELL CALL CLEAR DURING HO (c4039)INT CELL CALL CLEAR DURING HO (c4039)

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover duecell TCH to TCH handover dueto call clearing during handoverto call clearing during handover

Description: Number of intraDescription: Number of intra--cell HOs that arecell HOs that are

unsuccessful because the call is cleared.unsuccessful because the call is cleared.

Updated:Updated:

a) When the subscriber clears the call during the HO.a) When the subscriber clears the call during the HO.

b) When channel blocking is started during the HO.b) When channel blocking is started during the HO.


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Contd.Contd.

INT UNSUCC A INT CIRC TYPE (c4098):INT UNSUCC A INT CIRC TYPE (c4098):

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover because nocell TCH to TCH handover because noradio resources are available due to switch_crc_poolradio resources are available due to switch_crc_pool

Successful handover type reselection from an internal intraSuccessful handover type reselection from an internal intra--cell TCH tocell TCH toTCH handover to an external handover due to switching the circuitTCH handover to an external handover due to switching the circuit

poolpool Description: Number of HOs unsuccessful due to a wrong A interfaceDescription: Number of HOs unsuccessful due to a wrong A interface

circuit type.circuit type.

Updated: When an internal intraUpdated: When an internal intra--cell HO attempt is interruptedcell HO attempt is interruptedbecause the BSC wants to change the A interface circuit pool beforebecause the BSC wants to change the A interface circuit pool beforeTCH allocation.FeatureBSS5010 Half RateTCH allocation.FeatureBSS5010 Half Rate

ImpactHO failureImpactHO failure


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Contd.Contd.

CELL DROP CALLS (c4085)CELL DROP CALLS (c4085)

Unsuccessful internal intraUnsuccessful internal intra--cell TCH to TCH handover due to losingcell TCH to TCH handover due to losingthe MS during handover. The GSM timer T3107 expiresthe MS during handover. The GSM timer T3107 expires

Description: Number of calls dropped during intraDescription: Number of calls dropped during intra--cell HOs.cell HOs.

Updated:Updated:

a) When the MS is lost (timer T3107 expires).a) When the MS is lost (timer T3107 expires). b) When switching from a unidirectional to a bib) When switching from a unidirectional to a bi--directional speech pathdirectional speech path

fails.fails.

Dependencies with other counters/PI(s)a) Counter 004020 is updatedDependencies with other counters/PI(s)a) Counter 004020 is updatedalong with this counter. b) Counter 004021 is updated along with thisalong with this counter. b) Counter 004021 is updated along with thiscounter.counter.

Impact: Call clearedImpact: Call cleared The timer T3107 supervises the assignment procedure and the internalThe timer T3107 supervises the assignment procedure and the internal

intracell handover.intracell handover.


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Documents

Handovers_1