hand over
DESCRIPTION
overview and algothrim handoverTRANSCRIPT
Handover is key technology of Mobile
communication system and make
continued conversation possible.
Handover algorithm in Huawei product
is flexible and powerful
� Upon completion this course, you will be
able to:
�Understand the type of handover.
�Master handover judgment flow
�Configure handover data
�Master handover signaling flow
ChapterChapter 1 1 Introduction of HandoverIntroduction of Handover
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
ChapterChapter 3 3 HO Data ConfigurationHO Data Configuration
ChapterChapter 4 4 HO Signaling processHO Signaling process
Purposes of HO
� To keep a continuous communication with a moving MS
�To improve network service performance
− To reduce the call drop rate
− To reduce the congestion rate
� Emergency HO
�Timing Advance (TA) Emergency HO
�Bad quality (BQ) Emergency HO
�Rx_Level_Drop Emergency HO
� Interference Emergency HO
� load HO
� Normal HO
�Edge HO
�Layer HO
�Power Budget (PBGT) HO
� Speed-sensitive HO (Fast moving MS HO)
� Concentric Cell HO
Classification by Reason
Classification by Synchronization
� Synchronous handover: source
and target cell belong the same
BTS
� Asynchronous handover: source and
target cell belong the different BTS
ChapterChapter 1 1 Introduction of HandoverIntroduction of Handover
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
ChapterChapter 3 3 HO Data ConfigurationHO Data Configuration
ChapterChapter 4 4 HO Signaling processHO Signaling process
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
1.1 1.1 General HO processGeneral HO process
1.2 1.2 Measurement report preprocessingMeasurement report preprocessing
1.3 1.3 Penalty processingPenalty processing
1.4 1.4 Basic ranking and Secondary rankingBasic ranking and Secondary ranking
1.5 Condition of 1.5 Condition of handoverhandover
General process of HO Algorithm
M.R.preprocessing
Penalty processing
Basic ranking
Secondary ranking
HO judgment
TA emergency HO
BQ emergency HO
RSD emergency HO
Interf. emergency HO
Load Sharing HO
Edge HO
Layer HO
PBGT HO
Processing program
OM forced HO
Directed retry
Overlaid/underlaid HO
Fast moving MSHO
1
1
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
1.1 1.1 General HO processGeneral HO process
1.2 1.2 Measurement report preprocessingMeasurement report preprocessing
1.3 1.3 Penalty processingPenalty processing
1.4 1.4 Basic ranking and Secondary rankingBasic ranking and Secondary ranking
1.5 Condition of 1.5 Condition of handoverhandover
Measurement Report
� Uplink MR includes uplink receiving level and quality.
� Downlink MR includes downlink receiving level, downlink
receiving quality of the serving cell and other downlink
receiving levels from the neighbor cells.
Serving cell Neighbour cell
The downlink measurement report
of the serving cell
The uplink measurement
report of MSThe downlink measurement reportof the neighbour cell (BCCH)
Measurement Report
Period of measurement report
� The downlink MR is sent to BTS in SACCH uplink
�The interval is 480ms/per time when MS is on TCH
�The interval is 470ms/per time when MS is on SDCCH
12TCH 12TCH1SACCH 1 Idle
480ms 4 TCH multi-frames
MR interpolation
�Every time BSC receives a measurement report, there will
be an update to the basic rank of the cells.
�BTS may fail to receive the measurement report from MS.
Before the rank-update, BSC needs to recover the lost
measurement reports according to Filter Table. If the lost
MR amount is within the allowed range, then recovers the
lost MR according to the algorithm.
MR MR MR MR MR
Measurement report No. n
Measurement report No. n+4
Continuous MR flow
How to interpolate MR?
Filter----Average several continuous MR.
MR MR MR MR MR MR
Continuous MR flow
filtering
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
1.1 1.1 General HO processGeneral HO process
1.2 1.2 Measurement report preprocessingMeasurement report preprocessing
1.3 1.3 Penalty processingPenalty processing
1.4 1.4 Basic ranking and Secondary rankingBasic ranking and Secondary ranking
1.5 Condition of 1.5 Condition of handoverhandover
Penalty Processing
� There are altogether four types of penalty process (second step of
HO algorithm process )
� Penalty on the target cell when a HO fails.
� Penalty on the original serving cell when an emergency HO
( base on BQ and TA ) is performed.
� Penalty on other high priority layer cells after a fast moving HO
is performed.
� A new HO attempt is prohibited within the penalty time after an
overlaid/underlaid HO fails.
BTS
HO failure
BSC
Cell A
Cell B
Penalty on the Target Cell
Punish the target cell when a HO fails. This is to avoid the
MS to select this cell again in next HO judgment.
BTS
BQ& TA HO
BSC
Cell A
Cell B
Penalty on the Source Cell
Punish the original serving cell when an emergency HO
( due to BQ and TA) occurs.
Back? No way!Back? No way!
Umbrella
Micro cell
penalty on Non-umbrella Layer
� Giving penalty on the other three layers after MS handovers to
Umbrella cell by fast-moving-HO. This is to keep MS staying in
the umbrella cell and avoid frequent HO.
Underlaid
Overlaid Do not attempt
again after a failed HO!
Penalty on Overlaid/underlaid Cell
� A new Overlaid/underlaid HO is prohibited within a penalty time
after an Overlaid/Underlaid HO failure.
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
1.1 1.1 General HO processGeneral HO process
1.2 1.2 Measurement report preprocessingMeasurement report preprocessing
1.3 1.3 Penalty processingPenalty processing
1.4 1.4 Basic ranking and Secondary rankingBasic ranking and Secondary ranking
1.5 Condition of 1.5 Condition of handoverhandover
Procedure of Ranking
� Basic ranking and secondary ranking of cells are major parts of
the HO judgment. Ranking is made through 16bits-algorithm.
The serving cell and the neighbor cells will be listed in a cell list
according to their 16bits value. The ranking processes include:
�M rule
�K rule
�16bits ranking
M rule � Only the cells with received signal level satisfy the following conditions
can be put into the candidate cell list.
� For serving cell
� RX_LEV (o) >MSRXMIN(o) + MAX(0,Pa(o))
� For Neighbor cell
� RX_LEV (n) > MSRXMIN(n)+ MAX(0,Pa(n))+ OFFSET
�Pa(0) : MS_TXPWR_MAX(0) – P
�Pa(n) : MS_TXPWR_MAX(n) – P
�MS_TXPWR_MAX( ) : The appointed MS transmitting power by the
BSS.
�P : Max_Power_of_MS
�Max_Power_of_MS : MS maximum transmitting power
K rule Criterion
� After the M rule , the serving cell and candidate neighbor cells are
ranked in descending order according to the receiving level only
� Both the serving cell and the neighbor cells have their own 16bits value.
The smaller the value is, the higher the priority and position the cell is in
the cell list.
� The 1st-3rd bits: bit value is decided according to the cell signal level and the penalty process taking place beforehand.
�The values come from max. 6 candidate cells and 1 serving cell
according to the level ranges from 000~110. The value for the cell
with the strongest signal level is 000.
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The 4th bit: determined by HO hysteresis
� The 4th bit: bit value is determined by inter-cell HO ( of the same layer )
hysteresis.
� The 4th bit of the serving cell is always 0,
� The receiving signal level of the neighbor cell >= The receiving level of the
serving cell + Inter-cell HO ( of the same layer ) hysteresis, bit 4th is set to 0.
� The receiving level of the neighbor cell < The receiving level of the serving
cell + Inter-cell HO ( of the same layer ) hysteresis, bit 4th is set to 1.
�Note: In PBGT HO, whichever the greater of the inter-cell ( of the same
layer ) hysteresis and PBGT threshold, that value will be used in the
PBGT HO.
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The 5th—10th bit: determined by Layer
� The 5th-10th bits: bit value is decided according to their position in
Huawei hierarchical network structure.
� When the signal level of the neighbor cells or the serving cell is lower
than the layer HO threshold and hysteresis, this function is turned off
and all bits are set to 0.
� That is to say only when the above criterions are met, then this
function take effect.
� Huawei cell layers can be divided into 4 layers and each layer can be
further divided into 16 different priorities. So there are 64 different
priorities in Huawei hierarchical cell structure.
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GSM900
Cell
Micro Cell
Umbrella
Cell GSM 900
GSM1800 GSM1800GSM1800
GSM 900 GSM 900 GSM 900
GSM900GSM900
GSM1800GSM1800
GSM900 GSM900
GSM1800 GSM1800
GSM1800
Cell
Hierarchical cell structure
The 11th bit: determined by load
� The 11th bit: bit value is decided by cell-load-sharing criterion.
� Serving cell: if Cell Load>= Start threshold of load HO, bit 11th is set to 1,
otherwise is set to 0.
� Neighbor cell: if Cell Load>=Receive threshold of load HO, bit 11th is set to 1,
otherwise is set to 0.
� Refer to Load HO Table for the load HO threshold and load req. on
candidate cell.
�Clue : When the cell load is higher than the threshold, then the bit 11th is
set to 1.This is done in order to put the cell in a lower part of the cell list.
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The 12th/13th bit: determined by co-BSC/MSC
� 12th bit: bit value is decided by co-BSC criterion.
�Serving cell: is always set to 0.
�Neighbor cell: if co-BSC with the serving cell, 12th bit is set to 0,
otherwise is set to 1.
�When the signal level from the neighbor cell or the serving cell is lower
than layer HO threshold and hysteresis. This function is turned off and
the value is set to 0.
� If the parameter – “Co-BSC/MSC Adj.” in the HO control table is set to
“No”, then this function is turned off and the value is 0.
� 13th bit : Bit value is decided by Co-MSC parameter, having the same
concept as the 12th bit.
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The 14th bit: determined by Layer HO
� The 14th bit: Layer HO threshold adjustment bit
� Serving cell criterion
�Receive level >= layer HO threshold – layer HO hysteresis, bit 14th
is set to 0. At the same time, bit 13th, 12th and 10th—5th bits are
set to 0.
� If the above criterion is not met, then bit 14th is set to 1.
�Example : 20-5 = 15 ( -95 dBm )
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The 14th bit: determined by Layer HO
� Neighbor cell criterion
�Receive level >=layer HO threshold + layer HO hysteresis, bit 14th is set to 0. At the same time, bit 13th, 12th and 10th—5th bits are set to 0
� If the above criterion is not met, then bit 14th is set to 1.
�Example : 20+5 = 25 ( -85 dBm )
� note
�The layer HO threshold and hierarchical hysteresis correspond to the value of that individual cell’s value.
�Usual situation : When the neighbor cells are of the same layer, each of the neighbor cell’s layer HO threshold value will be the same. Same concept goes for the layer HO hysteresis. This can maintain the entire hierarchical layers of the cell.
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The 15th bit: determined by Cell Type
� The 15th bit: Bit value is decided by cell type
− Serving cell or Neighbor cells:
− When cell type is extension cell �1.
− When cell type is normal cell �0.
� The 16th bit: Reserved bit
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ChapterChapter 2 2 HO Algorithm processHO Algorithm process
1.1 1.1 General HO processGeneral HO process
1.2 1.2 Measurement report preprocessingMeasurement report preprocessing
1.3 1.3 Penalty processingPenalty processing
1.4 1.4 Basic ranking and Secondary rankingBasic ranking and Secondary ranking
1.5 Condition of 1.5 Condition of handoverhandover
Types of HO
� Emergency HO
�TA HO
�BQ HO
� interference HO
�Rx_Level_Drop HO
� Load HO
� Normal HO
�Edge HO, layer cell HO and PBGT HO
� Fast moving HO
� Overlaid/underlaid HO
TA&Bad Quality HO
� TA HO criterion :
�TA of the serving cell > TA Thrsh.
� BQ HO criterion :
�The average value of the uplink quality of the serving cell >
� UL Qual. Thrsh.
�The average value of the downlink quality of the serving cell >
DL Qual. Thrsh.
� Requirements on the target cell (same as the above two types of
HO)
�Select the first cell in the neighbor cell list i.e. lowest 16bits
value.
Rx_Level_Drop HO
� Rx_Level_Drop HO
�Due to downlink signal level drop
�Triggered upon detecting rapid level drop during MS busy
mode.
� Requirements for the target cell:
�The target cell is the first cell in the neighbor cell list.
Interference HO
� Interference HO (DL&UL) :
�When the receiving level > receiving threshold level. But
Receiving quality < threshold of quality interference.
� Requirements for the target cell:
�The target cell is in the cell list.
Cell Load HO
� Cell Load HO Criterions :
�System load of BSC < Permissible load of HO threshold
�Load of serving cell > Load HO threshold
� Requirements for the target cell
�Load of target cell < Load HO threshold
BTS
BSC
Edge HO
� Edge HO Criterion:
� In N seconds, when there are P seconds that neighbor
cell’s DL or MS’s UL signal level is lower than the Edge HO
threshold. Then the criterion is met and Edge HO occurs.
This method utilizes the P/N rule.
� Requirements for the target cell:
�The target cell should be ranked in front of the serving cell.
Layer HO
� Layer HO criterions:
�Serving cell :
− No requirement.
�Target cell :
− Layer of the target cell is lower than the serving cell.
− Receive level of the target cell > layer cell threshold +
layer cell hysteresis.
− Target cell should be ranked in front of the serving cell.
The priority of target cell should be higher than the
serving cell’s.
PBGT HO
� PBGT HO Criterions :
�Target cell’s path loss is smaller than the serving cell’s path
loss by the PBGT threshold value.
�Satisfying the P/N rule.
�Target cell should be ranked in front of the serving cell.
� Note :
�PBGT HO can only occur between same-priority cell. If the
system permits PBGT HO for the cell, PBGT HO can occur
in either inter-BSC or inter-MSC.
Fast-Moving HO
� When the serving cell is micro cell :
�When the MS has traveled through P numbers of cell, and
there are Q (=<P) numbers of cell that the MS has traveled
in high speed, the criteria is satisfied. MS will be handed
over to umbrella cell.
� When the serving cell is umbrella cell :
�When the MS is traveling high speed in umbrella cell, a
greater penalty can be given to the micro cell for a duration
of time (penalty time). In this way, the MS will not use the
micro cell. Note :In this case, the micro cell is only used
under urgency conditions( Poor TA and BQ ).
Overlaid/Underlaid Cell
Assume, 6TRX in one cell, one CDU and one SCU are adopted
Where can we configure BCCH CH? CDU or SCU?
SCU
CDU
Antenna
Antenna
TRX
TRX
TRX
TRX
TRX
TRX
Overlaid/Underlaid Cell
� Purpose
�Maximize coverage area
�Reduce interference and improve frequency reuse density
� Construct method
�Different combiner loss
�Decrease the power of TRX
�By HO parameter, it is called IUO
� Classify
�Normal Underlaid/Overlaid
� IUO: Enhance Underlaid/Overlaid
How to Allocate SDCCH/TCH?
� SDCCH
�SDCCH are always allocated in Underlaid
�Layer is allocated according the transmission delay of
access burst
� TCH
�The receiving level
�TA
�They are included in MR of SDCCH CH on uplink reported
by BTS
Factor of Handover between Under/Overlaid
� Normal Underlaid/Overlaid
�Receiving level
�Time Advance
�Quality
� Enhanced Underlaid/Overlaid
�Receiving level
�Time Advance
�Quality
�Traffic Load of Underlaid
underlaid
overlaid
:
Division of underlaid and overlaid is decided by MS
downlink receive level ,TA value and quality.
Normal Overlaid/Underlaid HONormal Overlaid/Underlaid HO
The quality boundary is elided in this figure
Normal Overlaid/Underlaid HO
� Criterion for HO from overlaid to underlaid:
�TA value => TA threshold + TA hysteresis OR
� RX_LEV <= RX_LEV threshold -RX_LEV hysteresis OR
� Qua. =>Qua. threshold
�Satisfying P/N rule
� Criterion for HO from underlaid to overlaid:
�TA value =< TA threshold - TA hysteresis AND
� RX_LEV >=RX_LEV threshold + RX_LEV hysteresis AND
� Qua. =<Qua. threshold
�Satisfying P/N rule
Enhance Overlaid/Underlaid HO
� Criterion for HO from overlaid to underlaid:
�TA value => TA threshold + TA hysteresis OR
� RX_LEV <= O to U level OR
� Qua. =>Qua. threshold
�Satisfying P/N rule
� Criterion for HO from underlaid to overlaid:
�TA value =< TA threshold - TA hysteresis AND
� RX_LEV >= U to O level AND
� Qua. =<Qua. Threshold
� If the box “U to O HO traffic threshold” is checked, just in the condition
that underlaid load is more than this threshold, U to O handover based
on previous conditions can be triggered
�Satisfying P/N rule
ChapterChapter 1 1 Introduction of HandoverIntroduction of Handover
ChapterChapter 2 2 HO Algorithm processHO Algorithm process
ChapterChapter 3 3 HO Data ConfigurationHO Data Configuration
ChapterChapter 4 4 HO Signaling processHO Signaling process
ChapterChapter 4 4 HO Signaling process HO Signaling process
1.1 1.1 Intra BSC HandoverIntra BSC Handover
1.2 1.2 Intra MSC HandoverIntra MSC Handover
1.3 1.3 Inter MSC HandoverInter MSC Handover
Intra-BSC Handover Signaling process
MS MSBTS1 BTS2BSC MSC
Measurement Report from MS
Channel_Active
Channel_Active ACK
HANDOVER COMMAND
Handover Access
Handover_DetectPHY INFO
First SABM
Establish_IND
PHY INFO
Handover Complete
Handover_Performed
Intra-BSC Handover Signaling process
� Attention
� In asynchronous HO, if MS could not reach the new TCH
channel after the target cell has sent PHY INFO up to max
times, the target cell reports CONN FAIL IND to BSC with
the reason: HO access failure.
�After the above message is received, BSC release the
assigned TCH channel in the target cell .
�Max resend times of physical information*Radio link
connection timer > Time interval between EST IND and HO
DETECT (120~180ms). This is to make sure that the
physical information reach MS.
MS BTS BTSBSC MSCMeasurement Report
Measurement Report
Channel_Activate
Channel_Activate ACK
Handover Command (Old FACCH)
Handover Access (New FACCH)
Handover Complete (New FACCH)
RF Channel ReleaseHandover Performed
T09++
T12++
T10++
T13++
Attempted outgoing internal inter cell handovers
Attempted incoming internal inter cell handovers
Successful incoming internal inter cell handovers
Successful outgoing internal inter cell handovers
(Original) (Target)
Intra-BSC Handover Signaling processIntra-BSC Handover Signaling process
Measurement Points of Intra BSC Handover
� Handover formula definition
� Internal inter cell radio handover success rate
�=(Successful incoming internal inter cell handovers +
Successful outgoing internal inter cell handovers) /
(Incoming internal inter cell handovers + Outgoing internal
inter cell handovers )
� Internal inter cell handover success rate
� =(Successful incoming internal inter cell handovers +
Successful outgoing internal inter cell handovers) /
(Attempted incoming internal inter cell handovers +
Attempted outgoing internal inter cell handovers)
� Internal inter cell radio handover success rate >= Internal inter
cell handover success rate
ChapterChapter 4 4 HO Signaling process HO Signaling process
1.1 1.1 Intra BSC HandoverIntra BSC Handover
1.2 1.2 Intra MSC HandoverIntra MSC Handover
1.3 1.3 Inter MSC HandoverInter MSC Handover
MS BTS BTSBSC1 BSC2MSC(original) (Target)
Measurement Report
Measurement ReportHandover Required
Handover Request
Channel_Active
Channel_Active_ACKHandover_Request_ACK
Handover Command
Handover Access
Handover Detect
Handover Complete
Handover Complete
Clear Command (HO Successful)
RF Channel Release
Clear Complete
Attempted outgoing interBSC inter cell handovers
Attempted incoming interBSC inter cell handovers
Successful incoming inter BSC handovers
Successful outgoing interBSC inter cell handovers
Intra-MSC HO Signaling processIntra-MSC HO Signaling process
Channel Release process
MS BTS BSC MSCDisconnect
Release
Release Complete
Clear_CMD
Clear_CMPChannel Release
Deactive_SACCH
First DISC
UA
Release_IND
RF_Release_REQ
RF_Release_REQ_ACK
ChapterChapter 4 4 HO Signaling process HO Signaling process
1.1 1.1 Intra BSC HandoverIntra BSC Handover
1.2 1.2 Intra MSC HandoverIntra MSC Handover
1.3 1.3 Inter MSC HandoverInter MSC Handover
MSC-BMSC-A VLR-BBSC-A BSC-B
HO-REQUIREDMAP_Prepare_HO
MAP_Prepare_HO_ACK
MAP_Allocate_HO_NUM
MAP_Send_HO_Report
MAP_Send_HO_Report_ACK
MS
HO-REQUEST
HO-REQUEST-ACK
HO-Command
MS
HO-AccessMAP_Process_Access_Signalling
HO-CompleteMAP_Send_End_Signal
Clear-Command
Clear-Complete
MAP_Send_End_Signal_ACK
Some intermediate steps are omitted
IAI
ACM
Signaling process between MSC
MSC-BMSC-A VLR-BBSC-A BSC-B
HO-REQUIREDMAP_Prepare_HO
MAP_Prepare_HO_ACK
MAP_Allocate_HO_NUM
MAP_Send_HO_Report
MAP_Send_HO_Report_ACK
MS
HO-REQUEST
HO-REQUEST-ACK
HO-Command
MS
HO-AccessMAP_Process_Access_Signalling
HO-CompleteMAP_Send_End_Signal
Clear-Command
Clear-Complete
MAP_Send_End_Signal_ACK
Some intermediate steps are omitted
IAI
ACM
Signaling process between MSC
Inter-MSC HO Signaling process
� Signaling process – Abnormal conditions
�The following conditions will cause HO failure
− MSC-B fails to identify the target cell.
− MSC-B does not allow HO to the indicated target cell.
− The target cell has no channel available.
− VLR-B has no HO number available.
− HO error or unsuitable data.
Roaming
E
MS
MSCa MSCbMSCb'
VLRbVLRb'
BSS2
BSS2'
Radio transmission signal measurementHO REQUIRED (target cell table)
Perform subsequent HO(MAP) (target cell ID, serving cell ID, MSC number)
Perform HO
(target cell ID, serving cell ID, channel type)HO REQUEST (PCM&Channel type)
HO REQUEST ACKNOWLmargin (including New TCH number and HO number)
Allocate HO number
Send HO report(HON)Radio channel ack. (MAP) (includes New TCH number and HON)
IAI
ACM
Subsequent HO ack.
HO COMMAND HO DETECT
HO COMPLETESend end signal (MAP)
ANS
End signal (MAP)Release HO report Release HON
CLEAR COMMAND
CLEAR COMPLETERelease (TUP)
Cut physical connection between MSCa and MSCb
End signal (MAP)
Release (TUP/ISUP)Release HO report Release HON
Cut physical connection between MSCAa and MSCb'
~~ ~~
MS
Inter MSC HO—Subsequent HO process
Highway
MSC-AMSC-C
MSC-B MSC-C
Inter MSC HO—Subsequent HO process
� Subsequent HO
Inter MSC HO Signaling process
� Statistics counter—same as Intra MSC HO, Statistics is
handled by BSC
� HO formula-- same as Intra MSC HO
Major differences
� There is no “HO request” information for intra-BSC HO, and all of the HO are analyzed
and processed in BSC. Once the target cell as required is found in the BSC, “Channel
activation” information is sent to it directly.
� When the target cell is not in the same BSC, BSC reports CGI numbers of the serving
cell and target cell, and HO cause to MSC through “Ho-Required”. When MSC finds
the LAC of the target cell is in the MSC, it sends “Ho-Request” to the BSC of the target
cell, and the target BSC activates the target cell channel to complete the following
procedure.
� When MSC finds that the target cell LAC does not belong to the MSC, it will query its
“LAI and GCI Table” (including LAC and router address of the adjacent MSC), and
send “Prepare-HO” message to the target MSC-B according to the router address.
The message includes CGI of the target cell and indication whether or not to allocate
HO number, etc. According to the message, the target MSC-B sends “HO-Request”
message to the target BSC-B after demanding HO number (unless it is not required in
the indication) from VLR-B, and sends “Prepare-HO acknowledgement” to serving
MSC after received “HO-Request acknowledgement”, to execute the next procedure.
Major differences
� Inter BSC HO transfers “HO-REQ” message through MSC,
with CGI of the serving cell and target cell carried in the
message.
� Intra BSC HO does not have any CGI in any messages, it is
handled inside BSC.
� Intra BSC HO only sends “HO-Performed” to MSC upon
completion of HO, and MSC is not involved before that time.
� In inter BSC HO, MSC is involved since the HO request .
Summary
In this course, we have learned:
� Classify of handover
� Judgment and Ranking step
� Handover Data Configuration
� Handover signaling Flow
SummarySummary