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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Handover
Page2Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Foreword
� Handover is a key technology of mobile communication
system and make continued conversation possible.
� Handover algorithm in Huawei product is flexible and
powerful.
Page3Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
� Upon completion of this course, you will be able to:
� Understand the types of handover.
� Master handover judgment flow.
� Configure handover data.
� Master handover signaling flow.
Page4Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Introduction of Handover
2. HO Algorithm Process
3. HO Data Configuration
4. HO Signaling Process
Page5Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page6Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
� 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
� Fast moving MS HO (Speed-sensitive HO )
� Concentric cell HO
Classification by Reason
Page7Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Classification by Synchronization
� Synchronous handover
� Source and target cell belong the same BTS
� Asynchronous handover
� Source and target cell belong the different BTS
Page8Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Introduction of Handover
2. HO Algorithm Process
3. HO Data Configuration
4. HO Signaling Process
Page9Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. HO Algorithm Process
2.1 General HO Process
2.2 Measurement Report Preprocessing
2.3 Penalty Processing
2.4 Basic Ranking and Secondary Ranking
2.5 Condition of Handover
Page10Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
General Process of HO AlgorithmM.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 MS HO
1
1
Page11Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. HO Algorithm Process
2.1 General HO Process
2.2 Measurement Report Preprocessing
2.3 Penalty Processing
2.4 Basic Ranking and Secondary Ranking
2.5 Condition of Handover
Page12Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 Neighbor cell
The downlink measurement report
of the serving cell
The uplink measurement
report of MS
The downlink measurement reportof the neighbor cell (BCCH)
Page13Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Measurement Report
Page14Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page15Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page16Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
MR MR MR MR MR
Measurement report No. n
Measurement report No. n+4
Continuous MR flow
How to Interpolate MR?
Page17Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Filter----Average several continuous MR.
MR MR MR MR MR MR
Continuous MR flow
MR Filtering
Page18Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. HO Algorithm Process
2.1 General HO Process
2.2 Measurement Report Preprocessing
2.3 Penalty Processing
2.4 Basic Ranking and Secondary Ranking
2.5 Condition of Handover
Page19Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 IUO cell HO attempt is prohibited within the penalty time
after an IUO cell HO fails.
Page20Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Cell A
BTS
HO failure
BSC
Cell B
Page21Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page22Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page23Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page24Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. HO Algorithm Process
2.1 General HO Process
2.2 Measurement Report Preprocessing
2.3 Penalty Processing
2.4 Basic Ranking and Secondary Ranking
2.5 Condition of Handover
Page25Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page26Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
� MSRXMIN(o) and MSRXMIN(n)-- Lowest MS received signal level required
by the serving cell and neighbor cell.
� 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 : MS maximum transmitting power
Page27Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
141516 12345678910111213
Page28Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
141516 12345678910111213
Page29Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
141516 12345678910111213
Page30Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page31Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
141516 12345678910111213
Page32Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
141516 12345678910111213
Page33Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
� If the above criterion is not met, then bit 14th is set to 1.
At the same time, bit 13th, 12th and 10th—5th bits are turned off.
141516 12345678910111213
Page34Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
The 14th Bit: Determined by Layer HO
� Neighbor cell criterion
� RXLEV >=layer HO threshold + layer HO hysteresis�0.
� If the above criterion is not met �1.
� At the same time, bit 13th, 12th and 10th—5th bits are turned off.
� 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.
141516 12345678910111213
Page35Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
The 15th Bit: Determined by Cell Type
� The 15th bit: bit value is decided by cell type.
� Serving cell or Neighbor cell criterion
� When cell type is extension cell �1.
� When cell type is normal cell �0.
141516 12345678910111213
Page36Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
The 16th Bit: Determined by MNC HO Strategy
� The 16th bit: bit value is decided by MNC HO strategy.
� Serving cell: is always set to 0.
� Neighbor cell criterion
� When MNC HO adjustment is supported, digit 16 is valid, otherwise, it is 0.
� When co-MNC HO adjustment is with priority, digit 16 of the neighboring
cell of different MNC with the service cell is 1; otherwise, it is 0.
� When HO between different MNC is with priority, digit 16 is 1 if digit 14 is 1
or the neighboring cell and service cell are of the same MNC, otherwise, it
is 0.
141516 12345678910111213
Page37Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. HO Algorithm Process
2.1 General HO Process
2.2 Measurement Report Preprocessing
2.3 Penalty Processing
2.4 Basic Ranking and Secondary Ranking
2.5 Condition of Handover
Page38Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page39Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
TA HO
� Triggering condition
� The actual TA > TA HO Thrsh.
� Object cell selection
� The cell must be of the highest priority in the candidate cell sequence
and meet the following restrictions.
� Restriction
� The service cell cannot be the object cell.
� HO is not allowed when TA Thresh. of the neighboring cell with the
same BTS is smaller than that of the service cell.
Page40Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Bad Quality HO
� Triggering condition
� UL receiving quality >=UL receiving quality thrsh. of the service cell.
� OR DL receiving quality >=DL receiving quality thrsh. of the service
cell.
� Object cell selection
� The cells must be of the highest priority in the candidate cell sequence
and meet the following restrictions.
� Restriction
� Handover to the neighboring cell with the highest priority. If there is no
neighboring cell, handover to the service cell, and the channel at
different TRX is preference.
Page41Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Signal Level Rapid Drop HO
� Triggering condition
� Due to downlink signal level drop
� Triggered upon detecting rapid level drop during MS busy mode
� Object cell selection
� The neighboring cell with the highest priority and whose priority is
higher than that of the service cell in the candidate cell group.
� Restriction
� The service cell cannot be the object cell.
Page42Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Interference HO
� Triggering condition
� UL receiving quality>=Service cell UL receiving quality Thrsh. AND UL receiving
level>=Service cell UL receiving level Thrsh.
� OR DL receiving quality>=Service cell DL receiving quality Thrsh. AND DL
receiving level>=Service cell DL receiving level Thrsh.
� Object cell selection
� The cells must be of the highest priority in the candidate cell sequence and meet
the following restrictions.
� Restriction
� The service cell that is not in the penalty time for intra-cell handover.
� The neighboring cell with the receiving level higher than the inter layer HO Thrsh.
Page43Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Interference Handover
Lev_Thr
Rx_Qual
RX_Lev
Qual_Thr
InterferenceOrigin
Serving Cell Neighboring Cell
Handover Triggering Zone
Page44Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Load HO
� Triggering condition
� The load HO switch of the service cell is enabled.
� The system signaling flow is not larger than the Load HO system flow Thrsh.
� The service cell traffic is larger than the Load HO Thrsh.
� The DL receiving level is in the load HO zones.
� Object cell selection
� The service cell cannot be the object cell.
� The traffic of the neighboring cell must be lower than its load HO receiving thrsh.
� The neighboring cell with the receiving level higher than the inter layer HO
Thrsh.
� Restriction
� It is not available with SDCCH.
� Load HO just occur within the same BSC.
Page45Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Load HandoverHandover triggering
zone
Load HO Thr
Time
Traffic of Serving Cell
Receiving Threshold
Traffic of Neighboring Cell
Congested CellCongested Cell
Congested Cell
Page46Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Cell A Cell B
Norm al HO border
CONF_HO_RXLEV
CONF_HO_RXLEV+CLS_Ram p
CONF_HO_RXLEV+CLS_Offset
Load HO zone
Load HO
� As load HO may trigger more HOs, consider the CPU load
(system flow level) before triggering it. In addition, load is taken by
step, that is, the edge HO thrsh. raises according to certain step
and period and stops after without the Load HO Zone.
Load HO bandwidth Edge HO threshold
Load HO step level
Page47Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Edge HO
� Triggering condition
� The DL receiving level < Edge HO DL RX_LEV Thrsh.
� OR The UL receiving level < Edge HO UL RX_LEV Thrsh.
� Satisfying P/N rule.
� Object cell selection
� The service cell cannot be the object cell.
� The neighboring cell with the highest priority and whose priority
is higher than that of the service cell.
Page48Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Edge HandoverHandoverTriggering
P/N
Serving Cell Neighboring Cell
P: Watch TimeN: Valid Time
RX_LEV Thr
Time
RX_Lev
Page49Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Layer HO
� Triggering condition
� The layer of the object cell is lower than that of the service cell.
� The DL level of the object cell is higher than the inter layer HO thrsh.
� Satisfying P/N rule.
� Object cell selection
� The service cell cannot be the object cell.
� The neighboring cell with the highest priority and whose priority is
higher than that of the service cell.
Page50Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PBGT HO� Triggering condition
� The layer and level of the object cell are the same as those of the
service cell.
� The DL level must be the result of the following formula.
� Object cell selection
� The service cell cannot be the object cell.
� The neighboring cell with the highest priority and whose priority is
higher than that of the service cell.
� Restriction
� It is not available with SDCCH.
Page51Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Fast-Moving HO
� Triggering condition
� In Fast Moving Watch Time, the mobile phone moves through Q
cells of P.
� The layer of Q cells must be less than four (none Umbrella cell).
� Object cell selection
� The neighboring cell with the highest priority and meet the
following condition.
� The layer of the object cell must be no less than four, that is, the
Umbrella cell.
� The receiving level of the object cell >= the inter layer HO thrsh. +
inter layer HO hysterisis.
Page52Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
MS Fast-Moving Handover
Handover Triggering
Time Thr
Umbrella Cell
Time
P/N
P: Watch CellsN: Valid Cells
1 1 2 3
Micro Cell
Cells Number
Page53Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Overlaid/Underlaid Cell
Assume: 6TRX in one cell, two CDUs and one SCU are adopted
Where can we configure BCCH CH, CDU or SCU?
SCU
CDU
CDU
Antenna
TRX
TRX
TRX
TRX
TRX
TRX
Antenna
Page54Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 Overlaid/Underlaid
� Enhance Overlaid/Underlaid
Page55Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 on uplink reported by BTS
Page56Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Factor of Handover between Overlaid/Underlaid
� Normal Overlaid/Underlaid
� Receiving level
� Time Advance
� Quality
� Enhanced Overlaid/Underlaid
� Receiving level
� Time Advance
� Quality
� Traffic Load of Underlaid
Page57Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
underlaid
overlaid
Normal Overlaid/Underlaid HO
� Division of underlaid and overlaid is decided by MS
downlink receive level ,TA value and quality.
The quality boundary is elided in this figure
Page58Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page59Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page60Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Introduction of Handover
2. HO Algorithm Process
3. HO Data Configuration
4. HO Signaling Process
Page61Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Major HO Parameters Configuration
� Major HO parameter configuration
� 1.[Handover Control Table]
� 2.[Cell Description Table]
� 3.[Adjacent Cell Relation Table]
� 4.[Penalty Table]
� 5.[Emergency Handover Table]
� 6.[Load Handover Table]
� 7.[Normal Handover Table]
� 8.[Fast-Moving Handover Table]
� 9.[Concentric Cell Handover Table
Page62Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
NoYes, No
It determines whether to handle the fast moving MS with the algorithm. It is only recommended in special area (such as a highway), to lower CPU load. This algorithm should only be used in suitable conditions, and usually it is not applied
MS Fast
moving HO
allowed
NoYes, No
It determines whether to perform the handover to share traffic load. Load sharing can lower the channel assignment failure ratio caused by cell congestion, so as to make evener allocation of the service in respective cells, and lower the cell congestion rate , and improve network performance. It on ly applies in the same BSC or cells at the same level
Load HO
allowed
YesYes, No
It determines whether to punish the target cell of handover failure, or the original served cell of handover upon too big TA or bad quality. The penalty measures can apply to cells in or out of the same BSC
Penalty
allowed
YesYes, No
It means whether the 12 and 13 bits acts in the 16bit order. “Yes” means handover in the same BSC/MSC is preferred. “No” means that the 12 and 13 bits are shielded and set to”0.
Co BSC/MSC
Adj.
Recommendvalue
Value rangeMeaning
Parametername
Handover Control Table
Page63Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
YesYes, No
It means after a handover whether MS is to use proper predicted transmitting power to access thenew channel. This can reduce system interferenceand improve service quality y (this parameter acts when intra BSC handover occurs
MS powerprediction
afterHO
YesYes, No
It means whether PBGT handover algorithm is allowed. PBGT handover algorithm currently is processed on LAPD board. To avoid Ping -pang handover, PBGT handover is only performed between cells at the same layer and with the same priority, and meanwhile it is only triggered on TCH.
PBGT HOallowed
NoYes, No
It means whether RX _ Level Drop emergencyhandover algorithm is allowed, handover the MSwhich receiving signal level is dropping quickly inadvance to avoid potential call drop. This algorithmshould be applied in suitable conditions, and usually it is not used. To apply the handover algorithm, BSC must have original measurement report.
RX _Level Drop
HO allowed
Recommended value
Value range
MeaningParameter name
Handover Control Table
Page64Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
YesYes, No
“Yes” means perform measurement report
preprocessing on BTS “No” means preprocessing
on BSC, then the two parameters of “Send original
measurement report” and “Send BS/MS power
level” do not act. “Yes” means decreasing of Abis
interface signaling and BSC load, and improving of
network response time performance. The switch
determines where to perform power control. When
it is set to “Yes”, power control is performed at BTS
side. When it is set to “No”, power control is
performed at BSC side. When setting this
parameter, first be clear whether BTS supports the
power control algorithm to set or not.
MR.
reprocessing
Recommended
value Value rangeMeaning
Parameter
name
Handover Control Table
Page65Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
YesYes, No
It means whether to send BS/MS power level from
BTS to BSC. This function is used to view the effect
of power control on BTS. Meanwhile, when
preprocessing is available , if BS/MS power level is
not reported, the uplink and downlink balance
measurements will be affected,and handover types
such as PBGT handover and overlaid/underlaid
handover needing power compensation will be
abnormal.
Transfer
BS/MS power
class
NoYes, No
It means whether to send the original measurement
report to BSC after measurement report
preprocessing
on BTS. When it is set to “Yes”, BTS sends not only
processed measurement rep ort but also original
measurement report to BSC.
Transfer
Original MR.
Recommended
value
Value
rangeMeaning
Parameter
name
Handover Control Table
Page66Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
According to
Concrete
conditions
Twice
per
second,
Once
per
second
It indicates the time interval at which a measurement
report is preprocessed at B TS side and sent to BSC
the preprocessed measurement report. This parameter
acts only when “Measurement t report preprocessing”
is enabled. For 15:1 link configuration, the report
frequency should be as low as once per second due to
limited link resource. At this time, for handover nee
ding P/N judgment such as edge handover, layer
handover, PBGT handover and overlaid/underlaid
handover
Sent Freq. of
Preprocessed
MR.
Recommended
value
Value
rangeMeaning
Parameter
name
Handover Control Table
Page67Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
30 ~ 63
dBWorks together with the Layer handover threshold.
Layer HOhysteresis
25
0 ~ 63
(-110~-47dBm)
It affects the value of the 14th bit in the 16bit ranking , and it is also the level requirement on the target cell for interference handover and load handover. Then such level should be higher than layer handover threshold + layerhandover hysteresis. The layer handover threshold should be set >= Edge handover threshold + Inter cell handover hysteresis.
Layer HOThresh.
11 ~ 16
Each layer may have 16 priorities, used to control the handover priority between cells at the same layer. Usually priorities of prioritiescells at the same layer are set the same. For cells at the same layer, the smaller the priority value, the higher the priority
Cell priority
M900 : layer 3M1800:Laye 2
1 ~ 4
Huawei hierarchical network structure is divided into 4 layers. 16 Thepriorities can be set for each layer, which provides enough room of network planning for the operator to adapt to various complexnetwork environment. Normally, Macro layer is the major 900 layers layer, Micro layer is the major 1800 layer, Pico is the 900 and 1800 micro cell layer. The smaller layer value, the higher priority.
Layer of thecell
Recommended value
Valuerange
MeaningParameter
name
Cell Description Table
Page68Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
150 ~ 63
This is the min signal level requirement for the cell itself
to be a candidate cell low configuration may easily
cause call drops, while too high a configuration might
turn handover too hard to occur.
Min DL level
0n
Candidate
cell
400 ~ 255 s
It means that within this time, the penalty on the other
neighbor cells will be exerted after MS is handed over
to umbrella cell by fast moving HO.
Penalty
Time on MS
Fasting
moving HO
300~ 63 dB
It is valid when the fast moving handover algorithm is
enabled . It is the signal level penalty value on the other
neighbor cells when MS moves fast and is handed over
To umbrella cell. The parameter is only valid within the
penalty time.
Penalty on
MS Fasting
moving HO
Recommended
value
Value
rangeMeaning
Parameter
name
Cell Description Table
Page69Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
00 ~ 63 dB
This offset is based on “Min downlink level of handover candidate cell”. Different offsets can be defined for different adjacent cells, and to enter the candidate cell list, the corresponding adjacent cell receiving signal level must be higher than the sum of “Min. downlink level of handover candidate cell”and “ Min. Access level offset”.
Min accesslevel offset
It is around 4 in the densely populateddowntown, andaround 8 on theoutskirts.
0 ~ 63 dB
Handover hysteresis between an adjacent cell and the serving cell. It is set to reduce “Ping pang” HO. The hysteresis value also needs to be adjusted according to the handover performance statistics result and live network. Flexible configuration of the value can effectively lead handover andtraffic between two adjacent cells.
Inter cell HOhysteresis
It is around 68 in thedensely populated downtown, andaround 72 on theoutskirts.
0~127 corresponding to-64~63dB
It means that PBGT handover is performed when thedifference between the target cell downlink path loss and the corresponding to serving cell downlink path loss is bigger than PBGT handover threshold. When PBGT handover is enabled, and “Inter cell handover hysteresis” > “PBGT handover threshold (corresponding dB value)”, “Intercell handover hysteresis” takes place of “PBGT handover threshold”to act. . PBGT handover threshold also needs to be adjusted according to handover performance statistics result
PBGT HOThresh.
RecommendedvalueValue rangeMeaningParameter
name
Adjacent Cell Relation Table
Page70Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
100 ~ 60 sPenalty time for the original serving cell after BQ
HO. seconds
Penalty time
after BQ HO
fail
630 ~ 63 dB
The signal level penalty value for the original
serving cell, to avoid “Ping- pang” handover after
emergency handover upon bad quality. It is only
valid within the
penalty time for BQ HO.
Penalty level
after BQ HO
fail
100 ~ 60 sPenalty time on the corresponding target cell after
seconds handover failure
Penalty time
after HO fail
300 ~ 63 dB
The signal level value in dB, to punish the target
cell which has caused a HO failure due to problems
such as congestion , to prevent MS from a
handover attempt to that cell again. This value is
only valid within the penalty time for handover
failure.
Penalty level
after HO fail
Recommended
valueValue rangeMeaning
Parameter
name
Penalty Table
Page71Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
100 ~ 16 s
After an overlaid/underlaid handover failure (big circle
hands Seconds over to small circle or vice versa), within
certain time (this Parameter configuration value)
overlaid/underlaid handover is forbidden for the same call
Penalty time
after IUO
HO fail
100 ~ 60 sPenalty time for the original serving cell after TA
emergency Seconds handover
Penalty time
after TA HO
fail
630 ~ 63
dB
The signal strength penalty value for the original serving
cell, to avoid “Ping - pang” handover after TA emergency
handover. It is only valid within the penalty time for ta
handover
Penalty
level after
TA HO fail
Recommended
value
Value
rangeMeaning
Parameter
name
Penalty Table
Page72Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Emergency Handover Table
60
corresponding to BQ levels of
0~7
The uplink receiving quality threshold for BQ emergency HO.
UL QUAL. Thrsh.
60
0 ~ 70, correspondi
ng to BQ levels of
0~7
The downlink receiving quality threshold for BQ emergency handover. When frequency hopping or DTX is enabled, RQ becomes worse (normal phenomenon), this value should be set to 70. The adjustment should also base on the current network quality and handover statistics. When triggering emergency handover, the first to select is the inter-cell handover, the intra-cell handover is only triggered when there is no candidate cell and the intra-cell handover is allowed in the serving cell.
DL QUAL. Thrsh
630 ~ 63 bit
periodWhen TA≥this value, emergency handover is triggered
TA Thrsh.
Recommended value
Value range
MeaningParameter
name
Page73Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
50
0 ~ 70,
corresponding
to BQ levels of
0~7
Downlink receiving quality threshold in the serving cell for
interference handover.
DL Qua.
Thresh.
For
interf HO
50, interference
quality threshold
must be better
than
the emergency
quality threshold
0 ~ 70,
corresponding
to BQ levels of
0~7
Uplink receiving quality threshold in the serving cell for
interference handover. When frequency hopping or DTX
is to enabled , RQ becomes worse (normal phenomenon),
this value should be set to 60. The adjustment should also
base on the current network quality and handover
statistics. When triggering interference handover. If the
serving cell is in the first position and intra cell handover is
permitted, perform intra cell handover . Otherwise select
the second candidate cell to perform inter cell handover.
UL
Qua.
Thresh
for interf.
HO
Recommended
valueValue rangeMeaning
Parameter
name
Emergency Handover Table
Page74Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
300 ~ 63Min downlink receiving power threshold from the serving
cell required for interf. HO.
DL
RX_LEV
Thresh. For
Interf. HO
250 ~ 63
Min uplink receiving power threshold from the serving cell
required for interf. HO, when interference handover is
triggered if the uplink quality is worse than quality
thresholdand at this time the uplink signal level is higher
than the signal threshold. When triggering interference
handover, If the serving cell is in the first position in the
cell list, and intra cell handover permitted , then start intra
cell HO. Otherwise select the second cell to perform
inter-cell HO.
UL
RX_LEV
Thresh. For
interf.HO
Recommended
value
Value
rangeMeaning
Parameter
name
Emergency Handover Table
Page75Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
00 ~ 255Used for configuration of filter for rapid signal drop judgment. Please refer to the explanation for A1~A8 of filter.
Filterparameter B
100 ~ 20
Used for configuration of filter for rapid signaldrop judgment, and together with filter parameterB, they are 9 parameters for a filter. The corresponding formula is (in the program, A1~A8 is configuration value minus 10 and B is the negative configuration value):C1(nt)=A1×C(nt)+A2×C(nt-t)+A3×C(nt - 2t)++A8×C(nt-7t) Where, C (nt) is the receiving signal level in the uplink measurement report of the serving cellsent at the time of nt. If C1 ( nt ) < B, and C (nt) is below the edge handover threshold, then the signal level is considered to be of rapid drop.
FilterParameters
A1~A8
Recommendedvalue
Value range
MeaningParameter
name.
Emergency Handover Table
Page76Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
2
0 ~ 7,
Corresponding
to 0 , 50 , 60 , 70 ,
75, 80 , 85 , 90
The Load threshold for the target cells that can accept
MS from serving cell in load HO, i.e. when the TCH
under Idle mode in the neighbor cell is lower than the
corresponding percentage the cell refuses to accept MS
from serving cell handed over due to the load reason
Load Req.
on
candidate
cell
5
0 ~ 7
cell load levels,
Corresponding
to 0 , 50 , 60 , 70 ,
75, 80 , 85 , 90
Load handover is triggered when the serving cell load is
than the threshold, TCH seized in the cell has reaching
the corresponding percentage.
Load HO
Thresh
10
0, 8~11
system flow levels
Corresponding
0, 70, 80, 90
and 95.
The pre condition for load HO is that the system flow
(signaling flow) is lower the threshold. This value can
not be set too high because load handover upon max
threshold may cause serious effect to the system.
System
flux
Thresh.
For
load HO
Recomme
nded
value
Value rangeMeaningParameter
name
Load Handover Table
Page77Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Load Handover Table
51 ~ 63 dbThe whole load HO bandwidth will be divided into several
Sub-bands by this parameter.
Load HO
step
level
101~60 s
When a cell is up to conditions for load handover, all calls
within the serving cell will send handover request at the
same time, this will cause abrupt increase on processor
load, and under certain conditions this will cause the
target cell congestion and result in call drops. Thereby,
step by step load handover algorithm is used to control
handover. The cycle is the time needed for handovers of
each step.
Load HO
step
period
250~ 63 db
This configuration is related to the edge handover
threshold. Load handover is only allowed when the MS
receiving level from the serving cell is within the range of
margin handover threshold, margin handover threshold +
load handover bandwidth
Load HO
bandwidth
Recomm
ended
value
Value rangeMeaningParameter
name
Page78Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Normal Handover Table
30 (without PBGT
handover, downtown),
20 (single station on
outskirts), 20 (with
PBGT handover,
downtown)
0 ~ 63Downlink consideration for edge HO
Edge HO DL
RX_LEV
Thresh.
25 (without PBGT
handover, downtown),
15 (single station on
outskirts), 15 (with
PBGT handover,
downtown)
0 ~ 63
During the statistics time, if the time in which the uplink
receiving level is lower than the value is longer than
certain time called continuous time, edge handover
will be performed. If PBGT handover is enabled,
Corresponding edge handover threshold will be set
lower
Edge HO UL
RX_LEV
Thresh.
Recommended
value
Value
rangeMeaning
Parameter
name
Page79Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Normal Handover Table
41 ~16See the above.Edge valid
time
51 ~16 s
It means that within the time statistics, if the
time in which the signal level is lower than
threshold is higher than the continuous time,
then margin HO is to be triggered
Edge HO
watch time
Recommended
valueValue rangeMeaning
Parameter
name
Page80Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Normal Handover Table
51 ~ 16 sstatistics time for Layer HO judgmentLayer HO
watch time
41 ~ 16 sContinuous time for Layer HO judgmentLayer HO
valid time
41 ~ 16 s
Continuous time for PBGT HO signal level
judgment.PBGT valid
time
51 ~ 16 sStatistics time for PBGT HO signal level
judgment.
PBGT watch
time
Recommended
valueValue rangeMeaning
Parameter
name
Page81Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Normal Handover Table
151 ~ 225
The time threshold (2r/v) determined by the cell radius
(r) and moving speed (v). If the time in which MS
seconds passes the cell is smaller than the threshold,
then MS is judged to quickly pass the cell.
MS
Fast –
moving
Time Thresh.
21 ~ 10
The cell sum N by which MS actually quickly passes. If
within P cells that MS continuously past, the number of
cells by which the MS is judged to pass quickly is equal
to or more than N, then the MS will be judged as a fast
moving MS.
MS
Fast –
moving
valid cells
31 ~ 10
The cell sum P for judge whether MS is fast moving.
The value, if too large, may cause abrupt increase of
system flow, while too small value may cause inaccurate
judgment for fast moving MS.
MS
Fast -moving
watch cells
Recommended
value
Value
rangeMeaning
Parameter
name
Page82Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Concentric Data
0 ~ 63
If system optimization is selected, estimate (interpolate, filter) current SDCCH level value through uplink measurement value in the former SDCCH measurement report, and compare with “ Assign-optimum Level threshold”, so as to assign overlaid or underlaid channel.If SDCCH is in the overlaid : edge handover threshold + signal intensity difference between underlaid and overlaid + uplink and downlink balance allowance + SDCCH and TCH difference allowance. If SDCCH is in the underlaid : edge handover threshold + uplink and downlink balance allowance + SDCCH and TCH difference allowance.
Assign-optimum level Thresh.
System optimization
System optimization, overlaid , underlaid , no preferential
In Overlaid/Underlaid, the following selection are available for TCH assignment: (1) The system judges according to the measurement report on SDCCH and assign to the best sub-cell. (2) Select the overlaid first for TCH assignment. (3) Select the underlaid first for TCH assignment. (4) Do not give extra priority.
Assign optimum layer
Recommended value
Value rangeMeaningParamete
r name
Page83Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Concentric Data
None
overlaid ,
underlaid ,
none
If there is a incoming BSC HO, and the target cell
is a Overlaid/Underlaid, then, this parameter will
show which layer is preferred to provide service for
the MS.
Incoming-
to-BSC HO
optimum
layer
YesYes, No
When the cell is configured into a
Overlaid/Underlaid, there are two processing
methods for incoming handover request in BSC: (1)
No special processing for channel assignment. (2)
Add BCCH signal level value of the target cell in
inter-cell handover request message to BSC to
make BSC allocate optimum channel for MS from
underlaid or overlaid
Pref.
subcell in
HO of intra-
BSC
Recommended
value
Value
rangeMeaning
Parameter
Name
Page84Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Concentric Data
600 ~ 70In case of Qua. Is worse than this value, MS handover from overlay to underlay
RX_QUAL Thresh.
50 ~ 16 sP/N judgment statistics time for U/O HO judgment.
UO HO watch time
40 ~ 16 sP/N judgment continuous time for U/O HO judgment.
UO HO valid time
According concrete condition
0 ~ 63TA is more than this value, TCH in underlay will be allocated
TA thresh. Of Assignment Pref.
According concrete condition
0 ~ 63TA is more than this value, SDCCH in underlay will be allocated
TA Thresh. Of IMM-Assign Pref.
According concrete conditionYes, NoTA attend allocation of SDCCH or not
TA Prefer Of IMM-Assign Allowed
Recommended valueValue rangeMeaningParameter
name
Page85Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Concentric Data
50 ~ 16 sP/N judgment statistics time for U/O HO
judgment.
UO HO
watch time
40 ~ 16 sP/N judgment continuous time for U/O HO
judgment.
UO HO
valid time
0 ~ 63 bit
periodWorks with TA threshold.
TA
hysteresis
0 ~ 63 bit
period, with 1
bit period
corresponding
to 0.55km
It must be bigger than TA emergency handover
threshold.TA Thresh.
Recommended
valueValue rangeMeaning
Parameter
name
Page86Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Normal Concentric Data
50 ~ 63Works with Rx threshold.RX_LEV
hysteresis
250 ~ 63
Rx level hysteresis, Receiving Quality Thrsh.,TA threshold and TA hysteresis jointly define underlaid area and overlaid area. It must be bigger than edge handover threshold, and the recommended value is: edge handover threshold + signal intensity difference between underlaid and overlaid .
RX_LEV Thresh
Set according to actual conditions
0 ~ 63 dB
Transmitting Power at antenna difference between underlaid and overlaid may cause MS receiving signal intensity difference in underlaid and overlaid . The parameter usually indicates the antenna EIRP difference in dB between underlaid cell and overlaid cell. According to field measurement, multi-point measurement is necessary if the underlaid and overlaid use different antenna.
UO signal intensity
difference
Recommended value
Value rangeMeaningParameter
name
Page87Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Enhance IUO Data
350 ~ 63
In case of receiving level in underlay is more
than this value, and traffic in underlay is more
than Traffic Thresh. Of Underlay, HO occurs
from underlay to overlay
UtoO HO
Received
Level Thresh.
250 ~ 63In case of receiving level in overlay is less than
this value, HO occurs from overlay to underlay
OtoU HO
Received
Level Thresh.
Set according to
actual
conditionsYes, NoEnable traffic to be one condition of HO or not
UtoO Traffic
HO Allowed
Set according to
actual
conditionsYes, NoEnable function of Enhance IUO or not
Enhance
IUO Allowed
Recommended
value
Value
rangeMeaning
Parameter
name
Page88Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Concentric Cell Handover Table
800 ~ 100 %If the traffic in underlay is over this value,
MS will handover from under to overlay
Traffic Thresh. Of Underlay
51 ~ 255 s
If there are some handover requests from under to overlay at the same time, system will handover the call with level firstly. This value determine period per step
Underlay HO Step Period
51 ~ 63 dB
It is the step that handover band decreases, used to control the grade by grade handover band from underlay to overlay with “underlay HO step level”
Underlay HO Step Level
101 ~ 255 s
To prevent ping-pong handover, the call can’t be handed over back within penalty time when a call is handed over from underlay to overlay
Penalty Time of UtoO HO
Recommended value
Value rangeMeaningParameter
name
Page89Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
HO Data Lookup Process
� BA2 table defines BCCH frequencies of all neighbor cells. It is
sent to MS by system message 5, system message 5-bis and
system message 5ter on SACCH channel.
� MS reports the serving cell and BCCH, BSIC and signal levels of 6
strongest neighbor cells to BSS. This is done through SACCH.
� MR pre-process is done in BTS. Module number, cell number
and CGI of all neighbor cells are derived from Adjacent cell
Relation Table, and Cell Description Table (or External Cell
Description Table) through BCCH and BSIC in the MR.
Page90Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
HO Data Lookup Process
� BSC performs HO judgment process, such as basic rank of
cells (completed in LAPD board). When BSC finds suitable
target, It sends HO request messages containing the target CGI
to MPU of BSC. According to CGI, MPU derive the module
number of the cell from Cell Module Information Table.
� MPU sends a HO command message to the target module and
step up the ‘inter-cell/ intra-cell HO request’ counter by one.
Page91Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Introduction of Handover
2. HO Algorithm Process
3. HO Data Configuration
4. HO Signaling Process
Page92Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. HO Signaling Process
4.1 Intra BSC Handover
4.2 Intra MSC Handover
4.3 Inter MSC Handover
Page93Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page94Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page95Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Intra-BSC Handover Signaling ProcessIntra-BSC Handover Signaling Process
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)
Page96Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page97Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. HO Signaling Process
4.1 Intra BSC Handover
4.2 Intra MSC Handover
4.3 Inter MSC Handover
Page98Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page99Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page100Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. HO Signaling Process
4.1 Intra BSC Handover
4.2 Intra MSC Handover
4.3 Inter MSC Handover
Page101Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page102Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page103Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page104Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page105Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Highway
MSC-AMSC-C
MSC-B MSC-C
Inter MSC HO—Subsequent HO Process
� Subsequent HO
Page106Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Inter MSC HO Signaling Process
� Statistics counter—same as Intra MSC HO, Statistics is
handled by BSC
� HO formula-- same as Intra MSC HO
Page107Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page108Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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.
Page109Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Summary
� In this course, we have learned:
� Classify of handover
� Judgment and ranking step
� Handover data configuration
� Handover signaling flow
Thank youwww.huawei.com