2. Review
Parameter optimization is an important step
after RF Optimization.
Parameter optimization improves service
quality and utilization of network resources.
4. Objectives
Upon completion of this course, you can:
Understand the process of parameter
optimization
Master the contents of parameter
optimization
7. Data Input and Find Problems
Find problems from the input data, such as:
• Low success rate of call setup
• Low success rate of handover
• High rate of call drop
9. Parameter Classification
Mobile Management Parameters
Power Control Parameters
Power Configuration Parameters
Load Control Parameters
Other Parameters
10. Determine Parameter Values
List the form for changing parameters
(original parameter values vs. new parameter values)
List MML commands for changing parameters
Note:
Maybe some tradeoff considerations need to be considered to assure
the maximal improvement in the whole view such as “coverage and
capacity”,“ fast and stable”, “improvement and risk”, “cost (or efforts)
and gain”.
11. Impact
Impact on customer service and other networks
Impact on OMC (efforts, maintenance)
12. Prepare Test Plan and Change Parameters
Prepare test schedule, routes, tools and be ready to get
Information.
Change parameters and make records.
14. Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
Note:
There are too many parameters to introduce. Only some parameters about
network optimization are mentioned here and maybe more parameters
need to be added in the future.
15. Mobile Management Parameter Optimization
Cell Selection & Reselection
The changing of cell on which UE camped in idle mode or in Cell FACH, Cell
PCH, URA PCH states. That assures UE camping the most suitable cell,
receiving system information and establishing an RRC connection on a best
serving cell.
Handover
The changing of cells with which UE connected in DCH mode.
That assures seamless coverage and load balancing.
16. Cell Selection & Reselection Procedure
go here whenever a
new PLMN is
selected
cell information no cell information
stored for the PLMN 1 stored for the PLMN
Stored Initial
information no suitable cell found Cell Selection
Cell Selection
no suitable
cell found suitable cell found 2 suitable cell found
no suitable
cell found
Cell Selection NAS indicates that
when leaving suitable Camped registration on selected
connected cell found normally PLMN is rejected
mode (except with cause #14
or #15 [5][16])
return to leave trigger
idle mode idle mode suitable
cell found
Connected Cell
mode Reselection no suitable
Evaluation cell found
Process
go here
when no
USIM in
the UE
Any Cell
no acceptable cell found Selection
USIM inserted
acceptable
cell found
1
Cell Selection
acceptable
when leaving Camped on suitable
cell found
connected any cell cell found 2
mode
return to leave trigger
idle mode idle mode acceptable
cell found
Connected
mode Cell
(Emergency Reselection no acceptable
calls only) Evaluation cell found
Process
17. Cell Selection Criteria (S Criteria)
The cell selection criterion S is fulfilled when:
for FDD cells: Srxlev > 0 AND Squal > 0
for TDD cells: Srxlev > 0
Where:
Squal = Qqualmeas – Qqualmin
Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation
When a UE wants to select a UMTS cell, the cell must satisfy S criterion.
19. Cell Re-selection Measure Condition
Use Squal for FDD cells and Srxlev for TDD for Sx
1. If Sx > Sintrasearch, UE need not perform intra-frequency measurements.
If Sx <= Sintrasearch, perform intra-frequency measurements.
If Sintrasearch, is not sent for serving cell, perform intra-frequency measurements.
2. If Sx > Sintersearch, UE need not perform inter-frequency measurements.
If Sx <= Sintersearch, perform inter-frequency measurements.
If Sintersearch, is not sent for serving cell, perform inter-frequency measurements.
3. If Sx > SsearchRAT m, UE need not perform measurements on cells of RAT“
m".
If Sx <= SsearchRAT m, perform measurements on cells of RAT "m".
If SsearchRAT m, is not sent for serving cell, perform measurements on cells of
RAT "m".
20. Cell Reselection Criteria (R Criteria)
All cells should satisfy S Criteria.
Select the Cell with the highest R value using the following method to compute.
Rs = Q meas ,s + Qhysts
Rn = Q meas ,n - Qoffsets,n
The cells shall be ranked according to the R criteria specified above, deriving Qmeas,n and
Qmeas,s and calculating the R values using CPICH RSCP, P-CCPCH RSCP and the averaged received
signal level for FDD, TDD and GSM cells, respectively.
The offset Qoffset1s,n is used for Qoffsets,n to calculate Rn, the hysteresis Qhyst1s is used
for Qhysts to calculate Rs.
If an FDD cell is ranked as the best cell and the quality measure for cell selection and re-selection is set to
CPICH Ec/No, the UE shall perform a second ranking of the FDD cells according to the R criteria specified
above, but using the measurement quantity CPICH Ec/No for deriving the Qmeas,n and Qmeas,s and
calculating the R values of the FDD cells. The offset Qoffset2s,n is used for Qoffsets,n to calculate Rn, the
hysteresis Qhyst2s is used for Qhysts to calculate Rs. Following this second ranking, the UE shall perform cell
re-selection to the best ranked FDD cell.
In all cases, the UE shall reselect the new cell, only if the following conditions are met:
- the new cell is better ranked than the serving cell during a time interval Treselection.
- more than 1 second has elapsed since the UE camped on the current serving cell.
23. Cell Reselection from GSM to UMTS
If the 3G Cell Reselection list includes UTRAN frequencies, the MS shall, at least every 5 s
update the value RLA_C for the serving cell and each of the at least 6 strongest non-serving
GSM cells.
The MS shall then reselect a suitable (see TS 25.304) UTRAN cell if its measured RSCP value
exceeds the value of RLA_C for the serving cell and all of the suitable (see 3GPP TS 03.22) non-
serving GSM cells by the value XXX_Qoffset for a period of 5 seconds and, for FDD, the UTRAN
cells measured Ec/No value is equal or greater than the value FDD_Qmin. In case of a cell
reselection occurring within the previous 15 seconds, XXX_Qoffset is increased by 5 dB.
where Ec/No and RSCP are the measured quantities.
FDD_Qmin and XXX_Qoffset are broadcast on BCCH of the serving cell. XXX indicates
other radio access technology/mode.
Note:The parameters required to determine if the UTRAN cell is suitable are broadcast on
BCCH of the UTRAN cell. An MS may start reselection towards the UTRAN cell before
decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the
UTRAN cell is not suitable.
Cell reselection to UTRAN shall not occur within 5 seconds after the MS has reselected a
GSM cell from an UTRAN cell if a suitable GSM cell can be found.
If more than one UTRAN cell fulfils the above criteria, the MS shall select the cell with the
greatest RSCP value.
25. Handover Procedure
Neighbor cells both from same NodeB or
other NodeBs
Measurement control
Node B
Measurement and filtering
Node B
Measurement report
Node B
Handover decision
Handover execution
Intra-frequency cells
28. Soft Handover Event – 1A
1A (add a cell in Active Set)
NA
10 ⋅ LogM New + CIONew ≥ W ⋅10 ⋅ Log ∑ M i + (1 − W ) ⋅10 ⋅ LogM Best − ( R1a − H1a / 2)
i =1
MNew : the measurement result of the cell entering the reporting range.
CIONew : the individual cell offset for the cell entering the reporting range
if an individual cell offset is stored for that cell. Otherwise it is equal to 0.
Mi : measurement result of a cell not forbidden to affect reporting range in
the active set.
NA : the number of cells not forbidden to affect reporting range in the
current active set.
MBest : the measurement result of the cell not forbidden to affect reporting range
in the active set with the highest measurement result, not taking into account
any cell individual offset.
W : a parameter sent from UTRAN to UE.
R1a : the reporting range constant.
H1a : the hysteresis parameter for the event 1a.
29. Soft Handover Event – 1B
1B (Remove a cell from Active Set)
NA
10 ⋅ LogM Old + CIOOld ≤ W ⋅10 ⋅ Log ∑ M i + (1 − W ) ⋅10 ⋅ LogM Best − ( R1b + H1b / 2)
i =1
MOld : the measurement result of the cell leaving the reporting range.
CIOOld : the individual cell offset for the cell leaving the reporting range if
an individual cell offset is stored for that cell. Otherwise it is equal to 0.
Mi : measurement result of a cell not forbidden to affect reporting range in the
active set.
NA : the number of cells not forbidden to affect reporting range in the current
active set.
MBest : the measurement result of the cell not forbidden to affect reporting range
in the active set with the lowest measurement result, not taking into account
any cell individual offset.
W : a parameter sent from UTRAN to UE.
R1b : the reporting range constant.
H1b : the hysteresis parameter for the event 1b.
30. Soft Handover Event – 1C
1C (a non-active primary CPICH becomes better than an active
primary CPICH. If Active Set is not full, add the non-active cell into
active set .Otherwise use the cell substitute the active cell.)
10 ⋅ LogM New + CIONew ≥ 10 ⋅ LogM InAS + CIOInAS + H1c / 2
MNew : the measurement result of the cell not included in the active set.
CIONew : the individual cell offset for the cell becoming better than the cell in the active
set if an individual cell offset is stored for that cell. Otherwise it is equal to 0.
MInAS : the measurement result of the cell in the active set with the highest
measurement result.
MInAS : the measurement result of the cell in the active set with the lowest
measurement result.
CIOInAS : the individual cell offset for the cell in the active set that is becoming worse
than the new cell.
H1c : the hysteresis parameter for the event 1c.
31. Soft Handover Event – 1D
1D (Change of best cell. If the chosen cell is not in Active Set,
add the cell into Active Set and modify measurement control
.Otherwise only modify measurement control. )
10 ⋅ LogM NotBest + CIONotBest ≥ 10 ⋅ LogM Best + CIOBest + H 1d / 2
MNotBest : the measurement result of a cell not stored in "best cell"
CIONotBest : the cell individual offset of a cell not stored in "best cell" .
MBest: the measurement result of the cell stored in "best cell".
CIOBest : the cell individual offset of a cell stored in "best cell" .
H1d : the hysteresis parameter for the event 1d.
32. Soft Handover Parameters
Parameter Name Description Default Setting
IntraRelThdFor1A Relative thresholds of soft handover for Event 1A (R1a) 10, namely 5dB (step 0.5)
IntraRelThdFor1B Relative thresholds of soft handover for Event 1B (R1b) 10, namely 5dB (step 0.5)
Hystfor1A, Hystfor1B, Soft handover hysteresis (H1x) 6,namely 3dB (step 0.5) for H1a .
Hystfor1C, Hystfor1D 8,namely 4dB(step 0.5) for H1b,
H1c,H1d.
CellIndividalOffset Cell CPICH measured value offset; the sum of this 0
parameter value and the actually tested value is used for
UE event estimation. (CIO)
WEIGHT Weighting factor, used to determine the relative 0
threshold of soft handover according to the measured
value of each cell in the active set.
TrigTime1A,TrigTime1B, Soft handover time-to-trigger parameters (event time-to- D640, namely 640ms .
TrigTime1C,TrigTime1D trigger parameters. Only the equation are always
satisfied during the trigger time, the event will be
triggered).
FilterCoef Filter coefficient of L3 intra-frequency measurement D5,namely 5
34. Inter-system Handover Measure
1) Use Inter-frequency measurement reporting Event 2d, 2f
to reflect the currently used frequency quality.
Event 2d: The estimated quality of the currently used frequency is below a certain threshold.
QUsed ≤TUsed 2 d − H 2 d / 2
The variables in the formula are defined as follows:
QUsed is the quality estimate of the used frequency.
TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.
H2d is the hysteresis parameter for the event 2d.
Event 2f: The estimated quality of the currently used frequency is above a certain threshold.
QUsed ≥TUsed 2f +H 2 f / 2
The variables in the formula are defined as follows:
QUsed is the quality estimate of the used frequency.
TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.
H2f is the hysteresis parameter for the event 2f.
35. Inter-system Handover Measure
2 ) When Received 2D reports ( that means the currently used frequency signal is poor ), RNC
sends Measurement Control (ID3) to let UE begin to measure other system signal . UE will
send measurement result reports periodically . When Received 2F reports (that means the
currently used frequency signal is not poor), RNC sends Measurement Control (ID3,but
different contents) to let UE stop measuring other system signal .
3) When received the periodical reports, RNC use the following formula to judge whether should
handover UE to another system .
Mother_RAT + CIO > Tother_RAT + H/2
Tother_RAT : the inter-system handover decision threshold;
Mother_RAT : the inter-system (GSM RSSI) measurement result received by RNC;
CIO: Cell Individual Offset, which is the inter-system cell setting offset;
H : refers to hysteresis,
If the formula is met, a trigger-timer called TimeToTrigForSysHo will be started, and a handover decision will be
made when the timer times out;
Note: if the inter-system quality satisfies the following condition before the timer times out:
Mother_RAT + CIO < Tother_RAT - H/2
The timer will be stopped, and RNC will go on waiting to receive the next inter-system measurement report.
The length of the trigger-timer is called time-to-trigger.
37. Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
38. Power Control parameter optimization
Power Control Characteristics
Minimize the interference in the network, thus improve
capacity and quality
Maintain the link quality in uplink and downlink by adjusting
the powers
Mitigate the near far effect by providing minimum required
power
level for each connection
Provides protection against shadowing and fast fading
39. Power Control Classification
Open Loop Power Control
Open loop power control is used to determine UE’s initial uplink transmit power in PRACH and
NodeB’s initial downlink transmit power in DPDCH. It is used to set initial power reference values for
power control.
Outer Loop power control
Outer loop power control is used to maintain the quality of communication at the level of bearer
service quality requirement, while using as low power as possible.
Inner loop power control (also called fast closed loop power control)
Inner loop power control is used to adjust UE’s uplink / NodeB’s downlink Dpch Power every one slot
in accordance with TPC commands. Inner loop power control frequency is 1500Hz.
40. Open Loop Power Control - Uplink
BCH£ º PICH channel power
BCH£ C PICH channel power
C
º
UL interference leve
UL interference leve
Constant Value
Constant Value
RACH
RACH
Measure CPICH_RSCP
Measure CPICH_RSCP
and determine the initial
and determine the initial
transmitted power
transmitted power
Preamble_Initial_Power = Primary CPICH TX power - CPICH_RSCP
+ UL interference + Constant Value
where Primary CPICH TX power, UL interference and Constant Value are broadcasted
in the System Information , and CPICH_RSCP is the measured value by UE 。
41. Open Loop Power Control - Downlink
Determine the downlink initial power
Determine the downlink initial power
control
control
DCH
DCH
RACH reports the
RACH reports the
measured value
measured value
Measure CPICH Ec/I0
Measure CPICH Ec/I0
Eb R E
P= × ×( PCPICH /( c )cpich −α × Ptotal )
Io W Io
• Where R is the user bit rate. W is the chip rate (3.84M).
• Pcpich is the Primary CPICH transmit power.
• Eb/Io is the downlink required Eb/Io value for a bearer service.
• (Ec/Io)cpich is measurement value reported by the UE.
•αis downlink cell orthogonal factor.
• Ptotal is the current cell’s carrier transmit power measured at the NodeB
and reported to the RNC.
43. Outer Loop Power Control
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Outer loop control is used to setting SirTarget (Signal to Interference Ratio Target) for inner loop power control. It
is divided into uplink outer loop power control and downlink outer loop power control.
The uplink outer loop power control is controlled by SRNC (serving RNC) for setting a target SIR for each UE. This
target SIR is updated according to the estimated uplink quality (Block Error Ratio/ Bit Error Ratio).
If UE is not in DTX (Discontinuous Transmission)status (that means RNC can receive uplink traffic data),
RNC will use Bler (Block Error Ratio) to compute SirTarget . Otherwise, RNC will use Ber (Bit Error Ratio) to
compute SirTarget.
The downlink outer loop power control is controlled by the UE receiver to converge to required link quality (BLER)
set by the network (RNC) in downlink.
45. Inner Loop Power Control
The inner loop power control adjusts the UE or NodeB transmit
power in order to keep the received signal-to-interference ratio
(SIR) at a given SIR target, SIRtarget.
It is also divided into uplink inner loop power control and
downlink inner loop power control.
46. Uplink Inner Loop Power Control
UTRAN behaviour
The serving cells (cells in the active set) should estimate signal-to-interference ratio
SIRest of the received uplink DPCH. The serving cells should then generate TPC
commands and transmit the commands once per slot according to the following rule: if
SIRest > SIRtarget then the TPC command to transmit is "0", while if SIRest < SIRtarget
then the TPC command to transmit is "1".
UE behaviour
Upon reception of one or more TPC commands in a slot, the UE shall derive a single TPC
command, TPC_cmd, for each slot, combining multiple TPC commands if more than one
is received in a slot. This is also valid when SSDT transmission is used in the downlink.
Two algorithms shall be supported by the UE for deriving a TPC_cmd. Which of these
two algorithms is used is determined by a UE-specific higher-layer parameter,
"PowerControlAlgorithm", and is under the control of the UTRAN. If
"PowerControlAlgorithm" indicates "algorithm1", then the layer 1 parameter PCA shall
take the value 1 and if "PowerControlAlgorithm" indicates "algorithm2" then PCA shall
take the value 2.
47. Uplink Inner Loop Power Control
The step size DTPC is a layer 1 parameter which is derived from the UE-specific higher-
layer parameter "TPC-StepSize" which is under the control of the UTRAN. If "TPC-
StepSize" has the value "dB1", then the layer 1 parameter DTPC shall take the value
1 dB and if "TPC-StepSize" has the value "dB2", then DTPC shall take the value 2 dB.
The parameter "TPC-StepSize" only applies to Algorithm 1 . For Algorithm 2 DTPC shall
always take the value 1 dB.
After deriving of the combined TPC command TPC_cmd using one of the two supported
algorithms, the UE shall adjust the transmit power of the uplink DPCCH with a step of
DDPCCH (in dB) which is given by:
DDPCCH = DTPC × TPC_cmd.
48. Uplink Inner Loop Power Control
Algorithm 1 for processing TPC commands
When a UE is not in soft handover, only one TPC command will be received in each
slot. In this case, the value of TPC_cmd shall be derived as follows:
- If the received TPC command is equal to 0 then TPC_cmd for that slot is –1.
- If the received TPC command is equal to 1, then TPC_cmd for that slot is
Algorithm 2 for processing TPC commands
When a UE is not in soft handover, only one TPC command will be received in each
slot. In this case, the UE shall process received TPC commands on a 5-slot cycle,
where the sets of 5 slots shall be aligned to the frame boundaries and there shall
be no overlap between each set of 5 slots.
The value of TPC_cmd shall be derived as follows:
- For the first 4 slots of a set, TPC_cmd = 0.
- For the fifth slot of a set, the UE uses hard decisions on each of the 5
received TPC commands as follows:
If all 5 hard decisions within a set are 1 then TPC_cmd = 1 in the 5th slot.
If all 5 hard decisions within a set are 0 then TPC_cmd = -1 in the 5th slot.
Otherwise, TPC_cmd = 0 in the 5th slot.
49. Downlink Inner Loop Power Control
UE behaviour
The UE shall generate TPC commands to control the network transmit power
and send them in the TPC field of the uplink DPCCH. The UE shall check
the downlink power control mode (DPC_MODE) before generating
the TPC command:
If DPC_MODE = 0 : the UE sends a unique TPC command in each slot and the
TPC command generated is transmitted in the first available TPC field in the uplink
DPCCH;
If DPC_MODE = 1 : the UE repeats the same TPC command over 3 slots and the
new TPC command is transmitted such that there is a new command at the
beginning of the frame.
The DPC_MODE parameter is a UE specific parameter controlled by the
UTRAN.
50. Downlink Inner Loop Power Control
UTRAN behaviour
Upon receiving the TPC commands UTRAN shall adjust its downlink DPCCH/DPDCH
power accordingly. For DPC_MODE = 0, UTRAN shall estimate the transmitted TPC
command TPCest to be 0 or 1, and shall update the power every slot. If DPC_MODE =
1, UTRAN shall estimate the transmitted TPC command TPCest over three slots to be 0
or 1, and shall update the power every three slots.
52. Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
56. Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
57. Load Control Parameter Optimization
Call Admission Control (CAC)
Call admission control is used to control cell’s load by
admission/rejection request to assure a cell’s load under control.
Dynamic Channel Configuration Control (DCCC)
Dynamic Channel Configuration Control is used to dynamically
change a connection’s load to improve cell resource utilization
and control cell’s load.
59. Call Admission Control Parameters
Different service type can be configured different threshold. That means leave some
resources for important service ( or request), such as HO > Conversation > Other.
Ul(Dl)TotolKThd is used when NodeB load report is not available . It uses equivalent
12.2k-voice users number method.
60. Dynamic Channel Configuration Control
Dynamic channel configuration control (DCCC) aims to make full use
of radio resource (codes, power, CE )
- Configured bandwidth is fixed with no DCCC
Rate or band
- Configured bandwidth is changing with DCCC
- Traffic rate
61. DCCC Procedure
Traffic Volume measurement
control
UE and RNC Measurement
Measurement report
DCCC decision
DCCC execution
62. Traffic Volume Measurement
Transport
Channel
Traffic
Volume
Threshold
Time
Reporting Reporting
event 4A event 4A
Transport
Channel
Traffic
Volume
Threshold
Time
Reporting Reporting Reporting
event 4B event 4B event 4B
63. DCCC Decision
1) 4a event report -> increase bandwidth
4b event report -> decrease bandwidth
2) if current bandwidth <= DCCC threshold,
do not decrease bandwidth
66. Summary
Parameter Optimization improves network quality and solves
network problems.
Parameter Optimization is a complicated procedure and
needs parameter and algorithm knowledge.
Parameter Optimization will be combined with other
optimization activities making network better !