Parameter Optimization
Review
ď Ź
Parameter optimization is an important step after RF Optimization.
ď Ź
Parameter
optimization
improves
service
quality and utilization of network resources.
Review
Objectives
Upon completion of this course, you can:
Understand the process of parameter optimization
Master the contents of parameter optimization
Contents
Parameter optimization procedure Parameter optimization contents
Parameter Optimization Process
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
Verify Parameter Problems
Parameter Classification
Mobile Management Parameters
Power Control Parameters
Power Configuration Parameters
Load Control Parameters
Other Parameters
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”.
Impact
ď Ź
Impact on customer service and other networks
ď Ź
Impact on OMC (efforts, maintenance)
Prepare Test Plan and Change Parameters
ď Ź
Prepare test schedule, routes, tools and be ready to get Information.
ď Ź
Change parameters and make records.
Course Contents
Parameter optimization Procedure Parameter optimization Contents
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.
Mobile Management Parameter Optimization
ď Ź
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.
ď Ź
Handover
The changing of cells with which UE connected in DCH mode. That assures seamless coverage and load balancing.
Cell Selection & Reselection Procedure go here whenever a new PLMN is selected
cell information stored for the PLMN Stored information Cell Selection no suitable cell found
no cell information stored for the PLMN
1
Initial Cell Selection
no suitable cell found
2
suitable cell found
suitable cell found no suitable cell found
Cell Selection when leaving connected mode
return to idle mode
suitable cell found
leave idle mode
Connected mode
Camped normally
NAS indicates that registration on selected PLMN is rejected (except with cause #14 or #15 [5][16])
trigger suitable cell found
Cell Reselection Evaluation Process
no suitable cell found
Any Cell Selection
no acceptable cell found
go here when no USIM in the UE
USIM inserted acceptable cell found Cell Selection when leaving connected mode
return to idle mode
Connected mode (Emergency calls only)
acceptable cell found
leave idle mode
Camped on any cell
suitable cell found
1
2
trigger acceptable cell found
Cell Reselection Evaluation Process
no acceptable cell found
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.
Cell Selection Parameters
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".
Cell Reselection Criteria (R Criteria)
ď Ź
All cells should satisfy S Criteria.
ď Ź
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.
Cell Reselection Parameters
Cell Reselection Parameters
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) nonserving 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.
Cell Reselection Parameters from GSM to UMTS
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
Soft Handover Example
Soft Handover Procedure
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.
Soft Handover Event – 1B
1B (Remove a cell from Active Set) 10 ⋅ LogM Old + CIOOld
NA ≤ 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.
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.
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.
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,
Soft handover hysteresis (H1x)
6,namely 3dB (step 0.5) for H1a .
Hystfor1B,
Hystfor1C, Hystfor1D
8,namely
4dB(step
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-
TrigTime1C,TrigTime1D
trigger parameters. Only the equation are always
D640, namely 640ms .
satisfied during the trigger time, the event will be triggered). FilterCoef
Filter coefficient of L3 intra-frequency measurement
D5,namely 5
0.5)
for
H1b,
Inter-system Handover â&#x20AC;&#x201C; CS Domain Procedure UE
NODEB
3G MSC
RNC
1. RRC Connect Req 2. RRC Setup Complete 3. Measure Control (measure ID 0x1 ) 4. Measure Control (measure ID 0x2 5.Initial ) UE message(service request) 6.DL DT (Authentication Request) 7.UL DT (Authentication Response) 10. Security Mode Command 11. Security Mode CMP 13. UL DT(Setup) 14. DL DT(Call proceeding) 16.RL Recfg Prep 17.RL Recfg Ready 18.RL Recfg Commit 19 RB Setup 20 RB Setup Cmp 22. DL DT( Alerting ) 23. DL DT( Connect) 24. UL DT(Connect Ack)
8.Common ID 9. Security Mode Command 12. Security Mode CMP 15. RAB Assign Req
21 RAB Assign Resp
25 Measure Report(2D) 26.RL Recfg Prep 27.RL Recfg Ready 28 PhyCh Reconfig
29.RL Recfg Comit 30 PhyCh Reconfig CMP 31 Meaure Control(ID3 ) 32Measure Report 35. HandoverFromUtranCommand 45 RL Del Req 46 RL Del Resp
33 Relocation Required 34 Relocation Command 44 Iu Release Req 47 Iu Release Complete
2G MSC
BSS
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.
Inter-system Handover Measure 2ďź&#x2030;
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.
Inter-system Handover Parameters
Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
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
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.
Open Loop Power Control - Uplink
BCH£ ºº BCH£ C CPICH PICH channel channel power power UL interference leve UL interference leve Constant Constant Value Value
RACH RACH
Measure Measure CPICH_RSCP CPICH_RSCP and and determine determine the the initial initial transmitted transmitted power 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 。
Open Loop Power Control - Downlink Determine Determine the the downlink downlink initial initial power power control control DCH DCH
RACH RACH reports reports the the measured measured value value
Measure Measure CPICH CPICH Ec/I0 Ec/I0
P=
Eb R E × ×( 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.
Open Loop Power Control Parameters
Outer Loop Power Control Macro Macro diversity diversity combining combining Set Set SIR SIR target target
SRNC Set Set SIR SIR target target
DRNC Set Set SIR SIR target target
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.
Outer Loop Power Control Parameters
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.
Uplink Inner Loop Power Control ď Ź
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".
ď Ź
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.
Uplink Inner Loop Power Control
The step size DTPC is a layer 1 parameter which is derived from the UE-specific higherlayer parameter "TPC-StepSize" which is under the control of the UTRAN. If "TPCStepSize" 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.
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.
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.
Downlink Inner Loop Power Control
ď Ź
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.
Inner Loop Power Control Parameters
Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
Physical Channels Types
Common Channel Parameters
All channelsâ&#x20AC;&#x2122; power refers to PCPICH power expect PCPICH.
Dedicated Channel Parameters
Dedicated Channel Power refers to PCPICH Power.
Parameter Optimization Contents
Mobile Management parameter optimization
Power Control parameter optimization
Power Configuration parameter optimization
Load Control parameter optimization
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.
Call Admission Control Procedure
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.
Dynamic Channel Configuration Control ď Ź
Dynamic channel configuration control (DCCC) aims to make full use of radio resource (codes, power, CE )
Rate or band
- Configured bandwidth is fixed with no DCCC - Configured bandwidth is changing with DCCC - Traffic rate
DCCC Procedure Traffic Volume measurement control
UE and RNC Measurement
Measurement report
DCCC decision
DCCC execution
Traffic Volume Measurement Transport Channel Traffic Volume Threshold
Time
Reporting event 4A
Reporting event 4A
Transport Channel Traffic Volume
Threshold Time
Reporting event 4B
Reporting event 4B
Reporting event 4B
DCCC Decision 1) 4a event report -> increase bandwidth 4b event report -> decrease bandwidth 2) if current bandwidth <= DCCC threshold, do not decrease bandwidth
Dynamic Channel Configuration Control Parameters
Dynamic Channel Configuration Control Parameters
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
optimization activities making network better !
with
other