Download - RANPAR Combined LoadControl v1.2
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Load Control:
Module Objectives
At the end of the module you will be able to:
Describe the principles of Load Control and it's parameters in detail
Describe the relationships of Load Control with AC and PS
Identify the parameters influencing BTS load measurements
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Load Control
Load Control Functions
Radio Interface Load
Power based Radio Resource Management
Throughput based Radio Resource Management
Planning thresholds for cell loading
BTS Measurements and Reporting Common Measurements
Dedicated Measurements
Filtering of Measurements
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Load Control Functional Overview
LCis a cell based RRM Function, utilising cell specific:
thresholds set by RNP, load measurements,
AC, PS & LC algorithms.
LCperforms the function of load control
in association with AC & PS
LCupdates load status using resource measurements & estimations provided by AC & PS
Continuously feeds cell load information to the other RRM functions, e.g. PS & AC
LC
AC
PSRM
RNC
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Load Control Functional Overview
RRM in RNC
LC
AC
PS
Load changeestimations
Load changeestimations
Schedul ing
per iod
PRACH load
measurement
WBTS NB/RSNBAP-PRIVATE:
RRIndPeriod o r
3GPP NBAP :
COMMONMEASUREMENT
REPORT
Dedicatedmeasurement report ing
parameters
parameters
measurements
est imat ions
when
changed Load change info
Load status request
Load status
NRT load
measurements
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Load Control
Load Control Functions
Radio Interface Load
Power based Radio Resource Management
Throughput based Radio Resource Management
Planning thresholds for cell loading
BTS Measurements and Reporting Common Measurements
Dedicated Measurements
Filtering of Measurements
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NSN RRM: Power & Throughput based
DLuses Power Measurementsand calculations for RRM decisions
ULuses Power & Throughputestimations and calculations for RRM decisions
=
=N
jjUL loadi
1
)1(hNRP
P
totalrx
noiserx
UL
111
_
_-=-=h
max,_
_
BTStx
totaltx
DLP
P=h
definingLoad
= 0% 100%
jjbj
j
NE
RWL
1
/
/1
1
0
=
definingLittle i
Slide 9/10
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Load Estimation Methods and other cell interference
Throughputbased
threshold
WidebandPowerbased
threshold
Own cell load factor(capacity)
i=0.5
i=0
i=1
2 Load estimation
methods:
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UL power based load measurement
PRx_Own
PRxTotal = PRx_Own + PRx_Other + PNoise
=PRx_NRT + PRx_RT + PRx_Other + PNoise
= PRx_NRT + PRx_NC
PRx_Other
iUL= PRx_Other/ PRx_Own
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DL power based load measurement
PTx_Own
PTxTotal = PTx_Own
=PTx_NRT + PTx_RT + PTx_Common
= PTx_NRT + PTx_NC
PTx_Common
PRx_Own_DL
PRx_Other_DL
iDL= PRx_Other_DL/ PRx_Own_DL
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Radio Interface Load
The BTS measures the total received power (PrxTotal) and the total transmitted power
(PtxTotal) on cell basis
The BTS reports PrxTotal& PtxTotalof each cell to the RNC
LC updates
Cell load status for each cell based on RADIO RESOURCE INDICATION
Non-controllable UL (PrxNC) & DL (PtxNC) load in cell
Semi-controllable UL (Prx_SC) & DL (Ptx_SC) load in the cell (related to PS Streaming)
ACand PSalgorithms work on the current cell load status provided by LC
Denying call admission(AC) & throttling back NRT traffic(PS) are the overload actions
After scheduling PS provides LC with PrxNRT, PtxNRT & LNRTestimates
After admitting RT RAB, AC provides LC with NC load increase estimate
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System Noise & PrxNoise Autotuning Algorithm
System noise PrxNoiseis the sum of all stationary noises: thermal noise
interference caused by spurious emissions of other systems, noise caused by additional equipment such as repeaters
PrxNoisecan vary place to place & even time to time
PrxNoisesetting affects the capacity of cell: PrxNoisetoo low: overestimationof cell load and can lead to unnecessary call blocking
PrxNoisetoo high: underestimationof cell load and can lead to overload situation
RNC providesAutotuning-Toolto measure unloaded system noise:
PrxUnloaded; it adjusts PrxNoise parameter based on these measurements
PrxTotal = PrxUnloadedwhen own cell considered unloaded/ very low load;
LRTUnloadedRT& LNRTUnloadedNRT& no EDCH users in the cell
UnloadedRT& UnloadedNRTare RNC parameters (values for NRT: 1 %, RT: 2 %)
LRT &LNRT: UL load factor for own cell RT (AC estimates) & PS users (PS estimates)
PrxNoise updated by the autotuning algorithm based on PrxUnloaded
PrxNoise autotuning step size limited by PrxNoiseMaxTuneAbsolute
PrxNoiseWCEL: -130..-50; 0.1; -105 dBm
PrxNoiseAutotuningWCEL: 0 (Off) / 1 (On)
PrxNoiseMaxTuneAbsoluteWCEL: 0..60; 0.5; 255 dB
255 dB: Autotuning is not limited
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UL Preventive & Overload Thresholds
Prx Target [dB]
PrxTarget [dB] + PrxOffset [dB]
load factor
Range [0..1]
NoiseRise[dB]
Overloaded Area
Marginal Load Area
Feasible Load Area
PrxTarget: WCEL; 0 .. 30; 0.1;4dB
PrxOffset: WCEL; 0 .. 6; 0.1;1dB
dBLog h-- 110 10PrxTarget =
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DL Preventive & Overload Thresholds
Ptx Target [dBm]
Ptx Target [dBm] + PtxOffset [dB]
load factor
totaltransmitted
po
wer
PtxTotal[dBm]
Overloaded Area
Marginal Load Area
Feasible Load Area
Cell Maximum
PtxTarget: WCEL; -10 .. 50; 0.1;40 dBm
PtxOffset: WCEL; 0 .. 6; 0.1;1dB
PtxCellMax WCEL: 050; 0.1; 43dBm
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Load Control
Load Control Functions
Radio Interface Load Power based Radio Resource Management
Throughput based Radio Resource Management
BTS Measurements and Reporting
Common Measurements
Dedicated Measurements
Filtering of Measurements
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Common measurements taken & reported by WBTS
PtxTotalTransmitted Carrier Power
Nokia Private NBAP PtxNonHSPATransmitted Code Power of all codes not used for HSDPA
Nokia Private NBAP
PrxTotalReceived Total Wideband Power
Nokia Private NBAP
REPSReceived E-DCH Power Share
Nokia Private NBAP
Acknowledged PRACH preambles
Nokia Private NBAP
Provided HSDPA Bitrate
Provided HSUPA Bitrate
Required Power
RRM in RNC needs this information for Streaming mapped on HSPA
(NSTNon Scheduled Transmission)
Nokia Private part is protocol extension specified in 3GPP
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WBTS Common Measurements sent to CRNC
WBTS sends measurements periodically according setting of RRM parameter:
(Nokia Private part)
RADIO RESOURCE MEASUREMENT REPORT
RRIndPeriodRadio Resource Indication Period
WBTS; 200 .. 2000; 100; 400 ms
RACHloadIndicationPeriod
WBTS; 0 (Off); 1 .. 20; 1; 1 RRI report
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Measurement filtering & reporting criteria in BTS
BTS measurements are averaged/filtered in BTS before reporting
L1 filtering L3 filtering
Higher Layer filtering
BTS reports measurements to RNC when needed
Reporting criteria
Step 1:
L1 Filtering:
1 Frame = 10 ms
Step 2
L1 measurement period
(= L1 Filtering)
= 100 ms = 10 frames
(Slide 30)Step 3:
L3 Filtering:
RRI period = 400 ms(Slide 27)
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L1 Filtering: Prx and Ptx Total Measurements
Frame average measurements
Frame Prx and Ptx Totalmeasurements
=14
0
//15
1TotalPTotalP txrxtxrx
0 141 2 ...
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L3 filtering: Higher layer filtering
The Measurement Filter Coefficient (k) IE indicates how filtering of the measurementvalues shall be performed before measurement event evaluation and reporting.
The averaging shall be performed according to the following formula.
L1 measurement period is 100 ms(20 ms for Acknowledged PRACH preambles)
Filter response
32
33
34
35
36
37
38
39
40
41
42
t 1 3 5 7 911
13
15
17
19
21
23
25
27
29
31
33
Measurements
Value,
dB Measured
Filtered, k = 3
Filtered, k = 7
Filter response
-105.5
-105
-104.5
-104
-103.5
-103
-102.5
-102
-101.5
t 1 3 5 7 911
13
15
17
19
21
23
25
27
29
31
33
Measurements
Value,
dB Measured
Filtered, k = 3
Filtered, k = 7
The higher the coefficient value, the more
emphasis on old filtered measurements
Examples:
k=2, a=0,5both an old filtered measurement and
a new measurement have the weight of 50%
K = 0a = 1no L3 filtering
MeasFiltCoeffMeasurement filter
coefficient kWCEL; 0 (Off); 1 ..
14; 1; 5
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Measurement filtering
The RNC can order BTSs to report cell-based & connection-based measurements only if internal
thresholds are exceeded.
However, a report is sent at least once per 10 reporting periods(RNP parameters).
The filtering functionality decreases the amount of measurement messages between the BTS and the
RNC and thus decreases the load of RNC computer units.
Internally RNC repeats the cell based measurements every WBTS: RRIndPeriodto provide RRM
functions a continuous flow of measurements
BTS Measurements
Reporting period
10 * Reporting period
RRIndPeriodWBTS; 200 .. 2000;
100; 400 ms
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WBTS Measurements sent to CRNC
WBTS can filter a measurement report (not sent to RNC)
only inform RNC about important load changes
reduce common NBAP signaling on IuB interface
RNC provides load thresholdand value changethreshold to WBTS
Measured
entity
Max amount of
consecutive filteredreports
Reporting period
Change threshold
Load Threshold
Report Report Report Report Time ReportReport
Parameter settings for
PtxTotal Measurement
0,5 dB
20 % of Ptx max
non-configurable:
PtxTotalLoadThreshold: 20%
PtxTotalChangeThreshold: 0.5dB
PrxTotalLoadThreshold: 20%
PrxTotalChangeThreshold: 0.2dB
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Dedicated Measurements in BTS
Transmitted Code Power
WBTS send periodic measurement reports with code power measurement results from all Radio
Links (UEs in Cell_DCH)
Depending on allocated service typeWBTS applies different reporting frequency:
CS Services &SRB:
CS Data Services:
PS Data Services:
DedicatedMeasRepPeriodWBTS; 0.5..5; 0.5; 2.5 s
DediMeasRepPeriodCSdataWBTS; 0.5..5; 0.5; 1.5 s
DediMeasRepPeriodPSdataWBTS; 0.5..5; 0.5; 0.5 s