Cell load KPIs can be used to trigger events and identify candidate cells for cell yield management (CYM) by observing near real-time cell load measurements extracted from the RNC at intervals of around 15 minutes. The cell load will be quantified using KPI thresholds that compare measurements like transmitted carrier power, noise rise, code tree utilization, and channel element utilization against thresholds. Cells where the KPIs are below the thresholds will be identified as candidates for CYM offers to increase utilization. Specific counters from different RNC vendors can be used to calculate the KPI measures and determine if a cell is eligible as a CYM candidate.

1. Cell Load KPIs for
Event Triggered CYM

2. Revision History
Revision Date Status Revised By Revision Details
0.1 21 Dec 2010 Dr. Asoka Korale KPIs for triggering events and determining candidate
cells for CYM. (Draft)
2

3. 1.0 Introduction
Cell utilizations can be enhanced by observing cell load on a near real time basis and
making offers to those subscribers in under utilized cells at those times when the cell can
accommodate a higher level of traffic.
In principal it is possible to extract cell load measurements from the RNC at intervals of
about 15 minutes? (need Huawei confirmation), which should be sufficient to gain a fair
picture of the prevailing load, in the absence of unforeseen events. The cell load will be
quantified via the definition of KPIs, which in turn will be compared against cell load
thresholds and the results of these comparisons used to generate events. A message to the
core network will be generated depending on the particular event, and a suitable offer
made to the subscribers in the identified cell. Three RNC vendors in the Dialog network
will require three sets of KPIs/ trigger thresholds depending on the available
measurements.
The offer/ discount can be communicated to subscribers through cell broadcast, which
requires a cell broadcast center that can receive as input a list of cells and a corresponding
message to be broadcast in each of those cells without placing any constraints as to the
list of cells or broadcast messages (TeleDNA CBC meets this requirement).
These schemes have already been implemented in certain Indian/African markets and
ready made solutions in the form of Dynamic Discount Systems are available from
Huawei/ Ericsson. These DDS schemes are integrated with cell broadcast as the means of
communicating the offer.
This note briefly describes a few KPIs that can be used for measuring cell load and
defining trigger thresholds. The trigger thresholds will also depend on the likelihood of
the measured quantity exceeding the thresholds and so will ideally be set after observing
the distribution of the studied quantity in that cell/ group of cells and through experience.
2.0 Measurements
It would be advantageous if measurements are configured at frequent intervals (on the
order of 100ms may be sufficient) allowable by Iub bandwidth and equipment
limitations.
If measurements are being accumulated at the PM device, then the measurements
themselves can be made with a filter with short memory (“a” large) assuming this setting
does not impact the measurement requirement of other RRM algorithms.
nnn MaFaF ⋅+⋅−= −1)1(
3

4. Note: In the case of each of the vendor specific measurements they would need to be
aggregated over common measurement intervals so that the ratios (KPIs) would be
consistent.
3.0 Some General Cell Load Measures
The relevant NBAP 3GPP 4.33 extracts which define the available measurements on a
per cell basis are found in the appendix
Uplink:
1. A measure of the Noise Rise in the cell can be estimated by the ratio between RTWP
and noise floor. The noise floor (on the order of -108dbm) can be used as a parameter or
if a measurement via the RNC is available at a suitable load level/time of day.
2. Average Channel Element Utilization:
Down Link:
1. Transmitted Carrier Power as a proportion of total transmitted carrier power capability
of the cell.
MAX
TX
P
P
=
4
PNonHS
PHSDPA
PMAX
Shared Single Carrier
PTX

5. 2. Transmitted carrier power of all codes not used for HS transmission as a proportion of
total transmitted carrier power capability of cell.
MAX
NonHS
P
P
=
2a. The ratio between Transmitted carrier power of all codes not used for HS
transmission to the total transmitted carrier power capability less Transmitted carrier
power plus the Transmitted carrier power of all codes not used for HS transmission can
be considered.
TXMAXNonHS
NonHS
PPP
P
−+
=
3. Ratio of Transmitted carrier power less Transmitted carrier power of all codes not
used for HS transmission to total transmitted carrier power capability of cell.
MAX
NonHSTX
P
PP −
=
3a. Ratio between Total transmitted carrier power less Transmitted carrier power of all
codes not used for HS transmission to Total transmitted power capability less
Transmitted carrier power of all codes not used for HS transmission.
NonHSMAX
NonHSTX
PP
PP
−
−
=
Note: In multi carrier environments with dedicated carrier for HSDPA, direct ratio
between HSDPA power and max carrier power can be used to estimate utilization. In
dynamic power allocation schemes all measures would be applicable. If however fixed
allocation is used for reserving power for HSDPA measures 1,2,3 could be used and
additionally 2a and 3a could be used as is or by accounting for the proportion that is
reserved.
5

6. 4. Level of Code tree utilization., May not be available directly from all vendors and so
will need to be derived either from average data rate/ bearer spreading factor
measurements.
If the average spreading factors (SF) of the bearers in use during a particular
measurement period is available, it would be possible to determine an estimate for the
code weight of each bearer by dividing 512 by SF. Thus if two bearers of spreading
factor 128 and 64 were in use in the measurement period, the code weight could be
considered to be 512/128 + 512/64 = 12, giving an average utilization of 12/512 (this is a
bit doggy as the bearers wont be active all the time and a time weighted average is what
should really be used, if however the sampling intervals are relatively short a fairly
accurate estimate can be obtained). In systems where dynamic code allocation is
implemented sharing of code resource between R99 and HSDPA enables direct measure
of utilization, else the reserved portion can be counted as part of the tree that is utilized.
5. Average Channel Element Utilization:
6. Iub resource availability:
May need to factor this depending on the current network planning.
4.0 Specific counters from each vendor
Use of transmit power capability / max transmit power depends on whether power local
cell groups are defined.
4.1 ZTE
The following counters enable calculation of the load measures defined in 3.0
UpLink:
• An estimate for Noise Rise: Is there a dynamic noise floor measure available at
RNC? Determine average RTWP measure as the ratio between C301300076 sum
of RTWP and C301300078 reported times of RTWP Take ratio with noise floor
which may be a parameter.
• Maximum noise rise: ratio of C301300077 maximum RTWP to noise floor
• Average UL Channel Element Utilisation: (On a per NodeB basis) Determine as
the ratio between C301830008 Sum use ratio of uplink Node B CE to C30180009
Times of uplink NodeB CE.
6

7. Down Link:
TCP utilization: If sum of utilizing rate of TCP C301300071 is used, we would need to
rescale to get dBm value. Is this a sum of ratios (TCP utilizations) that is output, or are
linear values (TCP values) calculated averaged and then the ratio produced as output?
Maximum utilization rate TCP: C301300072 maximum utilizing rate of TCP
Mean TCP: Take ratio between sum of TCP over sampling period via C301300073
(dBm) , and C301300075 reported times of TCP.
• Determine measure 1, using mean TCP.
Max TCP: C301300074 maximum TCP (dBm)
Average Non HSDPA TCP: The cumulative sum of the Non HSDPA power in the cell
over the sampling interval can be obtained via C301310079 Sum of non HSDPA TCP
(verify whether this is dBm or ratio). The number of samples is given via C301310080
Statistics times of nonHSDPA TCP. The ratio of the two quantities (better if non HSDPA
power is in dBm) is the average nonHSDPA power
• The measures 2, 2a, 3, 3b can be determined utilising the average non HSDPA
TCP and Mean TCP.
Additionally a conservative estimate of available resources can be obtained by using the
average maximum non HSDPA power (C301380082 Maximum nonHSDPA TC, %)
measure in place of average non HSDPA power.
Note: there is some confusion as to the HSPA related measurements listed on p 227, need
verification.
• The average level of code resource availability in the cell can be estimated by
taking the ratio between C301270048 Sum of available ratio of code resource (%)
to C301270049 Statistics times of code resource. (Clarify whether C301270048 is
proportion of available codes or utilised codes)
• Average DL Channel Element Utilization: (On a per Node B basis) Determine as
the ratio between C301830012 Sum use ratio of downlink NodeB CE (%) to
C301830013 Times of Downlink NodeB CE. Alternately there is also
C301830012 Maximum use ratio of DL Node B CE (%) for a more conservative
level of operation.
(need to verify whether we can have different reporting rates for the quantities, or if a
single common measurement report is used)
7

8. 4.2 Huawei
(Need detailed info about counters, averaging periods, units ect, awaiting clarication from
vendor)
UpLink:
• Use either Mean RTWP (measurement ID 67199617, counter VS.MeanRTWP) or
Max RTWP (measurement ID 67199680, counter VS.MaxRTWP) to determine
mean/max estimate for noise rise using either parameter or measurement value for
noise floor.
• Channel element utilization:?
DownLink:
Mean TCP is available via measurement ID 67199618, counter VS.MeanTCP.
• Determine measure 1, utilising mean TCP.
Max TCP is available via measurement ID 67199682, counter VS.MaxTCP
Mean Non HSDPA TCP measurement is available via measurement ID 67202902,
counter VS.MeanTCPNonHS
Max Non HSDPA TCP is available via measurement ID 67202900 counter
VS.MaxTCPNonHS.
• Determine measures 2, 2a, 3, 3a using Mean TCP and Mean Non HSDPA TCP.
Alternatively a conservative estimate can be obtained by using Max Non HSDPA
TCP in the same measures.
• Max code tree utilisation available via measurement ID 67191657, counter
VS.RAB.SFOccupy.Max (verify whether proportion or percentage) or mean code
tree utilisation via measurement ID 67203416, counter VS.RAB.SFOccupy.
• Channel element utilization:?
4.3 Ericsson
8

9. The current RNC corresponds to release WRAN P6FP and the following are based on the
counters currently available (latest release available from Ericsson is WRAN W10A and
allows considerable more flexibility and function).
UpLink:
• Determine average RTWP as the ratio between counters pmSumUlRssi and
pmSamplesUlRssi. Either the average RTWP measure or a noise rise (calculated
using a noise floor measure based on parameter or measurement) measure can be
used for cell load estimate. (it would be better if a counter based on periodic
measurements was available)
• An average channel element utilization level can be obtained by the ratio between
the counters pmSumCapacityUlCe to pmSamplesCapacityUlCe.
DownLink:
Mean TCP: The counter pmTransmittedCarrierPower gives the distribution of the
transmitted carrier power, with the number of samples in a range of bins provided. Thus
to determine the mean TCP one has to compute ∑= )(xxPµ . Where
moplesTotnumofsaxNbinxP /)()( = , where Nbin(x) is the number of samples in bin, x
can represent bin center..Ideally one would convert dBm to mW and perform this as a
linear computation.
Mean Non HSDPA Power: The counter pmTransmittedCarrierPowerNonHs gives the
distribution of the transmitted carrier power, with the number of samples in a range of
bins provided. Thus to determine the mean Non HSDPA power one has to compute
∑= )(xxPµ . Where moplesTotnumofsaxNbinxP /)()( = , where Nbin(x) is the
number of samples in bin, x can represent bin center..Ideally one would convert dBm to
mW and perform this as a linear computation.
• Determine measures 2, 2a, 3, 3a using Mean TCP and Mean Non HSDPA TCP.
• A measure of average code tree utilization can be obtained by the ratio between
counters pmSumDlCode to pmSamplesDlCode. This measure omits codes
reserved for HS-DSCH and so the code reservation for HSDPA (verify that
dynamic code allocation is not present in this release. Also check that utilization
is in % or as a proportion of SF 256) must be accounted for in the final
determination of the total “average” code utilization.
9

10. • An average channel element utilization level can be obtained by the ratio between
the counters pmSumCapacityDlCe to pmSamplesCapacityDlCe.
5.0 Selecting Candidate Cell for CYM
Periodic Cell Measurements
Is UL Noise Rise (or RTWP) <
Noise Rise Activation threshold
Is UL CE Utilization < UL CE
Utilization Activation threshold
Is Code Utilization < Code
Utilization Activation threshold
Is DL Power KPI < DL Power
Activation threshold
Is DL CE Utilization < DL CE
Utilization Activation threshold
Is Iub Utilization < Iub Utilization
Activation threshold
Candidate Cell for CYM
Y
N
N
N
N
N
N
Y
Y
Y
Y
Y
10

11. 6.0 Observations
In this type of dynamic scheme one would need to have a good idea about the elasticities/
cross elasticities at different price / utilization levels in order to estimate the expected
return, and also to determine what if any the discount should be. It is likely that the
elasticity would change depending on which point on the utilization vs. price curve one is
operating at. Clearly having some data points for price vs utlisation would allow us to
either fit a curve and take the derivative (requires continuity) or carry out an interpolation
around the point of interest. In any case such a curve may only be generated once the
envisaged scheme gets underway.
7.0 Appendix
Common measurements extracted from NBAP (3GPP 25.433) for indicating cell load.
9.2.1.12 Common Measurement Value
The Common Measurement Value shall be the most recent value for this measurement,
for which the reporting criteria were met.
IE/Group Name Presence Range IE Type and
Reference
Semantics Description Criticality Assigned
Criticality
CHOICE Common
Measurement Value
M –
>Transmitted Carrier
Power
–
>>Transmitted Carrier
Power Value
M INTEGER
(0..100)
According to mapping
in [22] and [23]
–
>Received Total Wide
Band Power
–
>>Received Total Wide
Band Power Value
M INTEGER
(0..621)
According to mapping
in [22] and [23]
–
>>Transmitted Carrier
Power Of All Codes Not
Used For
HSTransmission
–
>>>Transmitted Carrier
Power Of All Codes Not
Used For
HSTransmission Value
M INTEGER
(0..100)
According to mapping
in [22], measurement
“Transmitted Carrier
Power Of All Codes Not
Used For HS-PDSCH,
HS-SCCH, E-AGCH,
E-RGCH or E-
HICHTransmission"
and mapping in [23],
measurement
“Transmitted Carrier
Power Of All Codes Not
Used For HS-PDSCH
YES ignore
11

12. Or HS-SCCH
Transmission"
>>HS-DSCH Required
Power
–
>>>HS-DSCH Required
Power Value Information
M 9.2.1.31Ic YES ignore
>>HS-DSCH Provided
Bit Rate
–
>>>HS-DSCH Provided
Bit Rate Value
Information
M 9.2.1.31Ib YES ignore
>>Transmitted Carrier
Power For Cell Portion
FDD Only –
>>>Transmitted Carrier
Power For Cell Portion
Value
1..<
maxNrO
fCellPort
ions>
GLOBAL ignore
>>>>Cell Portion ID M 9.2.2.1Ca –
>>>>Transmitted Carrier
Power Value
M INTEGER
(0..100)
According to mapping
in [22]
–
>>Received Total Wide
Band Power For Cell
Portion
FDD Only –
>>>Received Total Wide
Band Power For Cell
Portion Value
1..<
maxNrO
fCellPort
ions>
GLOBAL ignore
>>>>Cell Portion ID M 9.2.2.1Ca –
>>>>Received Total
Wide Band Power Value
M INTEGER
(0..621)
According to mapping
in [22]
–
>>Transmitted Carrier
Power Of All Codes Not
Used For HS-PDSCH,
HS-SCCH, E-AGCH, E-
RGCH or E-HICH
Transmission For Cell
Portion
FDD Only –
>>>Transmitted Carrier
Power Of All Codes Not
Used For HS-PDSCH,
HS-SCCH, E-AGCH, E-
RGCH or E-HICH
Transmission For Cell
Portion Value
1..<
maxNrO
fCellPort
ions>
GLOBAL ignore
>>>>Cell Portion ID M 9.2.2.1Ca –
>>>>Transmitted Carrier
Power Of All Codes Not
Used For HS-PDSCH,
HS-SCCH, E-AGCH, E-
RGCH or E-HICH
Transmission Value
M INTEGER
(0..100)
According to mapping
in [22]
–
>>HS-DSCH Required
Power For Cell Portion
FDD Only –
>>>HS-DSCH Required
Power For Cell Portion
Information
1..<max
NrOfCell
Portions
>
GLOBAL ignore
>>>>Cell Portion ID M 9.2.2.1Ca –
>>>>HS-DSCH Required
Power Value Information
M 9.2.1.31Ic –
>>HS-DSCH Provided FDD Only –
12

13. Bit Rate For Cell Portion
>>>HS-DSCH Provided
Bit Rate For Cell Portion
Information
1..<max
NrOfCell
Portions
>
GLOBAL ignore
>>>>Cell Portion ID M 9.2.2.1Ca –
>>>>HS-DSCH Provided
Bit Rate Value
Information
M 9.2.1.31Ib –
>>E-DCH Provided Bit
Rate
FDD Only –
>>>E-DCH Provided Bit
Rate Value Information
M 9.2.2.13S YES ignore
>>E-DCH Non-serving
Relative Grant Down
Commands
FDD Only –
>>>E-DCH Non-serving
Relative Grant Down
Commands Value
Information
M INTEGER
(0..100,…)
Down Commands per
second
YES ignore
9.2.1.39 Maximum DL Power Capability
This parameter indicates the maximum DL power capability for a local cell or a Power Local Cell Group within the
Node B. The reference point is the antenna connector. If Transmit Diversity can be used in the local cell, the parameter
indicates the maximum for the linear sum of the power that can be used on all branches.
IE/Group Name Presence Range IE Type and Reference Semantics Description
Maximum DL Power Capability INTEGER (0..500) Unit: dBm
Range: 0..50 dBm
Step: 0.1 dB
9.2.1.40 Maximum Transmission Power
The Maximum Transmission Power is the maximum value for the linear sum of the power of all downlink
physical channels, that is allowed to be used in a cell. If Transmit Diversity is applied to one downlink
physical channel, the power to be considered for this downlink physical channel is the linear sum of the
power used for this downlink physical channel on all branches. The reference point is the antenna
connector.
IE/Group Name Presence Range IE Type and
Reference
Semantics Description
Maximum Transmission
Power
INTEGER (0..500) Unit: dBm
Range: 0..50
Step: 0.1 dB
13