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A scheme for enhancing cellular yield in 3G systems. Cell utilization 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.

- 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