nokia bss12 edge and gprs key performance indicators

EDGE and GPRS KeyPerformance Indicators

DN7032527Issue 4-1 en

# Nokia Corporation 1 (49)

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2 (49) # Nokia Corporation DN7032527Issue 4-1 en

EDGE and GPRS Key Performance Indicators

Contents

Contents 3

Summary of changes 5

1 EDGE and GPRS key performance indicators (KPIs) 9

2 EDGE and GPRS KPI categories 11

3 Network usage KPIs 13

4 Congestion KPIs 234.1 PDTCH congestion KPIs 234.2 Abis congestion KPIs 244.3 PCU congestion KPIs 254.4 Gb congestion KPIs 27

5 PDTCH quality KPIs 29

6 Mobility KPIs 35

7 Availability KPIs 37

8 User experience KPIs 39

9 Reference for used formulas 41

10 Traffic monitoring principles 47



Contents

Summary of changes

Changes between document issues are cumulative. Therefore, the latest documentissue contains all changes made to previous issues.

Changes made between issues 4-1 and 4-0

Changes made between issues 4-1 and 4-0 lists the main changes made to thedocument after the Nokia GSM/EDGE BSS, Rel. BSS12, System Documentationpilot release. The following changes have been made:

. Use section under Downlink multislot soft blocking, S10.5 (blck_33) hasbeen modified.


Chapter Quality KPIs has been renamed to PDTCH quality KPIs.

Chapter Traffic monitoring principles has been added to the document. In theearlier releases this chapter was part of the EDGE dimensioning documents.

Information on Enhanced Quality of Service (EQoS) has been removed because itis not supported in BSS12.

The following KPIs have been added:

. dtm_3

. dtm_4

. dtm_5

. trf_170

. trf_171a

. trf_202a

. trf_242

. tbf_61



Summary of changes

. tbf_65

. llc_3a

. llc_4a

. tbf_66

. nccr_1

. nccr_13

The following KPIs have been removed:

. trf_231

. trf_232

. llc_3


The key performance indicators (KPIs) have been updated to BSS11.5, version 3level.

The following KPI has been removed:

. tbf_36a

The following KPIs have been added:

. ava_68

. ava_71

. ava_72

. dap_9

. llc_3

. tbf_64

. trf_161h

. trf_162f

. trf_204

. trf_203b



. trf_205b

. trf_208b

The version of the following KPIs has been changed:

Old version New version

trf_213b trf_213c

trf_212b trf_212c

trf_214b trf_214a

trf_237c trf_237b

trf_235a trf_235b

trf_233b trf_233c

trf_234a trf_234

dap_7b dap_7a

Accuracy information has been added to formulas trf_214a and trf_237b inNetwork usage KPIs.

GPRS has been changed to EGPRS in the name of formulas trf_236 and trf_234in Quality KPIs.

Availability KPIs and User experience KPIs have been added.

In addition, the naming conventions have been unified.



Summary of changes

1 EDGE and GPRS key performanceindicators (KPIs)

These are the Nokia recommendations for the EDGE and GPRS key performanceindicators (KPIs). KPIs for CS-3 and CS-4 are also included.

These definitions are subject to change. Nokia improves the definitions and thelist of KPIs according to received feedback and results from testing and fieldoperations.

A KPI is a value that presents some vital information about the network. TheKPIs are mapped directly from performance indicators (PIs), a formula of severalPIs, or directly from network counters.

Nokia has divided the EDGE and GPRS KPIs into the following categories:

. Network usage

. Congestion

. Quality

. Mobility

. Availability

. User experience

Related topics

. EDGE and GPRS KPI categories

. Network usage KPIs

. Congestion KPIs

. Quality KPIs

. Mobility KPIs

. Availability KPIs



EDGE and GPRS key performance indicators (KPIs)

. User experience KPIs

. Reference for used formulas



2 EDGE and GPRS KPI categories

Table KPI groups and formula names lists the key performance indicator (KPI)groups.

The last letter after the formula ID number is for version control. When smallimprovements to the formula are made, the last letter is incremented but theformula number remains unchanged.

Table 1. KPI groups and formula names

KPI group Description Formula ID

Network usage DownlinkGPRSRLC payload trf_213c

Uplink GPRS RLC payload trf_212c

Downlink EGPRS RLC payload trf_215a

Uplink EGPRS RLC payload trf_214a

DTM PS payload ratio dtm_3

PSerlangs trf_237b

Relative share of PS Erlangs trf_242

Downlink GPRS erlangs trf_208b

Uplink GPRS erlangs trf_205b

Downlink EGPRS erlangs trf_162f

Uplink EGPRS erlangs trf_161h

Uplink signalling TBFs usage ratio tbf_61

Share of EDGE requests tbf_65

PDTCH congestion Downlink multislot allocationblocking

tbf_16

Downlink multislot soft blocking blck_33

Downlink TBFs per timeslot tbf_38c

Abis congestion Inadequate EDAP resources indownlink

dap_7a



EDGE and GPRS KPI categories

Table 1. KPI groups and formula names (cont.)

PCU congestion Territory upgrade rejections due toa lack of PCU capacity

blck_32

Downlink MCS selection limited byPCU

dap_9

Gb congestion Downlink Gb load frl_8a

PDTCH quality Downlink GPRS RLC throughput trf_235b

Uplink GPRS RLC throughput trf_233c

Downlink EGPRS RLC throughput trf_236

Uplink EGPRS RLC throughput trf_234

TBF establishment failure ratio tbf_66

Mobility Downlink flush per minute tbf_64

NCCR success ratio nccr_13

Availability Data service availability ratio ava_68

User experience LLC throughput for 4-tsl EDGEMSs

llc_3a

LLC throughput for GPRS MSs (foreach QoS class)

llc_4a

Most of the KPIs are combined to be common for one BTS. Abis, PCU, and Gbcongestion KPIs are related to the Abis interface (Dynamic Abis), BSC, and Gbinterface respectively. However, the BTS KPIs can be summed up (that is, overone BSC) to obtain the corresponding KPIs at the BSC level.



3 Network usage KPIsDownlink GPRS RLC payload, S9 (trf_213c)

Use:

Indicates all GPRS payload data in downlink.

Formula (NetAct names):

All GPRS DL payload data (kbytes) =

sum(a.rlc_data_blocks_dl_cs1 x 20

+ a.rlc_data_blocks_dl_cs2 x 30

+ sum over MCS-11 (b.dl_rlc_blocks_in_ack_mode +

b.dl_rlc_blocks_in_unack_mode) x 36

+ sum over MCS-12 (b.dl_rlc_blocks_in_ack_mode +

b.dl_rlc_blocks_in_unack_mode) x 50

)/1024

Counters from table(s):

a = p_nbsc_packet_control_unit

b = p_nbsc_coding_scheme

Unit:

kbytes

Uplink GPRS RLC payload, S9 (trf_212c)

Use:

Indicates all GPRS payload data in uplink.


All GPRS UL payload data (kbytes) =

sum(a.rlc_data_blocks_ul_cs1 x 20

+ a.rlc_data_blocks_ul_cs2 x 30

+ sum over MCS-11 (b.ul_rlc_blocks_in_ack_mode +

b.ul_rlc_blocks_in_unack_mode) x 36

+ sum over MCS-12 (b.ul_rlc_blocks_in_ack_mode +

b.ul_rlc_blocks_in_unack_mode) x 50



Network usage KPIs

)/1024




Unit:

kbytes

Downlink EGPRS RLC payload, S10.5 (trf_215a)

Use:

Indicates all EGPRS payload data in downlink.

Formula:

(sum over MCS-1 (xx) x 22 +

sum over MCS-2 (xx) x 28 +





sum over MCS-7 (xx/2) x 112 +


sum over MCS-9 (xx/2) x 148)

/1024

where xx =

(DL_RLC_BLOCKS_IN_ACK_MODE + DL_RLC_BLOCKS_IN_UNACK_MODE)


p_nbsc_coding_scheme

Unit:

kbytes

Uplink EGPRS RLC payload, S10.5 (trf_214a)

Use:

Indicates all EGPRS payload data in uplink.

Note

This KPI calculates UL payload inaccurately prior to S11.5 CD4.0. Accuratecalculation is available from S11.5 CD4.0 onwards.




(sum over MCS-1 (xx) x 22 +








sum over MCS-9 (xx/2) x 148))

)/1024

where xx =

(UL_RLC_BLOCKS_IN_ACK_MODE + UL_RLC_BLOCKS_IN_UNACK_MODE)



Unit:

kbytes

DTM PS payload ratio, S12 (dtm_3)

Use:

Ratio of DTM PS payload (UL plus DL) to all PS payload.


(dtm_4 + dtm_5) / (trf_212c + trf_213c + trf_214a + trf_215a)

Unit:

%

PS erlangs, S10.5 (trf_237b)

Use:

Detects the maximum amount of PS data traffic during the measurement period.

Note

This KPI calculates UL payload inaccurately prior to S11.5 CD4.0. Accuratecalculation is available from S11.5 CD4.0 onwards.



Network usage KPIs


PS Erlangs = max(UL PS Erlangs, DL PS Erlangs) =

Max((a.rlc_data_blocks_ul_cs1

+ a.rlc_data_blocks_ul_cs2

+ a.BAD_FRAME_IND_UL_CS1

+ a.BAD_FRAME_IND_UL_CS2

+ a.BAD_FRAME_IND_UL_UNACK

+ a.rlc_mac_cntrl_blocks_ul

+ a.ignor_rlc_data_bl_ul_due_bsn x X

+ sum over MCS0..6 of (b.ul_rlc_blocks_in_ack_mode +

b.ul_rlc_blocks_in_unack_mode +

b.bad_rlc_valid_hdr_ul_ack +

b.bad_rlc_valid_hdr_ul_unack +

b.bad_rlc_bad_hdr_ul_ack +

b.bad_rlc_bad_hdr_ul_unack)

+ sum over MCS7..9 of (b.ul_rlc_blocks_in_ack_mode +

b.ul_rlc_blocks_in_unack_mode +




b.bad_rlc_bad_hdr_ul_unack)/2)

+ sum over MCS-11..12 of (b.ul_rlc_blocks_in_ack_mode +




b.bad_rlc_bad_hdr_ul_unack +

b.ul_rlc_blocks_in_unack_mode)

------------------------------------------------------------------

, period_duration x 60 x 50

(a.rlc_data_blocks_dl_cs1 +

a.rlc_data_blocks_dl_cs2 +

a.retra_rlc_data_blocks_dl_cs1 +

a.retra_rlc_data_blocks_dl_cs2 +

a.rlc_mac_cntrl_blocks_dl

+ sum over mcs1..6 of (b.dl_rlc_blocks_in_ack_mode +

b.dl_rlc_blocks_in_unack_mode +

b.retrans_rlc_data_blocks_dl)

+ sum over mcs7..9 of (b.dl_rlc_blocks_in_ack_mode +


b.retrans_rlc_data_blocks_dl)/2)

+ sum over MCS-11..12 of (b.dl_rlc_blocks_in_ack_mode +


b.retrans_rlc_data_blocks_dl))

-------------------------------------------------------------------

period_duration x 60 x 50)

Where X = 0.5 x A/(A+B) + 1 x B/(A+B)

A = sum over MCS7...9 of (b.ul_rlc_blocks_in_ack_mode +


B = (sum over MCS1...6 of (b.ul_rlc_blocks_in_ack_mode +

b.ul_rlc_blocks_in_unack_mode))

+ a.rlc_data_blocks_ul_cs1 + a.rlc_data_blocks_ul_cs2

+ sum over MCS-11..12 of (b.ul_rlc_blocks_in_ack_mode +







Unit:

Erlangs

Relative share of PS Erlangs, S12 (trf_242)

Use:

Indicates the ratio of PS traffic in erlangs compared to all erlangs (PS + CS).


trf_237b

100 * ----------------

trf_237b + trf_171a

Unit:

%

Downlink GPRS traffic, S11.5 (trf_208b)

Use:

Indicates the amount of resources (timeslots) the GPRS traffic (excluding EDGEtraffic) consumes, on average, during the period. This information is useful, forexample, in estimating the need for capacity extension. 50 blocks/sec/TSL is usedto estimate the timeslots.

OSS4.0 is needed to collect all counters.

Formula (logical):

Actual DL data throughput (blocks)

------------------------------------------------------------- =

nbr of blocks equivalent to 1 tsl full use in each BTS of area


sum(a.rlc_data_blocks_dl_cs1

+ a.rlc_data_blocks_dl_cs2

+ a.retra_rlc_data_blocks_dl_cs1

+ a.retra_rlc_data_blocks_dl_cs2)



Network usage KPIs

+ sum over MCS-11..12 (b.dl_rlc_blocks_in_ack_mode

+ b.dl_rlc_blocks_in_unack_mode

+ b.retrans_rlc_data_blocks_dl)

+ (a.rlc_mac_cntrl_blocks_dl - a.egprs_dl_ctrl_blocks)

------------------------------------------------------

sum(period_duration*60)*50; 50 blocks /sec /tsl




Unit:

TSL or erlang

Uplink GPRS traffic, S11.5 (trf_205b)

Use:

Indicates the amount of resources (timeslots) the GPRS traffic (excluding EDGEtraffic) consumes, on average, during the period. This information is useful, forexample, in estimating the need for capacity extension. 50 blocks/sec/TSL is usedto estimate the timeslots.



Actual UL data throughput (blocks)

------------------------------------------------------------- =


sum(a.rlc_data_blocks_ul_cs1


+ a.bad_frame_ind_ul_cs1

+ a.bad_frame_ind_ul_cs2

+ a.bad_frame_ind_ul_unack

+ sum over MCS-11..12 (b.ul_rlc_blocks_in_ack_mode

+ b.ul_rlc_blocks_in_unack_mode

+ b.bad_rlc_valid_hdr_ul_unack

+ b.bad_rlc_bad_hdr_ul_unack

+ b.bad_rlc_valid_hdr_ul_ack

+ b.bad_rlc_bad_hdr_ul_ack)

+ (a.rlc_mac_cntrl_blocks_ul - a.egprs_ul_ctrl_blocks)

+ [ignor rlc data bl ul due bsn gprs])

----------------------------------------------------

sum(period_duration*60)*50 ; 50 blocks /sec /tsl

[ignor rlc data bl ul due bsn gprs] =

trf_203b

a.ignor_rlc_data_bl_ul_due_bsn * -----------------

trf_203b + trf_204






Unit:

TSL or erlang

Downlink EGPRS erlangs, S11.5 (trf_162f)

Use:

Indicates the amount of resources (timeslots) the DL EGPRS traffic dataconsumes. This information is useful, for example, in estimating the need forcapacity extension.

For area level, this formula should be first collected for all BTSs in the area.Then, the results should be summed up for the area.


Formula (logical):

Actual DL data throughput (blocks)

------------------------------------------------------------- =



sum over mcs1..6 of (

a.dl_rlc_blocks_in_ack_mode

+ a.retrans_rlc_data_blocks_dl

+ a.dl_rlc_blocks_in_unack_mode

)

+ sum over mcs7..9 of (

a.dl_rlc_blocks_in_ack_mode

+ a.retrans_rlc_data_blocks_dl

+ a.dl_rlc_blocks_in_unack_mode

)/2

+ (b.egprs_dl_ctrl_blocks)

------------------------------------------------

sum(b.period_duration*60)*50 ;50 blocks/sec/tsl


a = p_nsbc_coding_scheme

b = p_nsbc_packet_control_unit

Unit:



Network usage KPIs

TSL or erlang

Uplink EGPRS erlangs, S11.5 (trf_161h)

Use:

Indicates the amount of resources (timeslots) the EGPRS traffic data consumes,on average, during the period. This information is useful, for example, inestimating the need for capacity extension. 50 blocks/sec/TSL is used to estimatethe timeslots.

For area level, this formula should be first collected for all BTSs in the area.Then, the results should be summed up for the area.


Formula (logical):

actual UL data throughput (blocks)

-------------------------------------------------------------- =



sum over MCS0..6 of

( a.ul_rlc_blocks_in_ack_mode

+ a.BAD_RLC_VALID_HDR_UL_ACK

+ a.bad_rlc_valid_hdr_ul_unack

+ a.ul_rlc_blocks_in_unack_mode

+ a.bad_rlc_bad_hdr_ul_ack

+ a.bad_rlc_bad_hdr_ul_unack)

+ sum over MCS7..9 of

( a.ul_rlc_blocks_in_ack_mode

+ a.bad_rlc_bad_hdr_ul_ack

+ a.bad_rlc_bad_hdr_ul_unack

+ a.BAD_RLC_VALID_HDR_UL_ACK

+ a.bad_rlc_valid_hdr_ul_unack

+ a.ul_rlc_blocks_in_unack_mode)/2

+ egprs_ul_ctrl_blocks

+ [ignor rlc radio bl ul due bsn egprs]

-------------------------------------------------------------

avg(period_duration*60) x count( distinct period_start_time)

x 50 ; 50 blocks/sec/tsl

[ignor rlc radio bl ul due bsn egprs] =

trf_204

ignor_rlc_data_bl_ul_due_bsn x X x ------------------

trf_203b + trf_204

Where X = 0.5 x A/(A+B) + 1 x B/(A+B)

A = sum over MCS7...9 of (a.ul_rlc_blocks_in_ack_mode +



a.ul_rlc_blocks_in_unack_mode)

B = sum over MCS1...6 of (a.ul_rlc_blocks_in_ack_mode +

a.ul_rlc_blocks_in_unack_mode)


a = p_nbsc_coding_scheme

b = p_nbsc_packet_control_unit

Unit:

TSL or erlang

Uplink signalling TBFs usage ratio, S12 (tbf_61)

Use:

Indicates the percentage of signalling TBFs from the total of all UL TBFs.

Formula:

Sum(ul_tbf_for_signalling)

100* --------------------------------------------

sum(ul_tbf_for_signalling + ul_tbf_for_data)

Unit:

%

Share of EDGE requests, S12 (tbf_65)

Use:

Shows the ratio of timeslot requests where EDGE resources are required. Worksalso if EDGE is not activated in the network.

Formula:

sum(req_1_tsl_ul_for_egprs_ms

+ req_2_tsl_ul_for_egprs_ms







+ req_1_tsl_dl_for_egprs_ms






Network usage KPIs




+ req_8_tsl_dl_for_egprs_ms)

100 * ------------------------------

sum(req_1_tsl_ul

+ req_2_tsl_ul

+ req_3_tsl_ul

+ req_4_tsl_ul

+ req_5_tsl_ul

+ req_6_tsl_ul

+ req_7_tsl_ul

+ req_8_tsl_ul

+ req_1_tsl_dl

+ req_2_tsl_dl

+ req_3_tsl_dl

+ req_4_tsl_dl

+ req_5_tsl_dl

+ req_6_tsl_dl

+ req_7_tsl_dl

+ req_8_tsl_dl)

Unit:

%



4 Congestion KPIs

4.1 PDTCH congestion KPIs

Downlink multislot allocation blocking, S9 (tbf_16)

Use:

If blocking happens regularly, either the territory (CS traffic low) or TCHcapacity (CS traffic high) needs to be expanded.

Note

If the statistics show that there is blocking but no upgrade requests yet, thereason may be that the territory is smaller than defined in the default settings(CS use). The PCU will not make an upgrade request. This is because theCSW side returns the default channels back to the PS territory as soon as theCSW load allows this.

Formula:

sum(NO_RADIO_RES_AVA_DL_TBF)

100 x -------------------------------------------------------- %

sum(req_1_TSL_DL + req_2_TSL_DL + req_3_TSL_DL

+ req_4_TSL_DL + req_5_8_TSL_DL)


p_nbsc_packet_control_unit

Downlink multislot soft blocking, S10.5 (blck_33)

Use:

Indicates the ratio of unserved timeslots requests to all requests in downlink. IfHigh Multislot Classes (HMC) has been activated in the network, formulablck_33a (100-msl_6a) is recommended to be used.



Congestion KPIs

Formula:

100 - msl_6



For the msl_6 definition, see Ratio of served GPRS DL TSL requests, S9 (msl_6).

Downlink TBFs per timeslot, S9 (tbf_38c)

Use:

Indicates how many downlink TBFs there are, on average, per timeslot.

Formula:

sum(aver_tbfs_per_tsl_dl_sum)

-----------------------------------

sum(aver_tbfs_per_tsl_dl_den) x 100



4.2 Abis congestion KPIs

Inadequate EDAP resources in downlink, S11 (dap_7a)

Use:

Indicates time per kilobytes when the available downlink EDAP resources areinadequate.

Indicates the time per gigabytes when the available downlink EDAP resources areinadequate because of the size of the EDAP. The formula may not give correctvalues if:

. the object aggregation level is smaller than the BSC level, and

. one or more BTSs in the area has more than one dynamic Abis poolconnected.


Sum (DL_indadeq_time_minutes) /

Sum (DL GPRS payload_Gbyte + DL EGPRS payload_Gbyte)

=



sum( a.dl_tbfs_with_inadeq_edap_res -

a.dl_mcs_limited_by_pcu) / (50 x 60)

-------------------------------------

sum over BTS with EGENA = Y

( b.rlc_data_blocks_dl_cs1 x 20

+ b.rlc_data_blocks_dl_cs2 x 30

+ sum over MCS-1 (xx) x 22






+ sum over MCS-7 (xx/2) x112

+ sum over MCS-8 (xx/2) x 136


+ sum over MCS-11(xx) x 36


) / (1024 x 1024 x 1024)

where xx = (c.dl_rlc_blocks_in_ack_mode

+ c.dl_rlc_blocks_in_unack_mode)


a = p_nbsc_dynamic_abis


c = p_nbsc_coding_scheme

Unit:

min/GB

Note that minutes here refer to radio timeslot minutes, not to end user minutes.

4.3 PCU congestion KPIs

Territory upgrade rejections due to a lack of PCU capacity, S9 (blck_32)

Use:

Indicates the ratio of territory upgrade requests that result in rejection because ofPCU capacity.

Formula:

sum(gprs_ter_ug_rej_due_lack_pcu)

100 x ----------------------------------%

sum(gprs_ter_upgrd_req)


p_nbsc_traffic



Congestion KPIs

Downlink MCS selection limited by PCU, S11.5 (dap_9)

Use:

Indicates the time per gigabytes when the available downlink EDAP resources areinadequate (for a scheduled downlink TBF in BTSs where EGPRS is enabled)because of PCU capacity. The formula may not give correct values if:

. the object aggregation level is smaller than the BSC level, and

. one or more BTSs in the area has more than one dynamic Abis poolconnected.



Sum (DL_indadeq_time_minutes) /

Sum (DL GPRS payload_Gbyte + DL EGPRS payload_Gbyte)

=

sum (a.dl_mcs_limited_by_pcu) / (50 x 60)

------------------------------------------

sum over BTS with EGENA = Y

( b.rlc_data_blocks_dl_cs1 x 20

+ b.rlc_data_blocks_dl_cs2 x 30












) / (1024 x 1024 x 1024)

where xx = (c.dl_rlc_blocks_in_ack_mode

+ c.dl_rlc_blocks_in_unack_mode)


a = p_nbsc_dynamic_abis


c = p_nbsc_coding_scheme

Unit:

min/GB



4.4 Gb congestion KPIs

Downlink Gb load, S9 (frl_8a)

Use:

Indicates the load percentage of the frame relay bearer for incoming data from theSGSN.

Formula:

sum(8 x (dlci_1_bytes_rec

+ dlci_2_bytes_rec

+ dlci_3_bytes_rec

+ dlci_4_bytes_rec

+ dlci_5_bytes_rec)/(period_duration x 60))

100 x ------------------------------------------------ %

sum per frbc over all unlocked child nsvc

(c_nsvc.committed_info_rate x 16);

frbc object_instance = bearer_id in p_nbsc_frame_relay


p_nbsc_frame_relay



Congestion KPIs

5 PDTCH quality KPIsDownlink GPRS RLC throughput, S10 (trf_235b)

Use:

Indicates the impact of the radio link quality on net data rate per used timeslot,taking into account the retransmissions and coding scheme selection. The lowerthe value, the poorer the radio link quality. This causes retransmissions and theuse of lower coding schemes.

The numerator does not contain the RLC header bytes; neither does the MACheader. This is because the aim is to count the data volume from as close to theuser’s point of view as possible.


GPRS ACK DL payload data in (kilobits)

---------------------------------------- =

GPRS ACK DL time for data transfer (sec)

sum((a.rlc_data_blocks_dl_CS1

- a.rlc_data_blocks_dl_unack) x 20

+ a.rlc_data_blocks_dl_CS2 x 30

+ sum over MCS-11 (b.DL_RLC_BLOCKS_IN_ACK_MODE) x 36

+ sum over MCS-12 (b.DL_RLC_BLOCKS_IN_ACK_MODE) x 50) x 8 /1000

------------------------------------------------------------------

sum (a.rlc_data_blocks_dl_cs1

- a.rlc_data_blocks_dl_unack

+ a.rlc_data_blocks_dl_cs2

+ RETRA_RLC_DATA_BLOCKS_DL_CS1

+ RETRA_RLC_DATA_BLOCKS_DL_CS2

+ sum over MCS-11..12 (b.DL_RLC_BLOCKS_IN_ACK_MODE

+ b.RETRANS_RLC_DATA_BLOCKS_DL)) /50




Unit:

kbit/sec/TSL



PDTCH quality KPIs

Uplink GPRS RLC throughput, S11.5 (trf_233c)

Use:



The denominator is built on the fact that one timeslot can carry 50 RLC blocksper second.


GPRS UL payload ACK data in (kilobits)

----------------------------------------- =

GPRS UL time for ACK data transfer (sec)

sum((a.rlc_data_blocks_ul_cs1

- a.rlc_data_blocks_ul_unack) x 20

+ a.rlc_data_blocks_ul_cs2 x 30

+ sum over MCS-11 (b.ul_rlc_blocks_in_ack_mode) x 36

+ sum over MCS-12 (b.ul_rlc_blocks_in_ack_mode) x 50) x 8 /1000

------------------------------------------------------------------

sum(a.rlc_data_blocks_ul_cs1

- a.rlc_data_blocks_ul_unack


+ a.retra_data_blocks_ul_cs1

+ a.retra_data_blocks_ul_cs2

+ sum over MCS-11..12 (b.ul_rlc_blocks_in_ack_mode

+ b.retrans_rlc_data_blocks_ul)) /50




Unit:

kbit/sec/TSL

Downlink EGPRS RLC throughput, S10 (trf_236)

Use:





Formula:

EGPRS ACK DL payload data in (kilobits)

---------------------------------------- =

EGPRS ACK DL time for data transfer (sec)

(sum over MCS-1 (xx) x 22








+ sum over MCS-9 (xx) x 74) x 8/1000

-------------------------------------

sum over msc1…6 of (yy)/50

+ sum over msc7…9 of (yy)/2/50

where

xx = b.dl_rlc_blocks_in_ack_mode

yy = b.dl_rlc_blocks_in_ack_mode

+ b.retrans_rlc_data_blocks_dl



Unit:

kbit/sec/TSL

Average effective ACK EGPRS Uplink throughput per used TSL, S11.5(trf_234)

Use:




PDTCH quality KPIs


The denominator is built on the fact that one timeslot can carry 50 RLC blocksper second.


EGPRS UL payload ACK data in (kilobits)

--------------------------------------- =

EGPRS UL time for ACK data transfer (sec)

(sum over MCS-1 (xx)*22

+ sum over MCS-2 (xx)*28







+ sum over MCS-9 (xx)*74)*8/1000

---------------------------------------

sum over MCS1..6 of (yy)/50

+ sum over MCS7..9 of (yy)/2 /50

where

xx = b.ul_rlc_blocks_in_ack_mode

yy = b.ul_rlc_blocks_in_ack_mode

+ b.retrans_rlc_data_blocks_ul




Unit:

kbit/sec/TSL

TBF establishment failure ratio, S12 (tbf_66)

Use:

This KPI calculates ratio of failed UL and DL TBFs due to no response from MSto all TBFs (UL and DL).


sum(DL_TBF_Establishment_Failed + DL_EGPRS_TBF_REL_DUE_NO_RESP)

+ sum(UL_TBF_Establishment_Failed + UL_EGPRS_TBF_REL_DUE_NO_RESP)

100 * -----------------------------------------------------------



sum(Nbr_Of_DL_TBF + Nbr_Of_UL_TBF)

Unit:

%



PDTCH quality KPIs

6 Mobility KPIsDownlink flush per minute, S9 (tbf_64)

Use:

Indicates the number of temporary block flows (TBFs) that are interrupted by cellreselections per "TBF minute". Indicates the level of subscriber mobility.


60 x 100 x DL_TBF_REL_DUE_TO_FLUSH/AVE_DUR_DL_TBF_SUM



Unit:

number/min

NCCR success ratio, S12 (nccr_13)

Use:

Ratio of successful NCCRs to total NCCR attempts.


nccr_succ_flush_received

100 * ----------------------------

nccr_1

Unit:

%



Mobility KPIs

7 Availability KPIsData service availability ratio, S9 (ava_68)

Use:

Data service availability (DSA) gives the estimated percentage of on-air GPRS-capable BTSs that are able to provide the GPRS service. Detects outages in theGPRS and EGPRS services. Outages may be caused by a fault in hardware orsoftware.

Note that in some situations the system can generate an 11-bit random accesschannel (RACH) burst without a real mobile station (MS) on the cell. This causestemporary block flow (TBF) establishments in the BSC and also increments thepacket_ch_req counter. Therefore, the limit used in the condition "packet_ch_req>= 100" should be adjusted according to the real network conditions. Often, thevalue of 100 is enough in many cases and should be used as the default setting.This KPI should be used with a 24-hour measurement period. However,excluding maintenance hours at night from the data collection time might help toreduce false triggering.

Formula (logical):

100 x ((1 - Subscriber access outage rate)

x (1 - Number of no data activity case))


100 x

(

1 - (

ava_71

--------------------------------

count(x)

where (a.packet_ch_req >= 100)

)

x

1 - (

ava_72

---------------------------------------------------------------

count(x)



Availability KPIs

where ((b.ave_tch_busy_full + b.ave_tch_busy_half) >= 0.2) and

(b.ave_gprs_channels_sum > 0) and

(c.tch_call_req > 10)

)

)



b = p_nbsc_res_avail

c = p_nbsc_service

Unit:

%



8 User experience KPIsLLC throughput for 4-tsl EDGE MSs, S12 (llc_3a)

Use:

Indicates, on average, successfully transferred kilobits per second when at leastone of the following conditions is met:

. temporary block flow (TBF) duration is longer than four seconds

. logical link control (LLC) bytes are more than 1560


sum(VWTHR_NUMERATOR_EDGE_4_DL) * 8

-------------------------------------

sum(VWTHR_DENOMINATOR_EDGE_4_DL) * 10



Unit:

kbps

LLC throughput for GPRS MSs (for each QoS class), S12 (llc_4a)

Use:

Indicates, on average, successfully transferred kilobits per second when at leastone of the following conditions is met:

. temporary block flow (TBF) duration is longer than four seconds

. logical link control (LLC) bytes are more than 1560



User experience KPIs

Note

Names used from OSS4 CDSet2 ongoing.


sum(VWTHR_NUMERATOR_GPRS) * 8

-------------------------------

sum(VWTHR_DENOMINATOR_GPRS) * 10


p_nbsc_QoS

Unit:

kbps



9 Reference for used formulas

The KPIs described here have been used in the previous benchmark KPIdefinitions.

Average CS traffic, S12 (trf_171a)

Use:

This is a speech (circuit switched) traffic indicator. Speech traffic is a basicindicator needed to see how much TCH capacity is consumed. When the trafficincreases without the increase in capacity, the probability of blocking increases.The relationship between traffic, capacity and blocking is described for speechtraffic in the formula known as Erlang B. This KPI includes all types of CS traffic(single TCH, HSCSD, DTM).


trf_202a ; CS traffic on normal TRXs

+ trf_170 ; CS traffic on extended TRXs

Unit

E

Average CS traffic, extended TRXs, S12 (trf_170)

Use:

This is a speech (circuit switched) traffic indicator. Speech traffic is a basicindicator needed to see how much TCH capacity is consumed. When the trafficincreases without the increase of the capacity, the probability of blocking grows.The relationship between traffic, capacity and blocking is described for speechtraffic in the formula known as Erlang B. This KPI includes all types of CS traffic(single TCH, HSCSD) on extended TRXs.




Reference for used formulas

sum(decode(trx_type,1,ave_busy_tch))

-----------------------------------

avg(decode(trx_type,1,res_av_denom14)) * count(distinct period_start_time)


p_nbsc_res_avail

Unit

E

Average CS traffic, normal TRXs, S12 (trf_202a)

Use:

This is a speech (circuit switched) traffic indicator. Speech traffic is a basicindicator needed to see how much TCH capacity is consumed. When the trafficincreases without the increase in capacity, the probability of blocking grows. Therelationship between traffic, capacity and blocking is described for speech trafficin the formula known as Erlang B. This KPI includes all types of CS traffic(single TCH, HSCSD, DTM) on normal TRXs.


tcount(distinct period_start_time) *

(

sum(decode(trx_type,0,a.ave_busy_tch))

-------------------------------------

avg(decode(trx_type,0,a.res_av_denom14))

+

sum(decode(trx_type,0,((0.5*b.DTM_duration_sum_HR

+ b.DTM_duration_sum_FR) /100)))

-------------------------------------------------

avg(decode(trx_type,0,(period_duration*60)))

)


a = p_nbsc_res_avail

b = p_nbsc_ps_dtm

Unit

E



DL DTM PS payload, S12 (dtm_5)

Use:

DL payload (GPRS plus EDGE) is generated by DTM PS connections.


(sum(a.DL_RLC_CS1_BLKS_TO_DTM_MS*20 + a.DL_RLC_CS2_BLKS_TO_DTM_MS*30) +

sum over MCS-1 (xx*22) +






sum over MCS-7 (xx/2) * 112 +




sum over MCS-12 (xx*50))/1024

where xx = (b.DL_RLC_MCS_N_BLKS_TO_DTM_MS)




Unit

kbyte

Ratio of served GPRS DL TSL requests, S9 (msl_6)

Use:

Indicates the ratio of timeslot allocations to requests in downlink.

Formula:

sum(alloc_1_TSL_DL + 2 x alloc_2_TSL_DL

+ 3 x alloc_3_TSL_DL

+ 4 x alloc_4_TSL_DL)

100 x -------------------------------------------------------------------- %

sum(req_1_TSL_DL + 2 x req_2_TSL_DL + 3 x req_3_TSL_DL + 4 x req_4_TSL_DL)






Total NCCR attempts, S11.5 (nccr_1)

Use:

Total NCCR attempts include an attempt when any of the NCCR triggers isfulfilled.


sum(

a.NCCR_NOT_STARTED_DUE_AC

+ b.NCCR_QC_TRIG_NO_GOOD_NEIG

+ b.NCCR_SERV_ISNCCR_NO_GOOD_NEIG

+ a.PCCO_TO_GPRS_MS_DUE_PWR_BDGT

+ a.PCCO_TO_EGPRS_MS_DUE_PWR_BDGT

+ a.PCCO_SENT_DUE_SERV_ISNCCR

+ a.PCCO_SENT_DUE_COVERAGE_ISNCCR

+ a.PCCO_SENT_DUE_QUAL_CTRL

)


a = P_NBSC_CELL_RESELECTION

b = P_NBSC_PACKET_CONTROL_UNIT

Unit

#

UL DTM PS payload, S12 (dtm_4)

Use:

UL payload (GPRS plus EDGE) generated by DTM PS connections.


(sum(a.UL_RLC_CS1_BLKS_FROM_DTM_MS*20 + a.UL_RLC_CS2_BLKS_FROM_DTM_MS*30) +











sum over MCS-12 (xx*50))/1024

where xx = (b.UL_RLC_MCS_N_BLKS_FROM_DTM_MS)






Unit

kbyte

Uplink GPRS RLC blocks, S10 (trf_203b)


Actual UL data blocks

Sum (a.rlc_data_blocks_ul_cs1 + a.rlc_data_blocks_ul_cs2

+ sum over MCS-11 (b.ul_rlc_blocks_in_ack_mode

+ b.ul_rlc_blocks_in_unack_mode)

+ sum over MCS-12 (b.ul_rlc_blocks_in_ack_mode

+ b.ul_rlc_blocks_in_unack_mode))




Unit

Number of blocks

Uplink EGPRS RLC blocks, S10 (trf_204)


Actual UL data blocks

sum over MCS1-9 of

(ul_rlc_blocks_in_ack_mode + ul_rlc_blocks_in_unack_mode)



Unit

Number of blocks

Subscriber access outage rate, S9 (ava_71)

Use:




Subscriber access outage rate is triggered when a significant number of packet-switched service attempts are made on the BTS, but none of the attempts aresuccessful. Note that when Subscriber access outage rate is triggered, it indicatesa hardware or software fault that causes GPRS/EGPRS service outage.


count(x)

where (packet_ch_req > 100) and

(nbr_of_ul_tbf + no_radio_res_ava_ul_tbf) > 80 and

(ave_dur_ul_tbf_sum = 0 or ave_dur_dl_tbf_sum=0))



Unit

Number of attempts

Number of no data activity cases, S9 (ava_72)

Use:

Number of no data activity cases is triggered when a fair amount of traffic issetting up on a GPRS-capable BTS but no packet-switched service attempts arebeing made. If there are no dedicated GPRS radio timeslots (RTLSs), Number ofno data activity cases might be pegged if the peak number of circuit-switchedRTSLs equals the maximum number of traffic channels and GPRS RTSLs duringall packet-switched connection attempts within the measurement period.

Note that the triggering of Number of no data activity cases indicates a problemwith the SYSTEM INFORMATION TYPE 13 message where mobile stations ignorethe BTS/SEG for packet-switched connections.


count(x)

where (a.ave_tch_busy_full + a.ave_tch_busy_half) >= 0.2 and

(a.ave_gprs_channels_sum > 0) and

(b.packet_ch_req = 0 and c.tch_call_req > 10)


a = p_nbsc_res_avail


c = p_nbsc_service

Unit

Number of cases



10 Traffic monitoring principles

Once the network has been dimensioned, the network planning, implementation,and optimisation phases follow. Network planning typically includes a detailedconfiguration and parameter plan, where features are planned in detail. Networkmonitoring is a part of a typical optimisation process. It can be used to veritywhether the original dimensioning assumptions were correct. Traffic monitoringis used to trigger a network configuration change when the amount of traffic ishigher or lower than assumed in the original dimensioning.

To perform monitoring, we can use the values of the counters implemented in thenetwork element or some formulas involving several of these counters. Ingeneral, performance indicators (PIs) and key performance indicators (KPIs) aredefined.

A KPI is a value that presents some vital information about the network. TheKPIs are mapped directly from PIs, a formula of several PIs, or directly fromnetwork counters.

Measurements

In Nokia BSS, the BSC is responsible for traffic measurements. Eachmeasurement type can activate a certain amount of counters, and eachmeasurement has to be activated for all required BSCs. Typically, measurementsprovide data for all BTSs under the BSC. In addition to measurements,observations can be used for data collection. Observations are specialmeasurements for a limited number of network objects. Observations typicallyprovide a large amount of data. Measurements and observations are divided intothe following groups according to their function:

. Call control measurements (CSW)

. GPRS measurements (PSW)

. Transmission measurements

. Observations

The following are EGPRS measurements:



Traffic monitoring principles

. 72 Packet control unit measurement

. 73 RLC blocks per TRX measurement

. 74 Frame relay measurement

. 76 Dynamic Abis measurement

. 79 Coding scheme measurement

. 90 Quality of Service measurement

. 91 PBCCH availability measurement

. 95 GPRS cell reselection measurement

. 96 GPRS RX level and quality measurement

. 97 Enhanced Quality of Service measurement

. 98 Gb over IP measurement

Some of the above-mentioned measurements are related to optional features andare not useful if the feature has not been activated.

When BTS/BSC expansion needs are evaluated, monitoring both CSW and PSWtraffic is required. There are several CSW related measurements, but mostimportant for EGPRS are the following:

1. Traffic measurement

2. Resource availability measurement

3. Resource access measurement

4. Handover measurement

KPIs

The operator needs KPIs to monitor the performance of the network, totroubleshoot failures, and to ensure that the end user has the best possibleperception of the service. To improve the performance of the network it istherefore important to check how the network is performing. This can be done bylooking into different key performance indicators and setting the criteria for thenetwork improvement or deciding when to increase capacity.

EDGE KPIs are also available in the NetAct Reporter tool.



Related topics

. BTS EDGE dimensioning

. Abis EDGE dimensioning

. BSC EDGE dimensioning

. Gb EDGE dimensioning

. SGSN EDGE dimensioning



Traffic monitoring principles

nokia bss12 edge and gprs key performance indicators

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