1. RNO Wind
Part III

2. Part III - Content Call Setup Time UL Interference PS Utilization
Cell Reselection

3. Call Setup Time

4. Call setup Time – Preamble PRACH
During drive testing can be noted that there are call setup failures where the network does not seem to respond to RRC Connection Requests with RRC Connection Setup –message.These are problems due to the spiky UL noise and due to that the power ramping is not aggressive enough to provide high enough Tx power for the terminal during open loop PC
PowerOffsetLastPreamblePRACHmessage
L1ACK/AICH
PtxAICH
Downlink / BS
PowerRampStepPRACHpreamble
UEtxPowerMaxPRACH …. ….
PRACHRequiredReceivedCI
Uplink / UE
Preamble 1
Preamble n
RACH
Message part
PRACH_preamble_retrans: The maximum number of preambles allowed in one preamble ramping cycle
RACH_tx_Max: # of preamble power ramping cycles that can be done before RACH transmission failure is reported,
Note: The power ramp-up process will continue until
1) A positive or negative AI is received from the network
2) RACH_tx_MAX value is reached
3) UE reaches UEtxPowerMaxPRACH value

5. Call setup Time – Preamble PRACH
The parameters affecting to open loop power control are, in brackets are the recommended values:
PRACH_preamble_retrans (7)
RACH_tx_Max (16)
PowerOffsetLastPreamblePRACHmessage (2 dB)
PowerRampStepPRACHpreamble (2dB)
The PRACHRequiredReceivedCI (-20dB) allow to calculate the UEpower for the fist preambleas in the
following:
Ptx = CPICHtransmissionPower-RSCP(CPICH) +RSSI(BS) + PRACHRequiredReceivedCI (-20dB)
Example:
CPICH = 33dBm (Parameter per Node-B)
RSCP = -80dBm (Measured by UE)
RSSI = -85 dBm
UL_Required_C/I = -25 dB (Parameter per Node-B)
UE PRACH First Preamble Power = 33 dBm – (-80 dBm) + (-85
dBm) + (-25 dB) = 8 dBm
The parameter PRACHRequiredReceivedCI can be set to -18…-20dB instead of the default -25dB (typically -20dB is enough)

6. Call setup Time – Preamble PRACH
Typical improvement passing from -25dB to -20dB:
Clear improvement in number of needed RRC Connection Request messages per call. For –20dB 100% of established calls are setup with only 1 RRC Connection Request message
Clear improvement number of sent preambles per RRC Connection Request for –20dB case. For –20dB 50% of cases the needed number of preambles is <=4 where as for –25dB it is ~6.5
There should be significant improvement also for call setup delay

7. Call setup Time – Preamble PRACH
The average number of acknowledged PRACH preambles during the RRI period can be calculated based on the KPI below
RACH load due to preamble can then be calculated by dividing the above further by the max number preambles can be received during RRI
For example if RRI period is 200ms the are 10 20ms RACH frames and in each 20ms RACH frame there are 15 RACH sub slots within each it is possible to receive and decode max 4 preambles -> therefore in 200ms it is possible to receive 15*4*10=600 preambles

8. Call Setup Time – SRB Rate
Why 13.6kbit/s?
Use of 13.6 kbit/s SRB also in highly loaded networks
Decreased setup times (PDP context activation minimum 0.7s lower)
Improved Iub efficiency
Typical improvement passing from 3.4 to 13.6

9. Call setup Time – KPI
In RN2.2 the following counters are available to monitor the Call Setup Time
RRC Setup Time
M1001C221/M1001C222
RAB Setup Time
M1001C223 / M1001C for CS
M1001C235 / M1001C for DATA BACKGR
In detail we have:
M1001C221 - SUM OF RRC SETUP TIMES
Sum of RRC setup times. This counter divided by the DENOMINATOR - M1001C222 gives the average
RRC setup time. RRC setup time is defined as the time between the RRC: RRC CONNECTION REQUEST
message and the RRC: RRC CONNECTION SETUP COMPLETE message.
M1001C223/235 - SUM OF RAB SETUP TIMES FOR CS VOICE/FOR DATA BACKGR
Sum of RAB setup times. This counter divided by the DENOMINATOR - M1001C224/236 gives the average
RAB setup time. RAB setup time is defined as the time between the RANAP: RAB ASSIGNMENT
REQUEST and RANAP: RAB ASSIGNMENT RESPONSE messages during RAB establishment.

10. Call setup Time – Annex1
Average paging delay of 320 ms assumed (640 ms paging cycle)
Typical value for CS Call Setup Time
Parallel RB setup for MO-UE and paging of MT-UE (CS core feature)
RACH/FACH
RACH/FACH
<3.0 s mobile-to-mobile AMR call setup time

11. Call setup Time – Annex2 Typical value for PS Call Setup Time
Common channels used for setup to avoid slow synchronized reconfigurations later
Parallel RB setup and RL/AAL2 setups (or pre-reserved Radio links)
RACH/FACH
Initial bit rate DCH allocated directly together with SRB
<1.6 s PS call setup time

12. UL Interference

13. What’s Interference?
PrxTarget [dB] + PrxOffset [dB]
Overload Area
Wideband power level Itotal
Prx Target [dB]
Marginal Load Area
Feasible Load Area
LRT  UnloadedRT and LNRT  UnloadedNRT
Unloaded Area
Own cell load factor 
Any working point turned off from the expected load curve can be considered as interference.
Interference can be internal or external.
Internal interference can be caused by not appropriate dimensioning, planning or commissioning
External is usually referred to mobile or other RF sources

14. Load vs. Power
Typical mismatch among load and Power can be easily found in a live network.
Above is reported a qualitative behaviour in class_1 power for some Wind WBTSs that are experiencing a 1<rt_load<2 (rt_load relative value from 0 to 4) and the related nrt_load and Prx_power.
The nrt load added to rt can not give sense of the Prx spike

15. NSN Load Areas & Class of Power
PrxTarget [dB] + PrxOffset [dB]
Overload Area
Class4
Prx Target [dB]
Marginal Load Area
Class3
Wideband power level Itotal
Feasible Load Area_2
Class2
PrxTarget [dB] - PrxOffset [dB]
Feasible Load Area_1
Class1
LRT  UnloadedRT and LNRT  UnloadedNRT
Unloaded Area
Class0
Own cell load factor 
CLASS
AREA
INCREMENTED IF
CLASS 0
Unloaded
(Lrt=<UnloadedRT) AND (Lnrt=<UnloadedNRT)
CLASS 1
Feasible_Load_Area_1
(PrxTarget -PrxOffset >= PrxTotal ) AND ((Lrt>UnloadedRT) OR (Lnrt>UnloadedNRT))
CLASS 2
Feasible_Load_Area_2
(PrxTarget > PrxTotal > PrxTarget -PrxOffset) AND ((Lrt>=UnloadedRT) OR (Lnrt>= UnloadedNRT))
CLASS 3
Marginal_Load_Area
(PrxTarget + PrxOffset > PrxTotal >=PrxTarget) AND ((Lrt>UnloadedRT) OR(Lnrt> UnloadedNRT))
CLASS 4
Overload_Area
(PrxTotal >= PrxTarget + PrxOffset) AND ((Lrt>UnloadedRT) OR (Lnrt>UnloadedNRT))

16. UL Interferece Detection Method
Different approach can be applied to detect UL interference.
Mainly we have:
- Field measurement
- Counters Analysis
Using the Counters Analysis approach dedicate counters are available for UL Interfernce detection as MAXPrxNoise and MINPrxNoise (M1000C12 and M1000C13)
The UL interference severity can be estimated by analysing: MAXPrxNoise – MINPrxNoise, but these counters are incremented only when cell is unloaded.
Here we propose a line for a method that approximately return the WBTS interfered.
The method takes the basis from the autotuning algorithm and use the value of Prx returned to detect the interfered cell.
The first step is the localization of reference point for each class
Then different kind of statistical model can be applied for evaluating the drawn from them
Finally a w.w.w concept is used to derive information from space and time recurrence
Some help could come from counters that trigger downgrade or release bocause of interference (e.g. M1000C147RB_DOWNGR_DUE_PBS_INTERF M1000C159RB_RELEASE_DUE_PBS_INTERF if PBS is enabled)

17. Wideband power level Itotal
Prx Autotuning
The auto-tuning algorithm moves the reference point of the load curve and this means that all the areas can be shifted up and down during the day this means that a certain value of PrxTotal (which is measured by the bts) may trigger different areas during the day. For example the sample 4 triggers in the first case the class 2 while in the second case the class 1, but it’s the same value of power!
Main idea is to use this gap to detect interference t0 t1
Prx Target_t0 [dB]
Prx Target_t1 [dB]
Overload Area
Wideband power level Itotal
Marginal Load Area 4 4
Feasible Load Area 2
Feasible Load Area 1
Unloaded Area
Time

18. Class Power Reference Point
It is not an easy task to find the expected value of Prx in each class.
Different masking effect are present either for the granularity of the measurement available that are not appropriate for this kind of analysis or for the inherent difficulty in evaluating the real load experienced.
Here a shot for class1 considering the stay time in the class is attempted
The spike are more accentuated for low permanence and diluited for the high one
Prx Displacement
Prx Displacement
An average can be attempted filtering off the spike and the default value

19. Power Class Distribution Function
Probable Interfered
WCEL
Probable Interfered
WCEL
Here a Prx Distribution over the all WCELs is presented. Typical value of the reference point are represented individuating areas where interference can be detected.
The different shape of the curve of the Feasible_Load_Area_2 and the Marginal_Load_Area_2 respect to the Class_0, Class_1 and Class_4 seems due to the different behaviour of the algorithm.
The step visible in C2 and C3 could be due to the strict margin in term of Power Budget to react to the load increase. The overshoot of the C0 curve over the C1 is due to to the different triggering condition that for C0 is load based instead of Power Level driven.
Finally C1 having a greater budget maintain a smoother shape.

20. W.W.W. Approach
stable interference for a adjacent cluster of cell +
F_time
Commissioning /
Dimensioning
Fixed Ext. Source - +
F_space
Adj missing
Mobile Ext. Source -
periodical spot interference
A single interfernce event can not raise any relevant bother. A statistical analysis is needed. The Who? When? Where? approach is used to derive information and troubleshoot the probable interferer source. The space-time diagram has to be intended as a recurrence indicator for the interference event. In the left side of the F_space axis are reported occurences not adjoined in space. Same concept for F_time.

21. Class 0
Class0 can act as the third dimension of the WWW Approach diagram.
Considering Class0 as the unlaoded class in the sense that the unloaded limit for RT and NRT (1% and
2% respectively) is not exceeded the interference detection in this class can have two advantages:
More interference sentivity because of low load
Easier discrimination between internal and external interference
The first point is assured by the triggering condition and can be strenghtened superimposing a second
condition over the load.
Imposing the LoadRT = 0 and LoadNRT = 0 we have more reliable result for interference
This condition triggered mainly during the nigh-time returns the possibility to have an easier
troubleshooting

22. PS Utilization

23. Traffic Mix KPI
The KPI provides an indication of the percentage of CS voice, CS data, PS data RAB establishment attempts relative to the total number of RAB establishment attempts
The KPI is meaningful for cluster/cell level and on day/hour basis. Same KPI can be obtained using RAB ACC COMP
These KPI are intended to provide a high level indication of the traffic profile loading the network:
CS_VOICE
CS_CONV
CS_STREA
PS_CONV
PS_STREA
PS_INTER
PS_BACKG
Example for CS_VOICE:
To take into consideration that PS might cause many attempts in each call another option is to consider the duration counters!

24. Traffic Mix KPI For each Traffic Class Only for NRT Traffic Class
For each traffic class there are counters for RAB Holding time (incremented when the RAB is released only on the cell that was the reference when the RAB is released)
If a distribution on cell level is required the RAB_HOLD_TIME_IN_REF_CELL can be used
For NRT traffic classes (inter and backg) there are also counters for DCH Holding time (incremented when the RAB is released only on the cell that was the reference when the RAB is released)
For each
Traffic Class
Only for
NRT Traffic Class

25. From Cell_DCH to Cell_FACH
RLC buffer payload (transport channel traffic volume)
CELL_FACH state
CELL_DCH state UE
CELL_ DCH
CELL_ FACH
InactivityTimerUL(DL)DCH
After the inactivity timer expires the RRC radio bearer reconfiguration–procedure is performed.
RRC sends an RRC: RADIO BEARER RECONFIGURATION message to the UE.
UE acknowledges by sending the RRC: RADIO BEARER RECONFIGURATION COMPLETE –message to the
RRC signaling entity of the RNC which starts L2 reconfiguration (as well as PS is informed about the
cell state change).
Radio link and AAL2 resources are then released and UE is changed to CELL_FACH state.
In case the UE is having RT RB which has become inactive and at the same time it is having inactive
NRT RB then RADIO BEARER RELEASE procedure is used (instead of RADIO BEARER RECONFIGURATION).

26. From Cell_FACH to Cell_DCH
RLC buffer payload (transport channel traffic volume)
CELL_ FACH
CELL_ DCH UE
CELL_DCH state
TrafVolThresholdDL(UL)High
TrafVolThresholdDL(UL)Low
(WCEL)
CELL_FACH state
In uplink direction the need for the capacity is detected by the MAC of UE.
UE requests dedicated capacity by sending an RRC: MEASUREMENT REPORT message on RACH to the
RRC signaling entity of RNC
After the procedure, data transmission on DCH can begin and UE is in CELL_DCH state.
In downlink direction the capacity need is detected by the UE MAC entity of RNC.
PS requests the RRC signaling entity of RNC to start transport channel reconfiguration –procedure
The RRC signaling entity sends an RRC: TRANSPORT CHANNEL RECONFIGURATION message to the UE
on FACH, which is acknowledged with an RRC: TRANSPORT CHANNEL RECONFIGURATION COMPLETE

27. Cell-DCH/Cell-FACH KPIs
Percentage of time in cell dch:
Similar KPI giving the ratio between FACH and DCH can be constructed starting from
M1006C90 SUM OF UE OPERATING TIME IN CELL_FACH
M1006C87 SUM OF UE OPERATING TIME IN CELL_DCH
Dividing per the number of UE is possible to have average time for user:
M1006C90 SUM OF UE OPERATING TIME IN CELL_FACH/M1006C92 NUM OF UE MEASURED IN CELL_FACH
M1006C87 SUM OF UE OPERATING TIME IN CELL_DCH / M1006C89 NUM OF UE MEASURED IN CELL_DCH
The number of transition can be monitored as well:
M1006C45 CELL DCH STATE TO CELL FACH
M1006C46 CELL FACH STATE TO CELL DCH
CELL_FACH
CELL_DCH
CELL_FACH
Uplink DCH
Downlink DCH
NRT RB data transfer active
NRT RB inactivity timer running

28. Measuring the RACH/FACH Channel
The RACH channel average throughput for both data and signaling can be measured by the following KPI
The FACH Total throughput means all the user related data (FACH-u) and signalling (FACH-c) for a SCCPCH
including PCH can be measured by the follwing KPI
Load KPI are available as well using the following counters
M1000C64 AVE SCCPCH INC PCH LOAD
M1000C65 SCCPCH LOAD DENOM 0
When the throughput approach the maximum allowed or the load the 100% for the actual configuration a
parameter tuning to avoid the starvation in CCH or an expansion of RACH and FACH channel is required. The
decision outcomes from different input:
DCH resources available
Marketing Strategy

29. Cell Reselection

30. Cell Reselection 2G -> 3G
Cell Reselection List
BCCH: FDD_Qmin, FDD_Qoffset
GSM MS starts WCDMA measurements if :
RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7 or
RLA_C> F(Qsearch_I) for 7<Qsearch_I<=15
Start
measurement
If, for suitable UMTS cell & for a period of 5 s:
CPICH RSCP > RLA_C + FDD_Qoffset
WCDMA cell reselection
and
CPICH Ec/No  FDD_Qmin

31. 2G -> 3G Measurement
Depending on operator´s 2G – 3G interworking strategy parameter Q_search_I should planned accordingly.
In the best case, 3G cell measurements are possible when RLA_C level < –74 dBm
In the best case, 3G cell measurements are restricted to the condition:
RLA_C level > –78 dBm
GSM
GSM 3G 3G 3G
GSM
Configuration 1
RLA_C< F(Qsearch_I)
( 0<Qsearch_I<=6 )
Configuration 2
RLA_C> F(Qsearch_I)
( 7<Qsearch_I<=15 )
Configuration 3
RLA_C<  (always). (Qsearch_I=7)

32. 2G -> 3G Cell Re-selection Parameters
Qsearch_I and Qsearch_P define the threshold for non-GPRS/GPRS (respectively) capable UEs to measure 3G
neighbour cells when a running average of the received downlink signal level (RLA_C) of the serving cell
below (0-7) or above (8-15) the threshold
Value 1 … 6 7 8 9 10 14 15
dBm
-98
-94
-74
Always
-78
-70
-54
Never
UE always measures 3G cells
If RLA_C > -70 UE starts 3G measurements
If RLA_C < -94 UE starts 3G measurements
FDD_Qoffset and FDD_GPRS_Offset the non-GPRS/GPRS (respectively) capable UEs add this offset to the
RLA_C of the GSM cells. After that the UE compares the measured RSCP values of 3G cells with signal levels
of the GSM cells
Value 1 2 3 … 8 14 15
dBm
Always
-28
-24
-20 24 28
Always select irrespective of RSCP value
Reselect in case RSCP > GSM RXLev (RLA_C) +28dB
FDD_Qmin, defines minimum Ec/No threshold that a 3G cell must exceed, in order the UE makes a cell reselection from 2G to 3G.

33. Cell Re-selection Example-Weaker WCDMA Non GPRS case
RSCP/
RLA_C
Ec/No
Cell re-selection to WCDMA
Serving GSM Cell
RLA_C
Qsearch_I=0
(-98 dBm)
FDD_Qoffset =6 (-8 dB)
Measurements starts (serving cell)
FDD_Qmin=0
(-20 dB)
RSCP
Neighbour WCDMA Cell
Ec/N0
Minimum Quality Requirement for WCDMA t
5 sec.

34. Cell Re-selection Example-Weaker WCDMA GPRS case
RSCP/
RLA_C
Ec/No
RLA_P
Cell re-selection to WCDMA
FDD_GPRS_Qoffset =10 (8 dB)
Serving GSM Cell (Best)
Qsearch_P=0
(-98 dBm)
RSCP
Measurements starts (serving cell)
FDD_Qmin
=-20 dB
Neighbour WCDMA Cell
Ec/N0
Minimum Quality Requirement for WCDMA t
5 sec.

35. Cell Reselection 3G -> 2G
Whilst camping in a 3G cell the UE performs intra-frequency, inter-frequency, and inter-system
measurements based on the measured CPICH EcNo.
Serving cell parameters Sintrasearch, Sintersearch and SsearchRAT are compared with Squal (CPICH Ec/No – Qqualmin) in S-criteria for cell re-selection
1 - None (Squal > Sintrasearch )
2 - WCDMA intra-frequency (Sintersearch < Squal  Sintrasearch)
3 - WCDMA intra- and inter- frequency, no inter-RAT cells (SsearchRAT < Squal  Sintersearch)
4 - WCDMA intra- and inter-frequency and inter-RAT cells (Squal  SsearchRAT )
Sintrasearch
Sintersearch
SsearchRAT
WCDMA
CELL 1 2 3 4

36. Cell Reselection 3G -> 2G
UE starts GSM measurements if
CPICH Ec/No =< qQualMin + sSearchRAT
CPICH EcNo
Serving WCDMA cell
calculation, with
hysteresis parameter
SintraSearch
First ranking of all the cells based on
CPICH RSCP (WCDMA) and RSSI (GSM)
Rs = CPICH RSCP + Qhyst1
Rn= Rxlev(n) - Qoffset1
SinterSearch
Neighbour WCDMA or GSM
cell calculation with offset
parameter
SsearchRAT
qQualMin
Rn (GSM) > Rs (WCDMA)
And
Rxlev (GSM) >QrxlevMin No
Yes
Second ranking only for WCDMA
cells based on CPICH Ec/No
Rs = CPICH Ec/No + Qhyst2
Rn=CPICH_Ec/No(n)-Qoffset2
Cell re-selection
to GSM
Cell re-selection to
WCDMA cell of highest
R value

37. Cell Reselection 3G -> 2G
UE ranks the serving cell and the measured neighboring cells to find out if reselection should be made
All the measured suitable cells (S-criteria) are included in the ranking.
Criteria for a suitable cell (S-criteria) is defined as
WCDMA intra-frequency neighbour cell:
CPICH Ec/No > AdjsQqualmin and CPICH RSCP > AdjsQrexlevmin
WCDMA inter-frequency cell:
CPICH Ec/No > AdjiQqualmin and CPICH RSCP > AdjiQrexlevmin
GSM cell:
Rxlev > Qrxlevmin
Ranking is done using Criteria R, and the UE reselects to the cell with highest R-criteria. R-criteria is defined
as:
For serving cell: Rs = Qmeas,s + Qhysts
For neighboring cell Rn = Qmeas,n – Qoffsetts,n
Qmeas is CPICH Ec/No for WCDMA cell and RxLev for GSM cell

38. How to avoid ping pong ?
When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of serving cell is below Ssearch_RAT + QqualMin.
When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of the candidate is above FDD_Qmin.
Therefore, to avoid ping pongs between 3G and GSM the following condition should be met:
FDD_Qmin >= QqualMin + Ssearch_RAT
CPICH Ec/Io
FDD_Qmin >= -12 dB
QqualMin +Ssearch_RAT
Ssearch_RAT=4 dB
QqualMin=-18 dB
Camping on 3G
Measure GSM
Camping on 3G t

39. How to avoid ping pong ? Parameters for cell reselections
Qqualmin = -18dB Ssearch_RAT =2dB -> the 3G->2G cell reselection starts when Ec/No hits -16dB
FDDQmin(GPRSFDDQmin) = -14dB (6) and QsearchP/QsearchI = always
The cell reselection paramters 3G -> 2G and 2G -> 3G provide only 2dB hysteresis which is not enough and should be noticed from the RNC statistics as high amount of INTR_RAT_CELL_RE_SEL_ATTS from all the RRC Connection Setup Attempts
Recommendation is to adjust the FDDQmin from -14dB to -10dB (or even up to -8dB) to provide 6 to 8 dB hysteresis between 3G to 2G cell reselection and 2G to 3G cell reselection
Another parameter to tune is Qrxlevmin
On top of Treselection the above parameters will slow down further the 2G to 3G and 3G to 2G cell reselections

40. Treselection
How long the reselection conditions must be fulfilled before reselection is triggered?
Treselection
Impacts all cell reselections : Inter RAT, intra frequency and inter frequency
The UE reselects the new cell, if the cell reselection criteria (R-criteria, see next slide) are fulfilled during a time interval
As this parameter impacts on all the cell reselections too long Treselection timer might cause problems in high mobility areas but too short timer causes too fast cell reselections and eventually causes also cell reselection ping pong
Recommended value 1s should work in every conditions i.e. enough averaging to make sure that correct cell is selected
However careful testing is needed to check the performance of different areas
(Dense) Urban area, slow moving UEs with occasional need for fast and accurate (to correct cell) reselections e.g. outdoor to indoor scenarios or city highways – in some cases cell by cell parameter tuning is performed to find most optimal value between 0s and 2s but typically 1s is optimal value when workload is considered as well
Highways, fast moving UEs must reselect correct cell – typically 1s works the best (however occasionally also 0s might be needed in fast speed outdoor to indoor cell reselections e.g. tunnels)
Rural areas, slow or fast moving UEs need very often reselect between different RATs and make proper cell reselections even when the coverage is poor – typically 1s works the best
Location Area Borders, usually the coverage is fairly poor – typically 1s works the best but sometimes to reduce location area reselection ping pong 1s is used when going from LA1 to LA2 and 2s from LA2 to LA1

41. Cell Reselection KPIs
RRC connection request amount for inter RAT cell reselection ratio to all RRC Connection request causes
When hysteresis is increased this KPI should decrease
RRC connection request amount for registrations ratio to all RRC Connection request causes