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• RAS06 with RU10 experience 
• HSDPA optimization experience 
• Nokia 3G, HSPA advanced parameterization experience 
• Experience with Report Builder and Report Explorer mandatory 
• Broad band optimization experience 

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Drive Test Procedure Part VI

Idle Drive is performed in two fashion 

•Normal Drive 
•Frequency Lock Drive 

Normal Drive 

This is done to frame the potential area of the new site planned. It also helps us to 
get to know the important neighboring sites for which the handover has to take place. 

Frequency Lock Drive 

This is done by locking the BCCH frequency of the serving cell and performing the 
drive for the same cell unless the mobile enters into No Service Mode. This is use- 
ful for making decision related to GSM antenna height, tilt, and orientation.

Dedicated Drive

Dedicated drive is an important part of Drive Test. Here call is made to a test number and drive is done for the potential areas of the Site. During drive being carried out one has constantly monitor parameters such as RX Level, RX Quality, SQI, DTX, C/I Ratio, Hopping Channel, Neighbor list, TA (Timing Advance). 
Constant changes in these parameter are helpful for post Optimization of the site.

Rules during drive test:

1- Choose the site under surveying to be above the clutter and repeat types of the clutter you would be looking at.
2- Any thing with clutter less than 100 is not enough.
3- Make sure that the GPS surveying option is the same as the one used where the drive test is being performed.
4- Make sure that the Dautch value of the GPS is the same as the one set for the country where the drive test is being made.
5- Better collect data in the format of, Degrees: Decimal Points Degrees.
6- Every 6 degrees you move result is one point change in the whole picture the UK being the reference point at 30, To the left it increases and to the right it decreases.
7- Sampling rate, 40 Samples per 40 wavelengths. To reduce the effect of Radio fading.
8- Sampling can be in Distance and Time. Better do it in Distance especially if you are driving in traffic jams.
9- Do not drive away too much from the site.
10- Drive in to the Site passing through the clutter as well as crossing the clutter
11- Try and drive many roads close to the site unless the clutter is so important.
12- Try to avoid driving the same road twice.
13- Do not drive over a bridge or in to a tunnel inside a clutter area, otherwise take that parts of data a out of the data file collected for this clutter.
14- Make short calls and Long calls, Short calls is the average duration by customers, short calls are to know whether calls will survive the setup and the termination successfully, it also determines the setup time…
15- Long calls are to test the hand over capabilities.
16- Adjacent channels are channels with coverage of 9db more than the serving cell.
17- The co-channel interference is interference from channels have frequency lower the serving channel.
18- For the adjacent channel you could be served from this adjacent channel but the system can not read it and it gives the name of another channel
19- The 6 neighboring cells are those who are listed in the scan list these do not mean that these are the only channels that the phone can see.
20- You have to make sure of the values you are getting out of the surveying equipment do actually make sense.
21- Know the exact power out of the antenna, ERP level, (Effective Radiation Power).
22- Everything about the antenna conditions, during the test time should be reported in the final report.
23- Weather conditions should be reported as well.
24- Know the distance and direction of any buildings blocking your way.
25- Finally, report all sorts of problems.

Drive Test Procedure Part V

TRX Test

TRX Test is done to check whether calls originated are being handled by all the TRX’s. Call made during the process is tracked by the MAIO number displayed on the screen for all the TRX’s.

E.g. for Site of configuration 6 TRX per sector the MAIO values for TRX test shall be 0,1,2,3,4. Call can be originated on the BCCH or the TCH frequencies. Hence MAIO values will be reflected only for calls on TCH frequency and not on BCCH frequency.

Drive Test Procedure Part IV

GPRS (General Packet Radio System)

This is performed to check whether GPRS is working on the Site. This is done
by browsing a web page in browser of the phone. For GPRS to be checked it is
necessary to see that the handset is WAP, GPRS enabled.

Intra Site Handover

Intra Handover is performed to check whether handover is taking place both ways
on the Site.
Handover is performed among all the Sectors of the Site.

Inter Site Handover

Inter Handover is performed to check whether handover is taking place both ways
on the Site with it’s adjacent neighbor. Handover needs to checked mandatorarily
for primary neighbor.
Handover is performed with all the defined neighbor's in the integration sheet.

Drive Test Procedure III

MOC and MTC

Given are parameter need to be checked while performing MOC and MTC

RX Level (-47 dbm to -110dbm)

RX Quality (0 to 7)

SQI (20 to 30)

DTX

HSN (Hopping Sequence Number) (0 to 63)

MAIO

Hopping Frequency

C/ I Ratio (>15 dbm)

C/ A Ratio (>12 dbm)

Definition of Radio Parameters:

 
RxLev : Receiving level in terms of dBm that mobile is receiving from the site. Range of -30 dBm to -110dBm. 
 
RxQual : Quality of voice which is measured on basis of BER. Range of RxQual 0 -7. 
 
FER : Frame Erasure Rate it represents the percentage of frames being dropped due to high number of non-corrected bit errors in the frame. It is indication of voice quality in network. 
 
BER Actual : Ratio of the number of bit errors to the total number of bits transmitted in a given time interval. BER is a measure for the voice quality in network.. Depending on BER RxQual is measured. E,g, BER 0 to 0.2 % corresponds to RxQual 0. Max. BER countable and useful is up to 12.8 % which corresponds to RxQual of max. 7. 
 
SQI : SQI is a more sophisticated measure which is dedicated to reflecting the quality of the speech (as opposed to radio environment conditions). This means that when optimizing the speech quality in your network, SQI is the best criterion to use. SQI is updated at 0.5 s intervals. It is computed on basis of BER and FER. For EFR 30, FR – 21 & HR – 17 are respectively ideal values. 
 
C/I : The carrier-over-interference ratio is the ratio between the signal strength of the current serving cell and the signal strength of undesired (interfering) signal components. It should be atleast > 9 . 
 
MS Power Control Level : Displays range of power control from 0 to 8 depending upon network design. E.g. 0 means no power control and 1 means level that is defined by operator viz. 2 dBm less acc. To airtel. 

DTX : Discontinuous transmission (DTX) is a mechanism allowing the radio transmitter to be switched off during speech pauses. This feature reduces the power consumption of the transmitter, which is important for MSs, and decreases the overall interference level on the radio channels affecting the capacity of the network.. 
 
TA : Value that the base station calculates from access bursts and sends to the mobile station (MS) enabling the MS to advance the timing of its transmissions to the BS so as to compensate for propagation delay. Value of 0 means MS in radius of 550mt. From BS.
 
RL Timeout Counter (Cur) : This parameter define the maximum value of the radio link counter expressed in SACCH blocks. Range of 4 – 64 in step size of 4. it shows current value of RLT. Decrease by 1 but increase by 2. When it reaches zero it results in normal DROP Call. 
 
RL Timeout Counter (MAX) : This parameter define the maximum value of the radio link counter expressed in SACCH blocks. Range of 4 – 64 in step size of 4. it shows current value of RLT. Normally 16, 20, 24.  
 
MS Behavior Modified : This window shows current settings for the mobile station, for instance whether handover is disabled or multiband reporting enabled.  
 

Drive Test Procedure Part II

CPC (Cell Parameter Check)
Given are the parameters that need to be checked while performing CPC.
CGI (Cell Global Identity) consists if MCC+NCC+LAC+CI
BCCH Frequency
BSIC
GSM Band

Definitions:

Time: It is system time of computer. 

Cell name: It displays the name of the sector which is serving according to the cellfile that is loaded in TEMS. 

CGI : It stands for the Cell Global Identity which is unique for every sector of the site. It consists of MCC,MNC,LAC,CI. 

MCC: Mobile Country Code 0 – 999 MNC: Mobile Network Code 0 – 99 LAC : Location Area Code 0 -65535 CI: Cell Identity 0 – 65535 

Cell GPRS Support: Tells sector is having GPRS or not. Values are Yes or No . 

Band : It tells in which Freq. Band mobile is operating e.g. GSM 900/ 1800. 

BCCH ARFCN: It tells by which BCCH is the mobile station getting served. 

TCH ARFCN: On which Traffic Freq. call is going on. 

BSIC (Base Station Identity Code) : It is combination of Network Color Code (NCC) (0 – 7) & Base Station Color Code (BCC) (0 – 7). e.g. 62. It is decoded by mobile on every Sync. Channel Message.  

Mode: It is shows in which state is mobile operating, Idle, Dedicated & Packet. 
 
Time slot: On which time slot of current TCH call is going on. Viz. time slot no. of TRX. 
 
Channel Type: Type of channel mobile is getting now. Like BCCH / SDCCH/8 + SACCH/C8 or CBCH / TCH/F +FACCH/F +SACCH/F. 
 
Channel Mode : Shows mode of coding like Speech Full Rate of Half Rate. 
 
Speech Codec: It shows FR for Full Rate, HR for Half Rate & EFR for Enhanced Full Rate. 
 
Ciphering Algorithm : It shows ciphering algorithm used by the system to protect data for privacy. E.g. Cipher by A5/2. 
 
Sub Channel Number: It is displayed at a time when mobile is on dedicated mode at time of call setup when it is getting SDCCH at that time it shows which SDCCH it is getting out of 8 available. E.g. 2.
 
Hopping Channel : It shows that current sector is having hopping feature or not. Values are Yes or No. 
 
Hopping Frequencies : It displays no. of freq. on which mobile is allowed to hop. viz. MA List for hopping of that sector. 
 
Mobile Allocation Index Offset (MAIO): It is the number which tells from which freq. from given MA list for sector hopping has to be started. E.g. 0 means sector will start from first freq. to hop. 
 
Hopping Sequence Number (HSN) : Indicates sequence in which frequencies are allowed to hop from the MA List. 0- 63. 0 for Cyclic Hopping, 1 – 63 random hopping sequences.

Drive Test Procedure Part I

Steps followed to perform Drive Test 

•Physical Verification 

•Alarm Checking 

•Frequency Plan Verification

•Hardware Configuration Verification

Physical Verification 
Physical Verification is carried out by verifying physical parameter of the New Site with the TSSR (Technical Site Survey Report) such as Address, Lat, Long, Building Height, Antenna Height, Antenna Type, Orientation, Tilt. 

Alarm Verification 
Alarms are generated mainly due to number of reasons, and these needs to checked before Drive is being carried out for the Site. Alarms are checked from the NOC (Network Operating Centre) and if found needs to be verified before drive being carried out. 

Frequency Plan Verification 
Frequency Plan can be verified from the NOC (Network Operating Centre) for BCCH and TCH frequencies being implemented as per the Site Integration Sheet sent to NOC (Network Operating Centre). 

Hardware Configuration Verification 
Hardware verification is performed to know the Site type, BTS Type, TRX Configuration, VSWR checking , Power measurement for each TRX.

Following is the procedure and parameters that need to checked while performing Drive Test for a New Site. 

•CPC (Cell Parameter Check) 

•MOC (Mobile Originated Calls) 

•MTC (Mobile Terminated Calls – Prepaid to Postpaid) 

•SMS (Short Messaging Service) 

•GPRS 

•Intra Site Handover 

•Inter Site Handover 

•TRX Test 

•Idle Drive (Normal Drive & Frequency Lock Drive) 

•Dedicated Drive

Handover Success Rate (HOSR):

If HOSR will be good TCH drop will also be good.
If Handover success rate degrades call drop rate will take place.

Reasons for Poor HOSR:
Improper Neighbor planning.
CO-BCCH-BSIC issues in Neigh.
Parameter Check.
HSN clash.
SL value.
LAC boundary.
DAC value mismatch.
Syn mismatch.
Overshoot.
HW Issues.
Low Coverage

Solutions for removal of HOSR:

Arrange Drive Test:

The best way to find the real issues for HO fail make DT and check layer 3 msg for HO fail. By DT it is very easy to find the fail between cells.

Neighbor Tuning:

Try to retune neighbors
Avoid CO-BCCH-BSIC neighbors.
Avoid extra neighs.
Delete long distance neighs.
Check neighs are defined form both ends.
If there are high fail delete and recreate neighs.

Parameter Check:
1. Retune SL.It can change bw -90,-95,-105.
2. Check HSN.
3. Check SYN.
4. Retune LDR, LUR, IDR, IUR.
5. Retune LMRG, QMRG, PMRG.

DAC value Check:

Check DAC value. If DAC value is high or low tune it at the TH value. It should be 2050.

Overshoot:

When neighs are far away then chances of HO fail increases. In this case ping-pong HO takes place by which fail takes place. So if the inter distance is high its better to delete that kind of neighbour.

LAC Boundary-

Check LAC boundry.
High fail takes place there will be Inter BSC cells.
High fail takes place there will be Inter MSC cells.
Define proper LAC in neigh cells.

HW Issues:
Clear HW issues.
Check TRXs.
Check outages.
Check BOIA Card. Because if it is faulty incoming and outgoing HO will be fail.

Clear Reports:

Clear ZEAT.
Clear 60.
Clear 67.
Clear 61.

Reports for HOSR :
153 reports for HO fail bw two cells.
154 HO analyses.
60 for discrepancy.
67 for Sync report.
61 for one way neigh.
    ZEAT for CO-BCCH-BSIC neighs
74 for HO definition report.
ZELO for inter MSC HO report.
150 for high HO fail.
157 for high HO attempt and call ratio.
158 for intra BSS HO observation.
62 for Adj cell having same or adj freq.

TCH Blocking

When TCH is not allocated to the user after SD allocation, it is TCH Blocking.

It is the failed call attempts which the MS user can notice.
It takes place due to lack of TCH Resource.

Reasons for TCH Blocking:

Some of them are-
High Utilization of TCH
Time slot faulty.
Lock TRXs.
HW Problem.

Solutions for removal of TCH Blocking:

Implement half rate or Dual rate.

Check FRL & FRU.
Add another TRX. If TRX addition not possible, try to share the traffic of that cell with the neighboring cell by changing tilt or orientation.

Useful Report for TCH Blocking:
135 TCH Congestion.

TCH Drop

Drop during conversation is known as TCH drop. It takes place after connect ACK msg on TCH.TCH drop occurring. For TCH drop first cross check the BCCH of that cell, hardware issue may be, change RXP* and RLT** value. Find out there is any interference, neighbor defined.

Reasons for TCH Drop:
Wrong Parameter Planning.
BAD HOSR.
Hardware Fault.
High TR Fail.
Overshoot.
Outage.
Due to Low Coverage.
Due to ICM Band(CDMA)

Solutions for removal of TCH Drop:

Check Parameter:
Check the BCCH Plan (C/I or C/A). Co-BSIC & Co BCCH.
Check the Timer T 100(should be 20 ms)

Check Overshooting:
If a cell is picking call from long distance, Check the sample log according to TA.
Site Orientation.
Effective tilt should be check.
Mount position should be check

Improve HOSR:
Check the Hopping plan.
Check the Neighbor Plan

High TR Fail:
Check and clear TR fail from oss end.

Bad Coverage:

If the drop call is due to low signal strength uplink, check the receive path of this particular TRX. Check receiver sensitivity, VSWR, feeder connection and etc. Drops due to Low Signal Strength.

If the drop call reason is due to low signal strength downlink, then, check the transmit path. Check cards, feeder and etc.

Use MapInfo or Google Earth to find location of sites.

Effective tilt should be check.

Mount position should be check.

Check HW:
Check Alarms on site.
Check TRXs.
Check Slips.
Check the Hopping plan.
Check BB2F card.
Check VSWR,
Path imbalance.
Connector Connection.
Check TMA

Reports for TCH Drop:
163 for TCH Drop
ZEOL for alarms.
ZAHP for Flicks.
232 for TA report.
208 Path Imbalance report.
204 for BTS report.
216 for all parameter.
196 for UL-DL Qul.
62 for Adj cell having same or adj freq.

NOTE:

* Rxlev access min (RXP): With this parameter we define the minimum power level an MS has to receive before it is allowed to access the cell.
  Range: -110..-47 (dBm)
  Default: -105

**Radio link timeout (RLT): With this parameter we define the maximum value of the radio link counter expressed in SACCH blocks.
  Range: 4..64, with step size of 4
  Default: 20

TCH Assignment

It’s a process of by which TCH is assigned to the MS. After the SD request MS gets TCH successfully and the call transfers to TCH it means TCH assignment is successful.

For the best KPI TCH assignment should tend to 100%.
It degrades due to HW problems.

Reasons for TCH Assignment failure:
Hardware Fault(TRXs,Combiner,Duplexer,Cables)
VSWR
High Path Loss.
Faulty TMA.
High TCH Blocking.
Loose connections.
DR being used extensively

Solutions for removal of TCH Assignment:
Clear VSWR
IF TRXs are faulty lock them and try to replace them soon to avoid blocking.
Path Imbalance clear.
Connection from BTS to Antenna
Connector connection
Check TMA.
Check Duplexer,Combiner,TRXs connections, Multicoupler etc.

Reports for TCH Assignment:
ZEOL to check alarms
208 for path imbalance
196 for UL-DL interference
ZAHP for Flick report

SDCCH Drop

When we assigned SD for call origination and at that time due to some problem or any mismatch comes by which SD loss occurs, it is called as SD Drop.

It occurs between allocation of SD and before TCH allocation. Sometimes SD drop occurs because queuing is not activated in the system.

If SD drop is high plz look on parameters likeovershooting, shift the SD timeslot , may be hardware issue, interference, change the values of RXP, PMAX, may be issue of uplink or downlink issue in that cells for UL put a TMA in that cell and for DL provide tilt ,re orient that antenna.

If SD Drop is high:
If SD drop is high plz look on parameters like-
Overshooting
Shift the SD time slot
Hardware issue
Interference
Change the values of RXP PMAX
It may be uplink or downlink issue in which cells for UL put a TMA in that cell and for DL provide tilt Re orient that antenna.

Reasons of SD Drop:
Hardware Fault.
Interference.
MAIO mismatch.
Bad Coverage.
High TR Fail.
Outage.
Overshooting.
Abis Drop.
High Path Loss.
Wrong Parameter Planning.
Due to ICM Band(CDMA)
High LAPD Utilization
Heavy blocking and DR feature being used extensively

Solutions for removal of SD Drop:

Interference:

Check the BCCH Plan (C/I or C/A).
Co-BSIC & Co BCCH.
Use latest ND 111 and MapInfo to find out proper frequency to reduce interference.

Arrange Drive Test:

The best way to find the real issues for Interference makes DT.
Check interference by Interference scanning.
Check clean BCCH by frequency scanning.

Overshooting:
LAC Planning.
If a cell is picking call from long distance,Check the sample log according to TA.
Cell orientation need to be defined according to clutter.
Mount position
Effective Tilt

High TR Fail:
Check and clear TR fail from OSS end.

Bad Coverage:

If the drop call is due to low signal strength uplink, check the receive path of this particular TRX. Check receiver sensitivity, VSWR, feeder connection and etc. Drops due to Low Signal Strength.
If the drop call reason is due to low signal strength downlink, then, check the transmit path. Check cards, feeder and etc.
Use MapInfo or Google Earth to find location of sites.

High LAPD Utilization:

Check LAPD util report from OSS, and define 32 kbps signaling instead of 16kbps.

Hardware Fault:
Check Alarms.
TRX condition.
Check Path Imbalance.
VSWR of the Cell.
Connector Connection.
Some times you will find issues on BCCH TRX.In this case BCCH shift from one to other TRX will reduce SD drop.

Check for parameter:
Check the Timer T 3101
Check the Timer T 200(20ms)
T11 Expired(10 s)
MAIO check.


Useful Reports for SD Drop:
Use report ZEOL to find the alarms.
Use 208 for Path loss analysis.
Use 196 for UL-DL Interference.
Use 163 report for SD drop.
Use report 216 for detail SD Drop.
232 report for TA report.
62 for Adj cell having same or adj freq.
ND 111 for freq plan.
204 for BTS and cell report.

Blocking and Congestion

Difference Between Blocking and Congestion:

It is very important to know difference between blocking and congestion. Some people think that both are same, but they differ from each other. If all the SD resources are full and not available for SD assign then its come into congestion. If at a particular time call is attempted and it fails then it known as Blocking.

SDCCH Blocking

SD blocking means that you are not getting SD resource for the call origination. When MS connects with NW then RACH and AGCH are provided. After AGCH,SDCCH is provided but if SDCCH is not provided at this time due some problems or due to unavailable of SD by BSC ,it’s called as SD Blocking. There are no of reasons for that.If such a case arises the customer will not be able to originate any call.

Reasons for SD Blocking:

Some of them are-

LAC boundary.
HW Prob.

Solutions for removal of SD Blocking:

Here are some steps by which we can reduce SD Blocking-

1. Check the No. of SDCCH channel Available, if less then increase SD channel taking care that there is no TCH Blocking.

2. Check LAC boundary, If location update is more then change theLAC of that site and set C2 and HYS.

3. Use of Dynamic SDCCH (It is a BSC parameter and will be applied on whole BTS).

4. Hardware check / shift SD to new time slot.

5. Some times BMA and HYS parameters are useful to remove SDBlocking.

Usefull Reports For SD Blocking:

Use 182 to analyses SD Blocking reasons.

130 for SD congestion.

                                        --*-*--