path balance motorola

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Path Balance Trouble Shooting

May 20, 2005

Reiny Ba


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Motorola Internal Use Only MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2004.

•Description of the path balance statistic

•Possible sources for poor PB

•Trouble shooting Procedure

1. Content


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•The Path balance (PB) statistic provides anindication of the RF link between the MS and BTS.

•An operator may be able to use thePATH_BALANCE statistic to identify a fault in theRX or TX signal path.

2. Description of the PB


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path_balance = path_loss_difference + 110

and

Path_loss_difference =

uplink path loss – downlink path loss

uplink path loss = ms_txpwr_dbm – bts_rxlev_dbm

downlink path loss = bts_txpwr_dbm –ms_rxlev_dbm

2. Description of the PB (Cont.)Forula：


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2. Description of the PB (Cont.)

Uplink path loss is the signal loss from the mobile to the BTS.

Downlink path loss is the signal loss from the BTS to the mobile.


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The OMC PATH_BALANCE metric is a statistic derived on atimeslot basis and calculated using four parameters:

1. Mobile Tx power – The TX power level reported by the MS

(ms_txpwr_dBm)2. Mobile Rx power – The RX power level reported by the MS

(ms_rxlev__dBm)

3. BTS Tx power – The TX power level reported by the BTS

(bts_txpwr_dbm)4. BTS Rx Power – The RX power level reported by the BTS

(bts_rxlev_dbm)

2. Description of the PB (Cont.)


7/19Motorola Internal Use Only MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2004.

1. PB=110 which is an ideal number ;

2. PB value should be taken into account the variation ofdifferent conditions；

3. Over time inaccuracies in any one mobile will have littleaffect on the PB number;

4. Any problem at the BTS TX and/or RX path loss or wrongpower reporting will cause a continuous change in the PBnumber.

5. TX gain ↓ (↑)DL pass Loss ↓(↑) PB↑(↓)

RX gain↓ (↑)UL pass Loss ↑(↓) PB↑(↓)

2. Description of the PB (Cont.)!ote：



1. Invalid or inaccurate TX/BAY CAL• If the radio is a new spare；

• If the radio was swapped from one slot to another and preserve bay levelcal feature is not enabled；

• If an expansion cabinet is added to the configuration；

• If external combining, filtering or amplification is added to theconfiguration。

2.HW/Connection problem with the cabinetslot/cabling/antenna

An element in the received path might have failed, or might not be used or

installed correctly.3. HW problem with the DRI: A HW component of the transceiver (CTU or CTU2) can have failed whichresults in abnormal noise in the transceiver or loss of output power.

". Po##ible #ource# $or %oor PBThree different possible known sources of poor PB:



PB #ue

WARNING:

Throughout

this procedure,

keep logs of all

MMI

commands and

all the resultsor you tests.

&n'e#tigation

Proceure

Yes

No

No

Yes

Yes

oor B

detected!

否

"#ontact the local office to see if there is a

know issue affecting the B number and to

see if an S$ has already been opened

"%pen an S$ &pro'ide a description of the

problem and attach the logs you gathered

during your in'estigation(

"#ontact the network optimi)ation team

是

T*ST + Section -.-

Is the problem due

to other /0 failure!

T*ST +- Section -.1

Is the problem due to the

en'ironment

T*ST +2 Section -. Is the

calibration data accurate!

Section -.3 4ather generic

configuration information on

the radio and the site.

$eturn or fi5 the faulty

e6uipment and

monitor the B again

T*ST +3 Section -.2

Is the 7S0$ good!

&82.93(

No

:i5 7S0$issue and

monitor B

#alibrate the radioand monitor the

B again

Yes

" #ontact the network

optimi)ation team and;or

" Modify the fre6uencies

to be used on this sector

Yes

No



Thanks



4.1General information gather

1. The radios’ state and configuration;

2. Is there TX combining or is there an amp in the TX or RX

after the cabinet?

3. How many radios/sectors are affected?

4. What type of radio is affected (CTU, CTU2, both)?

5. For all radios affected, get OMC INTF_ON_IDLE statistic. MonitorPB, BER, call drop rates and IOI performance, if High IOI please

see IOI white paper Did the problem start after an upgrade, a cellreplanning, or HW change?

6. Check with the Local Office if there is a known issue

. PB i##ue #hoot #te%



4.2.TEST #1: Check Antenna VSWR

The fist step due to convenience is to check the VSWR of the affectedantenna.

It has been seen in some cases that poor antenna VSWR can lead to badpath_balance numbers.

VSWR should be less than 2.61

. PB i##ue #hoot #te% (Cont.)

If there is a 7S0$ problem, then the result for T*ST +3 is



4.3.TEST #2: Calibration Verification

Verify the calibration data is valid for the antenna and branch(es) .1. Verification that the calibration data is valid

CTU radio

EQCP TEST > calchk

EQCP TEST >

RX Branch 1: CAL CHECKSUM RX Branch 2: CAL CHECKSUM

AIC YES 0001 AIC YES 0007

AGC YES d3f0 AGC YES b845 BAY YES 7f3b BAY YES 7f3b

BBG YES 002a (This is for both branches.)

…. … CTU2 radio

CTU2.carA.ts_0>cal_status tall

CalCa BrStatus Result Valid Checksum Ver S/HC--------------------------------------------------------------------- RX FR B 1 pass valid 0xa8f593e0 1 / 1

RX CAB A 0 pass valid 0x53703256 0 / 1

RX CAB B 0 pass valid 0x45562835 0 / 1

TX VVA A 0 pass valid 0xb0be7eb2 1 / 1

TX VVA B 0 pass valid 0x96686359 1 / 1




4.3.TEST #2: Calibration Verification (Cont.)

2. Manual verification (bay level offset is accurate).

3. Recalibration of the radio


If the #=> data is not right or in'alid, should do the #alibration.=nd then if the offset is not accurate, do the bay le'el #=>.

If they are all ok , do the $ecalibration. %therwise go to &-.-(

below.



4.4.TEST #3: Cabinet/Cabling Issues

requiring a detailed inspection on the cabinet looking for damaged connectorsand cables

TX Path

RX Path

RX/TX PathExternal Combining, Filtering, Amplification

SURF/SURF2


If you ha'e found a faulty cable, connector, e6uipment, etc. thenthe answer to T*ST + is ?*S " replace the faulty part and re

calibrate both the T@ and B=? offsets. If no faulty e6uipment is

found the answer to T*ST + is



4.5.TEST #4: Environment issue

Check that there is not a signal in the radio’s environment at thefrequency (or frequencies) which the radio is tuned to.

Use of a spectrum analyzer


If you find spurs or humps on the fre6uencies being used by the

radio then the answer to T*ST +- is ?*S. %therwise, itAs



5. 附录QUICK GUIDE FOR FIELD ENGINEER



5. 附录

*ttachent

gsm_g_bss_133_1-PB&IOI.pdf

01 Path Balance Bulletin.pdf

PB QUIC !UI"#

% $I#&" #'!I'##

PB (uic) guidesheet


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path balance motorola

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