Path Balance/Imbalance

[guess.who]

Can someone plz explain what it means by path balance and path imbalance....what are the parameters and KPIs to observe and understand path balancing and imbalancing (in HUAWEI/2G)..

Thanks in advance...

BR
Guess

[Optimal]

Uplink-and-Downlink Balance Measurement per TRX

Description

In an optimum system, power should be well estimated in design to enable the balance between the coverage of uplink signals and the coverage of downlink signlas. If the coverage of uplink signals is wider than the coverage of downlink signals, the downlink signals at the cell edge are weak and easy to be overwhelmed by strong signals in other cells. If the coverage of downlink signals is wider than the coverage of uplink signals, the MS has to camp on the cell with strong signals; however, the uplink signals are weak and the speech quality is poor. The balance does not refer to the absolute balance. The MR on the Abis interface can be used to check whether the coverage of uplink signals and the coverage of downlink signals are in balance.
The MR received by the BSC contains the uplink receive level and the downlink receive level. Subtract the uplink receive level and the parameter X from the downlink receive level. The results in dB are graded from levels 1 to 11, and the number of MRs of each level is calculated. Table 1 (http://www.finetopix.com/#bsc-mr.balanceorig.trx__bsc-mr.balanceorig.trx__table1) lists the mapping between the balance level and the receive level.

Table 1 Mapping between the uplink-downlink balance level and the receive levelLevel of the Balance Between the Uplink and the Downlink
Downlink Receive Level - Uplink Receive Level - Parameter X
1=≤-15 dB
2=-14 dB, -13 dB, -12 dB, -11 dB, -10 dB
3=-9 dB, -8 dB, -7 dB, -6 dB
4=-5 dB, -4 dB, -3 dB
5=-2 dB, -1 dB, 0 dB
6=0 dB
7=1 dB, 2 dB
8=3 dB, 4 dB, 5 dB
9=6 dB, 7 dB, 8 dB, 9 dB
10=10 dB, 11 dB, 12 dB, 13 dB, 14 dB
11=15 dB, 16 dB, 17 dB, 18 dB, 19 dB, 20 dB


Measurement Counters:

TRX_BALANCE_LEV_1
TRX_BALANCE_LEV_2
TRX_BALANCE_LEV_3
TRX_BALANCE_LEV_4
TRX_BALANCE_LEV_5
TRX_BALANCE_LEV_6
TRX_BALANCE_LEV_7
TRX_BALANCE_LEV_8
TRX_BALANCE_LEV_9
TRX_BALANCE_LEV_10
TRX_BALANCE_LEV_11

[guess.who]

any suggestions of how to remove if we face this kind of imbalance???

[agenov]

Can someone plz explain what it means by path balance and path imbalance....what are the parameters and KPIs to observe and understand path balancing and imbalancing (in HUAWEI/2G)..

Thanks in advance...

BR
Guess

Path balance simply means that signal losses in DL direction should be equal to that in the UL direction (or at least to have 3dB difference due to diversity ) i.e provides an indication of the RF link between the MS and BTS. Usually when you have very big difference in path balance distribution first step is to check the equipment - TRX calibration, malfunction, poor cabling installation, present of interferences in the RF environment, some UEs also can distort path balance and etc. there are really many reasons and you have to identify where the problem is.

path balance = path losses difference = UL path loss - DL path loss.
(Amplifiers external to the cabinet, mast mount pre-amps, power amps excreta, are not included in the calculation and will have a larger impact on the PB number)

[luganomu]

By looking into tx_balance_lev 1 to 11 how does this statistics suppose to look like for me to say this site cell is having poor path balance. please explain.

thanks in advance

[luganomu]

Optimal

Can you also tell me in Huawei 2g how can you check analyze uplink bit erroe rate(UBER) and down link bit error rate(DBER)

[leelio]

to add on the troubleshooting of poor path balance causes

1. if the problem exists on one radio, you can try to swap with another radio of the same site! and check if the problem followed the rtf or stayed with the radio.If the problem is on multiple radios then focus on number 2 below

2.Is there poor VSWR ,if return loss is more than 6dBm?, try to focus on cabinet/antenna cabling,the enviroment,backplane, bad duplexer..

[agenov]

By looking into tx_balance_lev 1 to 11 how does this statistics suppose to look like for me to say this site cell is having poor path balance. please explain.

thanks in advance


I really don't understand Huawei 2G and their statistics but obviously if you have 5-7 (or even 4-8) is OK and for everything above/below i.e 1-4/8-11 you should pay attention. There are some vendors that even tollerate 10dB difference. The best is to check what Huawei recommendation is.

[justdream]

By looking into tx_balance_lev 1 to 11 how does this statistics suppose to look like for me to say this site cell is having poor path balance. please explain.

thanks in advance

it will be like that

[haq_enam]

Uplink-and-Downlink Balance Measurement per TRX

Description

In an optimum system, power should be well estimated in design to enable the balance between the coverage of uplink signals and the coverage of downlink signlas. If the coverage of uplink signals is wider than the coverage of downlink signals, the downlink signals at the cell edge are weak and easy to be overwhelmed by strong signals in other cells. If the coverage of downlink signals is wider than the coverage of uplink signals, the MS has to camp on the cell with strong signals; however, the uplink signals are weak and the speech quality is poor. The balance does not refer to the absolute balance. The MR on the Abis interface can be used to check whether the coverage of uplink signals and the coverage of downlink signals are in balance.
The MR received by the BSC contains the uplink receive level and the downlink receive level. Subtract the uplink receive level and the parameter X from the downlink receive level. The results in dB are graded from levels 1 to 11, and the number of MRs of each level is calculated. Table 1 (http://www.finetopix.com/#bsc-mr.balanceorig.trx__bsc-mr.balanceorig.trx__table1) lists the mapping between the balance level and the receive level.

Table 1 Mapping between the uplink-downlink balance level and the receive levelLevel of the Balance Between the Uplink and the Downlink
Downlink Receive Level - Uplink Receive Level - Parameter X
1=≤-15 dB
2=-14 dB, -13 dB, -12 dB, -11 dB, -10 dB
3=-9 dB, -8 dB, -7 dB, -6 dB
4=-5 dB, -4 dB, -3 dB
5=-2 dB, -1 dB, 0 dB
6=0 dB
7=1 dB, 2 dB
8=3 dB, 4 dB, 5 dB
9=6 dB, 7 dB, 8 dB, 9 dB
10=10 dB, 11 dB, 12 dB, 13 dB, 14 dB
11=15 dB, 16 dB, 17 dB, 18 dB, 19 dB, 20 dB


Measurement Counters:

TRX_BALANCE_LEV_1
TRX_BALANCE_LEV_2
TRX_BALANCE_LEV_3
TRX_BALANCE_LEV_4
TRX_BALANCE_LEV_5
TRX_BALANCE_LEV_6
TRX_BALANCE_LEV_7
TRX_BALANCE_LEV_8
TRX_BALANCE_LEV_9
TRX_BALANCE_LEV_10
TRX_BALANCE_LEV_11


Very good explain..thanks a lot...

[luganomu]

Thank you team for the usefull information.

[luganomu]

Can you also tell me in Huawei 2g how can you check analyze uplink bit erroe rate(UBER) and down link bit error rate(DBER)

http://www.finetopix.com/images/misc/progress.gif

[tthach830]

Path balance or LinkBudget is DL_RSSI - UL_RSSI. You want that to be closer to 0 as possible.

However, I have often see uplink (signal level from your phone) being weaker than downlink (signal from your the cell tower).

I am actually looking at a RSSI measurements on a Nortel GSM 1900 w/o TMA:
Avg DL RSSI is at around -90.85dB
Avg UL RSSI is at around -98.15dB
Avg LinkBudget/PathBalance is -90.85dB - -98.15dB = 7.03dB.


On a GSM 1900 with TMA I normally see -6 to -10 dB in a linkBudget.


I hope that helps.

[luganomu]

We always calibrate TRX to balance power

[faares]

We always calibrate TRX to balance power

can you telll me please what how you do TRX Calibration in huawei Vendor
thanks

[s52d]

Path balance or LinkBudget is DL_RSSI - UL_RSSI. You want that to be closer to 0 as possible.

However, I have often see uplink (signal level from your phone) being weaker than downlink (signal from your the cell tower).

I am actually looking at a RSSI measurements on a Nortel GSM 1900 w/o TMA:
Avg DL RSSI is at around -90.85dB
Avg UL RSSI is at around -98.15dB
Avg LinkBudget/PathBalance is -90.85dB - -98.15dB = 7.03dB.

On a GSM 1900 with TMA I normally see -6 to -10 dB in a linkBudget.
I hope that helps.

Hi!
This might be due to more aggressive power regulation on uplink?
Are you looking at power regulation compensated measurements?
Is TMA calculated properly? I've seen wrong numbers reported by stats,
people do not understand impact of TMA on RX noise.

Anyhow, in order to have link balance, you tune TX power following simple rule:
"If terminal can hear BCCH, it can make a call".
Some vendors like to push 100W ;-) to a BSS carrier, our MBA bosess are happy,
(wow, I have 4 bars everywhere...) and then you read on the net:
"How come: with operator A, I can make a call if I have two bars, with operator B I need 4 bars to make a call".

Assuming no TMA, we have same in both directions:
- cable loss + antennas gain
- radio link loss
What makes a difference is: some 2 dB better RX on base station, some 3 dB for RX diversity.
Add some to compensate fading. To save battery, 30 dBm terminals are often
27.1 dBm (on 1.8 GHz) maximum, so calculate with 28 dBm on terminal side.
Thus, 8 W on cabinet connector is enough.
When using TMA, you compensate BS cable loss (3 dB in average), and it is good to
put 8W on BS antenna connector to make link balance.

Rest is generating "false coverage to make MBAs happy", intentional interference
and excessive power consumption.

Of course, if your internal benchmarking, or, more common, government benchmarking, is
looking only at downlink power, then you use full power and degrade user performance.
Such networks are build for benchmarks, not for users.

As question is about Huawey: I strongly bielive you can decrease maximum TX power.
There is no magic: just adjusting TX power so answering terminal can be heard by TRX.

BR
s52d

[luganomu]

Hi

please can some one let me know if the attached mr measurement show a path balance or imbalance? and which TRX indexes?

[luganomu]

This is a good Image

[esreeha]

Seems UL is weak

add TMA or

REduce TRX radiating power.

[luganomu]

Any one with more explanation?

[mohyedeen_alkousy]

Hi

please can some one let me know if the attached mr measurement show a path balance or imbalance? and which TRX indexes?

pictures is not clear but u have to browse them one by one to judge clearly
also better to browse them as rates and accumulate them to three columns bad uplink-acceptable-bad downlink

[luganomu]

See attached example

[luganomu]

another snapshot

[zeezzoo]

i think you have a problem in the first attachment .

check the full description from Huawei :

Uplink-and-Downlink Balance Measurement per TRX(MR.BalanceOrig.TRX)

Overview

In an optimum system, power should be well estimated in design to enable the balance between the coverage of uplink signals and the coverage of downlink signals. If the coverage of uplink signals is wider than the coverage of downlink signals, the downlink signals at the cell edge are weak and overwhelmed by strong signals in other cells. If the coverage of downlink signals is wider than the coverage of uplink signals, the MS has to camp on the cell with strong signals; however, the uplink signals are weak and the speech quality is poor. The balance does not refer to the absolute balance. The MR on the Abis interface can be used to check whether the coverage of uplink signals and the coverage of downlink signals are in balance.
The MR received by the BSC contains the uplink receive level and the downlink receive level. The uplink/downlink balance factor is calculated through the following formula. The results in dB are graded from levels 1 to 11, and the number of MRs of each level is calculated.
The formulas are as follows:
Uplink/downlink balance = uplink path loss - downlink path loss
= (actual TX power of the UE - uplink receive level) - (TRX power on top of the cabinet - downlink receive level)
TRX power on top of the cabinet = TRX initial power - TRX power level x 2 + fine tune of power - combination loss - downlink dynamic power control level x 2 + dynamic PBT gain
Where:
TRX initial power: the power corresponding to the TRX power type, expressed in dBm;
Fine tune of power: power fine tune of the TRX;
Power loss in combination: combination loss of the cell x (0.1);
Dynamic PBT gain: if the dynamic PBT function is enabled in the call, the dynamic PBT gain is 3 dB; otherwise, the dynamic PBT gain is 0 dB.


Level 1: <= -15 dB
Level 2: -14 dB, -13 dB, -12 dB, -11 dB
Level 3: -10 dB, -9 dB, -8 dB
Level 4: -7 dB, -6 dB, -5 dB
Level 5: -4 dB, -3 dB, -2 dB
Level 6: -1 dB, 0 dB, 1 dB
Level 7: 2 dB, 3 dB, 4 dB
Level 8: 5 dB, 6 dB, 7 dB
Level 9: 8 dB, 9 dB, 10 dB
Level 10: 11 dB, 12 dB, 13 dB, 14 dB
Level 11: >= 15 dB

If the balance between the uplink and the downlink is mainly at level 1, you can infer that the downlink loss is too great or the downlink transmit power is too small. If the balance between the uplink and the downlink is mainly at level 11, you can infer that the uplink loss is too great or the uplink transmit power is too small. The balance level helps to locate the faults in the TX/RX channel, such as the TRX and the antenna.

[kyokuman]

Hi,

It is an old post, but Im suddenly interested in it as I have Pathbalance showing that My Downlink has more losses than Uplink!

I am not using any TMA.


Additional question : How TRX power can affect pathbalance, as if im not mistaken, pathbalance is the difference of pathloss !


Thanks for your help!