[Antapé]

i have a cell with high call drop radio, i check HO causes and i find that UL Lev HO is very high. can somebody give possible solution?

[RH]

Is the HO_Lost due to uplink level HO is higher?..then it’s one of the reason for higher drop call rate for that cell.
You can add new sites,use TMA to increase the coverage, can try by changing ho_margin if any cell have sufficient level that can proceed the call.

[Pix]

Can you please check the value of the Path Balance for this cell, and for each TRX ?

(in CELL or TRX Indicators > Radio Measurements > PathBalance_Avg)

Check the values over several days.

[Antapé]

yes there is power unbalanced for all TRX. i have also low incoming HO success for one of my cell neighbor.

[pix]

i assume the value of the path balance is negative ? meaning that the TRX has a poor UL sensitivity (due to TRX problems or feeder problems or ANC problems).

so it’s normal to have high amount of HO due to poor UL level: your hardware is faulty.

[hasan]

Hi Pix,
Can you describe how the neagative value in pathbalance indicates poor uplink level ?

[pix]

hasan,

yes, sure 🙂
path balance = (rxlev_ul – ms_txpwr) – (rxlev_dl – bts_txpwr)

this path balance is computed every 480ms by the BSC, based on the measurement results.

let’s take an example:
rxlev_ul = -80dBm (measured)
ms_txpwr = 33dBm (calculated, depends on MS_TXPWR_MAX and value of MS_TXPWR attenuation due to UL power control)

rxlev_dl = -70dBm (measured)
bts_txpwr = 42.5dBm (calculated, depends on TRX output power, attenuation by combiner, value of BS_TXPWR attenuation and DL power control)

as you see, in this example, i don’t use power control, all tx power are at maximum output power.

path balance = -80 + 33 – (-70 + 42.5)
= -0.5dB

That’s balanced.
Now let’s assume that there is an issue in UL. What is the impact?
–> The rxlev_ul is decreased, but the MS TXPWR is unchanged (this is a stupid calculation, based on parameters).

path balance = -100 + 33 – (-70 + 42.5) = -20.5 –> value becomes NEGATIVE.

possible cause : all mobiles in the cell are faulty (… impossible …) or the cell is having a poor UL sensitivity due to faulty HW (yes, that must be it !!)

if there is an issue in DL, the result is the opposite : the rxlev_dl is poor –> the path balance is very positive.
possible cause : all mobiles are faulty (iphones??) or the cell is having a faulty transmission.

well, i hope it’s clearer now, let me know.

regards,
pix

[Antapé]

Thank you for help, i will consider it, but i have too many sites with this call drop problem presenting high rate of ul_lev_ho.

bye!

[hasan]

Hi Pix,
I found that ,
Path Balance= (UL Path Loss) – (DL Path Loss);
which should be equal to:

(MS_tx_pwr – Rx_Lev_BTS) – (BTS_tx_pwr – Rx_Lev_MS).

So,if I calculated by using this formula, poor uplink sensitivity will results in Positive value.
That is my confusion.
Please correct me if I am wrong here.

[pix]

in alcatel-lucent, the path balance indicator is computed in RNO/NPO with the formula is gave you. No doubt about this 🙂

for other vendors or tools, the formula is perhaps different.

[hasan]

Thanks Pix.

[FF]

I ‘ve a hight SDCCH Assign Fail in somme of my cells PIX can you help me to investigate

[Antapé]

FF, it’s due to which cause? radio, congestion or BSS problem?

[FF]

Antapé, think it’s radio cause. Because i’ve any problémes like congestion or hard ware. since the probleme is only in 0ne BTS of the BSC, there aren’t BSS probleme.
Think you for your ideas

[Pix]

FF,

Hello,

What Antapé means is that you should check the cause of the SDCCH Assign Fail in the indicators. You can find the details. But I assume it’s radio.
What values are you getting ? 10% ? 20% ?

Are you using Abis over satellite ?

[Author]

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