- This topic has 9 replies, 1 voice, and was last updated 8 years, 3 months ago by pix.
13th March 2012 at 08:17 #67985eorenmhGuest
Dear fellow telco engineers,
kindly need your advice on my Siemens network that currently having high TCH Drop Call Rate.
I have suspect on interference issue related with TX Power.
What can i do with this to adjust any parameters related?
thank you in advance13th March 2012 at 08:51 #67986pixGuest
to reduce intereferences caused by an excessive tx power, you should activate the Power Control in UL and in DL.
If both directions are already activated, then you should fine-tune the thresholds, averaging windows and power step sizes in order to make it more “aggressive” (= more “efficient”).
Pix14th March 2012 at 23:41 #67987eorenmhGuest
thank you much for your reply
i wonder what is the relation between power and interference?
perhaps if power is full, then the interference would be bad? or the opposite?
and what is difference between UL power and DL power?
if im not mistaken, DL is from BTS into MS, and UL is from MS to BTS, is that correct?
thank you again in advance 🙂15th March 2012 at 13:07 #67988pixGuest
power => the device transmits more power. As a result, this signal is stronger and will interfer with the signals which are sent by other devices.
in UL : transmitter = MS, receiver = BTS
in DL : transmitter = BTS, receiver = MS
UL power is power used by the MS to send a signal to the BTS.
DL power is the power used by the BTS to send a signal to the MS.
I one MS sends a strong signal, then it might interfer with other mobiles located in other cells which are using the same frequencies.
pix17th September 2012 at 21:09 #67989VanGGuest
please advise me how to tune my parameters to make more agressive power control to improve the DL quality? What are the optimal value for PC thresholds, averaging windows and power step sizes ?
Thank you in advance,
Best regards.18th September 2012 at 05:05 #67990VimGuest
Can you please explore the the term “TCH Drop due to Radio Fail” and “TCH Drop due to Abis Fail”.
In My Network Many sites are having high abis fail but i found and checked that there is no issue with the Transmission end.
What we need to do to rectify this issue and improve the DCR KPI.
Vimal18th October 2012 at 18:03 #67991DellGuest
Is the param bs_txpwr_min important in power control?
Dell18th October 2012 at 18:52 #67992pixGuest
not really, as long as it is greater than 10dB. The most useful power backoff is in the 1st dBs. Reducing the power by 3dB goes a long way for the network. When PC is reducing power by 10dB, then it means the cell is not interfering with anyone anymore, for sure.
Going beyond that is required when you have tight frequency planning, or to further improve “noise”. That’s especially useful for EGPRS transfers.
a typical BS PWR MIN is around 14dB.
Going too low might slow down HO detection, and might make the radio link very sensitive to any little change.18th October 2012 at 21:19 #67993DellGuest
in some cells (dcs1800, not multiband) bs_txpwr_attenuation is 2 dB, but, bs_txpwr_min is -10 dB. In gsm900 cells that difference between max power and min power is 10 dB (if attenuation is 2 dB, bs_txpwr_min is -12 dB in gsm900). Should we decrease bs_txpwr_min to -12 dB as well in dcs1800 for txpwr_attenuation of 2 dB? Vendor is ALU release B11.
Dell19th October 2012 at 18:33 #67994pixGuest
what you should ask is “what is the purpose of “bts pwr min”…?”
– this is the maximum attenuation that can be applied to the signal with power control.
there is no correlation with the bts pwr attenuation, which is the “minimum attenuation” (which allows to compute the max power) on the cell. When pwr reaches this value, it means the cell is transmitting at max power. Max power is used at call setup, just after a HO, or when rxlev/rxqual are poor and PC will push the power to the max to save the call.
Also, this max power is used by EGPRS transfers.