Good RSCP, bad Ec/No ( in buillding )

[kunea]

Dear Bro,

How to improve Ec/No in situation : Good RSCP, bad Ec/No (Ex: in buillding ) ?

Thanks.

[babak1349]

Dear Bro,

How to improve Ec/No in situation : Good RSCP, bad Ec/No (Ex: in buillding ) ?

Thanks.
Hello,
There are different things which are affecting Ec/No
EcNo is RSCP/RSSI so if you have good RSCP it means you have high RSSI
RSSI is sum of White noise, Received signal from serving cell, received signal from other cells and also external interference
If the ratio of CPICH power to Maximum Transmitted power from serving cell is high it means the EcNo gets bad
If there are polution and too many strong signal from other cells, RSSI increases
If you have external interference RSSI increases
If the cell is very loaded it will transmit with maximum power so RSSI increases specially in the case of HSDPA instantaneous load increases from power consumption point of view PLEASE note it is normal when you are using HSDPA ECNo gets degraded
It is important how you are doing indoor coverage... are you using DAS, Micro cells and so on... It is important how you installed the equipment. Please remember the measuring point is port of antenna and bad equipment configuration can end up some problems


In the end it is important which EcNo is bad for you.... -2 dB, -10 dB, -15 dB -20 dB....???

Cheers

[anita_2k]

check RTWP of the site if its high.
sometimes combiner (common DAS) causing high UL interference.

br/Anita

[kunea]

Hello,
There are different things which are affecting Ec/No
EcNo is RSCP/RSSI so if you have good RSCP it means you have high RSSI
RSSI is sum of White noise, Received signal from serving cell, received signal from other cells and also external interference
If the ratio of CPICH power to Maximum Transmitted power from serving cell is high it means the EcNo gets bad
If there are polution and too many strong signal from other cells, RSSI increases
If you have external interference RSSI increases
If the cell is very loaded it will transmit with maximum power so RSSI increases specially in the case of HSDPA instantaneous load increases from power consumption point of view PLEASE note it is normal when you are using HSDPA ECNo gets degraded
It is important how you are doing indoor coverage... are you using DAS, Micro cells and so on... It is important how you installed the equipment. Please remember the measuring point is port of antenna and bad equipment configuration can end up some problems


In the end it is important which EcNo is bad for you.... -2 dB, -10 dB, -15 dB -20 dB....???

Cheers
I'm using Microcell to coverage this building. EcNo limitation : >= -12 dB.

[babak1349]

I'm using Microcell to coverage this building. EcNo limitation : >= -12 dB.
Hi again,
what is your CPICH power ? 32 dBm?
What is your maximum transmission power ? 46 dBm?
if you are using HSDPA it is normal to have low EcNo because HSDPA is using remaining cell power up to Maximum allowed Transmission power it means in most of cases when you are using HSDPA cell is tranmitting with maximum power. just as indicator you can do like this
EcNo < RSCP -MaximumTranmissionPower


cheers

[kunea]

Hi again,
what is your CPICH power ? 32 dBm?
What is your maximum transmission power ? 46 dBm?
if you are using HSDPA it is normal to have low EcNo because HSDPA is using remaining cell power up to Maximum allowed Transmission power it means in most of cases when you are using HSDPA cell is tranmitting with maximum power. just as indicator you can do like this
EcNo < RSCP -MaximumTranmissionPower


cheers
Hi Bro,

CPICH: 32dBm, Total Power : 46dBm. I have low EcNo when using CS, not HSDPA.

[electron]

Share A Log file for further look up. Seems some points are missed .


Cheers
Hi Bro,

CPICH: 32dBm, Total Power : 46dBm. I have low EcNo when using CS, not HSDPA.

[babak1349]

Hi Bro,

CPICH: 32dBm, Total Power : 46dBm. I have low EcNo when using CS, not HSDPA.
hi,
If there is any other user who is using HSDPA still you gonna have maximum Transmission power used . You are using it for CS but what about other users?? other user may use HSDPA
you do a test disable HSDPA in your cell for a short time and see how it works.... besides yuo need to check cell load .... if you have too many users you can have high power
You need to check power consumption as well through statistics
If you don't have too many users... you need to check allowed power per radio link.... long time ago I had a case.. .a cell was overshooting and with low traffic we had power blocking because system was allowing a far away user have as much as power he/she wanted and it was causing power blocking
if they are not the case you need to check cell HW configuration and see how dl and Ul attenuation has been set in nodeB
Other reason could be too many server indoor so you need to check it as well
The last thing could be external interference

Cheers

[shishio]

check the cell CS load if its much, if you have a lot of CS users on the cell it can cause low EcNo even with good RSCP, whats the cell RTWP? also check for external interference.
though i dont think an EcNo of -12 is cause for alarm.

[FrankPintor]

Have you checked the pilot pollution in your building? Also, PSC repetition… you don't have any cells with the same scrambling code anywhere close by? There are some limitations that apply in these circumstances: any cells not in the active set contribute to EcN0, but also you have the limitation of the rake receiver, which can decode a certain number of fingers, and reflections in buildings will create more multi path signals to be fingered and decoded. Any paths the receiver can't place a finger on contribute to EcN0. Also repeaters will create more multi path signals because of the delay through the repeater (I know, you didn't say you have a repeater, but it's worth mentioning anyway).

As the last contributor said, EcN0 of -12dB isn't so bad, why is this the limit? With 2-3 cells in the active set there's little danger of dropping a call. Is it because you set the event 2d threshold to this value?

[Philippe]

You have 32dBm CPICH poweer and 46dBm total power. Imagine 50% of the power is used at the time you mlade your measurement (do you have the power load of the cell?): this means 43dBm total output power in your cell.
The CPICH Ec/Io is so around 32-43= -11dB.
If I consider also intercell interference, let say F factor = Iextra/Intra = 0.6 (at cell edge it can go up to 2 or 3), the CPICH Ec/Io is so around 32-45 = -13dB.
Your CPICH Ec/Io of -12 dB is not an irrealistic or bad value.

[mypp]

Have you checked the pilot pollution in your building? Also, PSC repetition… you don't have any cells with the same scrambling code anywhere close by? There are some limitations that apply in these circumstances: any cells not in the active set contribute to EcN0, but also you have the limitation of the rake receiver, which can decode a certain number of fingers, and reflections in buildings will create more multi path signals to be fingered and decoded. Any paths the receiver can't place a finger on contribute to EcN0. Also repeaters will create more multi path signals because of the delay through the repeater (I know, you didn't say you have a repeater, but it's worth mentioning anyway).

As the last contributor said, EcN0 of -12dB isn't so bad, why is this the limit? With 2-3 cells in the active set there's little danger of dropping a call. Is it because you set the event 2d threshold to this value?

What finger means ?

[mypp]

You have 32dBm CPICH poweer and 46dBm total power. Imagine 50% of the power is used at the time you mlade your measurement (do you have the power load of the cell?): this means 43dBm total output power in your cell.
The CPICH Ec/Io is so around 32-43= -11dB.
If I consider also intercell interference, let say F factor = Iextra/Intra = 0.6 (at cell edge it can go up to 2 or 3), the CPICH Ec/Io is so around 32-45 = -13dB.
Your CPICH Ec/Io of -12 dB is not an irrealistic or bad value.

Dear Philippe (http://www.finetopix.com/member.php?52331-Philippe) ,

Can you explain how to calculate F factor as you mentioned ?

[Philippe]

F is the ratio between intracell and intercell interference. It depends on the location in the cell (and on the power load of the cells). When you are close to the main cell, the extracell interference will be low compared to the intracell so F is close to 0. If you are at the cell edge, the ratio will be close to 2 or 3 (can even be worse depending on shadowing effects). Imagine you are at equi-distance of 2 other cells and you have same power transmitted per cell and same pathloss at this position for the 3 cells, Iextra = 2xIintra. Its even worse as other cells are also using the same frequency and so increasing the intercell interference (but much more attenuated pathloss as more distant).
For hexagonal networks with frequency reuse 1, theroretical system level simulations can give you typical F factor distribution according to the position in the cell, taking into account propagation model and shadowing standard deviations impact.

[dekili]

Hi,
F is sometimes known as "little i". It seems to me that interference is a problem. It seems like too many servers are covering the same location. Next question is what is the position with poor Ec/Io and to determine is it from in-building network or poor isolation from outdoor. If the cell load is high then reduce the power on other sites and add new one. Also, how the building looks like? Any possible leakage through ventilation system or by other means?

cheers

[FrankPintor]

What finger means ?
From Wikipedia: "A rake receiver is a radio receiver (http://en.wikipedia.org/wiki/Receiver_(radio)) designed to counter the effects of multipath fading (http://en.wikipedia.org/wiki/Multipath_fading). It does this by using several "sub-receivers" called fingers, that is, several correlators each assigned to a different multipath (http://en.wikipedia.org/wiki/Multipath_propagation) component."