Poor Quality in Hopping TRXs

[070057r]

Dear Experts,

I observed poor quality in hopping TRXs and good quality while the call in BCCH TRX. For more details following facts can be provided, please help to improve the quality.
1. Hopping Band length is 12 frequencies
2. No HSN and MAIO conflicts
3. Serving the location by more than 3 cells in average rx levels. Pls find the below figure.

Capture.JPG

[captain_jejemon]

Check first if there is alarm or faulty TRX. check also which TRX have high ICM band.

[070057r]

No TRX faults. But there are number of hopping cells served by that location so I want to know how many hopping cells I can keep this. i.e. in 3G if a certain location is serving from the same carrier by more than three cells in -10db difference we call it piolt pollution.

thanks,

[JCarlos21]

Hi dear mate,

Do you know what is the distribution of HR and FR TRXs assignments?

Kind regards,

[fdanaei]

Hi dear friend, Based on your attached picture, BCCH signal level in that location is low (-84dBm). I think your problem is related to lack of dominant cell.
Do following steps (If you sure about MAIO Parameters):
1-Go to scan frequency part of TEMS Investigation and add your network BCCH frequencies in SCAN List, (Mark BSIC decode).
2-Find how many BCCH are in your location that have near signal level to the main BCCH signal. Then write related cells name (cells with Hopping in nonBCCH TRXs).
3-Investigate Antenna information of that cells and do suitable tilt control. Electrical Tilt is better than mechanical tilt for cell control (theoretical reason). High sites might control first. But you must be careful about missing some area coverage. I think interference controlling has more priority than level increasing.
4-Also you can increase level of dominant cell by Antenna height increase or antenna change to high gain if possible.
5-You can select good HSN Pair by referring to following link too: http://www.4shared.com/get/_T3HyGc9/...HSN_Pairs.html
Hope this helps,
Regards,

[070057r]

Do u mean FR to HR threshold . It is 70

[070057r]

Dear fdanaei
Thanks a lot for your kind help. But help me to resolve this. What I think it is ok to have any number of cells with non interfered BCCH frequencies (no co or adjacent) , but we can we have an idea about the hopping TRXs?

[fdanaei]

Hi again dear engineer, my idea about BCCH frequency was only for control of overshooting sites in the location, because you have only 12 hopping frequency. These numbers of frequencies are finished by four 4TRX cells.
But if you mean “Oscillation on Hopping Channels power” reason let to review some things together:

1-In your issue, as we can see in picture, hopping is synthesizer hopping that there TRX unit don’t change in Hopping time and only TRX frequency changes based on MAIO and HSN (in Base Band Hopping, as we know, Hopping TRX number (unit) changes in every hopping step then TRXs power difference and TRX faulty can affect quality) .

2-In synthesizer hopping, oscillation of power can be related to Air interface link (related obstacles and building) and its affection on different frequencies on different time. In Rayleigh fading, that there we don’t have line of sight signal, we can see more than 20dB oscillation in signal level.

3-In your issue, Traffic channel is half rate that it increase channel sensitivity to link condition.

4-In BTS of some vendors when half rate channel type is defined only in some TRXs of cell not all; it causes power and quality non stability in busy hours.

Hope this helps,
Regards,

Dear fdanaei
Thanks a lot for your kind help. But help me to resolve this. What I think it is ok to have any number of cells with non interfered BCCH frequencies (no co or adjacent) , but we can we have an idea about the hopping TRXs?

[JCarlos21]

Hi dear mate,

As our dear friend above said on 3) and 4), I would try to reduce as much as possible the assignment of HR channels.

Let us know if you get any result out of it.

Regards,

[hoangtuna]

Hi dear friend, Based on your attached picture, BCCH signal level in that location is low (-84dBm). I think your problem is related to lack of dominant cell. Do following steps (If you sure about MAIO Parameters): 1-Go to scan frequency part of TEMS Investigation and add your network BCCH frequencies in SCAN List, (Mark BSIC decode). 2-Find how many BCCH are in your location that have near signal level to the main BCCH signal. Then write related cells name (cells with Hopping in nonBCCH TRXs). 3-Investigate Antenna information of that cells and do suitable tilt control. Electrical Tilt is better than mechanical tilt for cell control (theoretical reason). High sites might control first. But you must be careful about missing some area coverage. I think interference controlling has more priority than level increasing. 4-Also you can increase level of dominant cell by Antenna height increase or antenna change to high gain if possible. 5-You can select good HSN Pair by referring to following link too: http://www.4shared.com/get/_T3HyGc9/...HSN_Pairs.html Hope this helps, Regards,

Dear my friend. Do you have full book of your document?