Optimization for multiple server issue in multi story ( high-rise) buildings

[ash_bansal]

Hi All,
Can anyone suggest, how to resolve the multi server issue in GSM at high-rise building ( multi story buildings) where we have severe issue due to multiple servers and unable to make a dominant a single server. We can not install repeater as well for each case. Kindly suggest someways to resolve the issues. Share if any document available.

Thanks in advance.


Than

[s52d]

Hi All,
Can anyone suggest, how to resolve the multi server issue in GSM at high-rise building ( multi story buildings) where we have severe issue due to multiple servers and unable to make a dominant a single server. We can not install repeater as well for each case. Kindly suggest someways to resolve the issues. Share if any document available.

Thanks in advance.


Than

Hi!
Each case is unique project, because topology of interferes is different.
Repeaters can be used underground: otherwise you add aditional interference.
Think of dedicated cell/site, using metalized windows and steel-concrete walls as
protection between inside/outside.

If you can not do anything inside, try from outside: just add another cell with uptilt
antenna to provide dominant server on upper floors.
We did it few times on 1800, while macro layer (downtilt antennas) is on 900 MHz.
Think of non-standard antennas, providing desired coverage.

Good luck,
s52d

[alkelani]

Try using asuitable antenna BW vertical 15 and Hor 67 but use the horizantal BW as your Vertical by placing the antenna in horizantal way
instead of vertical as usual .

[indoor]

Try using asuitable antenna BW vertical 15 and Hor 67 but use the horizantal BW as your Vertical by placing the antenna in horizantal way
instead of vertical as usual .

I did a quick link budget for this type of idea some years ago, (which I don't have any more sorry), and if your cell site is quite close (100-300 metres away) you can do this by tapping off a small amount of power from one of the sectors this can be 10dB coupler, so impact on original sector will be approx 1dB loss.

Anyway if you assume 20dB penetration loss into the building this gives loads of head room as FSPL for 300m at 1800 is only 87dB so should allow for greater than -70dBm in the building with antenna input power levels no greater than +20dBm per TRX (assuming antenna gain of 17dBi)

[telwind]

Hi!
---
We did it few times on 1800, while macro layer (downtilt antennas) is on 900 MHz.
---
s52d

Hi s52d,
I am very interesting with this solution. Could you share your experience on this?

[s52d]

Hi s52d,
I am very interesting with this solution. Could you share your experience on this?

Works. Radio coverage planning is 3D problem.

As we do not have "spare" 900 BCCH frequencies, we use 1800 for this.
Dedicate cell and point to upper floors of the building(s).
As described below, horizontally mounted antennas, different types,
putting antenna quite low on top on nearby house: all classic radio tricks.
Thus, dominant server is provided.
Together with Hierarchical Cell Structure we keep people on 1800.

Works for mountains as well: but we prefer 900 MHz there. If we can...

BR
s52d

[ash_bansal]

Need somemore detail on this. We are no having 1800 Mhz spectrum, only 900 is available.

[s52d]

Need somemore detail on this. We are no having 1800 Mhz spectrum, only 900 is available.

Then just pretend you have 1800 ;-)
Use your microcell band or whatever, just provide interference free coverage
with dominant cell. We keep some of 900 band for "dirty cells": etc.
But, if you do not have enough band, you shall either work hard to provide
interfernce free coverage or build indoor.

BR
s52d

[louvre]

Hi,

As you are playing with one band only it become difficult, i know a way it might just for your case but involves bit of optimization work.

Visit the high rise. note all the cell id you get in each floor you want to optimize in!! along with the RX level.

from the list find the cell id which can be best possible candidate for that building and other cells which are equally good candidate.

In the cell that you would like to make the mobile camp on the idle mode for the building change the c2 setting give it some positive start with a low value and increase till the value makes all mobile in that building always camp on to it. Now for the connected mode.

Make it very difficult for the call to jump out of this cell until it reaches some sort of threshold. HO parameter like PBGT/ Level /quality.

Thirdly if you have any feature by you can chain the HO then you can do it so that calls will move between best server to second best server, this will help you to steer the calls in the cells you would like to go.

Fourth if you need to optimize for elevators go for feature like rapid field drops and the chain cells stuff i said before. it will help you avoid unnecessary drop.


Take care with c2 with it good usefulness it can also cause a case of bad headache by overloading a cell and causing some extra HO. so check for sufficient capacity in the cell before tying.