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Chelox
2011-10-26, 04:53 AM
Hey guys!!!

I have a problem and I need your help please!!

We have assigned for 3G deployment AA' frequency band (894-900MHz and 939-945 MHz), but according with the regulator there are 2 other operators located in the adjacent inferior band. Operator 1: extended GSM (894-900MHz and 939-945 MHz) and Operator 2: GSM DL 890-891.5 MHz.

Do you have any experience with this? is it safe to deploy considering this adjacencies?? if so what considerations should be taken??

I´ll be grateful if you can help me with this!
Regards,
Chelox

Chelox
2011-11-02, 08:32 AM
Somebody??? Would be very helpful your experience...

srilasitha
2011-11-02, 01:19 PM
according to your description 1st operator uses the same frequency band of you. is it correct



Hey guys!!!

I have a problem and I need your help please!!

We have assigned for 3G deployment AA' frequency band (894-900MHz and 939-945 MHz), but according with the regulator there are 2 other operators located in the adjacent inferior band. Operator 1: extended GSM (894-900MHz and 939-945 MHz) and Operator 2: GSM DL 890-891.5 MHz.

Do you have any experience with this? is it safe to deploy considering this adjacencies?? if so what considerations should be taken??

I´ll be grateful if you can help me with this!
Regards,
Chelox

Chelox
2011-11-03, 07:06 AM
Sorry I made a mistake, this are the bands:

Operator 1: GSM Extended 850MHz Downlink (891.5-894)
Operator 2: GSM Downlink 890-891.5 MHz

My operador: UMTS 900MHz, 894-900MHz for uplink and 939-945 MHz for downlink.

Is it safe to deploy considering that Operator 1 is directly adjacent with the Uplink of my operator?

I done my research and I found many recommendations where they say that is safe if you leave 2.8 MHz spacing between UMTS carrier and the first GSM carrier, but I would like to know your opinion and your experience please!!!



according to your description 1st operator uses the same frequency band of you. is it correct

Originally Posted by Chelox
Hey guys!!!

I have a problem and I need your help please!!

We have assigned for 3G deployment AA' frequency band (894-900MHz and 939-945 MHz), but according with the regulator there are 2 other operators located in the adjacent inferior band. Operator 1: extended GSM (894-900MHz and 939-945 MHz) and Operator 2: GSM DL 890-891.5 MHz.

Do you have any experience with this? is it safe to deploy considering this adjacencies?? if so what considerations should be taken??

I´ll be grateful if you can help me with this!
Regards,
Chelox

beniy
2011-11-03, 07:18 AM
Sorry I made a mistake, this are the bands:

Operator 1: GSM Extended 850MHz Downlink (891.5-894)
Operator 2: GSM Downlink 890-891.5 MHz

My operador: UMTS 900MHz, 894-900MHz for uplink and 939-945 MHz for downlink.

Is it safe to deploy considering that Operator 1 is directly adjacent with the Uplink of my operator?

I done my research and I found many recommendations where they say that is safe if you leave 2.8 MHz spacing between UMTS carrier and the first GSM carrier, but I would like to know your opinion and your experience please!!!
Hi Dude,
All of them are ok.
But consider one thing, RF filtr in GSM working in 200 KHZ.
If you can go 400 KHZ more than 894 it means 894.4 MHZ.
THat's ok do not worry.
Second operator is totaly ok.
Here we have just one 200 KHZ guard and that's ok.

Please add my reputation if that's help you.
Thanks in advance.
http://www.finetopix.com/reputation.php?p=155683

srilasitha
2011-11-04, 01:28 PM
Hi Dude,
All of them are ok.
But consider one thing, RF filtr in GSM working in 200 KHZ.
If you can go 400 KHZ more than 894 it means 894.4 MHZ.
THat's ok do not worry.
Second operator is totaly ok.
Here we have just one 200 KHZ guard and that's ok.

Please add my reputation if that's help you.
Thanks in advance.
http://www.finetopix.com/reputation.php?p=155683

If the GSM operators down link is adjacent to your network 3G uplink. it is something you have to worry.:(

if your system colocate or have towers nearby interference is possible. please have a test on RTWP uplink if possible. better to shift to another band.

otherwise you needs to install bandpass filter to filter out GSM downlink band.

cooltyger
2011-11-04, 03:12 PM
Operator 1: GSM Extended 850MHz Downlink (891.5-894)
Operator 2: GSM Downlink 890-891.5 MHz

My operador: UMTS 900MHz, 894-900MHz for uplink and 939-945 MHz for downlink


It is pretty safe till the Operator 1 is in GSM. U can maybe extended your guard band near 894 MHz if its possible as the Operator 1 is in Downlink at 891.5-894 and you are in Uplink.
But if the Operator 1 changes/refarms to UMTS or EVDO with a higher bandwidth (though it looks unlikely as he has only 891.5-894) you may face Uplink issues(less throughput) to some extent if his filters in DL are not appropriate. And it may not be service effecting but the noise floor will rise and your UL throughput maybe less than expected!!!

dremka
2011-12-27, 06:21 AM
From my experience this situation is extremely unsafe. There are two aspects in colocation in this case - outband emission from interfering op and receiver blocking due to outband strong signal adjacent to uplink of vicitm's BTS. I recommend to do some testing before the deployment. In my case umts downlink (my op) to umts uplink (other op) was only 5 MHz apart and it caused victim's umts receiver blocking and desensitizing. The other op had applied high order passband filters (~1dB att in the passband and ~80 dB blocking in only 5 MHz) to eliminate blocking their uplink and we had added passband tx filters to supress outband emission. There are some regulations where allowed signal levels in adjacent bands are described, pls refer ETSI ts_125104, especially 'receiver characteristic' chapter.
We had problems even with BTS's spaced 200m apart with antennas directing to each other - it caused receiver blocking in the umts band in the victim's BTS (as it was Huawei the symptom was elevated RTWP level).
I have analyzed this issue deeply and from the norm mentioned above the minimal safe distance with 17 dBi antennas directing to each other and tx power 43 dBm with no filters applied is 3,6 km (!). With outband emission filters the safe distance is ca 430m. With outband emission and receiver antiblocking filters the safe distance depends on filter's attenuation and antenna spacing.
If you are interested in further info just PM me.

madthink
2012-01-03, 12:57 PM
check the combiner with spectrum analyzer

rishi
2012-01-03, 01:57 PM
According to my experience we have also UMTS 900 and we didnt faced much issues but some of those sites were defiently facing uplink issues butrecommending TMA or MHA can be a good solution to them.