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Ericsson_RND
2012-02-15, 05:45 AM
Dear Expert, I am facing problem regarding one new installed site.
New site installed with below configuration:

2 RBSs 2216V1 each RBS with 4+4+4 GSM900/4+4+4GSM1800.
Each RBS has specific TG.
The antenna is Dual band mode.

Once we operate the site the RX level near to the site is unstable for all cells (3 GSM900/3GSM1800).
Partial/Full swap and the VSWR were checkd, what are the expected reasons that led this site to have -70 dbm RXLevel signal within 100m distance, and many handover occurs to nearest sites located 5 Km far away from it.

The site TX power was set as MAX 47 for GSM900 45 for GSM1800

Regards
E*******_RND

zlobster
2012-02-15, 05:29 PM
Antenna model? Combining? Electrical tilt?

T_ADD
2012-02-15, 06:07 PM
In addition to the above - if new site, what about SW version, did you check Tx output power at different points with a RF meter?

auto_art
2012-02-15, 08:53 PM
Dear Expert, I am facing problem regarding one new installed site.
New site installed with below configuration:
2 RBSs 2216V1 each RBS with 4+4+4 GSM900/4+4+4GSM1800.
Each RBS has specific TG.
The antenna is Dual band mode.
Once we operate the site the RX level near to the site is unstable for all cells (3 GSM900/3GSM1800).
Partial/Full swap and the VSWR were checkd, what are the expected reasons that led this site to have -70 dbm RXLevel signal within 100m distance, and many handover occurs to nearest sites located 5 Km far away from it.

The site TX power was set as MAX 47 for GSM900 45 for GSM1800

Regards
E*******_RND

check the hybrid combined/uncombined chip at back of DRU>

Ericsson_RND
2012-02-16, 02:46 AM
Hi All;

The Antenna type is Kathrein-80010485, electrical tilt was set at 2 degree for GSM900, 4 degree for GSM1800, antenna height is 27 meter for three sectors.
In our design we are not using the combiner, 6 feeders for band 900 and 6 feeders for 1800 are used.
combined mode was used as RBS configration.

How can I check the Tx output power at different points with a RF meter.

Another thing based on MRR the sector of 900 band is carrying traffic 10 erlang from 3 KM, while 1800 band carrying 0.5 erlange from 2.5 Km, there are two sites are neigbouring faraway from this site 4 KM and once we make drive test the handover occure once we will be 250 m from the new site , to the neighbour site which faraway 3.8 km from it.

Ericsson_RND
2012-02-16, 03:09 AM
Adding to the above and based on MRR reading it was observed that there is bigh difference in the DL/UL propagation pathloss digram for all the sectors of this site compaired with remining network sites.

rffreeconsult
2012-02-16, 05:43 AM
Check the cable runs and all the connectors from the BTS output. Please note that your cable type depends on your cable length. If the length is long, u have to use low-loss cables (higher price and bigger diameter). The connectors may contribute to additional loss if they are loose and ill-adjusted. From your description, it seems that the antennas have the wrong tilts, based on the frequency & propagation characteristics, it should be the other way: 4 deg for the GSM900 and 2 deg for the GSM1800. If there is nothing wrong with the cables and connections, the wrong setting may explain the early HO and small footprint. Hope it help & good luck...

Inception
2012-02-17, 03:55 AM
HI Mate
Did you checked the O/L U/L?How About the Layers ?are they defined correctly ?

Br

Ericsson_RND
2012-02-18, 04:51 AM
layer threshould was set at 90 for 1800 band, and 75 for 900 mean that we push the traffic to be carried by the 1800.

The main observed issue in the MRR result is the big difference in the pathloss propagation for the both UL/DL for all other N/W sites there is small diviation for the both UL/DL for the same cell.

can any body tell me what are the main other reason which cause this difference VSWR/Full swap and patical, feeder type where checked and there is no problem.

The problem once we went around 200 m the handover done to the nearest site even its faraway 4 Km from this new site, this site and the other site has 30m antenna height