- This topic has 67 replies, 1 voice, and was last updated 14 years, 5 months ago by Pix.
9th January 2006 at 07:05 #43366Tech ManGuest
Since you have checked everything on the hardware part. There may be an external source of Interference like cordless phone users using the UL band. Why one of the operators here even found out the interference in G900 band was coming from odd sources like Marine radio from one of the merchant ships docked off the coast as well as a Church public address system 😉9th January 2006 at 08:03 #43367MadhuGuest
1)Tech Man is right even we have faced that problem
2)Try to find out if some indoor boosters are installed in the near by area, the antenna of these boosters produce very high interference
Madhu9th January 2006 at 11:32 #43368BokoGuest
We are using repeaters for some indoor locations. We very often have the same problem when there is some problem with them. And when you change the frequency of course the interference still exists. It could even be installed by the competitor (not band selective as they are cheeper) several times it was some bad GSM gateways also. Also illegal boosters and cordless phones…
Usually we go to the site with a yagi antenna and analyzer, and try to locate the interferer. the best way is to connect to analyzer to the GSM antenna to see the level of the interference.9th January 2006 at 17:00 #43369TagGuest
I think that is the only way i can do now.
We have use a spectrum analyzer and found out that the interfence is in a large bandwidth.
Any others to know who is transmitting?10th January 2006 at 08:17 #43370Tech ManGuest
Since as you said it is a wideband noise and no CDMA operators are present in your region.More likely than not, the external source of interference would be from an unknown source (eg. Illegal users etc) than a known source(Network operators), making it difficult to detect the source.
Please check the following in the vicinity of your site in question:
1) Any wideband repeater
2) Bad mast head amplifiers (If Any)
3) Earthing/ Sparking from any Electrical source.
Contact you local Telecommunication Spectrum Administrator for support, as they have the requisite equipment and powers to detect and regulate such source,11th January 2006 at 17:21 #43371JoeGuest
it is occured often that uncompliant to EMC (electro magnatic compatability) in telecom equipment make alots supirous & interference to receiver.
may such problem related with unefficent hardware immunity such as TRX damege or bad grounding, or probably Antenna defect(manufactury OR OLD antenna which may had metal part losses or radiators losses => intermodulation & degradation in Quality.
B Regards.30th January 2006 at 11:44 #43372VijayGuest
According to my knw the fre. band of radio is limited to 30 to 300 MHz so it cant affected to 900 Mhz GSM band.
according to u wht is the spectrum of Marine radio i heard first time this word.
t28: can u plz conform how many users in this two sectors?30th January 2006 at 12:26 #43373sachin bhushanGuest
what is SDCCH drop at Abis.?
what r the reasons ?14th February 2006 at 06:35 #43374joeGuest
In some countries coexist several radiocellular systems such as : TACS, AMPS, NMT900 with partly common frequency bands. It can be very difficult to detect if the interfered GSM frequency is not a BCCH.
The effect is:
• intermodulation with GSM BS/MS receiver,
• spurious RACH for AMPS (AMPS Tx bands close to GSM uplink band),
• TACS : coverage hole with 600 m from TACS BTS
• AMPS 50 % reduction of range if AMPS/GSM BTS collocated.
Other RF Interferer (Radar, shop anti-theft mechanisms, medical device …) must be check case per case with a spectrum analyser, most of time on long period to detect sporadic or interference.14th February 2006 at 06:39 #43375areebaGuest
When interferer is a single frequency or with spectrum width limited, it can be sufficient to change frequencies on impacted sites.
When disturbance is a spread over a large portion of spectrum, it could be necessary to add selective filters in BTS receiving section.
In terms of parameters, it can be better to deactivated intracell handover flag(s), EN_INTRA_UL, EN_INTRA_DL, or even HO_Intracell_Allowed.13th March 2006 at 11:47 #43376Rajiv GujralGuest
Is Uplink Qual goes worst only because of the other source of interference( that we can check in our daily report using avb_undec_RACH) or because of Hadware fault too..
Regards16th March 2006 at 13:46 #43377lodvicheGuest
Kindly i wonder about TRX hw problem, Cuz we encouter this in our network (alcatel) whereby we get LOW EFFICIENCY for TRXs daily, & just we replace it by other, so please what is the sensible reason beyond this problem, to avert this huge number of replacement which are (more than 4 low efficient TRXs per day)
any Ad is highly appriciated.21st March 2006 at 10:36 #43378LangerGuest
You may be facing a problem in the network because of improper installations. Better you check for VSWR. Also check the connectors connections properly.15th September 2006 at 08:33 #43379JohnGuest
What is the prime reason for Intra-Cell Handover failures?
John16th September 2006 at 00:21 #43380PixGuest
The intracell HO can be caused by :
– interference (UL or DL)
As any handover, the process of this HO can be divided into two parts : the preparation phase and the execution phase (respectively, the request is validated as an attempt, and the attempt becomes a success).
A preparation failure is due to congestion in the cell or a hardware failure (trx, combiner, sum, abis, bsc..).
An execution failure is due to radio problems (interference to high in the target frequency, radio link is lost, …), or again, a hardware failure. Execution failure can be “saved” by a Reversion to the Old Channel (ROC).
I hope it’ll help you…