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UL interference

Viewing 8 posts - 1 through 8 (of 8 total)
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  • 12th May 2010 at 05:19 #62606
    DENIS
    Guest

    Hi,

    Is downtilt help me for Up link interference ? (high ul bad quality drops)

    12th May 2010 at 10:51 #62607
    Brother
    Guest

    I dont think it will help, to protect ur system u need to find the interferer source, for downlink this can be another site which you may know so downtilt can be given, but for uplink signals are coming from mobiles or from another source u need to find, also 1 more thing you need to check vswr and hardware, these may be also creating problem and appears like uplink interference

    12th May 2010 at 12:33 #62608
    Pix
    Guest

    Hi,

    It will help a little because you actually focus your RX lobe more towards the “served” MS and less towards the “neighbour” MS.
    The C will increase, but the I will decrease.

    However the benefits strongly depend on your terrain topography. If flat city, then improvements are high. If hilly open area, improvements will be less.

    Another angle to decrease the UL interference is to adjust your UL power control settings to more aggressive thresholds (reduce by -5dB), and faster averaging windows. Try to decrease the power increment steps, so that MS won’t transmit too strong too quickly.

    Also, don’t forget to activate UL DTX for EFR and HR calls (it should be done by default).

    Best Regards,
    Pix

    12th May 2010 at 14:37 #62609
    DENIS
    Guest

    Pix,

    Actually I dont understand how “I” decrease with downtilt? Because normally UL interferer is MSs that independent of serving cell.

    14th May 2010 at 04:59 #62610
    Mania
    Guest

    Hi,
    Actually by downtilting you would be decreasing both cells’ coverage area and making signals stronger for the cells in its vacinity.
    Now that the far off mobiles no longer camp on to overshooting cell site and would not be transmitting at high power to generate interference for MS camped on to the other cell being interfered. So both the cell sites would be contained in UL too that would be reducing the Interference noise floor.
    Very effective in situation when using SFH like 1×1 or 1×3

    14th May 2010 at 13:23 #62611
    DENIS
    Guest

    OK mania,

    I got it.

    but my question is about serving cell. if ı give downtilt to serving cell is it effect ul interference on the cell which I apply downtilt?

    thanks

    17th May 2010 at 05:11 #62612
    Mania
    Guest

    Good tricky question,
    Well Look at this in this way that there is an idea cell whose antenna can only receive in its beamwidth now for now a jammer is installed in its main lobe. now if you down tilt the antenna coverage would shrink, the receiver lobe too would move towards the the site and jammer would be out of the lobe so the site would not experiance interference.
    Now in this example replace the jammer with a cell phone camped on to another site and the ideal antenna with a practical antenna which has greater loss outside its main lobe.
    Its just a hypothetical answer hope it is ok .. still open for any questions

    17th May 2010 at 11:00 #62613
    DENIS
    Guest

    “cell whose antenna can only receive in its beamwidth” – Mania

    “RX lobe more towards the “served” MS and less towards the “neighbour” MS” – Pix

    Thanks Pix and Mania,

    I got answer

    Actually I thought that UL interference is independent of RX lobe of BTS antenna. I overlooked Pix answer this is why I asked again.

    Sorry one more question ?

    Logically (I dont have some much experience so just ı am thinking theoretical)for UL interence to decrease antenna hieght will help me more then downtilt ? Is it like this?

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