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Thread: PRACH Improvement

  1. #1
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    Default PRACH Improvement

    dears
    please the PRACH SR in my network is almost 65 % , and almost failure is false alarm
    and we have already open the feature false alarm detection under SON but the problem still persist
    please any sugestion to improve it

    thanks

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  3. #2
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    Default Re: PRACH Improvement

    Quote Originally Posted by mounir34 View Post
    dears
    please the PRACH SR in my network is almost 65 % , and almost failure is false alarm
    and we have already open the feature false alarm detection under SON but the problem still persist
    please any sugestion to improve it

    thanks
    PRACH SR comes with Random access and handover. Check counter to make sure which one is failed. I belieave it comes from handover area, where having too many handover failure between overshot cells.

  4. #3
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    Default Re: PRACH Improvement

    dear
    the below formula used for troubleshooting ,
    GroupA False Alarm Rate is the main failure


    Contention Preamble Response Rate =(L.RA.GrpA.Resp + L.RA.GrpB.Resp) / (L.RA.GrpA.Att + L.RA.GrpB.Att) * 100
    Non Contention Preamble Response Rate= L.RA.Dedicate.Resp / L.RA.Dedicate.Att * 100
    Contention Resolution Ratio=(L.RA.GrpA.ContResolution + L.RA.GrpB.ContResolution) / (L.RA.GrpA.Resp + L.RA.GrpB.Resp) * 100
    Contention Preamble False Alarm Rate =(L.RA.GrpA.Att-L.RA.GrpA.ContResolution+L.RA.GrpB.Att-L.RA.GrpB.ContResolution)/(L.RA.GrpA.Att+L.RA.GrpB.Att)*100
    GroupA False Alarm Rate= (L.RA.GrpA.Att - L.RA.GrpA.ContResolution) / L.RA.GrpA.Att * 100
    GroupB False Alarm Rate= (L.RA.GrpB.Att - L.RA.GrpB.ContResolution) / L.RA.GrpB.Att * 100
    Non Contention Preamble False Alarm Rate= (L.RA.Dedicate.HO.Att - L.RA.Dedicate.HO.Msg3Rcv) / L.RA.Dedicate.HO.Att * 100

    Quote Originally Posted by linhhy View Post
    PRACH SR comes with Random access and handover. Check counter to make sure which one is failed. I belieave it comes from handover area, where having too many handover failure between overshot cells.

  5. #4
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    Default Re: PRACH Improvement

    dear
    also another question the PRACH SR is almost 65% ,is it normal ? if no how to improve based on abouve KPI,thx

    Quote Originally Posted by linhhy View Post
    PRACH SR comes with Random access and handover. Check counter to make sure which one is failed. I belieave it comes from handover area, where having too many handover failure between overshot cells.

  6. #5
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    Default Re: PRACH Improvement

    dear
    please check below the PRACH SR is very low ,any suggestion,thx

    Capture.JPG
    Quote Originally Posted by linhhy View Post
    PRACH SR comes with Random access and handover. Check counter to make sure which one is failed. I belieave it comes from handover area, where having too many handover failure between overshot cells.

  7. #6
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    Default Re: PRACH Improvement

    Dears,

    Check from the counters which have been mentioned above, identify which is contributed GrpA or BrpB ?

    If caused by GrpA -> Due to some UEs are located farther than the parameter Cellradius. For this case what you can do is reduce the overshooting issue by downtilting or expand the cell radius let say from 10 km to 15 km.

    If caused by GrpB -> Most probably due to collision of root sequence. Please check the planning parameter like rootsequenceidx and cellradius. Sample case the cellradius is 10km but minimum delta between RSI less then 8, while based on planning it requires minimum 8 root sequence.

    Just check first, then we can discuss more detail..
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  9. #7
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    Default Re: PRACH Improvement

    yes Sir is caused by GroupA that why we increase the Cell Reduis to 10km before it was 8km
    but also after increase cell reduis we noticed slight improvement in PRACH SR but also Outgoing HO degraded

    Quote Originally Posted by yoyokdp View Post
    Dears,

    Check from the counters which have been mentioned above, identify which is contributed GrpA or BrpB ?

    If caused by GrpA -> Due to some UEs are located farther than the parameter Cellradius. For this case what you can do is reduce the overshooting issue by downtilting or expand the cell radius let say from 10 km to 15 km.

    If caused by GrpB -> Most probably due to collision of root sequence. Please check the planning parameter like rootsequenceidx and cellradius. Sample case the cellradius is 10km but minimum delta between RSI less then 8, while based on planning it requires minimum 8 root sequence.

    Just check first, then we can discuss more detail..

  10. #8
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    Default Re: PRACH Improvement

    dears
    do you have some parameters to improve the PRACH SR or features
    because we have increase Cell reduis also we activated the RACH Optimization feature but SR still low,
    thanks
    Quote Originally Posted by yoyokdp View Post
    Dears,

    Check from the counters which have been mentioned above, identify which is contributed GrpA or BrpB ?

    If caused by GrpA -> Due to some UEs are located farther than the parameter Cellradius. For this case what you can do is reduce the overshooting issue by downtilting or expand the cell radius let say from 10 km to 15 km.

    If caused by GrpB -> Most probably due to collision of root sequence. Please check the planning parameter like rootsequenceidx and cellradius. Sample case the cellradius is 10km but minimum delta between RSI less then 8, while based on planning it requires minimum 8 root sequence.

    Just check first, then we can discuss more detail..

  11. #9
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    Default Re: PRACH Improvement

    yes Sir is caused by GroupA that why we increase the Cell Reduis to 10km before it was 8km
    but also after increase cell reduis we noticed slight improvement in PRACH SR but also Outgoing HO degraded
    you have to redo rootsequenceindex planning - the step in rootsequenceindex between cell should match cell radius.
    You most likely have overlap between preambles between cells on the same site. Therefore you have incorrect decoding of Prach, which leads also to poor HO SR. That is cell with poor HOSR will have overlap of upper part of preambles with cell that has poor PRACH SR in group A (which are located at the bottom part of preamble list).

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