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VIP Member
Reputation: 1017
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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2017-08-26 12:16 AM
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Senior Member
Reputation: 311
Re: PRACH Improvement
Originally Posted by
mounir34
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.
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VIP Member
Reputation: 1017
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 |
Originally Posted by
linhhy
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.
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VIP Member
Reputation: 1017
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
Originally Posted by
linhhy
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.
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VIP Member
Reputation: 1017
Re: PRACH Improvement
dear
please check below the PRACH SR is very low ,any suggestion,thx
Capture.JPG
Originally Posted by
linhhy
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.
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Senior Member
Reputation: 360
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..
Best people are those who are useful to others
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Post Thanks - 1 Thanks
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VIP Member
Reputation: 1017
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
Originally Posted by
yoyokdp
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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VIP Member
Reputation: 1017
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
Originally Posted by
yoyokdp
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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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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