High RTWP and High CDR Issue Resolved After Changing CQI Feedback Period Parameter

May 2, 2017 | Author: Seth Mawuli Dedzoe | Category: N/A
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High RTWP and High CDR issue resolved after changing CQI feedback period parameter Symptom: High CDR problem at 3 Top cells due to high RTWP issue. Problem Analysis: We were facing problem of high CDR at 3 cells of BKF0014U_8NB01_S01, BKF0014V_8NB01_S01, and BKF0014V_8NB01_S02. In primary counter level Analysis we found that drops are occurring due to RF reasons like SRB Reset, Uu no reply and UL Sync issue.

CDR of last 3 days was high and it increased even more on 03 June.

From M2000 counters we also found that RTWP increased due to increase in traffic on 03 June. And in other days also we observed Mean RTWP value high at these cells.

Handling Process: Now from counter level analysis from M2000 we were suspecting RTWP as cause of this high call drop rate. In order to reach some conclusion we analyzed these cells CDR with NP-Master. In this analysis we confirmed that main reason for high CDR at these cells is high RTWP. Results of NP-Master analysis are – Cell BKF0014U_8NB01_S01:

Cell BKF0014V_8NB01_S01:

Cell BKF0014V_8NB01_S02:

Now it was clear that this high CDR was due to high RTWP at these cells. Then we decided to see antenna check results from FMA in order to find if high RTWP is due to some antenna or inter-modulation. Antenna check results from FMA were normal and there was no case of inter-modulation.

As we not found any problem in Intercross check result and PIM check result from FMA and We already seen from M2000 counters that traffic also increased when RTWP increased. So we concluded this high RTWP was due to high traffic situation. Solution: In order to reduce RTWP in high traffic situation we decided to change CQI feedback period from 2 ms to 8 ms. Main concept behind this parameter is the shorter the CQI feedback period is, the better the downlink data transmission is. The longer the CQI feedback period is, the lower the load occupation is. After this change we monitored the RTWP and found that RTWP improved by about 7 to 8 dB. CDR of these cells also improved. Script: MOD UCELLHSDPCCH:CELLID=XXXX,CQIFBCK=D8,CQIFBCKFORSHO=D8,CQIFBCKFORCONVER=D8,CQIFBCKFO RMIMO=D8;

After running this script for cells which have high CDR due to high RTWP, we observed improvement in Mean RTWP and CDR.

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