Accessibility KPI

 Accessibility :If A UE Requested for the some services to the system and System will Response UE Properly, It means Accessibility is  completed successfully. Accessibility KPIs are used to measure how successfully user is able to access the Network. Divided in 3 segments.

  1. RRC Phase
  2. S1 Signaling Phase
  3. E-RAB Phase


In the Call Flow System, after the RACH Procedure,2nd Procedure comes the RRC Phase.
  • RRC Rejection due to Congestion:
    May be the Reason eNB will be busy or it is very congested, It don't have Resources, So that it can allow new user. 
                                             How we can Reduce the Congestion
  • Decrease the UE Inactive Timer to a smaller value(If we reduce this timer, UE will less stay in RRC connected mode, more offen release by enb). This will initiate early release for the users, Hence Load will be reduced. However this can increase the signaling load as idle user can try to come back to network more frequently which can increase CPU usage of the eNB. So, Only use this if the issue is related to user limitation while CPU usage is fine.
  • Physical Optimization down tilt the cell or Reduce the dlrsboost parameter in Nokia and crsgain in Ericson to remove the boundary cell users.
  • Mobility Load Balancing is another feature that can help in such scenario, we shift the users to the Near by the site or in the Different carrier or Different Band from the same site. this way we can reduce the user, So the eNB will be free.
  • a3offset If we reduce a3offset value that is the offset for the A3 event, UE will move very fast to the neighbor site or give the Handover.
  • RRC Setup Failure due to No Response:

  • UE fails to decode RRC Connection Setup message, So it will not send the RRC Connection Setup complete message.
  • Sometimes, Cell have a huge Interference and in this case eNB may not receive the RRC Connection Setup complete message.
  • eNB fails to decode the RRC Connection Setup Complete message. At the boundary of the cell, RRC connection Setup Complete message is accompanied by Attach Request message which is perceived as bulky/lengthy message hence UE at the Cell boundary may not be able to decode the message.
                                                 To Overcome this problem
  • Physical Optimization down tilt the cell or Reduce the value of dlrsboost parameter in Nokia and crsgain in Ericson to remove the boundary cell users.
  • Timer T300,T301,T302 etc retuning.
Timer T300: UE starts it after sending the RRC Connection Request and stops it at the receipt of RRC Connection setup or Reject message. If this timer is too small, the UE will stop waiting for the RRC Connection setup message and the RRC Procedure will fail. So increasing this timer can help in this phase.{Timer T300 Supervises the RRC Connection establishment procedure}.
Timer T301: UE starts it after sending the RRC Connection Reestablishment Request and stops it at the Receipt of RRC Connection Re-establishment setup or reject message. If this timer is too small, the UE will stop waiting for the RRC Connection Re- establishment setup message and the RRC Procedure will fail. So increasing this timer can help in this phase. {Timer T301 Supervises the RRC Connection Re-establishment procedure}.


Timer T302:When a UE gets a RRC Reject from eNB, It has to wait for T302 seconds before sending another RRC Connection Request. So increasing T302 will increase the interval between such RRC Connection Requests and Hence, Reduce the signaling load on the eNB.
{T302=eNB sends this parameter to the UE in the message RRC Connection Reject.1000...16000 ms. steps 1000 ms.

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