Random Access (RACH) Success :
Random Access Channel (RACH) is used by the MS on the “uplink” to request for allocation of an SDCCH. This request from the MS on the uplink could either be as a page response (or incoming call) or due to user trying to access the network to establish a call. Availability of SDCCH at the RBS will not have any impact on the Random Access Success.
The number of times an MS tries to access the network (repeated access in the event of no response from the BS in the form of immediate assignment or immediate assignment reject on AGCH) is decided by the BSS parameter MAXRET (maximum number of retransmissions) and the randomness in the time interval between each of these access request is defined by the parameter TX.
Random Access Success Rate = (CNROCNT)/ (CNROCNT+RAACCFA) * 100
RAACCFA: Failed Random Access
CNROCNT: All accepted Random Access
Root cause analysis of poor Random Access Success
Fish Bone diagram for root cause analysis of poor Random-Access Success Rate
Reason for Poor RACH Failure.
Poor BSIC Plan
Poor BCCH plan
Poor Coverage / Spillage
Phantom RACH
ACCMINand CRO
Faulty Antenna / Cable.
Poor BCCH plan
Poor Coverage / Spillage
Phantom RACH
ACCMINand CRO
Faulty Antenna / Cable.