In the existing system, Vidyalankar Institute of Technology henceforth addressed as VIT Library is situated on 3rd floor. Its a bit tiresome for students and professors to go upstairs for just returning books or just to extend the book return date. E
This presentation covers Call Setup Analysis with a Drive Testing perspective. It goes through the signaling as well as briefs the common causes of call setup failure.
Drop Calls on TCH B
Drop Calls on TCH
Check Lost Handover Bad Locating Parameter Setting?
Y
Correct Parameter Setting
Perform Handover Analysis
N
Y
Most dropped calls during handover?
Check Output Power N Check Site Position Is Power Regulation used properly?
N
Correct power regulation parameter
Remove site or change frequency
Y Drag on Site?
Y Is the Power Balanced?
N N
Adjust output power
Check BTS Error Log
Y Is DTX Used?
Y N
Swap & repair HW
HW Fault?
Introduce DTX
N
Y Is Frequency Hopping used?
N
Check link quality & synchronization
Activate Frequency Hopping
Y
Perform link investigation
Y
Check Dropped call reason
Bad Quality?
Y
N Low Signal Strength?
Perform Interference Analysis
Y
Perform low Signal Strength Analysis
Y
Check site location & TALIM
Y
Check reason for sudden loss
Add site
N
Transmission Fault? N Best server exists?
Y Check MS Problem
N Timing Advance?
Perform drive test
N Sudden Drop?
Perform CTR recordings
Perform site survey
N Other?
Y
Investigate possible Hardware fault
Check Antenna installation
N B
END
From technical perspective, dropped call show the number of abnormal disconnection’s during call setup, SMS, supplementary service activation or during conversation. They are a few different counters for dropped calls, i.e. dropped calls due to low signal strength, bad quality, too high timing advance and miscellaneous is used to get an indication of the reason for possible bad performance. From a subscriber point of view, dropped calls are those that interrupt an ongoing conversation, i.e. a call dropped on the TCH. If the call is dropped on the SDCCH the user simply re-dials again and hopefully succeeds with the new call setup. For this analysis we will focus on the drop call on the Traffic Channel (TCH). TCH drop call can be divided into a few categories: 1. Excessive Timing Advance 2. Low Signal Strength – UL/DL/BL 3. BL Bad Quality – UL/DL/BL 4. Sudden Loss 5. Other reason (not standalone counter) Dropped connection due to failure is counted in counter TFNDROP, which step for the number of abnormally terminated connections. These counters are incremented when the BSC send ‘CLEAR REQUEST’ and when ‘CLEAR COMMAND’ message is received if the code differs from the cause codes ‘CALL CONTROL’ and ‘Handover Successful’. If the ‘CLEAR REQUEST’ has been sent previously before ‘CLEAR COMMAND’, the counter will not step. When a call abnormally disconnected, that is ‘CLEAR REQUEST’ is sent to MSC, a check is made in the function assignment or handover if any of the following urgency state existed. If more than one type of urgency state are indicated by the locating procedure, the following priority (highest priority first) is used to determine the type of urgency state. 1. Excessive Timing Advance (TA) 2. Low Signal Strength in downlink and/or uplink 3. Bad Quality downlink and/or uplink 4. Sudden Loss of connection When type of urgency is determined, one of counters of this urgency state is stepped.
