QoS Measurements
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⚫ CSSR ◆ SDCCH Cong.
■ DCR ▲ TCCH Cong.

Airtel Data
CSSR
DCR
SDDCH
TCCH
9mobile Data
CSSR
DCR
SDDCH
TCCH
Globacom Data
CSSR
DCR
SDDCH
TCCH
MTN Data
CSSR
DCR
SDDCH
TCCH

The Call Setup Success Rate (CSSR) is calculated by taking the number of the unblocked call attempts divided by the total number of call attempts. A call setup is an exchange of signaling information in the call process that leads to Traffic Channel (TCH) seizure.

Performance Threshold: The CSSR should be equal to or greater than 98%.

CSSR(%) = Number of Unblocked
Call Attempts
 × 100
Total Number of Call Attempts

The Dropped Call Rate (DCR) - also called Call Drop Rate - is the number of dropped calls divided by the total number of call attempts. A dropped call is a call that is prematurely terminated before being released normally by either the caller or called party (i.e., the call is dropped before the exchange of Released Message "RL_M" and Released Complete Message "RLC_M" in the signaling flow).

Performance Threshold: The DCR should be equal to or less than 1%.

DCR(%) = Number of Prematurely
Terminated Calls
 × 100
Total Number of Call Attempts

The Standalone Dedicated Control Channel Congestion Rate is defined as the probability of failure of accessing a Standalone Dedicated Control Channel (SDCCH) during call set up. The SDCCH is used in the GSM system to provide a reliable connection for signalling and SMS (Short Message Service) messages.

Performance Threshold: The SDCCH Congestion Rate should be equal to or less than 0.2%.

SDCCH(%) = Number of Assignment
Related Connect Fails
 × 100
Mobile Originating Call Attempts

The Traffic Control Channel Congestion Rate is the probability of failure of accessing a traffic channel during call setup. Traffic Control Channels (TCCH) are responsible for transferring control information between mobiles and the BTS.

Performance Threshold: The TCCH Congestion Rate should be equal to or less than 2%.

TCCH(%) = Number of Call Connect Fails  × 100
Total Number of Call Attempts