Call Drop Analysis

Principle of Call Drop

There are two types of call drop: signaling plane call drop and user plane call drop:

Signaling plane call drop means RNC will send the message “IU RELEASE REQUEST” to CN after CN receives the “IU connection setup complete” 

User plane call drop means RNC will send the message”RAB release request “to CN after CN receives the “RAB setup complete”

Formula of Signaling Plane Call Drop Rate:

The formula of Call Drop Rate of CS Signaling Plane:

Call Drop Rate of CS Signaling Plane = RNC-originated CS Domain Iu Connection Release / RNC-originated CS Domain Iu

Connection Setup Success× 100% 
 

The formula of Call Drop Rate of PS Signaling Plane:

Call Drop Rate of PS Signaling Plane = RNC-originated PS Domain Iu Connection Release / RNC-originated PS Domain Iu

Connection Setup Success× 100%.

Cause of Signaling Plane call drop

Formula of User Plane Call Drop Rate

The formula of Call Drop Rate of CS User Plane:

Call Drop Rate of CS User Plane = RNC-originated CS Domain RAB Release / RNC-originated CS Domain RAB Setup Success × 100%

The formula of Call Drop Rate of PS User Plane:

Call Drop Rate of PS User Plane = RNC-originated PS Domain RAB Release / RNC-originated PS Domain RAB Setup Success × 100%