The Design And Implementation Of Lawful Interception System In CDMA Communications Network

Lawful Interception (LI) is a requirement placed upon service providers to provide legally sanctioned official access to private communication. Today, information industry is being developed at top speed in our country, till the end of 2006, the number of people using mobile telephone will up to 459 million. The quality of mobile telephone service doesn't only concern with the national interests, but also assume significant duty for the national security. As an important means to combat against criminal activity, the lawful interception is paid more and more attention by the national security sector. The telecommunication equipments should meet higher requirements for lawful interception.Based on China lawful interception standard, through the discussion of the implementation of the lawful interception system in Mobile Switch Center (MSC), the paper introduces a technological design and an implementation of lawful interception system in the CDMA mobile communications network in detail. The lawful interception system uses a modularized and stratified design scheme in the software framework, designs the Lawful Interception Server which implements the lawful interception function in conjugation with MSC, the system can reduce the negative influence on the normal performance and function as much as possible and well supports the future extent of the lawful interception standard.Firstly, the paper introduces the CDMA communications network and the MSC entity, analyses the concept and principle in China lawful interception standard systematically; Secondly, the paper proposes the software and hardware architecture and the network model of the lawful interception system, explains the critical technological principles in the software-subsystem implementation in detail, elaborates the methods and details of the implementation of the Interception Interface Model and discusses the technological main points; Finally, the paper designs the scheme for the lawful interception system's simulation test, analyses the system performance according to the test data.