Signaling Compression

Many application protocols used for multimedia communication today are not optimized in terms of size. Typical SIP messages can range from a few hundred bytes to many thousands of bytes. With low-rate IP connectivity, this can result in significant transmission delays, with both call setup and feature invocation times adversely affected by account retransmissions and multiple messaging. Our Signaling Compression (SigComp) stack helps solve this problem by offering robust, loss-less compression of application messages. As SIP is a text based protocol, and IMS involves heavy SIP signaling, 3GPP Release 5 standards mandate the use of SigComp.

Our SigComp stack can be used in 3G user terminals and all types of CSCFs. It should be integrated with applications for deployment and cannot be used independently in any deployment.

The major components of SigComp are the Compressor, Decompressor, and State Handler.

Compressor

The Compressor is the component that compresses messages and uploads the ByteCode for the corresponding decompression algorithm to the UDVM as part of the SigComp message.

Decompressor (UDVM)

UDVM provides a mechanism to uncompress messages by interpreting the corresponding ByteCode. The UDVM can be used to decompress the output of various compressors such as DEFLATE (RFC-1951).

State Handler

The State Handler retains information between received SigComp messages and thus eliminates the need to send decompression instructions with each of the compressed messages.