Lead Inventors:
Andrea Forte,
Henning Schulzrinne, Ph.D.
Session Initiation Protocol for Push-To-Talk Over Cellular Has Message Size Limitations:
There are two issues in using Session Initiation Protocol (SIP) for Push-to-talk over Cellular (PoC). First, the message size in PoC services is very limited. Existing techniques based on Signaling Compression (SigComp) mechanism, an Internet Engineering Task Force (IETF) standard, cannot achieve the compression levels desired by PoC services in IP Multimedia Subsystem (IMS). Further, existing text substitution compression techniques can also not achieve the desired compression rates. Second, without appropriate compression, SIP messages take a few seconds to complete in PoC, introducing a call setup delay.
Signal Compression Technology Allows for Bigger Message Size in Push-To-Talk Over Cellular:
This technology uses a template-based compression scheme for SIP. This scheme differentiates between SIP headers that may or may not change between calls, and applies the appropriate template compression.
Applications:
• Push-to-talk over cellular phones
• Low bit-rate, low delay SIP signaling
• Home wireless phones with multiple handsets
Advantages:
• Use of SIP as a PoC signaling protocol
• Use of existing IMS based system -- no need to have a separate management system for PoC services, which means lower costs
Patent Status: Patent Pending (
WO 2009/012462)
Publications:
Template-based Compression for Push-to-talk over Cellular (PoC)
Licensing Status: Available for Licensing and Sponsored Research Support