1. Activities in the field of header compression

2. Center for TeleInFrastructure 2 ROHC working group RFC 3095 ROHC (Framework + RTP. UDP, ESP, uncompressed) RFC 3242: LLA profile - ”0 byte” RFC 3408: 0-byte for R-mode RFC 3241: ROHC over PPP RFC 3816: ROHC MIB RFC 3843: ROHC for IP RFC 3220: SigComp

3. Center for TeleInFrastructure 3 Link-layer Assisted ROHC (0-byte)  Purpose is to efficiently match existing applications to existing link technologies  Air interfaces, as GSM and IS-95, will be used in all-IP networks, but their radio bearers are optimized for specific payload size.  Adding even 1 byte of ROHC header is costly  Header-free packet format

4. Center for TeleInFrastructure 4 LLA ROHC  Lower layers provide the necessary information  Care should be taken of  Packet type identifier  Sequence number  CRC 1 byte Smallest header in ROHC RTP Smallest header in LLA NHP (No Header Packet) Header field functionality provided by other means

5. Center for TeleInFrastructure 5 LLA ROHC  Zero-byte operation for U/O modes (RFC 3242)  Zero-byte operation for R-mode (RFC 3408)  Periodic context verification is performed  CSP (Context Synchronization Packet) contains only header information, no payload

6. Center for TeleInFrastructure 6 Interfaces towards the Assisting Layer ROHC RTP LLA profile Interface ROHC to AL Link technology ROHC RTP LLA profile Interface ROHC to AL Link technology channel

7. Center for TeleInFrastructure 7 Signaling Compression (SigComp)  Motivation  3GPP R5 introduces IP Multimedia subsystem (IMS) that uses Session Initiation Protocol (SIP) for call signaling and session setup  SIP is text-based. SIP message is from a few hundreds bytes up to two thousand bytes. On average 500 bytes  For cellular networks large message size is problematic  introduce delays  Compression of signaling messages is desirable

8. Center for TeleInFrastructure 8 Signaling Compression (SigComp)  SigComp RFC 3320  Requirements for Signaling Compression  Efficient compression 1:8 – 1:15  Compress any text based protocol  For bidirectional application protocol, the choice to use SigComp is independent in both directions  Transport independent

9. Center for TeleInFrastructure 9 SigComp Architecture Local application Transport layer Compressor dispatcher Compressor dispatcher Decompressor dispatcher Decompressor dispatcher Compressor 1 Compressor 2 State handler State 1 State 2 Decompressor (UDVM) Decompressor (UDVM) SigComp layer SigComp message SigComp message Application message and Compartment identifier Compartment identifier Decompressed message