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Activities in the field of header compression

Activities in the field of header compression. ROHC working group. RFC 3095 ROHC (Framework + RTP. UDP, ESP, uncompressed). RFC 3220: SigComp. 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.

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Activities in the field of header compression

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  1. Activities in the field of header compression

  2. ROHC working group RFC 3095 ROHC (Framework + RTP. UDP, ESP, uncompressed) RFC 3220: SigComp 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

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

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

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

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