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ROHC for GTP-U draft-lei-tsvwg-gtpu-compression-00

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Presentation on theme: "ROHC for GTP-U draft-lei-tsvwg-gtpu-compression-00"— Presentation transcript:

1 ROHC for GTP-U draft-lei-tsvwg-gtpu-compression-00
IETF 79th meeting Nov 2010 Lei Zhu

2 Scenarios to compress GTP-U header
LTE-A (to addressing IMT-Advanced requirements) developed Relay architectures by 3GPP RAN1/2/3 in Release 10. Relay architecture is to address the needs to optimize coverage and cell-edge user throughput Scenario Mobility Hops Purposes Urban Hot Spot Fixed, Nomadic Two hops Coverage and Throughput Dead spot Fixed Two hops or Multi-hops Coverage Indoor Hot Spot Throughput Rural Area Emergency or Temporary Coverage Nomadic Wireless Backhaul Only Coverage or Throughput

3 Needs to compress GTP-U header
The layer 3 Relay architecture was selected together with protocol stacks through L1/2 and L3 protocols. Shown below. For some reasons, protocol stack of the added interface (Un interface) cross IP/UDP/GTP-U at user plane and IP/SCTP at control plane. The traffic model at Un interface is not 100% sure, but VoIP applications are assumed by service providers when specify it. The mechanisms of basic ROHC profile are very good to be reused. But the alternative proposals are also possible to create since the signaling to exchange status and information are not owned by IETF.

4 Classification of GTP-U header fields
STATIC-DEF: Version, Protocol type, Extension Header Flag, Sequence Number Flag, N-PDU Number Flag, Message Type and TEID. PATTERN: Sequence number Result: IANA reserves a new compression profile identifier for IP/UDP/GTP-U header chain. The compression profile for GTP-U headers would be developed with minor changes to existing compression profile for IP/UDP/RTP. GTP-U header compression profile should take care the reuse the different sequence number(s) of GTP-U header, ROHC header and further RTP header and perform same behavior as profiles before, even it seems SN of GTP-U could not exist in real traffic.

5 Changes to ROHC IR packet
| Add-CID octet | if for small CIDs and (CID != 0) | | IR type octet : : / 0-2 octets of CID / 1-2 octets if for large CIDs : : | Profile = 0xXXXX | 1 octet | CRC | 1 octet | | / Static chain / variable length | | | | + Dynamic chain variable length / Payload / variable length

6 Extension to profile identifiers
The proposed compression profile need a reserved identifier which is to be carried in ROHC IR and CO packet. Existing compression profiles are historically referenced by 3GPP PDCP layer spec ( and ). The referenced RFCs are shown in the table. Profile Identifier Usage: Reference 0x0000 No compression RFC 4995 0x0001 RTP/UDP/IP RFC 3095, RFC 4815 0x0002 UDP/IP 0x0003 ESP/IP 0x0004 IP RFC 3843, RFC 4815 0x0006 TCP/IP RFC 4996 0x0101 RFC 5225 0x0102 0x0103 0x0104 Ox010n IP/IDP/GTP-U n/a

7 Conclusions The compression profile for GTP-U header is highly possible to IETF turn to develop a new profile in somewhere of tsv area. A new work item is expected to be approved ASAP. A working group draft addressing the needs to a compression profile for GTP-U are done before the end of next year and acts as fundamental reference.

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