Presentation on theme: "ROHC for GTP-U draft-lei-tsvwg-gtpu-compression-00"— Presentation transcript:
1ROHC for GTP-U draft-lei-tsvwg-gtpu-compression-00 IETF 79th meetingNov 2010Lei Zhu
2Scenarios 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 throughputScenarioMobilityHopsPurposesUrban Hot SpotFixed, NomadicTwo hopsCoverage and ThroughputDead spotFixedTwo hops or Multi-hopsCoverageIndoor Hot SpotThroughputRural AreaEmergency or Temporary CoverageNomadicWireless Backhaul OnlyCoverage or Throughput
3Needs 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.
4Classification 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 numberResult: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.
5Changes 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
6Extension 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 IdentifierUsage:Reference0x0000No compressionRFC 49950x0001RTP/UDP/IPRFC 3095, RFC 48150x0002UDP/IP0x0003ESP/IP0x0004IPRFC 3843, RFC 48150x0006TCP/IPRFC 49960x0101RFC 52250x01020x01030x0104Ox010nIP/IDP/GTP-Un/a
7ConclusionsThe 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.