ROHC Interaction in the 3GPP Architecture

Transcription

1 ROHC Interaction in the 3GPP Architecture Ana Carolina Minaburo Where are we with IPv6? Conference, Paris, October 2002 G6-Aristote

2 Summary ROHC Implementation 3GPP Architecture Conclusions G6-Aristote

3 ROHC Redundancy in the header fields and in consecutive headers in a stream. HEADER COMPRESSION G6-Aristote

4 ROHC Header Fields Classification INFERRED STATIC STATIC-DEF STATIC-KNOWN CHANGING They are never sent and they can be known by other champs in the header. Send only once, their values never change during the stream. Send only once, they give the definition of the stream. They are never sent and their values are known. Header fields with a changing value. The change can be periodic or randomly. They are always sent G6-Aristote

5 ROHC IPv6 Header Fields Classification INFERRED STATIC STATIC-DEF STATIC-KNOWN CHANGING IPv6 UDP RTP Ver ToS Flow ID Length Source Port Length Source Address Next Header Destination Address Hop Limit Destination Port Checksum Ver P E CCnt M P.Type Sequence Number Timestamp Source Synchronization Identification(SSRC) Source Contribution Identification (1 st.) (CSRC) Source Contribution Identification (last) Application Data G6-Aristote

6 ROHC General Diagram Negociation (N) ACK/ NACK (Bi) Unidirectional (U) Profiles {1,2,3} ACK (SN,U) ACK/NACK (R) Transition U-O ACK/ NACK (O) ACK/NACK (U) Bi-directional Optimist (O) Transition U-R ACK/ NACK (R) ACK (SN, O) Transition O-R Transition R-O ACK (SN,R) ACK (SN,R) ACK/NACK (O) Bi-directional Reliable (R) Profile {0} Bi-directional (Bi) Transition O/R-U ACK/NACK (U) G6-Aristote

7 ROHC Compression Levels in each Operation Mode Approach / ACK Initialization (IR) IR Approach / ACK Time out / Static-NACK Approach / ACK First Order (FO) IR-DYN, UOR-2 Time out / Static- NACK Time out / NACK / Update Second Order (SO) UO-1, R-1, UO-0, R-0 G6-Aristote

8 IMPLEMENTATION Information Flow C PPP link D C_mode=U C_Trans=D C_mode=O C_Trans=D C_mode=R C_Trans=I C_Trans=D NCP negotiation IR packet IR packet IR-DYN packet IR-DYN packet ACK(O) IR packet (O) IR packet (O) IR-DYN packet (O) IR-DYN packet (O) ACK(R) IR packet (SN,R) ACK (SN,R) R-1 D_mode=U D_Trans=D D_mode=O D_mode=O D_Trans=D D_Trans=I D_mode=R D_Trans=P D_Trans=D G6-Aristote

9 IMPLEMENTATION ROHC Compression with U,O,R operation mode 50 Non Compressed ROHC Compression ROHC Feedback Transition Header size ( bytes) U mode O mode R mode O mode U mode R mode Number of Packets per second ( bytes/second) G6-Aristote

10 IMPLEMENTATION ROHC IPv6 Profile 4 O-mode BER 1e-2 Non Compressed Payload ROHC bytes Paquets/second G6-Aristote

11 IMPLEMENTATION Compression Loss Application loss ROHC CRC fails Packets loss e-4 1e-3 4e-3 5e-3 1e-2 5e-2 Error Rate G6-Aristote

12 3GPP Architecture UMTS RTC or PLMN Base Station Base Station CN CS Node B Base Station UTRAN RNC MSC/VLR GMSC HLR/ AuC CN PS Base Station Base Station GGSN Internet Node B Base Station RNC SGSN GGSN other PLMN Signalization Traffic G6-Aristote

13 3GPP Architecture Control GC Nt DC User Non Access Duplication avoidance C-plane signaling GC Nt DC U-plane information UuS boundary The PDCP layer includes the RFC 3095 (ROHC) and the RFC control control control control RRC control PDCP PDCP L3 Radio Bearers L2/PDCP BMC L2/ BMC Access L2/ Logical Channels MAC L2/MAC Transport Channels PHY L1 G6-Aristote

14 3GPP Architecture Possible Header Compression In Layer 3 Non-Access forming a PPP Tunnel end to end (Header compression in an Internet Network). Transparent cross trough UTRAN In Layer 2 Access using PDCP to make the compression, from MS to UTRAN (Header compression in a 3GPP network) Non Access Application E.g., IP, PPP E.g., IP, PPP Relay Relay Access PDCP C/D PDCP C/D GTP-U UDP/IP GTP-U UDP/IP GTP-U UDP/IP GTP-U UDP/IP MAC MAC AAL5 AAL5 L2 L2 L1 MS L1 UTRAN BTS ATM ATM Uu Iu-PS Gn Gi 3G-SGSN L1 L1 3G-GGSN G6-Aristote

15 CONCLUSIONS The header compression reduce the quantity of sending bits. The number of packets sent with error is reduced by an error rate (par bit). The header compression could have consecutives lost and the system risk to loose at least the packets send in a RTT (Round Trip Time). When using IPv6 UDP checksum is mandatory the average header is 4 bytes. G6-Aristote