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LTE - end-to-end data flow eNB

LTE - end-to-end data flow eNB [Under LTE]
» E-UTRA and E-UTRAN overall description - 36.300, Rel 8 «
» E-UTRAN access - 23.401, Rel 8 «

Below diagram describe protocols involved in end-to-end data flow, starting at UE application till PGW:

Application
TCP/UDP/IP
Adaptor
PDCP
RLC
MAC
PHY
Relay
PDCP GTP-U
RLC UDP/IP
MAC L2
PHY L1
Relay
GTP-U
UDP/IP
L2
L1

Relay
  IP  
GTP-U
UDP/IP
L2 L2
L1 L1


  IP  

L2
L1
UE DRBs
(RRC DRB identity,
MAC LCID)
eNB S1 bearers
(E-RAB ID,
GTP TEID)
SGW S5/S8 bearers
(EPS bearer ID,
GTP TEID)
PGW PDN transport
(PDN address)
PDN

Below diagram shows how data flows at eNB:

 eNB Access stack 
PDCP
3GPP TS 36.323, TCP/UDP/IP header compression/decompression, sequence numbering, ciphering/deciphering

PDCP header  SDU 

  .  .  . 


Relay
Implementation specific (mainly buffering, scheduling)

IP header  Data 

  .  .  . 

GTP Tunnels
 eNB EPC stack 
GTP-U
3GPP TS 29.281, sequence numbering, tunneling

GTP-U header  IP datagram 

  .  .  . 

Socket
UDP
IETF rfc768

UDP header  Data 

  .  .  . 


IP
v4 IETF rfc791, v6 IETF rfc2460, fragmentation & reassembly, addressing

IP header  Data (fragments) 

  .  .  . 

L2 transport channels
L2

(L2 specific) 

  .  .  . 


L1

(L1 specific) 

  .  .  . 

Between UE and eNB, data flow are managed with Data Radio Bearers. eNB maps these DRBs to E-RAB ID and GTP tunnels between eNB and SGW. SGW further maps it to EPS Bearer ID and GTP tunnels between itself and PGW. PGW extracts the IP data coming from UE and routes it to PDN.

References: SAE and the Evolved Packet Core: Driving the Mobile Broadband Revolution by Olsson, Sultana, Rommer, Frid, and Mulligan.

Copyright © Samir Amberkar 2010-11§

LTE - end-to-end data flow UE « LTE Index » LTE - UE States (Attach)