LTE - end-to-end data flow UE [Under LTE]
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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
|
IP
|
|
GTP-U
|
|
UDP/IP
|
|
L2
|
L2
|
|
L1
|
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 UE:
|
UE App stack
|
|
Application (HTTP, FTP, RTP, SIP, IMAP, RPC etc.)
Protocol specific operations
|
|
 | Ports/Sockets |
TCP/UDP
TCP: IETF rfc793, segmentation, sequence numbering, checksum, UDP: IETF rfc768
|
|
|
TCP/UDP header
|
Application data (segments)
|
|
. . . |
|
IP
v4 IETF rfc791, v6 IETF rfc2460, fragmentation & reassembly, addressing
|
|
|
IP header
|
Data (fragments)
|
|
. . . |
|
| Data pipes |
Data plane stack adaptor
Implementation specific (mainly buffering), UL TFT based IP packet filtering
|
|
|
| | Data radio bearers |
|
UE Wireless stack
|
|
PDCP
3GPP TS 36.323, TCP/UDP/IP header compression/decompression, sequence numbering, ciphering/deciphering
|
|
RLC
3GPP TS 36.322, buffering, segmentation, concatenation, reassembly, ARQ
|
|
| Logical channels (DTCH) |
MAC
3GPP TS 36.321, channel mapping, multiplexing, channel prioritisation, HARQ
|
|
|
MAC header
|
MAC control elements
|
SDU
|
|
. . . |
|
| Transport channels (SCH) |
PHY
3GPP TS 36.201, modulation, coding, power control, cell search, measurements and other phy specific procedures
|
|
| Physical channels (DL-PDSCH, UL-PUSCH) |
|
Between UE and eNB, data flow are managed with Data Radio Bearers,
identified with DRB Identity, mapped to MAC Logical Channel
Identity. DRB identities range from 1 to 11. MAC LCIDs for DTCHs
range from 3 to 11.
In next article, we will look at data flow at eNode B.
References: 3G Evolution: HSPA and LTE by Dahlman,
Parkvall, Sköld, and Beming, LTE - From Theory to
Practice, Edited by Sesia, Toufik, and Baker, and SAE and the
Evolved Packet Core: Driving the Mobile Broadband Revolution by
Olsson, Sultana, Rommer, Frid, and Mulligan.
| Copyright © Samir Amberkar 2010-11 | § |
