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Report
LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
Understanding 3GPP Bearers
LTE / HSPA / EPC
‘knowledge nuggets’
Neil Wiffen - [email protected]
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Red Banana Wireless Ltd – Copyright 2013
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
Bearers for Quality of Service
QoS Characteristics
QoS Characteristics
QoS Characteristics
Traffic class, bit rate, delivery order, reliability, delay characteristics, priority etc.
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
UMTS Bearer Hierarchy
Terminal
Equipment
Mobile
Equipment
UTRAN
Core Network
Edge Node
Core Network
Gateway
Terminal
Equipment
End to End Service
UMTS
Bearer
Service
Local
Bearer
Service
Radio Access Bearer
Service
Core Network
Bearer Service
Radio
Bearer
Service
Iu
Bearer
Service
UTRA
FDD/TDD
Service
Physical
Bearer
Service
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External
Bearer
Service
3
Backbone
Bearer
Service
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
UMTS Bearer Components
RNC
CN node
Iu Signalling bearer
Signalling Radio Bearers
CS Radio Access Bearer (RAB)
MSC
CS Data bearer
CS Radio Bearers
PS Radio Access Bearer (RAB)
SGSN
PS Radio Bearer
PS Data bearer
PS Radio Access Bearer (RAB)
SGSN
PS Radio Bearer
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PS Data bearer
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
EPS Bearer Hierarchy
S-GW
e-NB
UE
Application
Peer
P-GW
End-to-end Service
EPS Bearer
E-RAB
S5/S8 Bearer
Radio Bearer
S1 Bearer
LTE-Uu
S1
S5/S8
E-UTRAN
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EPC
5
SGi
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
IP-Connectivity Access Network
Internet
GERAN,
UTRAN,
EUTRAN
BTS,
Nb,
eNb
GPRS CN,
UMTS CN,
EPC
SGSN,
S-GW
GGSN,
P-GW
IMS
Platform
Intranet
IP-CAN
IP-PDN
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
IP-CAN Bearers
SGSN
GGSN
PS-RAB
GTP-Tunnel
IP-CAN Bearer (PDP Context)
S-GW
P-GW
LTE-Bearer
GTP–Tunnel
IP-CAN Bearer
(EPS Bearer)
Interconnect / Roaming
support required
SGSN
PS-RAB
S-GW
GTP-Tunnel
P-GW
GTP–Tunnel
(EPS Bearer)
IP-CAN Bearer
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
LTE Connection components
SDFs
E-RABs
IP Flow(s)
IP-CAN Bearer
GTP
Tunnel(s)
RBs
GTP
Tunnel(s)
ISP / Transit
Networks(s)
SGW
SCTP
Association
PGW
MNO
EDGE
Router
Application / SP
EDGE Router
Application
Server
GTP-C
Tunnel
MME
MNO
Domain
HSS
PCRF
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SPR
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
Radio Bearer (RB)
• Radio Bearer
– L2 service provided for transfer of info on the Air Interface
– Describes L2 processes per bit-stream (flow)
– Different QoS requirements supported by different RBs
• Example
– Flow A requires low latency but can tolerate packet loss of 10-2
– Flow B has less stringent latency requirements, but can only tolerate a
packet loss of 10-6
– Flow A and B must be supported by 2 separate Radio Bearers
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
LTE Radio Bearer categories
• Signalling Radio Bearers (SRB)
– SRB0 is for RRC messages
• Using the CCCH logical channel
– SRB1 is for RRC / NAS messages
•
•
•
•
Used prior to the establishment of SRB2
Using DCCH logical channel
NAS messages may be piggybacked inside RRC messages
All messages are Integrity Protected and Ciphered after security activation
– SRB2 is for NAS messages
•
•
•
•
Using DCCH logical channel
May be contained in RRC messages, but with no RRC control content
All messages are Integrity Protected and Ciphered after security activation
Lower priority then SRB1
• Data Radio Bearers (DRB)
– Carry User Plane content on the Air Interface
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
Radio Bearers
SRB1
(RRC / NAS messages on DCCH)
SRB0
(RRC messages on CCCH)
Used for RRC connection setup
DRB1
(User content with QoS ‘A’ on DTCH1)
Multiple SRBs/DRBs to support
on-going user connection
SRB2
(NAS messages on DCCH)
DRB2
(User content with QoS ‘B’ on DTCH2)
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
Bearer Mapping
DRBs
Mapped to / from S1 Bearers
SRB RRC messages
Interpreted by UE / ENB
S1 GTP Tunnels
(S1 Bearers)
S5/S8 GTP Tunnels
(S5/S8 Bearers)
SGW
SCTP
Association
GTP-C
Tunnel
PGW
S1 Bearers
Mapped to/from
S5/S8 Bearers
MME
SRB NAS messages
Mapped to SCTP association
Interpreted by UE / MME
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LTE / HSPA / EPC knowledge nuggets
Understanding 3GPP Bearers
QoS and TFT
EPS Bearer with defined QoS
UL Traffic Flow
Aggregates
DL Traffic Flow
Aggregates
UL QoS
managed by
ENB ‘router’
UL / DL QoS
managed by
ENB scheduler
SGW
UL TFT
PGW
DL TFT
UL TFT  RB ID
RB ID  S1 TEID
RB ID  S1 TEID
Packet Filters applied to each
uplink IP-datagram
(QoS control)
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S1 TEID  S5/S8 TEID
S1 TEID  S5/S8 TEID
DL QoS
managed by
SGW ‘router’
13
S5/S8 TEID  DL TFT
Packet Filters applied to each
downlink IP-datagram
(QoS control)
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