The document provides an overview of an LTE network including: 1) The key components of an LTE network including the Evolved Packet Core (EPC), radio access network (eNodeB), and user equipment (UE). 2) Protocols and functions used within the LTE network for mobility, authentication, quality of service, charging, and multimedia services. 3) Interworking of the LTE network with external networks including legacy 3G networks, non-3GPP access like WiFi, IP Multimedia Subsystem (IMS) for voice, and IPX networks for roaming.

1. VISITED NETWORK HOME NETWORK
LTE Express: End-to-End LTE Network
TIME TO GET ON BOARD – THE ULTRA-BROADBAND EXPERIENCE CUSTOMERS EXPECT
STANDARDIZED LTE FREQUENCY BANDS GLOBAL VIEW:
LTE ACCESS AND
EPC NETWORK
PROTOCOLS AND SECURITY LTE AND EPC – MOBILITY
AND ROAMING
VOICE OVER LTE WITH ENHANCED
SINGLE RADIO VOICE CALL CONTINUITY
LTE EPS BEARER QoS LEVELS
NON-3GPP INTERWORKING
– DATA SERVICES
LEGACY 3GPP INTERWORKING
– DATA SERVICES
LEGACY 3GPP INTERWORKING
– VOICE SERVICES
FDD Band
1
2
3
4
5
7
8
9
10
11
12
13
14
17
18
19
20
21
22
23
24
25
26
27
28
291
30
31
Common name
IMT core (FDD)
US PCS
DCS
AWS-1
850 Cellular
IMT-E
E-GSM
UMTS 1700 Japan DCS
E-AWS (AWS-3)
Lower PDC (Japan)
NAR L700 (A/B/C)
NAR U700 ( C)
Upper 700 ( D - US Public Safety)
Lower 700 (B/C)
Japan Lower 800
Japan Upper 800
EU Digital Dividend
Upper PDC (Japan)
3.5 GHz FDD
S-Band (AWS-4)
L-Band
US Extended PCS
Extended Cellular
SMR
APT700 Digital Dividend
Lower SMH Blocks D/E
WCS Blocks A/B
450 Brazil
Frequencies (MHz – UL / DL)
1920-1980 / 2110-2170
1850-1910 / 1930-1990
1710-1785 / 1805-1880
1710-1755 / 2110-2155
824-849 / 869-894
2500-2570 / 2620-2690
880-915 / 925-960
1749.9-1784.9 / 1844.9-1879.9
1710-1770 / 2110-2170
1427.9-1447.9 / 1475.9-1495.9
699-716 / 729-746
777-787 / 746-756
788-798 / 758-768
704-716 / 734-746
815-830 / 860-875
830-845 / 875-890
832-862 / 791-821
1447.9-1462.9 / 1495.9-1510.9
3410-3490 / 3510-3590
2000-2020 / 2180-2200
1626.5-1660.5 / 1525-1559
1850-1915 / 1930-1995
814-849 / 859- 894
807-824 / 852-869
703-748 / 758-803
N/A / 717-728
2305-2315 / 2350-2360
452.5-457.5 / 462.5-467.5
TDD Band
33
34
35
36
37
38
39
40
41
42
43
44
RADIO LAYER AND FEATURES
• PHY (Physical layer): Radio transmission based
on high performance OFDM (Orthogonal
Frequency Division Multiplex) and MIMO
(Multiple In/Multiple Out) techniques
• MAC (Media Access Control): Schedules radio
transmissions, provides HARQ (Hybrid ARQ) error
handling, selects MCS (Modulation and Coding
Scheme) and handles Carrier Aggregation (CA)
process
• RLC (Radio Link Control): Maps radio bearers and
provide ARQ (Automatic Retransmission reQuest)
error handling
• PDCP (Packet Data Convergence Protocol): Maps
radio bearers and provides user and control
plane ciphering using AES and Snow algorithms
• RRC (Radio Resource Control): Controls radio
layers and access
• NAS (Non-Access Stratum): Provides secure
signalling link between UE and MME to carry EPS
(Evolved Packet System) Mobility Management
(EMM) and EPS Session Management (ESM)
messages
EVOLVED PACKET CORE (EPC)
• SGW and PGW: Extended to support
interface from SGW in visited
network to PGW located in home
network (S8), SGW provides charging
information and legal interception
for visited network
• PCRF: Extended to interface
between visited and home networks
(S9)
• MME and PCRF: Enhanced to enforce
roaming related policies
IP CORE NETWORK
• IPX: IP Packet exchange: Set of
networking functionality offering
user plane and control plane
END USER SERVICE
• IP access offered using both home
and/or visited network routed
services
NETWORK PROTOCOLS AND FEATURES
• GTP (GPRS Tunnel Protocol): Controls
establishment of interfaces (GTP-C) and transport
of user plane EPS bearers (GTP-U) between
network elements
• S1AP (S1 interface Application Part): Controls
establishment and management of eNB-MME
interface
• Diam(eter): Internet protocol used to carry
Authentication, Authorization and Accounting
(AAA) messages
• AKA (Authentication and Key Agreement (AKA):
Used to securely carry key management
messages between SIM, MME and HSS
• IPsec (IP Security protocol): Secure transport
tunnel for IP transmission from eNB to SeGW
(Security Gateway)
USER EQUIPMENT
• UE (User equipment):
Terminates LTE radio
interface and provides
IP transport for end-user
traffic
• SIM (Subscriber
Information Module):
Provides authentication of
securely stored subscriber
information and negotiates
encryption keys for
session protection
RADIO ACCESS
NETWORK
• eNB (evolved Node B):
Provides LTE access
including radio layer
encryption, terminates
network interfaces, maps
EPC bearers into LTE radio
access bearers, responsible
for MME selection and
forwarding of Non-Access
Stratum (NAS) signalling,
controls mobility between
eNBs, includes MBMS
Control Element (MCE)
function.
MULTIMEDIA
BROADCAST AND
MULTICAST
• BM-SC (Broadcast and
Multicast Service Centre):
Acts as gateway between
Application Server
providing broadcast
content and MBMS-GW
(SGmb for control and
SGi-mb for user plane),
provides UE MBMS
reception error handling
• MBMS-GW (Multimedia
Broadcast and Multicast
Service Gateway):
Provides IP source of
multicast flow to eNBs
(M1) and forwards service
requests from BM-SC to
MME (Sm)
CHARGING
• OCS (Online Charging
System): Performs online
credit control functions
for pre-paid and data
capped post-paid
subscribers
• OFCS (Offline Charging
System): Collects charging
records for post-paid
subscribers
END USER SERVICE
• IP address assignment
is provided to the UE by
the PGW based upon the
Access Point Name (APN)
of the service.
• Services offered using a
default bearer, typically
used for best effort Internet
access APN or SIP signalling
for VoLTE services using
IMS APN, which may be
supplemented with one or
more “dedicated bearers”
based on request from
application server using
SDP (Session Description
Protocol) formatted
messages
EVOLVED PACKET CORE
(EPC)
• PGW (PDN Gateway): Acts as
end-user IP layer first hop
router and IP anchor for a given
Packet Data Network (PDN) and
maps IP flows into EPC bearers,
assigns end-user IP address.
Provides charging information,
QoS with Policy Enforcement,
and legal interception
• SGW (Serving Gateway):
Provides traffic routing through
GTP tunnels between one or
more PGW (S5) and eNB (S1-u),
detects incoming end-user traffic
for idle UEs and notifies MME
• MME (Mobility Management
Entity): Manages UE
authentication, LTE RAN
connection (S1-MME), mobility
Note 1: Restricted to LTE operation when carrier aggregation is configured
Reference: 3GPP 36.101
Main or most commonly used bands are highlighted in Bold
Common name
Core IMT-TDD
Core IMT-unpaired
PCS (uplink)
PCS (downlink)
PCS (duplex gap)
IMT-E TDD
TDD 1900
TDD 2300
BRS/EBC
TDD 3500
TDD 3700
APT 700 Digital Dividend
Frequencies ( MHz )
1900 -1920
2010 -2025
1850 -1910
1930 -1990
1910 -1930
2570 -2620
1880 -1920
2300 -2400
2496 -2690
3400 -3600
3600 -3800
703 -803
AKA AKA AKA
NAS
IP IP
NAS
S1APS1AP Diam. Diam.RRCRRC
PDCP GTP
UDP
IP
GTP
UDP
IP
GTP GTP
IPsec IPsec
MME HSS VISITED NETWORK HOME NETWORK
PGWSGWSeGWeNBUE
UE
HSS
PCRF
BM-SCMBMS-GW
eNB
eNB
MME
PGW
OCS
IP Network
IP
Mobile
core
S1-MME, M3
X2
S1-u
Sm
M1
S5
S5
S11 Gx
Sp
S10
S6a Rx
SGi
SGi
Gy
Gz
Sy
SGmb, SGi-mb
END USER SERVICE
• LTE services are provided using a
default and optionally one or more
dedicated EPS (Evolved Packet
System) bearers per connected APN
END USER SERVICE
• EPC service continuity when using
non-3GPP access (CDMA or WLAN)
EVOLVED PACKET CORE (EPC)
• PGW: Acts as IP anchor point between LTE
and “non-3GPP” access such as CDMA
EV-DO and Wi-Fi. Supports “trusted” access
over S2a to HSGW (HRPD Serving GW)
and/or TWAG (Trusted WLAN Access GW)
and “untrusted” access over S2b to ePDG
(evolved Packet Data GW)
• 3GPP AAA: Authentication, Authorization
and Accounting. Authenticates the UE over
non-3GPP access. Acts as gateway between
AAA processes over STa/SWa/SWm and
SWx interfaces
LEGACY RAN
• Legacy RAN enhanced to support mobility
between access technologies
END USER SERVICE
• Legacy SMS delivery and trigger for Circuit
Switched Fallback (CSFB) mechanism for
legacy voice services
EVOLVED PACKET CORE (EPC)
• MME: Supports paging and SMS transfer
interface from MSC (SGs) to LTE access
• HSS: Supports legacy interface to MSC
(C and D)
LEGACY RAN AND CIRCUIT-SWITCHED
(CS) CORE
• MSC: Legacy visited MSC enhanced to
support new SGs interface
• RAN: Legacy RAN enhanced to support
rapid return to LTE access after voice call
• Each bearer has a corresponding QoS (Quality of Service) level
defined in terms of QCI (QoS Class Identifier), Maximum Bit Rate
(MBR), optionally a Guaranteed Bit Rate (GBR) and a TFT (Traffic
Flow Template) to map end-to-end IP flows onto EPS bearers
QCI Type Priority Delay Loss rate Example usage
1 GBR 2 100 ms 10-2
Voice
2 4 150 ms 10-3
Live video (conversational or streaming)
3 3 50 ms 10-3
Gaming
4 5 300 ms 10-6
Buffered streaming video
5 Non-GBR 1 100 ms 10-6
IMS Signalling (default bearer for IMS APN)
6 6 300 ms 10-6
High priority buffered streaming video, TCP, etc.
7 7 100 ms 10-3
Medium priority voice, video, gaming
8 8 300 ms 10-6
High priority best effort Internet
9 9 300 ms 10-6
Best effort Internet (default bearer for Internet)
IP MULTI-MEDIA SUBSYSTEM (IMS)
• CSCF (Call Session Control Function): Proxy, Interrogation
and Serving CSCF treat and forward SIP (Session Initiation
Protocol) messages
• TAS (Telephony Application Server): Provides Voice over LTE
(VoLTE) call logic and services
• MGCF (Media Gateway Control Function) and MGW (Media
Gateway): Provides interworking towards legacy voice networks.
Combined with Border Gateway Control & Function, it also
provides interworking towards VoIP networks
• MRF (Media Resource Function): Provides special media
resources (conference bridge, announcements, etc.)
• ATCF (Access Transfer Control Function) and ATGW (Access
Transfer Gateway): Support enhanced Single Radio Voice Call
Continuity (eSRVCC) mechanism from visited network
• SCC-AS (Service Centralization and Continuity AS): Support
eSRVCC mechanism in home network
END USER SERVICE
• Voice over IP using IMS including
voice call continuity and roaming
USER EQUIPMENT
• VoLTE client and CS functions
enhanced for SRVCC
LEGACY CIRCUIT SWITCH (CS) CORE
• Legacy MSC enhanced to support
SRVCC mechanism
EVOLVED PACKET CORE (EPC)
• PGW: Delivers VoLTE bearer with QoS
and charging
• MME: Supports SRVCC trigger to MSC (Sv)
• HSS: Supports IMS subscriber data
END USER SERVICE
• EPC service continuity when using legacy
3GPP access
EVOLVED PACKET CORE (EPC)
• PGW (acting as legacy GGSN): Acts as
mobility anchor point between LTE and
legacy 2/3G access such as GSM/GPRS,
WCDMA and TD-SCDMA using interface
between PGW and SGSN (Gn-u)
• MME: Supports legacy interface to SGSN
(Gn-c)
• HSS: Supports legacy interface to SGSN (Gr)
eNodeB
• eNB enhanced to support mobility between
access technologies.
LEGACY RAN
• Legacy RAN enhanced to support mobility
between access technologies
eNB
eNB
eNB
eNB
NB RNC
BTS BSC
Gz
Gz/Gy
S6a
S9
Rx
Sv Mw
Mw Mw
Cx
Sh
Sh
Mr
Mn
Mg
ISC
SWx
Abis
lub
NB RNC
MSC MSC
BTS BSC
Abis A
E
D
CSGs
lub
lups Gn-u
Gr
Gn-c
Gb
S5
S2a
STa/SWm/SWa
S2a
S2b
ISC
Gm
S8
MME PCRF
PGW
PGW
PCRF
HSS
SGW SGW
SGW
SGW
MME
MME
MME
SGSN
3GPP AAA
HSS
HSS
HSS
PGWHSGW
TWAG
ePDG
MSC MSC
MME
PCRF
P-CSCF
I-CSCF S-CSCF
SCC-AS
PGW
ATCF
MRF
MGW
TAS
HSS
MGCFATGW
SGW
IP
Mobile
core
IP
Mobile
core
IP Network
PSTN/VoIP
Application
server
App
App
2/3G
RAN
SIM
Note: 3GPP Rel-8 interfaces and interworking not shown
References: 3GPP 23.401 and 23.060
Reference: 3GPP 23.272
Reference: 3GPP 23.203
References: 3GPP 23.401, 23.203 and 36.300 References: 3GPP 23.228, 23.216 and 23.401 and GSMA IR.92
References: 3GPP 36.300 and 23.401
PGW
References: 3GPP 23.402 and 33.402, IEEE 802.11, 3GPP2 C.S0024References: 3GPP 23.401, 23.246 and 36.300
IPX
IPX
IPX
IPX
IPX
IPX
IPX
UE
SIM
UE
SIM
and bearer establishment.
Selects PGW(s) and SGW.
Manages MBMS service and legal
intercept on control signalling
• PCRF (Policy and Charging Rules
Function): Provides QoS and
Charging policies to the PGW
(possibly transformed by PGW
into operations on EPC bearers).
Policies obtained from various
sources including SPR (HSS) and
service requirements from
Application server
• HSS (Home Subscriber Server):
Central database for subscriber
data and user service profile,
performing user and network
access authentication and
mobility management functions.
UE
SIMUE
SIM
eNB
eNB
eNB
OFCS
SGW
SIM
AKA
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All rights reserved. NP2014014097 (01)
UE
SIM
CDMA EV-DO
access
Trusted
WLAN access
Untrusted
WLAN access
UDP
IP
UDP
IP
PDCP
RLC
MAC
PHY
RLC
MAC
PHY
26859_LTE_poster_HR.pdf 1 2014-06-03 11:50 AM