Jan 07, 2016
LTE Systems &
Architecture
OBJECTIVES
o Introduction
Wireless Technology Evolution Mobile Evolution Data Forecast 4th Generation Mobile System
o Network Architecture
4G Mobile System E-UTRAN Architecture UE eNodeB E-UTRAN Interfaces and Protocols
o LTE Air Interface Principle
Principles of OFDM LTE Channel Structure LTE Frame Structure
o Evolved Packet Core Architecture (SAE)
Mobility Management Entity Serving Gateway Packet Data Network Gateway IMS
OBJECTIVES
INTRODUCTION
Wireless Technology Evolution
Mobile Evolution
World Data Forecast
4th Generation Mobile System
Key IMT Advance Features
A high degree of common functionality worldwide while retaining the flexibility to support a
wide range of services and applications in a cost efficient manner
Compatibity of services within IMT and fixed networks
Capability of interworking with other radio access systems
High quality mobile services
User equipment suitable for worldwide use
User-friendly applications, services and equipment
Worldwide roaming
Enhanced peak data rates to support advanced services and applications (100Mbits/s for
high and 1Gbits/s for low mobility were identified as targets)
3GPP RELEASE
4th Generation Mobile System
GSM
9.6kbps
Phase 1
EDGE
473.6kbps
R99
HSDPA
14.4Mbps
R5
HSPA+
28.8Mbps
R7/8
Phase 2+(R97)GPRS
171.2kbps
R99UMTS
2Mbps
R6HSUPA
5.76Mbps
R8LTE
+300Mbps
R9/10LTE Advanced
E-UTRAN ARCHITECTURE
E-UTRAN ARCHITECTURE UE eNODEB
E-UTRAN ARCHITECTURE
eNB eNB
E-UTRAN EPC
MME
S-GW PDN-GWUE
IMS
Video ASCSCFHSS
USER EQUIPMENT
FUNCTIONAL ELEMENTS UE CATEGORIES UE IDENTITIES
USER EQUIPMENT (UE)
USIM Mobile Equipment (ME)
RADIO RESOURCE EMM(EPS Mobility Management) ESM(EPS Session Management)
FUNCTIONAL ELEMENTS:
LTE SIM
UE FUNCTIONAL ELEMENTS
EPS Mobility & EPS
Session
Management
IP Adaptation
Function
RADIO
RESOURCE
UEControl
Plane
User
Plane
EPS Session Management
Bearer Activation
Bearer Modification
Bearer Deactivation
EPS Mobility Management
Registration
Tracking Area Update
Handover
Radio Resource
RRC, PDCP, RLC, MAC & Phy
Layer Protocols
UE FUNCTIONAL ELEMENTS
UE
Category
Maximum
Downlink
Data Rate
Number of
Downlink
Data
Streams
Maximum
Uplink Data
Rate
Support
for Uplink
64QAM
1 10.3Mbits/s 1 5.2Mbits/s No
2 51.0Mbits/s 2 25.5Mbits/s No
3 102.0Mbits/s 2 51.0Mbits/s No
4 150.8Mbits/s 2 51.0Mbits/s No
5 302.8Mbits/s 4 75.4Mbits/s Yes
USER EQUIPMENT (UE)
IDENTITIES
MME Identity + MME Codes
MME Global Identity
Globally Unique MME Identity + MME-TMSI
Globally Unique Temporary Identification
GUTI
GUMMEI
MCC MNC MMEGI
MMEI MMEC
M-TMSI
eNODEB
FUNCTIONAL ELEMENTS eNODEB CATEGORIES
GSM / UMTS Network
Architecture
LTE Network Architecture
EPC
MME
S-GW
eNB
eNB
E-UTRAN
UE
eNODEB Functional Elements
Radio Resource
ManagementUL/DL Resources Allocation
Access Control
Mobility Control
Data Compression
Data ProtectionRoutingS1-C (MME)
S1-U (S-GW)
Packet Classification and
QoS Policy Enforcement
eNB
eNODEB Identities
TAI (Tracking Area Identities) ~ RAI
ECGI (Evolved Cell Data Identity) MCC+MNC+ECI
E-UTRAN INTERFACE AND
PROTOCOLS
Uu Interfaces
eNODEB Identities
EPC
MME
S-GW
eNB
eNB
E-UTRAN
X2
S1-MME
S1-MMES1-U
S1-U
Uu
UE
UU INTERFACE
eNODEB Identities
EPC
MME
S-GW
eNB
eNB
E-UTRAN
X2
S1-MME
S1-MMES1-U
S1-U
Uu
UE
LTE AIR INTERFACE
Radio Interface Techniques
4G and future wireless systems optimize a
combination of frequency, time and coding
e.g. OFDMA & SC-FDMA
FDMA: frequency domain multiple access
TDMA: time domain multiple access
CDMA: code domain multiple access
What is OFDM
Subcarriers used.
The subcarriers are orthogonal to
each other and can be overlapped.
Suitable for multipath fading
channels and high data rates`
OFDM Orthogonal Frequency Division Multiplexing
o Many closely-spaced sub-carriers, chosen to be
orthogonal, thus eliminating inter-carrier interference
o Varies bits per sub-carrier based on instantaneous
received power
LTE OFDM
Statistical Multiplexing ( in
OFDMA)
Dynamically allocates user data to sub-carriers based oninstantaneous data rates and varying sub-carrier capacities
Highly efficient use of spectrum
Robust against fading, e.g. for mobile operation
Orthogonal Frequency Division
Multiple Access ( OFDMA )
Orthogonal Frequency Division Multiple Access
Supercedes CDMA used in all 3G variants
OFDMA = Orthogonal Frequency Division Multiplexing(OFDM) plus statistical multiplexing
Optimization of time, frequency & code multiplexing
OFDMA already deployed in 802.11a & 802.11g
Took Wi-Fi from 11 Mbps to 54 Mbps & beyond
FDMA vs. OFDMA
OFDMA more frequency efficient
OFDMA Dynamically maps traffic to frequencies based on their
instantaneous throughput
FDMA
ChannelGuard
band
OFDMA
OFDMA
Each user allocated a
different resource which
can vary in time and
frequency
Frequency
Power
LTE Air Interface
Orthogonal Frequency Division Multiple
Access
Single Carrier-Frequency Division
Multiple Access
eNB
UE
OFDMA and SC-FDMA
OFDMA and SC-FDMA
ADVANTAGE:
High spectrum utilization efficiency due to orthogonal subcarriers need no protection bandwidth
(SC-FDMA) can release the (LTE)UE PA limitation caused by high PAPR(Peak to Average Power)
OFDMA Orthogonal FDMA
Orthogonal Frequency Division Multiple Access
Supercedes CDMA used in all 3G variants
OFDMA = Orthogonal Frequency Division Multiplexing(OFDM) plus statistical multiplexing
Optimization of time, frequency & code multiplexing
OFDMA already deployed in 802.11a & 802.11g
Took Wi-Fi from 11 Mbps to 54 Mbps & beyond
OFDMA Subcarrier
OFDM:
Spectral efficiency is achieved by reducing the spacing between FDM subcarrier
Subcarrier overlap due to their orthogonally with other subcarrier thus reduce adjacent channel interference
Frequency
Channel
Bandwidth
Orthogonal
Subcarrier
Center Subcarrier
Not Orthogonal
Fast Fourier Transform
SERIAL
TO
PARALLEL
IFFT RFCoded
Bits
Subcarrier
ModulationInverse Fast
Fourier
Transform
Complex
Waveform
LTE FFT Sizes
Channel
BandwidthFFT Size
Subcarrier
BandwidthSampling Rate
1.4Mhz 128 1.92Mhz
3Mhz 256 3.84Mhz
5Mhz 512 7.68Mhz
10Mhz 1024 15.36Mhz
15Mhz 1536 23.04Mhz
20Mhz 2048 30.72Mhz
15Khz
EXAMPLE:
For BW=10Mhz
15.36Mhz/15Khz=1024
OFDMA Symbol Mapping
Frequency
AmplitudeTime
Modulated
OFDM
Symbol
OFDM
Symbol
Cyclic
Prefix
CALCULATIONS:
1 OFDM Symbol = 12 Subcarriers
1 Subcarrier = 15Khz (BW)
12 SC x 15Khz = 180Khz (OFDM Symbol BW)
For a 10Mhz LTE Carrier:
10Mhz/180Khz ~ 55 (Rows of 12 OFDM
Symbols)
OFDMA Structure
PRB consist of 12
Subcarrier for 0.5ms
Time
Frequency
Channel
BandwidthOFDMA
Device is allocated one
or more PRB (Physical
Resource Blocks)
Channel
Bandwidth
(Mhz)
PRB
1.4 6
3 15
5 25
10 50
15 75
20 100
Physical Resource Block and
Resource Element
Slot 8 Slot 9
0 1 2 3 4 5 6 7 8 9
Radio Frame=10ms
Subframe
Resource Element
(RE)
1 2 3 4 5 6 7
2
3
4
5
6
7
8
9
10
11
12
Physical Resource
Block (PRB)
Symbols
Su
bca
rrie
r
Ph
ys
ica
l R
es
ou
rce
Blo
ck
(P
RB
)
CALCULATIONS:
12x7=84 RE
LTE Physical Signals
PCI, Physical Channel Id
= 0~503
= PSS+SSS
Where:
PSS= 0,1,2
SSS= 0~167
Synchronization Sequence
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
0 1 2 3 4 5
0 1 2 3 4 5 6
Repeated in
slots 0 and 10
PSS(Primary
Synchronization
Sequence)
SSS(Secondary
Synchronization
Sequence)
Bandwidth
Bandwidth
Extended CP
Normal CP72 Subcarriers62
SCFDMA Single Carrier FDMA
Single carrier multiple access
Used for LTE uplinks
Being considered for 802.16m uplink
Similar structure and performance to OFDMA
Single carrier modulation with DFT-spreadorthogonal frequency multiplexing and FD
equalization
Lower Peak to Average Power Ratio (PAPR)
Improves cell-edge performance
Transmit efficiency conserves handset battery life
SCFDMA Signal Generation
DFT Subcarrier
MappingIDFT
CP
InsertionSymbols
.
Time Domain Time DomainFrequency Domain
http://www.youtube.com/watch?v=
dr4YQAfifKA
MIMO
Multiple Input Multiple Output (MIMO)
o Multiple Input Multiple Output smart antenna
technology
o Multiple paths improve link reliability and
increase spectral efficiency (bps per Hz),
range and directionality
Multiple Input Multiple Output (MIMO)
LTE supports MIMO as the base option, with multipletransmitter and receiver antennas in a same eNode-B.
Up to four antennas can be used by a single LTE cell(gain: spatial multiplexing)
MIMO is considered to be the core technology toincrease spectral efficiency.
Rake receiver are use to efficiently received transmitted RF signal from eNODEB to UE ( User Equipment )
MIMO Category
Increase capacity
since a single user
benefits from multiple
data streams.
eNB
SU-MIMO
eNB
MU-MIMO
Increase sector
capacity by allowing
users to share
streams.
Spatial Multiplexing
eNB
MIMO
TB Port 0
Port 1TB
TB
TB
2X2 Spatial Multiplexing
Space Time Coding
eNB
MIMO
Port 0
Port 1
TB
Increase Robustness
1 2 3 4 5 6
TB
1 2 3 4 5 6
3 6 5 2 1 4
TB still recoverable
Interference
Adaptive MIMO Switch
eNB
High SNRLow SNR
Eff
icie
ncy
AMS Point
Spatial
Multiplexing
Space Time
Coding
TRANSMISSION MODES
LTE Types
o LTE FDD (Type 1)
Long Term Evolution Frequency Division Duplex Evolved from 3G HSPA
o LTE TDD (Type 2)
Long Term Evolution Time Division Duplex Evolved from WiMAX
FDD vs. TDD
o Differences between TDD and FDD These two standards are based on LTE network
technology and are similar in nature. The main
difference is in the actual physical layer.
FDD LTE is able to be linked to a subframe from an uplink.
the amount of uplink and downlink subframes differs which means that such associative links cannot be
made in TDD LTE TDD LTE performance is less efficient because of guard
periods.
FDD vs. TDD
o Advantage of TDD Channel estimations that are used for beam-forming
or similar antenna techniques have to apply for the
downlink and uplink
o Advantage of FDD The benefits of FDD only become apparent in cases
where both the downlink and uplink transmissions of
data are symmetrical in nature which makes
communication much more streamlined
Type 1 (LTE FDD)Uplink Downlink
(MHz) (MHz)
1 1920 - 1980 2110 - 2170 60
2 1850 - 1910 1930 - 1990 60
3 1710 - 1785 1805 -1880 75
4 1710 - 1755 2110 - 2155 45
5 824 - 849 869 - 894 25
6 830 - 840 875 - 885 10
7 2500 - 2570 2620 - 2690 70
8 880 - 915 925 - 960 35
9 1749.9 - 1784.9 1844.9 - 1879.9 35
10 1710 - 1770 2110 - 2170 60
11 1427.9 - 1452.9 1475.9 - 1500.9 20
12 698 - 716 728 - 746 18
13 777 - 787 746 - 756 10
14 788 - 798 758 - 768 10
15 1900 - 1920 2600 - 2620 20
16 2010 - 2025 2585 - 2600 15
17 704 - 716 734 - 746 12
18 815 - 830 860 - 875 15
19 830 - 845 875 - 890 15
20 832 - 862 791 - 821 30
21 1447.9 - 1462.9 1495.5 - 1510.9 15
22 3410 - 3500 3510 - 3600 90
23 2000 - 2020 2180 - 2200 20
24 1625.5 - 1660.5 1525 - 1559 34
25 1850 - 1915 1930 - 1995 65
Width of Band
(MHz)LTE Band
Type 1 (LTE FDD)
Uplink
Channel
Bandwidth
Downlink
Channel
Bandwidth
Duplex Spacing
Frequency
Type 1 (LTE TDD)
33 1900 - 1920 20
34 2010 - 2025 15
35 1850 - 1910 60
36 1930 - 1990 60
37 1910 - 1930 20
38 2570 - 2620 50
39 1880 - 1920 40
40 2300 - 2400 100
41 2496 - 2690 194
42 3400 - 3600 200
43 3600 - 3800 200
Allocation
(MHz)
Width of Band
(MHz)LTE Band
TDD
Frequency
Downlink
and Uplink
TimeDownlink Uplink
Asymmetric
Allocation
TDD Frame
LTE CHANNEL STRUCTURE
Logical Transport Physical Radio
Control Logical Channels
System Information
Messages
Paging Devices
Low Priority
NAS Signaling
DCCH
DCCH
CCCH
BCCH
PCCH
CCCH
SRB 0
SRB 0
SRB 1
SRB 2
Traffic Logical Channel
DTCH
Carries AM or UM
RLC Traffic
DRB
Transport Channel
RACH
UL-SCH
BCH
PCH
DL-SCH
Evolved Packet Core
Simplified LTE Architecture
eNB eNB
E-UTRAN EPC
MME
S-GW PDN-GWUE
IMS
Video ASCSCFHSS
SAE
MME Mobility Management Entity
MME
NAS Signaling
and Security
S-GW and
PDN-GW
Selection
Tracking Area List
Management and
Paging
Authentication
Inter MME
Mobility
Serving - Gateway
Mobility Anchor
Downlink
Packet
Buffering
Packet Routing and
Forwarding
GTP/PMIP
Support
Lawful
Interception
S-GW
PDN - Gateway
Packet Filtering
Lawful
Interception
IP Address
Allocation
Accounting
Transport Level
Packet Marking
PDN-GW
IMS IP Multimedia Subsystem
IMS
Video ASCSCFHSS
o IP Multimedia Subsystem
The IP Multimedia Subsystem (IMS) is a concept for an integrated network of telecommunications carriers
that would facilitate the use of IP (Internet Protocol)
for packet communications
Additional Network Elements
and Interface
EPC
MME
S-GW PDN-GW
MME
HSS
EIR
SGSN
PCRF
RNCePDG
CDMA
2000Untrusted
Non 3GPP
IP Access
CDMA
2000
Trusted
Non 3GPP
IP Access
S10
S5/S8
S11
S6a
S13
S3
S4
S12
S103 S2b
S2a
S101
Gx
Wn
Additional Network Elements
and Interface7
5
SGSN GGSNRNC
IP
BACKBONE
IP
BACKBON
E
Node B
eNode B
MME
S-GW/P-GW
DataIP
BACKBONE
LTE Network Diagram
3G Network Diagram
LTE Network Elements
EPC
S1 C S1 - MME
S1 U
THANK YOU!!!