Post on 08-Apr-2018
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 1/49
Technical Overview of 3GPP Long Term Evolution (LTE)
Feb. 8, 2007
Hyung G. Myung (hgmyung@ieee.org)
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 2/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 1
OutlineOutlineOutlineOutline
Introduction
LTE Downlink Physical Layer (OFDMA)
LTE Uplink Physical Layer (SC-FDMA)
Summary and Conclusions
LTE Physical Layer Procedures
LTE System Architecture
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 3/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 2
DisclaimerDisclaimerDisclaimerDisclaimer
• 3GPP LTE standardization process is still on-going at currentmoment.
⇒ Many of the technical details presented here may changeor evolve into different forms.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 4/49
Introduction
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 5/49Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 4
3GPP Evolution3GPP Evolution3GPP Evolution3GPP Evolution
• Release 99 (Mar. 2000): UMTS/WCDMA
• Rel-5 (Mar. 2002): HSDPA
• Rel-6 (Mar. 2005): HSUPA
• Rel-7 (???, 2007): DL MIMO, IMS (IP Multimedia Subsystem),
optimized real-time services (VoIP, gaming, push-to-talk).
• Long Term Evolution (LTE)
– 3GPP work on the Evolution of the 3G Mobile System started in
November 2004.– Currently, standardization in progress in the form of Rel-8.
– Spec scheduled to be finalized by the end of 2007/early 2008.
– Target deployment in 2010.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 6/49Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 5
Requirements of LTERequirements of LTERequirements of LTERequirements of LTE
• Peak data rate
– 100 Mbps DL/ 50 Mbps UL within 20 MHz bandwidth.
• Up to 200 active users in a cell (5 MHz)
• Less than 5 ms user-plane latency
• Mobility– Optimized for 0 ~ 15 km/h.
– 15 ~ 120 km/h supported with high performance.
– Supported up to 350 km/h or even up to 500 km/h.
• Coverage
– Performance should be met for 5 km cells with slight degradationfor 30 km cells. Up to 100 km cells not precluded.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 7/49Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 6
Requirements of LTERequirements of LTERequirements of LTERequirements of LTE ---- cont.cont.cont.cont.
• Enhanced multimedia broadcast multicast service (E-MBMS)
• Spectrum flexibility– 1.25 ~ 20 MHz
• Enhanced support for end-to-end QoS
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 8/49Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 7
Key Features of LTEKey Features of LTEKey Features of LTEKey Features of LTE
• Multiple access scheme
– DL: OFDMA with CP.
– UL: Single Carrier FDMA (SC-FDMA) with CP.
• Adaptive modulation and coding
– DL modulations: QPSK, 16QAM, and 64QAM
– UL modulations: QPSK and 16QAM
– Rel-6 Turbo code: Coding rate of 1/3, two 8-state constituentencoders, and a contention-free internal interleaver.
• Advanced MIMO spatial multiplexing techniques
– (2 or 4)x(2 or 4) downlink and uplink supported.• Multi-layer transmission with up to four streams.
– Multi-user MIMO also supported.
• ARQ within RLC sublayer and Hybrid ARQ within MAC sublayer.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 9/49Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 8
Key Features of LTEKey Features of LTEKey Features of LTEKey Features of LTE ---- cont.cont.cont.cont.
• Power control and link adaptation
• Implicit support for interference coordination
• Support for both FDD and TDD
• Possible support for operating as single frequency network
(SFN) to support MBMS– Time-synchronized common waveform transmitted from multiple
cells.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 10/49
Introduction
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 11/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 10
LTE Network ArchitectureLTE Network ArchitectureLTE Network ArchitectureLTE Network Architecture
• E-UTRAN (Evolved Universal Terrestrial Radio Access Network)
NB: NodeB (base station)
RNC: Radio Network ControllerSGSN: Serving GPRS Support NodeGGSN: Gateway GPRS Support Node
RNC RNC
SGSN
GGSN
NB NB NB NB
UMTS 3G: UTRAN
eNB
aGW (MME/UPE)
aGW (MME/UPE)
S1
X2
E-UTRAN
EPC (Evolved Packet Core)
eNB eNB
eNB
eNB: E-UTRAN NodeB
aGW: Access Gateway MME: Mobility Management Entity UPE: User Plane Entity
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 12/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 11
LTE Network ArchitectureLTE Network ArchitectureLTE Network ArchitectureLTE Network Architecture ---- cont.cont.cont.cont.
ePDG
EvolvedPacket Core
GPRS Core
Trusted non 3GPP IP A
ccess
WLAN
3GPP IPAccess
S2b
WLAN
Access NW
S5b
IASA
S5a
SAE
Anchor
3GPP
Anchor
S4
SGiEvolved RAN
S1
Op.
IP
Serv.
(IMS,
PSS,
etc…)
Rx+
GERAN
UTRAN
Gb
Iu
S3
MME
UPE
HSS
PCRF
S7
S6
SGSN
S2a
* 3GPP TR 23.882
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 13/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 12
eNB
LTE Network ArchitectureLTE Network ArchitectureLTE Network ArchitectureLTE Network Architecture ---- cont.cont.cont.cont.
• eNB
– All radio-related functions.
• MME
– Manage/store UE control
plane context.
– UE authentication.
– Mobility management.
• UPE– Manage/store UE context.
– Packet routing/forwarding.
aGW (MME/UPE)
aGW (MME/UPE)
S1
X2
E-UTRAN
EPC (Evolved Packet Core)
eNB eNB
eNB
eNB: E-UTRAN NodeBaGW: Access Gateway MME: Mobility Management Entity UPE: User Plane Entity
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 14/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 13
LTE Network ArchitectureLTE Network ArchitectureLTE Network ArchitectureLTE Network Architecture ---- cont.cont.cont.cont.
internet
eNB
RB Control
Connection
Mobility Cont.
eNB
Measurement
Configuration &
Provision
Dynamic
Resource
Allocation
(Scheduler)
RRC
PHY
MME
UPES1
MAC
PDCP
Inter Cell RRM
Radio
Admission
Control
RLC
E-UTRAN aGW
U-Plane
Protocol
Stack
C-PlaneProtocol
Stack
PDCP: Packet Data Convergence ProtocolNAS: Non-Access Stratum
* Details in 3GPP TS 36.300
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 15/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 14
PHY Layer Transport ChannelsPHY Layer Transport ChannelsPHY Layer Transport ChannelsPHY Layer Transport Channels
• DL transport channel types
– Broadcast Channel (BCH)
– Downlink Shared Channel (DL-SCH)
– Paging Channel (PCH)– Multicast Channel (MCH)
• UL transport channel types
– Uplink Shared Channel (UL-SCH)– Random Access Channel (RACH)
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 16/49
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 17/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 16
LTE Frame StructureLTE Frame StructureLTE Frame StructureLTE Frame Structure
• Two radio frame structures defined.
– Generic frame structure: FDD and TDD.
– Alternative frame structure: TDD only.
• Generic radio frame has duration of 10 ms. It consists of 20slots. A slot has a duration of 0.5 ms. 2 slots comprise a
subframe.
• A resource block (RB) spans 12 subcarriers over a slot duration
of 0.5 ms. One subcarrier has bandwidth of 15 kHz.
#0#0 #1#1 #2#2 #3#3 #19#19
One slot, T slot = 15360×T s = 0.5 ms
One radio frame, T f = 307200×T s=10 ms
#18#18
One subframe
* T s = 1/(15000×2048) sec
* Generic radio frame structurea.k.a. TTI (Transmission Time Interval)
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 18/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 17
LTE Layer 2LTE Layer 2LTE Layer 2LTE Layer 2
• Layer 2 has three sublayers
– MAC (Medium Access Control)
– RLC (Radio Link Control)– PDCP (Packet Data Convergence Protocol)
Multiplexing
...
HARQ
Scheduling / Priority Handling
Transport Channels
MAC
RLC
PDCP
Segm.ARQ
Segm.ARQ
Logical Channels
Radio Bearers
ROHC ROHC
SAE Bearers
Securtiy Security
DL UL
ROHC: Robust Header CompressionSAE: System Architecture Evolution
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 19/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 18
MACMACMACMAC----Layer Logical ChannelsLayer Logical ChannelsLayer Logical ChannelsLayer Logical Channels
• Control channels: Transfer of control-plane information.
– Broadcast Control Channel (BCCH), Paging Control Channel
(PCCH), Common Control Channel (CCCH), Multicast ControlChannel (MCCH; only used for MBMS), Dedicated ControlChannel (DCCH)
• Traffic channels: Transfer of user-plane information.
– Dedicated Traffic Channel (DTCH) and Multicast Traffic Channel(MTCH; only used for MBMS).
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 20/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 19
RRC LayerRRC LayerRRC LayerRRC Layer
• Terminated in eNB on the network side.
• Functions
– Broadcast
– Paging
– RRC connection management
– RB (Radio Bearer) management– Mobility functions
– UE measurement reporting and control
• RRC states– RRC_IDLE
– RRC_CONNECTED
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 21/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 20
MAC and RRC ControlMAC and RRC ControlMAC and RRC ControlMAC and RRC Control
Integrity protected
Ciphering (FFS)
No integrity protection
No ciphering
No integrity protection
No ciphering Security
HighLimitedNone or very limitedExtensibility
LongerShortVery shortControl delay
~ 10-6 (after ARQ)~ 10-3 (after HARQ)~ 10-2 (no retransmission)Signalling reliability
RRC messageMAC control PDUL1/L2 control channelSignalling
RRCMACControl entity
RRC controlMAC control
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 22/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 21
Resource Scheduling of Shared ChannelsResource Scheduling of Shared ChannelsResource Scheduling of Shared ChannelsResource Scheduling of Shared Channels
• Dynamic resource scheduler
resides in eNB on MAC layer.
• Radio resource assignment based
on radio condition, traffic volume,
and QoS requirements.
• Radio resource assignmentconsists of:
– Physical Resource Block (PRB)– Modulation and Coding Scheme
(MCS)
Fixed
Dy
namic
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 23/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 22
Radio Resource ManagementRadio Resource ManagementRadio Resource ManagementRadio Resource Management
• Radio bearer control (RBC)
• Radio admission control (RAC)
• Connection mobility control (CMC)
• Dynamic resource allocation (DRA) or packet scheduling (PS)
• Inter-cell interference coordination (ICIC)
• Load balancing (LB)
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 24/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 23
Other FeaturesOther FeaturesOther FeaturesOther Features
• ARQ (RLC) and HARQ (MAC)
• Mobility
• Rate control
• DRX (Discontinuous Reception)
• MBMS
• QoS
• Security
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 25/49
Overview of 3GPP LTE
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 26/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 25
DL OverviewDL OverviewDL OverviewDL Overview
• DL physical channels
– Physical Downlink Shared Channel (PDSCH)
– Physical Downlink Control Channel (PDCCH)– Common Control Physical Channel (CCPCH)
• DL physical signals
– Reference signal (RS)– Synchronization signal
• DL baseband signal generation
OFDM
Mapper
OFDM signal
generationLayer
Mapper
Layer
Mapper
Scrambling
Precoding
Modulation
Mapper
Modulation
Mapper
Modulation
Mapper
Modulation
Mapper
OFDM
Mapper
OFDM signal
generationScrambling
Related to MIMO transmission
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 27/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 26
DL Slot StructureDL Slot StructureDL Slot StructureDL Slot Structure
One downlink slot, Tslot
subcarriers
N
BW
DL
subcarriers
N
BW
DL
N
BW
DL
Resource element
OFDM symbolsDLsymbN OFDM symbolsDLsymbN
One resource block, NBW
subcar
riers
RB
One resource block, NBW
subcar
riers
RB
(16.67/512)
(16.67/384)
(16.67/256)
(16.67/128)
(16.67/64)(16.67/32)Long
(4.69/144)
× 6,(5.21/160)
×1
(4.69/108)
× 6,
(5.21/120)
× 1
(4.69/72) ×
6,
(5.21/80) ×
1
(4.69/36) ×
6,
(5.21/40) ×
1
(4.69/18) ×
6,
(5.21/20) ×
1
(4.69/9) ×
6,
(5.21/10) ×
1*
ShortCP
length(μμμμs/sam
ples)
7/6Number of OFDM symbols
per sub frame
(Short/Long CP)
120190160130115176
Number of
occupied
sub-carriers
204815361024512256128FFT size
30.72 MHz(8 × 3.84
MHz)
23.04 MHz(6 × 3.84
MHz)
15.36 MHz(4 × 3.84
MHz)
7.68 MHz(2 × 3.84
MHz)
3.84 MHz1.92 MHz(1/2 × 3.84
MHz)
Samplingfrequency
15 kHzSub-carrier
spacing
0.5 msSlot duration
20 MHz15 MHz10 MHz5 MHz2.5 MHz1.25 MHzTransmission BW
#0#0 #1#1 #2#2 #3#3 #19#19
One slot, T slot = 15360×T s = 0.5 ms
One radio frame, T f = 307200×T
s=10 ms
#18#18
One subframe
* 3GPP TR 25.814
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 28/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 27
DL Reference SignalDL Reference SignalDL Reference SignalDL Reference Signal
R0
R0
R0
R0
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R0
R0
R0
R0
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R0
R0
R0
R0
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R1
R1
R1
R1
R1
R1
R1
R1
0=l 6=l 0=l 6=l
R0
R0
R0
R0
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R0
R0
R0
R0
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R1
R1
R1
R1
R1
R1
R1
R1
0=l 6=l 0=l 6=l
R1
R1
R1
R1
R1
R1
R1
R1
0=l 6=l 0=l 6=l
even-numbered slots odd-numbered slots
R3
R3
R3
R3
0=l 6=l 0=l 6=l
R0
R0
R0
R0
even-numbered slots odd-numbered slots
R0
R0
R0
R0
0=l 6=l 0=l 6=l
R1
R1
R1
R1
even-numbered slots odd-numbered slots
R1
R1
R1
R1
0=l 6=l 0=l 6=l
even-numbered slots odd-numbered slots
R2
R2
R2
R2
0=l 6=l 0=l 6=l
One
virtual antenna
Two virtual antennas
Four virtual antennas
Antenna 0 Antenna 1 Antenna 2 Antenna 3
Not used for transmission on this antenna
Reference symbols on this antenna
( )lk ,elementResource
*For generic frame with normal CP
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 29/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 28
DL Reference SignalDL Reference SignalDL Reference SignalDL Reference Signal ---- cont.cont.cont.cont.
• 2D RS sequence is generated as the symbol-by-symbolproduct of a 2D orthogonal sequence (OS) and a 2D pseudo-random sequence (PRS).
– 3 different 2D OS and ~170 different PRS.
– Each cell (sector) ID corresponds to a unique combination of one OS and one PRS ⇒ ~510 unique cell IDs.
• CDM of RS for cells (sectors)of the same eNodeB (BS)
– Use complex orthogonal spreading codes.
• FDM of RS for each antenna in case of MIMO
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 30/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 29
DL MIMODL MIMODL MIMODL MIMO
• Support up to 4x4 configuration.
• Support for both spatial multiplexing (SM) and Tx diversity (TxD).
– SM
• Unitary precoding based scheme with codebook based feedback from user.
• Multiple codewords
– TxD: SFBC/STBC, switched TxD, CDD (Cyclic Delay Diversity)considered.
• MU-MIMO supported.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 31/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 30
Basic Idea of UnitaryBasic Idea of UnitaryBasic Idea of UnitaryBasic Idea of Unitary PrecodingPrecodingPrecodingPrecoding
• Parallel decomposition of a MIMO channel
1x
2x
t N x
1y
2y
r N y
11h21h
1r N h
r t N N h
11 11 1 1
1
t
r r r t t r
N
N N N N N N
h hy x n
y h h x n
y H x n
= ⋅ +
⇒ = ⋅ +
⋯
⋮ ⋮ ⋱ ⋮ ⋮ ⋮
⋯
H H
H H H H
I
H H H
x ny
H UDV y UDV x n
U y U U DV x U n
U y D
y x
U
D
V n
n
x
=
= ⇒ = +
= +
= +
= +
ɶ ɶɶ
ɶ ɶ ɶ* Narrowband channel
I. E. Telatar, “Capacity of Multi-Antenna Gaussian Channels,” Europ. Trans. Telecommu., vol. 10, Nov./Dec. 1999, pp. 585-595.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 32/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 31
Practical UnitaryPractical UnitaryPractical UnitaryPractical Unitary PrecodingPrecodingPrecodingPrecoding SystemSystemSystemSystem
• For subcarrier k (total of M subcarrriers).
Unitary Precoding
MIMO Channel
H k
Receiver
Feedback Processing:
(Averaging& quantization of V k’s)
⊕
k X
ˆk k k
X V X =ɶ
k k H X
k N
k Y
k Z
( )⋅F
ˆ ( )k k V F V =
{ } { }ˆ ˆ(Estimation of ) , ; 0, , 1 , ; 0, , 1= = = = − = = −ɶ … …H
k k k k k k k H H U D V V V k M V V k M
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 33/49
Overview of 3GPP LTE
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 34/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 33
Single Carrier FDMASingle Carrier FDMASingle Carrier FDMASingle Carrier FDMA
• What is Single Carrier FDMA (SC-FDMA)?
– Utilizes single carrier modulation and frequency domain
equalization.– Has similar performance and essentially the same overall structur
e as those of OFDMA system. Also, referred to as DFT-spreadOFDMA.
– Has low PAPR because of its inherent single carrier transmitter structure.
– An attractive alternative to OFDMA, especially in the uplink communications where lower PAPR greatly benefits the mobileterminal in terms of transmit power efficiency.
• For more technical information, a tutorial is available athttp://hgmyung.googlepages.com/scfdma .
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 35/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 34
UL OverviewUL OverviewUL OverviewUL Overview
LB #0CP LB #1C
P LB #2CP LB #3C
P LB #4CP LB #6C
P
1 slot = 0.5 ms
LB #5CP
Used for RS
• UL physical channels
– Physical Uplink Shared Channel (PUSCH)
– Physical Uplink Control Channel (PUCCH)
• UL physical signals
– Reference signal (RS)
– Random access preamble
#0#0 #1#1 #2#2 #3#3 #19#19
One slot, T slot = 15360×T s = 0.5 ms
One radio frame, T f = 307200×T s=10 ms
#18#18
One subframe
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 36/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 35
UL Signal GenerationUL Signal GenerationUL Signal GenerationUL Signal Generation
Serial-to-Parallel
M -pointIDFT
N -pointDFT
Zeros
{ }0 1 1, ,N
x x x −… Parallel-to-Serial
{ }0 1 1, , M x x x −ɶ ɶ ɶ…
SubcarrierMapping
subcarrier
0
M-1
Zeros
Modulation
mapper
Modulation
mapper
SC-FDMA
mapper
SC-FDMA
mapper SC-FDMAsignal gen.SC-FDMAsignal gen.Scrambling
One Block
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 37/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 36
UL Transmission ParametersUL Transmission ParametersUL Transmission ParametersUL Transmission Parameters
(3.65/7)
or (7.81/15)33.33/38/6466.67/75/1280.51.25
(3.91/15)
or (5.99/23)33.33/75/12866.67/150/2560.52.5
(4.04/31)
or (5.08/39)33.33/150/25666.67/300/5120.55
(4.1/63)
or (4.62/71)33.33/300/51266.67/600/10240.510
(4.12/95)
or (4.47/103)33.33/450/76866.67/900/15360.515
(4.13/127)
or (4.39/135)33.33/600/102466.67/1200/20480.520
CP duration
(µµµµs/# of subcarriers)
SB size (µµµµs/# of occupied subcarriers
/FFT size)
LB size (µµµµs/# of occupied subcarriers
/FFT size)
Slot duration
(ms)
Bandwidth
(MHz)
* 3GPP TR 25.814
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 38/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 37
UL Reference SignalUL Reference SignalUL Reference SignalUL Reference Signal
• Two types of UL RS
– Demodulation (DM) RS ⇒ Narrowband.
– Sounding RS: Used for UL resource scheduling ⇒ Broadband.
• RS based on Zadoff-Chu CAZAC (Constant Amplitude ZeroAuto-Correlation) polyphase sequence
– CAZAC sequence: Constant amplitude, zero circular auto-correlation, flat frequency response, and low circular cross-correlation between two different sequences.
2
2 , 0,1,2, , 1; for even
2
( 1)2 , 0,1,2, , 1; for odd
2
k
r k j qk k L L
L
r k k j qk k L L
L
ea
e
π
π
− + = −
+ − + = −
=
⋯
⋯
* r is any integer relatively prime
with L and q is any integer.
B. M. Popovic, “Generalized Chirp-like Polyphase Sequences with Optimal Correlation Properties,”IEEE Trans. Info. Theory, vol. 38, Jul. 1992, pp. 1406-1409.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 39/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 38
UL RS MultiplexingUL RS MultiplexingUL RS MultiplexingUL RS Multiplexing
subcarriers
User 1
User 2
User 3
subcarriers
FDM Pilots CDM Pilots
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 40/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 39
UL RS MultiplexingUL RS MultiplexingUL RS MultiplexingUL RS Multiplexing ---- cont.cont.cont.cont.
• DM RS
– For SIMO: FDM between different users.
– For SU-MIMO: CDM between RS from each antenna
– For MU-MIMO: CDM between RS from each antenna
• Sounding RS
– CDM when there is only one sounding bandwidth.
– CDM/FDM when there are multiple sounding bandwidths.
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 41/49
Overview of 3GPP LTE
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
ll hll hll hll h
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 42/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 41
Cell SearchCell SearchCell SearchCell Search
• Cell search: Mobile terminal or user equipment (UE) acquirestime and frequency synchronization with a cell and detectsthe cell ID of that cell.
– Based on BCH (Broadcast Channel) signal and hierarchical SCH(Synchronization Channel) signals.
• P-SCH (Primary-SCH) and S-SCH (Secondary-SCH) are transmitt
ed twice per radio frame(10 ms) for FDD.
• Cell search procedure
1. 5 ms timing identified using P-SCH.
2. Radio timing and group ID found from S-SCH.3. Full cell ID found from DL RS.
4. Decode BCH.
C ll S hC ll S hC ll S hC ll S h
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 43/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 42
Cell SearchCell SearchCell SearchCell Search ---- cont.cont.cont.cont.
Cell site with 20-MHz transmission bandwidth
SCH
Center carrier frequency
Step 1:Cell search using synchronizationchanneldetect center 1.25 spectrum ofentire 20-MHz spectrum
Example: 10-MHz UE in 20-MHz cell site, SCH bandwidth = 1.25 MHz and BCH bandwidth = 1.25 MHz
Step 2:BCH reception
BCH
BCHreception
Initiate data transmission using assigned spectrum
Step 3:UE shifts to the center carrier frequencyassigned by the system and initiatesdata transmission
R d AR d AR d AR d A
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 44/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 43
Random AccessRandom AccessRandom AccessRandom Access
• Non-synchronized random access.
• Open loop power controlled with power ramping similar to
WCDMA.
• RACH signal bandwidth: 1.08 MHz (6 RBs)
• Preamble based on CAZAC sequence.
CP Preamble
TCP TGP
RA slot = 1 ms
* TCP = 0.1 ms, TGP = 0.1 ms
UE eNB
Random Access Preamble1
Random Access Response 2
Scheduled Transmission3
Contention Resolution 4
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 45/49
Overview of 3GPP LTE
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 46/49
LTE System Architecture
LTE DL PHY Layer (OFDMA)
LTE UL PHY Layer (SC-FDMA)
LTE PHY Layer Procedures
Summary and Conclusions
S d C lS d C lS d C lS d C l
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 47/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 46
Summary and ConclusionsSummary and ConclusionsSummary and ConclusionsSummary and Conclusions
• On-going standardization in the form of 3GPP Release 8.
– Spec by the end of 2007/early 2008 and target deployment in2010.
• LTE air-interface.
– Downlink: OFDMA– Uplink: SC-FDMA
• Support for both FDD and TDD.
• Flexible spectrum allocation (1.25 ~ 20 MHz).
• Advanced MIMO system.
R f d RR f d RR f d RR f d R
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 48/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 47
References and ResourcesReferences and ResourcesReferences and ResourcesReferences and Resources
• http://hgmyung.googlepages.com/scfdma– LTE & SC-FDMA references
• LTE and SC-FDMA– H. Ekström et al., “Technical Solutions for the 3G Long-TermEvolution,” IEEE Commun. Mag., vol. 44, no. 3, March 2006, pp.38–45
– H. G. Myung et al., “Single Carrier FDMA Technique for Uplink
Wireless Transmission,” IEEE Vehicular Technology Magazine, Sep.2006– H. G. Myung, “Single Carrier Orthogonal Multiple Access
Technique for Broadband Wireless Communications,” PhDDissertation, Polytechnic University
• 3GPP LTE Activities– http://www.3gpp.org/tb/home.htm
• RAN WG1: Layer 1• RAN WG2: Layer 2 & 3
R f d RR f d RR f d RR f d R tttt
8/7/2019 LTE Overview_IEEE
http://slidepdf.com/reader/full/lte-overviewieee 49/49
Technical Overview of 3GPP LTE | Feb. 8, 07 | Hyung G. Myung 48
References and ResourcesReferences and ResourcesReferences and ResourcesReferences and Resources ---- cont.cont.cont.cont.
• 3GPP Release 8 Spec– http://www.3gpp.org/ftp/Specs/html-info/36-series.htm
• 36.201: Physical layer; General description
• 36.211: Physical Channels and Modulation• 36.212: Multiplexing and channel coding• 36.213: Physical layer procedures
• 36.214: Physical layer; Measurements• 36.300: E-UTRA and E-UTRAN; Overall description (layer 2&3 info)
• 36.401: E-UTRAN; Architecture description– http://www.3gpp.org/ftp/Specs/html-info/25814.htm (old)
• 3GPP LTE Layer 1 Contribution Papers (Tdoc)– http://www.3gpp.org/ftp/Specs/html-info/Meetings-R1.htm