Chap 1. stc lte e nb overview

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Jae ho, Lee
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Samsung Confidential Information. Official Commitment will be made in a formal form. Up to the best of Samsung’s knowledge 2Samsung Confidential Information. Official Commitment will be made in a formal form. Up to the best of Samsung’s knowledge
Intro
Network Architecture
Multiple Access
Frame Structure
Multiple Antenna Technique
LTE Evolution
Contents

Samsung Confidential Information. Official Commitment will be made in a formal form. Up to the best of Samsung’s knowledge 3
Intro

Demand for high-data-
rates
Improved system
capacity & coverage
Reduced cost
for the operator
UTRA : Universal Terrestrial Radio Access
UTRAN: UTRA Radio Access Network
Reduced Latency
LTE Background
Enhancement of
UTRA & UTRAN
<Source:
www.3gpp.org>
LTE Definition and History
R99 Rel4 Rel5 Rel6 Rel7 Rel8 Rel1
0
WCDMA HSDPA HSPA HSPA evolution
LTE LTE-advanced

Peak data rate
100 Mbps (DL) / 50 Mbps (UL)
Baseline: 20 MHz BW, 1TX & 2RX UE
Significantly reduced latency
Control-plane latency
– Idle ↔ active : < 100 ms
– dormant ↔ Active: < 50 ms
User-plane latency : < 5 ms in unload condition for small IP packet
Significantly improved throughput & spectrum efficiency
2 ~ 4 times Release 6 HSPA
Spectrum flexibility
Scalable bandwidth: 1.4/3/5/10/15/20 MHz
Camped-state
(idle)
Active
(Cell_DCH)
Dormant
(Cell_PCH)
Less than 100msec
Less than 50msec
Requirements of LTE (1/2) [Ref: TR 25.913]

Mobility
Optimized for low mobile speed 0 ~ 15 km/h
15 ~ 120 km/h should be supported with high performance
Connection maintained at speeds 120 ~ 350 km/h (or even up to
500 km/h)
Support for inter-working with existing 3G systems and non-
3GPP systems
Reduced CAPEX and OPEX including backhaul
Efficient support of the various types of services, especially
from the PS-domain
Web-browsing, FTP, video-streaming, VoIP
Requirements of LTE (2/2) [Ref: TR 25.913]

LTE Standard Specifications
Specification index Description of contents
TS 36.100 series
Equipment Requirements:
Terminals, Base stations, and Repeaters
TS 36.200 series
Layer 1 (Physical layer):
Physical channels, Modulation, Multiplexing, Channel
coding, etc.
TS 36.300 series
Layers 2 and 3:
Medium Access Control, Radio Link Control, and Radio
Resource Control.
TS 36.400 series
Network Signaling & Interfaces:
Architecture, S1, X2 Interfaces, etc.
TS 36.500 series UE equipment conformance testing
Free Download from http://www.3gpp.org/ftp/Specs/html-
info/36-series.htm

FDD TDD
TD-LTE Fundamental
LTE FDD
A paired frequency band allocation
Uplink and downlink selected from different frequency bands
LTE TDD
Enables use of unpaired frequency bands
The same frequency band for UL and DL, divided in time
Channel Reciprocity
TD-LTE and LTE FDD Difference
solely a physical layer manifestation and therefore invisible to
higher layers
there are no operational differences between the two modes in the
system architecture.

E-UTRA Operating Band
FDD - frequency division duplex
TDD - time division duplex

HARQ and control signaling
HARQ ACK/NACK
For FDD, the acknowledgement of data received in sub-frame n is
transmitted in sub-frame n+4
For TDD, the acknowledgement obviously cannot be transmitted until
an uplink sub-frame occurs
Multiple UL ACK/NACK Transmission
For, DL heavy case, the reception of several downlink sub-frames may
need to be acknowledged in a single uplink sub-frame.
ACK/NACK Bundling
- Combines the acknowledgements in time domain from multiple
hybrid-ARQ processes
ACK/NACK Multiplexing
- Combines the acknowledgements in codeword domain from multiple
hybrid-ARQ processes.

Network Architecture

Embedded Laptop
Dongle typeMobile PhoneSmartphone
WSM
Base Station Base Station Base Station Base Station
MME
LSM-C
ACR S-GW
P-GW (HA)
WiMAX + LTE Network Architecture

LTE Network Architecture II
NodeBNodeB
RNC
NodeBNodeB
RNC
GGSN
SGSN
• RNC: Radio Network Controller
• SGSN: Serving GPRS Support Node
• GGSN: Gateway GPRS Support Node
eNB
MME
S-GW/P-GW
MME
S-GW/P-GW
eNB
eNB
S1
S1
S1
S1
X2
X2
X2
E-UTRAN
EPC
3G UMTS LTE
* Source: 3GPP TS 36.300
• eNB: evolved NodeB
• MME: Mobility Management Entity
• S-GW: Serving Gateway
• P-GW: PDN (Packet Data Network) Gateway
• EPC: Evolved Packet Core
Entity Function
eNB All radio interface functions, Resource allocation
MME Manages mobility, UE identity, Security parameters
S-GW Terminates the interface towards E-UTRAN
P-GW Terminates the interface towards PDN, UE IP address allocation

Interface & Protocol Stack
Serving GW PDN GW
S5/S8
a
GTP-UGTP-U
UDP/IP UDP/IP
L2
Relay
L2
L1 L1
PDCP
RLC
MAC
L1
IP
Application
UDP/IP
L2
L1
GTP-U
IP
SGiS1-ULTE-Uu
eNodeB
RLC UDP/IP
L2
PDCP GTP-U
Relay
MAC
L1 L1
UE
SCTP
L2
L1
IP
L2
L1
IP
SCTP
S1-MME
eNodeB MME
S1-AP
S1-AP
NAS
MAC
L1
RLC
PDCP
UE
RRC
MAC
L1
RLC
PDCP
RRC
LTE-Uu
NAS
Relay
User plane Protocol Stack
Control plane Protocol Stack

internet
eNB
RB Control
Connection Mobility Cont.
eNB Measurement
Configuration & Provision
Dynamic Resource
Allocation (Scheduler)
PDCP
PHY
MME
S-GW
S1
MAC
Inter Cell RRM
Radio Admission Control
RLC
E-UTRAN EPC
RRC
Mobility
Anchoring
EPS Bearer Control
Idle State Mobility
Handling
NAS Security
P-GW
UE IP address
allocation
Packet Filtering
 Yellow boxes → logical nodes
 White boxes → functional entities of the control plane
 Blue boxes → radio protocol layers
• RRM: Radio Resource Management
• RB: Radio Bearer
• RRC: Radio Resource Control
• PDCP: Packet Data Convergence Protocol
• NAS: Non-Access Stratum
• EPS: Evolved Packet System
E-UTRAN & EPC functions
S1-U
S1-
MME

Multiple Access

Frequency
Range
UMTS FDD bands and UMTS TDD bands
Channel
Bandwidth,
1Resource Block
(RB) = 180KHz
1.4MHz 3MHz 5MHz 10MHz 15MHz 20MHz
6 RBs 15RBs 25RBs 50RBs 75RBs 100RBs
Modulation
scheme
Downlink: QPSK, 16QAM, 64QAM
Uplink: QPSK, 16QAM, 64QAM (optional for handset)
Multiple Access
Downlink: OFDMA
Uplink: SC-FDMA
MIMO
- Transmit diversity, Cyclic delay diversity (Max. 4 antenna at Base
station and handset)
- Spatial multiplexing, Multiuser MIMO
Peak Data rate
Downlink: 150Mbps (UE category 4, 2x2 MIMO, 20MHz)
300Mbps (UE category 5, 4x4 MIMO, 20MHz)
Uplink: 75Mbps (20MHz)
LTE Key Parameters

Brief Introduction of OFDMA
Each sub-carrier carries a separate low-rate stream of data
Sub-carriers
→ Orthogonal frequencies & independently modulated
Symbol duration >> channel delay spread
→ Much less ISI (Inter-Symbol Interference)
A guard time is added to each symbol
→ Cyclic Prefix in LTE
* Source: 3GPP TS25.892

Advantages & Disadvantages of OFDMA
Advantages
Scalable data rate
Simpler channel equalizer than CDMA
Robust against multipath fading by using CP
Dynamic resource allocation considering channel information
→ Maximize throughput
Disadvantages
High PAPR (Peak-to-Average Power Ratio)
Sensitive to frequency offset and clock offset
Requires guard interval
→ Reduces throughput

CDMA & OFDM vs. OFDMA
CDMA vs. OFDMA
Freq.
Time
Freq.
Time
Attribute CDMA OFDMA
Transmission bandwidth Full system bandwidth Variable up to full system bandwidth
Symbol period
Very short :
inverse of the system bandwidth
Very long :
Defined by subcarrier spacing and
independent of system bandwidth
Separation of users Orthogonal spreading codes Frequency and time
OFDM vs. OFDMA

DL/UL Multiplexing
DL Orthogonal Frequency Division Multiple Access (OFDMA)
No Inter Symbol and multipath interference
Frequency selective scheduling
Far improved MIMO performance
UL Single-Carrier FDMA (SC-FDMA)
No interference between intra cell users
Low PAPR (Peak to Average Ratio)
IDFT
S0 S1 S2 ……S10 S11
S0 S1 S2 ……S10 S11
Freq. IDFT
DFT
S0 S1 S2 ……S10 S11
Freq.
Downlink OFDMA Uplink SC-FDMA
IDFT: Invers Discrete Fourier Transform
DFT: Discrete Fourier Transform

OFDMA vs. SC-FDMA
In OFDMA, each sub-carrier only carries information related to one
specific symbol
In SC-FDMA, each sub-carrier contains information of ALL
transmitted symbols
Brief Introduction of SC-FDMA

Frame Structure

Frame Structure Type 1: for FDD
Each radio frame is 10ms long and consists of 20 slots of length
0.5ms, numbered from 0 to 19
#0 #1 #2 #3 #19
One slot, Tslot = 15360Ts = 0.5 ms
One radio frame, Tf = 307200Ts=10 ms
#18
One subframe
LTE Frame Structure
Frame Structure Type 2: for TDD
Special fields DwPTS, GP, and UpPTS in subframe #1 (always)

Frame Structure (TDD)
Special Sub-frame
DwPTS: used for downlink data transmission. (varied from three up
to twelve OFDM symbols)
GP: guard period for the downlink-to-uplink
• Guard period must cover the maximum roundtrip propagation delay within
the cell
• selected by taking eNB-to-eNB interference into account
• two to ten OFDM symbols, sufficient for cell sizes up to and beyond 100 km.

Resource Grid & Cyclic Prefix
* Source : 3GPP TS 36.211
------Slot #0
One DL slot (0.5 ms) slotT
0l
DL
symb
1l N 
RB
sc
UL
RBNNsubcarriers
RB
scNsubcarriers
DL RB
scsymb
N N
Resource block
resource elements
Resource element ),( lk
0k
DL RB
scRB
1k N N 
Slot #1 Slot #19
DL
symb
N OFDM symbols
0.5 ms * 180 kHz
Configuration
No. of
subcarrie
rs / RB
No. of
symbols/
RB
Normal CP
12
7
Extended CP
6
24 3
kHz15f
kHz5.7f
RB
scN
DL
symbN
kHz15f
Configuration CP length (μs)
Normal CP
5.21 (for l=0)
4.69 (for l=1,2,…,6)
Extended CP 16.67 for l=0,1,…,5
Extended CP
( )
33.33 for l=0,1,2
kHz5.7f

Asymmetric UL/DL Capacity Allocation
Single sub-frame for UL and 8times sub-frame for DL per 10ms frame
If maximally boosting UL capacity, then we can have 3 sub-frame for
UL and single sub-frame for DL per 5ms
UE is informed about UL/DL configuration via SIB-1, which is broadcast
via Broadcast Channel (BCH)
UL/DL Configuration

Special Sub-frame Configuration

10ms frame
#0 #1 #2 #3 #4 #5 #6 #7 #8 #9
Symbol :5th
6th
DC
System
Bandwidth
5 Reserved
31 subcarriers
31 subcarriers
Slot #0
Subframe
Primary
synchronization
signal
Secondary
synchronization
signal
5 Reserved
Slot #10
FDD
Synchronization Channel
Primary Synchronizing Signal(PSS)
Using non-coherent detection, estimate 5msec timing and physical-
layer identity(Cell ID Group)
Channel estimation information for SSS
Secondary Synchronizing Signal(SSS)
Physical-layer identity(Cell ID) is obtained
Radio-frame timing(10msec) identification

FDD
TDD
Synchronization Channel (FDD vs TDD)

Multiple Antenna Technique

Multiplexing
IDFT
S0 S1 S2 ……S10 S11
S0 S1 S2 ……S10 S11
Freq. IDFT
DFT
S0 S1 S2 ……S10 S11
Freq.
Downlink OFDMA Uplink SC-FDMA
• Performance improvement vs. WCDMA
• Simpler receiver implementation
• Larger UL cell coverage than OFDMA
IDFT: Invers Discrete Fourier Transform
DFT: Discrete Fourier Transform
DL Orthogonal Frequency Division Multiple Access(OFDMA)
No Inter Symbol and multipath interference
Frequency selective scheduling
Far improved MIMO performance
UL Single-Carrier FDMA(SC-FDMA)
No interference between intra cell users
Low PAPR(Peak to Average Radio

DL MIMO
11h
NMh
1Nh
1Mh
Precoder
Receiver
Precoder feedback
3W
data
streams
11h
NMh
1Nh
1Mh
Precoder
Receiver
data
streams
CDD
Closed-Loop MIMO Open-Loop MIMO
PMI: Precoding Matrix Information
CDD: Cyclic Delay Diversity
Supports 2X2, 4X2, 4X4 MIMOs, rank-r transmission, where
r=1,2,3,4
Precoding Operation
Codebook-based precoding
- Channel sensitive precoding based on UE’s PMI feedback
Large-delay CDD based Open-loop precoding
- Large delay CDD for robust communications against channel variation

Allocate the same resource blocks to
Multiple UEs
→ Improves spectrum efficiency
Selection of better link antenna
(with single TX RF at the UE)
→ Improves link performance
eNodeB
UE
UE
11h
NMh
1Nh
1Mh
UE
eNodeB
UL MIMO
Multi-user MIMO Antenna selection diversity

LTE Feature Introduction

Scheduler supports the standardized QoS class indicators (QCIs)
QCI: QoS Class Identifier PDB: Packet Delay Budget b/w UE and PGW (Soft upper bound) (3GPP TS23.203)
PELR: Packet Error Loss Rate GBR: Guaranteed Bit Rate
QCI Resource Type Priority PDB PELR Example Services
1
GBR
2 100 ms 10-2 Conversational Voice
2 4 150 ms 10-3 Conversational Video (Live Streaming)
3 3 50 ms 10-3 Real Time Gaming
4 5 300 ms 10-6 Non-Conversational Video (Buffered Streaming)
5
Non-GBR
1 100 ms 10-6 IMS Signalling
6 6 300 ms 10-6 Video (Buffered Streaming), TCP-based (e.g., www, e-
mail, chat, ftp, p2p file sharing, progressive video, etc.)
7 7 100 ms 10-3 Voice, Video (Live Streaming), Interactive Gaming
8 8
300 ms 10-6 Video (Buffered Streaming), TCP-based (e.g., www, e-
mail, chat, ftp, p2p file sharing, progressive video, etc.)
9 9
… … … … operator-specified class
Standard QoS Classes

SON Feature Overview
Rollout of the LTE leads to
Rapidly expanding number of Base Stations (new sites)
Parallel operation of 2G, 3G and LTE
Much higher complexity in network infrastructure and network
management (Operation & Maintenance)
Self-Organizing Network(SON) aims to configure and optimize the
LTE network automatically by

UE Category
Category 1 2 3 4 5
DL 10 50 100 150 300
UL 5 25 50 50 75
Category 1 2 3 4 5
DL QPSK, 16QAM, 64QAM
UL QPSK, 16QAM QPSK, 16QAM, 64QAM
Category 1 2 3 4 5
2Rx diversity Assumed in performance requirements across all LTE UE categories
2x2 MIMO Not supported Mandatory
4x4 MIMO Not supported Mandatory
LTE UE category data rates
LTE UE category modulation formats supported
LTE UE category modulation formats supported

LTE Evolution

3GPP Work Plan for IMT-Advanced
2009 2010 20112007 2008
3GPP RAN
ITU-R WP5D
Proposals
Evaluation
Consensus
Specification
Work ItemStudy Item
3GPP LTE stabilized on March 2009
Schedule of study/work item for LTE-Advanced
Early submission: Sep.2008
LTE-Advanced complete technical submission: Jun.2009
Release of Specification of LTE-Advanced: around 1Q 2011
3GPP Target of LTE-Advanced
Better performance than IMT-Advanced requirements

Key Technologies for LTE-Advanced
Peak Data Rate improvement
Support for large bandwidths (up to 100Mhz)
- Aggregation of contiguous/non-contiguous carriers)
DL MIMO enhancement
- Further performance improvement for 4X4 MIMO(LTE baseline 2X2)
- 8X8 MIMO is also considered
UL SU-MIMO support
- Introduce 2X4 or even 4X4 MIMO (LTE baseline 1X2)
Sector/cell throughput improvement
Advanced DL MU-MIMO with 8 Tx antenna
Multi-stream dedicated beamforming
Cell edge performance improvement
Relay-coverage extension
eICIC for deployments of heterogeneous networks

eICIC
Interference coordination for non-CA based heterogeneous
network (HetNet)
Time domain coordination
- Extend Rel 8/9 backhaul coordination for macro and pico deployments
Power control
- Femto eNB power reduction to avoid interference to macro UE
enhanced Inter-Cell Interference Coordination

MS
MS
MS
MS
MS
RS
BS
BS Coverage
Area
RS Coverage
Area
Relay for Coverage Extension
Reason for Relay
Coverage Extension
Throughput/capacity gain
Benefits of Relay vs. Pico eNB
Lower cost – no fiber backhaul
Flexibility

Chap 1. stc lte e nb overview

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