Lte presentation

UMTS Long Term Evolution LTE

Reiner Stuhlfauth [email protected] Training Centre Rohde & Schwarz, Germany Subject to change - Data without tolerance limits is not binding. R&S© is a registered trademark of Rohde & Schwarz GmbH & Co. KG. Trade names are trademarks of the owners.

2011 ROHDE & SCHWARZ GmbH & Co. KG Test & Measurement Division - Training Center -

This folder may be taken outside ROHDE & SCHWARZ facilities.

ROHDE & SCHWARZ GmbH reserves the copy right to all of any part of these course notes. Permission to produce, publish or copy sections or pages of these notes or to translate them must first be obtained in writing from ROHDE & SCHWARZ GmbH & Co. KG, Training Center, Mhldorfstr. 15, 81671 Munich, Germany

Overview 3GPP UMTS Evolution

Driven by Data Rate and Latency Requirements

WCDMA HSDPA/HSUPA HSPA+ LTE 384 kbps downlink 14 Mbps peak downlink 28 Mbps peak downlink 100 Mbps peak downlink

128 kbps uplink 5.7 Mbps peak uplink 11 Mbps peak uplink 50 Mbps peak uplink

RoundTripTime~150ms RoundTripTime<100ms RoundTripTime <50 ms RoundTripTime~10 ms

3GPP Release 99/4 3GPP Release 5/6 3GPP Release 7 7 3GPP Release 8 8

3GPP Release 99/4 3GPP Release 5/6

2003/4 2005/6 (HSDPA) 2008/9 2009/10 2007/8 (HSUPA)

Approx. year of specification freezing

November 2012 | LTE Introduction | 3

Overview 3GPP UMTS evolution

HSDPA/ LTE and LTE- WCDMA HSPA+ WCDMA HSUPA HSPA+ advanced

3GPP 3GPP Study 3GPP Release 99/4 3GPP Release 7 3GPP Release 5/6 3GPP Release 8 release Item initiated

App. year of 2005/6 (HSDPA) 2008/2009 2003/4 2010 network rollout 2007/8 (HSUPA)

Downlink LTE: 150 Mbps* (peak) 100 Mbps high mobility HSPA+: 42 Mbps (peak) 384 kbps (typ.) 28 Mbps (peak) 14 Mbps (peak) data rate 1 Gbps low mobility

Uplink LTE: 75 Mbps (peak) 128 kbps (typ.) 5.7 Mbps (peak) 11 Mbps (peak) data rate

Round LTE: ~10 ms < 50 ms < 100 ms ~ 150 ms Trip Time

*based on 2x2 MIMO and 20 MHz operation


Overview TD-SCDMA evolution towards LTE TDD

TD-LTE TD-SCDMA HSDPA HSUPA

HSPA+

3GPP release 3GPP Release 4 3GPP Release 5 3GPP Release 7 3GPP Release 8

Downlink 384/128 kbps (typ.) 2.8 Mbps (peak) 2.8 Mbps (peak)* LTE:100 Mbps(req.)

data rate

Uplink data rate 128 kbps (typ.) 128 kbps (typ.) 2.2 Mbs (peak)* LTE: 50 Mbps (req.)

* Higher data rate with the use of multi carrier possible


Why LTE? Ensuring Long Term Competitiveness of UMTS

l LTE is the next UMTS evolution step after HSPA and HSPA+.

l LTE is also referred to as EUTRA(N) = Evolved UMTS Terrestrial Radio Access (Network).

l Main targets of LTE:

l Peak data rates of 100 Mbps (downlink) and 50 Mbps (uplink)

l Scalable bandwidths up to 20 MHz

l Reduced latency

l Cost efficiency l Operation in paired (FDD) and unpaired (TDD) spectrum


Introduction to UMTS LTE: Key parameters Frequency

UMTS FDD bands and UMTS TDD bands Range

1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz Channel bandwidth,

6 15 25 50 75 100 1 Resource Resource Resource Resource Resource Resource Resource Block=180 kHz

Blocks Blocks Blocks Blocks Blocks Blocks

Modulation Downlink: QPSK, 16QAM, 64QAM Schemes Uplink: QPSK, 16QAM, 64QAM (optional for handset)

Downlink: OFDMA (Orthogonal Frequency Division Multiple Access) Multiple Access

Uplink: SC-FDMA (Single Carrier Frequency Division Multiple Access)

Downlink: Wide choice of MIMO configuration options for transmit diversity, spatial MIMO

multiplexing, and cyclic delay diversity (max. 4 antennas at base station and handset) technology Uplink: Multi user collaborative MIMO

Downlink: 150 Mbps (UE category 4, 2x2 MIMO, 20 MHz) Peak Data Rate 300 Mbps (UE category 5, 4x4 MIMO, 20 MHz)

Uplink: 75 Mbps (20 MHz)

LTE/LTE-A Frequency Bands (FDD) Uplink (UL) operating band Downlink (DL) operating band E - UTRA

BS receive UE transmit BS transmit UE receive Operating Duplex Mode Band

1 1920 MHz - 1980 MHz 2110 MHz - 2170 MHz FDD




5 824 MHz - 849 MHz 869 MHz - 894MHz FDD




9 1749.9 MHz - 1784.9 MHz 1844.9 MHz - 1879.9 MHz FDD













LTE/LTE-A Frequency Bands (TDD)

Uplink (UL) operating band Downlink (DL) operating band E - UTRA

BS receive UE transmit BS transmit UE receive Operating Duplex Mode

Band

33 1900 MHz - 1920 MHz 1900 MHz - 1920 MHz TDD








3400 MHz - 3400 MHz - 41 TDD

3600MHz 3600MHz


LTE frequency allocation - FDD

= Uplink frequency = Downlink frequency


Orthogonal Frequency Division Multiple Access

the modulation scheme for LTE in downlink and OFDM is uplink (as reference)

Some technical explanation about our physical base: radio link aspects


What does it mean to use the radio channel? Using the radio channel means to deal with aspects like:

C

A

D

B Receiver Transmitter

MPP

Time variant channel Doppler effect

attenuation Frequency selectivity November 2012 | LTE Introduction | 18

Types of degradation in cellular networks

l Multiple Access Interference (MAI) l Inter cell interference l Intra cell interference l Adjacent channel interference l Co channel interference

l Fading l Large scale fading

- Known as log-normal fading or shadowing

- Depends on distance between transmitter and receiver l Small scale fading - due to Multipath propagation and Doppler shift

- Depends on signal bandwidth, relative velocity, environment


What is OFDM?

Single carrier transmission, e.g. WCDMA

Broadband, e.g. 5MHz for WCDMA

Orthogonal Frequency Division Multiplex

Several 100 subcarriers, with x kHz spacing


OFDM signal generation e.g. QPSK

00 11 01 10 01 01 11 01 > .

h*(sin jwt + cos jwt )

h*(sin jwt + cos jwt )

=> S h * (sin.. + cos > )

Frequency

time

OFDM symbol duration ? t November 2012 | LTE Introduction | 29

OFDM Symbol

OFDM symbol duration ? t


Inter-Carrier-Interference (ICI) 10

0

-10

-20

-30 xx

S -40

-50

-60

-70 -1 -0.5 0 0.5 1

f -1 f 0 f 1 f f -2 f 2

ICI Problem of MC - FDM

Overlapp of neighbouring subcarriers

Inter Carrier Interference (ICI).

Solution

"Special" transmit g s (t) and receive filter g r (t) and frequencies f k allows orthogonal subcarrier

Orthogonal Frequency Division Multiplex (OFDM)


Rectangular Pulse

A(f)

Convolution sin(x)/x

t f

? t

? f time frequency


Orthogonality

Orthogonality condition: ? f = 1/ ? t

? f


ISI and ICI due to channel

Symbol l l-1 l+1

L L

Receiver DFT n Window

Delay spread

L L

L L L L

fade out (ISI) fade in (ISI)


ISI and ICI: Guard Interval

Symbol l l-1 l+1

L L

T G > Delay Spread


Delay spread

L L

L L L L

Guard Interval guarantees the suppression of ISI!


Guard Interval as Cyclic Prefix Cyclic Prefix

Symbol l l-1 l+1

L L

T G > Delay Spread


Delay spread

L L

L L L L

Cyclic Prefix guarantees the suppression of ISI and ICI!


Synchronisation

Cyclic Prefix l + 1 OFDM Symbol : l 1 l

CP CP CP CP

Metric

- Search window

~ n


DL CP-OFDM signal generation chain

l OFDM signal generation is based on Inverse Fast Fourier Transform (IFFT) operation on transmitter side:

N Useful Data QAM OFDM Cyclic prefix 1:N N:1 symbol IFFT OFDM source Modulator symbols insertion streams symbols

Frequency Domain Time Domain

l On receiver side, an FFT operation will be used.


OFDM: Pros and Cons

Pros:

scalable data rate

efficient use of the available bandwidth

robust against fading

1-tap equalization in frequency domain

Cons:

high crest factor or PAPR. Peak to average power ratio

very sensitive to phase noise, frequency- and clock-offset

guard intervals necessary (ISI, ICI) reduced data rate


MIMO Multiple Input Multiple Output Antennas


MIMO is defined by the number of Rx / Tx Antennas and not by the Mode which is supported

Mode

SISO Typical todays wireless Communication System 1 1

Single Input Single Output

Transmit Diversity

MISO l Maximum Ratio Combining (MRC) 1 1

l Matrix A also known as STC Multiple Input Single Output M l Space Time / Frequency Coding (STC / SFC)

Receive Diversity

SIMO l Maximum Ratio Combining (MRC) 1 1

Single Input Multiple Output Receive / Transmit Diversity M

Spatial Multiplexing (SM) also known as: l Space Division Multiplex (SDM) l

MIMO True MIMO 1 1 l Single User MIMO (SU-MIMO)

l Matrix B Multiple Input Multiple Output M M Space Division Multiple Access (SDMA) also known as: l Multi User MIMO (MU MIMO) l Virtual MIMO l Collaborative MIMO Definition is seen from Channel Beamforming Multiple In = Multiple Transmit Antennas


MIMO modes in LTE

-Spatial Multiplexing -Tx diversity

-Multi-User MIMO -Beamforming -Rx diversity

Increased Increased

Throughput per Throughput at

UE Better S/N Node B


RX Diversity

Maximum Ratio Combining depends on different fading of the

two received signals. In other words decorrelated fading channels


TX Diversity: Space Time Coding

Fading on the air interface

data The same signal is transmitted at differnet

antennas space Aim: increase of S/N ratio

increase of throughput * s 1 s 2 Alamouti Coding = diversity gain

time approaches * s 2 s 1

RX diversity gain with MRRC! Alamouti Coding -> benefit for mobile communications


MIMO Spatial Multiplexing C=B*T*ld(1+S/N)

SISO: Single Input Single Output

Higher capacity without additional spectrum! MIMO: S

T B ld ( 1 + ) ?

min( N T , N R )

i

N i i = 1

Multiple Input i

Multiple Output

Increasing capacity per cell


The MIMO promise l Channel capacity grows linearly with antennas

Max Capacity ~ min(N TX , N RX )

l Assumptions l Perfect channel knowledge l Spatially uncorrelated fading

l Reality l Imperfect channel knowledge l Correlation ? 0 and rather unknown


Spatial Multiplexing

Coding Fading on the air interface

data

data

<200% 200% 100% Throughput:

Spatial Multiplexing: We increase the throughput but we also increase the interference!


Introduction - Channel Model II

Correlation of propagation

h 11

pathes h 21

s 1 r 1 h M

R1

h 12

estimates s 2 h 22 r 2

Transmitter Receiver h M R2

h 1M h 2M

T T

N Tx N Rx h M sN Tx r NRx

antennas RMT

antennas

s r H

Rank indicator

Capacity ~ min(N TX , N RX ) max. possible rank!

But effective rank depends on channel, i.e. the correlation situation of H


Spatial Multiplexing prerequisites Decorrelation is achieved by:

difficult l Decorrelated data content on each spatial stream

l Large antenna spacing Channel condition

l Environment with a lot of scatters near the antenna (e.g. MS or indoor operation, but not BS)

Technical l Precoding assist

But, also possible that decorrelation

l Cyclic Delay Diversity is not given


MIMO: channel interference + precoding MIMO channel models: different ways to combat against

channel impact:

I.: Receiver cancels impact of channel

II.: Precoding by using codebook. Transmitter assists receiver in cancellation of channel impact

III.: Precoding at transmitter side to cancel channel impact


MIMO - work shift to transmitter

Channel Receiver Transmitter


MIMO precoding precoding Ant1 Ant2 t

+ 1

2 S 1

t +

1 -1 1 precoding

S =0

t t


MIMO - codebook based precoding Precoding codebook

noise

s r + R A H

receiver transmitter channel

Precoding Matrix Identifier, PMI

Codebook based precoding creates some kind of "beamforming lite"


MIMO: avoid inter-channel interference - future outlook

e.g. linear precoding: Y=H*F*S+V V 1,k

+ S Link adaptation H Space time Transmitter

receiver F

+ x k y k

V M,k

Feedback about H

Idea: F adapts transmitted signal to current channel conditions


MAS: "Dirty Paper" Coding - future outlook l Multiple Antenna Signal Processing: "Known Interference"

l Is like NO interference

l Analogy to writing on "dirty paper" by changing ink color accordingly

"Known "Known "Known "Known Interference Interference Interference Interference

is No is No is No is No Interference" Interference" Interference" Interference"


Spatial Multiplexing

Codeword Fading on the air interface

data

Codeword data

Spatial Multiplexing: We like to distinguish the 2 useful Propagation passes: How to do that? => one idea is SVD


Idea of Singular Value Decomposition MIMO s1 r1

know

r= H s+n s2 r2

channel H Singular Value Decomposition

~ ~ s1 r1 SISO

wanted ~ ~ s2 r2 ~ = D s + n ~ ~ r

channel D


MIMO transmission modes Transmission mode 2

Transmit diversity PDCCH indication via

DCI format 1 or 1A

Codeword is sent redundantly over several

streams 1 codeword

PDSCH transmission via 2 Or 4 antenna ports No feedback regarding

antenna selection or precoding needed


MIMO transmission modes

Closed loop MIMO = UE feedback needed regarding

Transmission mode 6 precoding and antenna Transmit diversity or Closed loop selection spatial multiplexing with 1 layer

PDCCH indication via DCI format 1A

1 codeword PDSCH transmission via 2 or 4 antenna ports

PDCCH indication via DCI format 1B

Codeword is split into 1 streams, both streams have codeword

to be combined

feedback

PDSCH spatial multiplexing, only 1 codeword


Beamforming

Closed loop precoded Adaptive Beamforming beamforming

Classic way Kind of MISO with channel

knowledge at transmitter Antenna weights to adjust beam

Precoding based on feedback Directional characteristics

No specific antenna Specific antenna array geometrie array geometrie

Dedicated pilots required Common pilots are sufficient


Spatial multiplexing vs beamforming

Spatial multiplexing increases throughput, but looses coverage


Spatial multiplexing vs beamforming

Beamforming increases coverage


System architecture evolution , SAE + IP multimedia subsystem , IMS


3 GPP System Architecture Evolution Signaling interfaces

Data transport interfaces RAN

Access PDN directly or via IMS

MME PDN UE Evolved nodeB

IMS S-GW P-GW

PSTN Evolved Packet Core external

IMS to control All interfaces are packet switched access + data

transfer


LTE: EPS Bearer

E-UTRAN EPC Internet

UE eNB S-GW P-GW Peer Entity

End-to-end Service

EPS Bearer External Bearer

Radio Bearer S1 Bearer S5/S8 Bearer

Radio S1 S5/S8 Gi


What is IMS? A high level summary l The success of the internet, using the Internet Protocol (IP) for

providing voice, data and media has been the catalyst for the convergence of industries, services, networks and business models, l IP provides a platform for network convergence enabling a

service provider to offer seamless access to any services, How to merge IP anytime, anywhere, and with any device,

and cellular l 3GPP has taken these developments into account world?? with specification of IMS,

l IMS stands for I P M ultimedia S ubsystem, l IMS is a global access-independent and standard-based IP

connectivity and service control architecture that enables various types of multimedia services to end-users using common internet-based protocols,

l Defines an architecture for the convergence of audio, video, data and fixed and mobile networks.


IMS: Reference Model (3GPP/3GPP2)


IMS simplified structure


IMS protocol structure

user plane

Control plane Voice messaging video

SIP/SDP IKE RTP MSRP

UDP / TCP / SCTP

IP / IP sec Layer 3 control

Layer 1/2 Layer 1/2 (other IP CAN)

Mobile com specific protocols IMS specific protocols


LTE physical layer aspects


Basic OFDM parameter LTE

1 T

F s = N FFT f

N FFT

3 . 84 Mcps 256

f = 2048 N FFT

Coded symbol rate= R

Sub-carrier CP S/P IFFT Mapping insertion

N Data symbols TX

Size-N FFT


Cyclic prefix length Normal cyclic prefix length: 1st CP is longer

1 2 3 4 5 6 7

1 slot = 0,5msec Mismatch in time!

1st Cyclic prefix is longer

1 2 3 4 5 6 7 Normal CP

OFDM OFDM OFDM OFDM OFDM OFDM Extended CP CP CP CP CP CP CP Symbol Symbol Symbol Symbol Symbol Symbol

2 different Cyclic prefix lengths are defined


Resource block definition

1 slot = 0,5msec

Resource block =6 or 7 symbols In 12 subcarriers

12 subcarriers

Resource element

UL N symb or N symb DL

6 or 7, Depending on cyclic prefix


LTE: new physical channels for data and control Physical Control Format Indicator Channel PCFICH:

Indicates Format of PDCCH

Physical Downlink Control Channel PDCCH: Downlink and uplink scheduling decisions

Physical Downlink Shared Channel PDSCH: Downlink data

Physical Hybrid ARQ Indicator Channel PHICH: ACK/NACK for uplink packets

Physical Uplink Shared Channel PUSCH: Uplink data

Physical Uplink Control Channel PUCCH: ACK/NACK for downlink packets, scheduling requests, channel quality info


LTE Downlink

OFDMA time-frequency multiplexing

frequency QPSK, 16QAM or 64QAM modulation

UE4 1 resource block =

180 kHz = 12 subcarriers UE5

UE3 UE2

UE6 Subcarrier spacing = 15 kHz time UE1

1 subframe = 1 slot = 0.5 ms = 1 ms= 1 TTI*= *TTI = transmission time interval 7 OFDM symbols** 1 resource block pair ** For normal cyclic prefix duration


Adaptive modulation and coding

Transportation block size

FEC User data

Flexible ratio between data and FEC = adaptive coding


Channel Coding Performance


Automatic repeat request, latency aspects

Transport block size = amount of data bits (excluding redundancy!)

TTI, Transmit Time Interval = time duration for transmitting 1 transport

block

Transport block Round Trip Time

ACK/NACK

Network UE

Immediate acknowledged or non-acknowledged feedback of data transmission


HARQ principle: Stop and Wait

? t = Round trip time

Data Data Data Data Data Data Data Data Data Data Tx

ACK/NACK

Demodulate, decode, descramble, Rx FFT operation, check CRC, etc.

process

Processing time for receiver

Described as 1 HARQ process


HARQ principle: Multitasking

? t = Round trip time

Data Data Data Data Data Data Data Data Data Data Tx

ACK/NACK

Demodulate, decode, descramble, Rx FFT operation, check CRC, etc.

process ACK/NACK

Processing time for receiver

Demodulate, decode, descramble, Rx FFT operation, check CRC, etc. process

t

Described as 1 HARQ process


LTE Round Trip Time RTT

n+4 n+4 n+4

ACK/NACK PDCC

H PHICH

Downlink

HARQ Data Data UL Uplink

t=0 t=1 t=2 t=3 t=4 t=5 t=6 t=7 t=8 t=9 t=0 t=1 t=2 t=3 t=4 t=5

1 frame = 10 subframes

8 HARQ processes RTT = 8 msec


HARQ principle: Soft combining l T i is a e am l o h n e co i g

Reception of first transportation block. Unfortunately containing transmission errors


HARQ principle: Soft combining

l hi i n x m le f cha n l c ing

Reception of retransmitted transportation block.

Still containing transmission errors


HARQ principle: Soft combining 1st transmission with puncturing scheme P1

l T i is a e am l o h n e co i g

2nd transmission with puncturing scheme P2

l hi i n x m le f cha n l c ing

Soft Combining = S of transmission 1 and 2 l Thi is an exam le of channel co ing

Final decoding

l This is an example of channel coding


Hybrid ARQ Chase Combining = identical retransmission

Turbo Encoder output (36 bits)

Systematic Bits Parity 1 Parity 2

Transmitted Bit Rate Matching to 16 bits (Puncturing)

Original Transmission Retransmission


Punctured Bit Chase Combining at receiver



Hybrid ARQ Incremental Redundancy

Turbo Encoder output (36 bits)


Rate Matching to 16 bits (Puncturing)

Original Transmission Retransmission


Punctured Bit Incremental Redundancy Combining at receiver



LTE Physical Layer: SC-FDMA in uplink

Single Carrier Frequency Division Multiple

Access


LTE Uplink: How to generate an SC-FDMA signal in theory?

Coded symbol rate= R

Sub-carrier CP DFT IFFT Mapping insertion

N TX symbols

Size-N FFT Size-N TX

LTE provides QPSK,16QAM, and 64QAM as uplink modulation schemes

DFT is first applied to block of N TX modulated data symbols to transform them into frequency domain

Sub-carrier mapping allows flexible allocation of signal to available sub-carriers

IFFT and cyclic prefix (CP) insertion as in OFDM

Each subcarrier carries a portion of superposed DFT spread data symbols

Can also be seen as " pre-coded OFDM " or " DFT-spread OFDM "


LTE Uplink: How does the SC-FDMA signal look like?

In principle similar to OFDMA, BUT : 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


LTE uplink SC-FDMA time-frequency multiplexing 1 resource block =

180 kHz = 12 subcarriers Subcarrier spacing = 15 kHz

frequency

UE1 UE2 UE3 1 slot = 0.5 ms = 7 SC-FDMA symbols**

1 subframe = 1 ms= 1 TTI*

UE4 UE5 UE6

*TTI = transmission time interval

** For normal cyclic prefix duration

time QPSK, 16QAM or 64QAM modulation


LTE Uplink: baseband signal generation

UE specific Scrambling code

Modulation Transform SC-FDMA Resource Scrambling mapper precoder element mapper signal gen.

Mapping on physical 1 stream = Discrete

Ressource, several Fourier Avoid QPSK i.e. subcarriers, Transform constant 16 QAM subcarriers based on sequences 64 QAM not used for Physical

(optional) reference ressource signals blocks


LTE Physical Layer:

Reference signals - general aspects

Reference signals in Downlink Reference signals in Uplink


LTE Reference signals in UL and DL overview

l i nk U pl own i nk D

Downlink reference signals: Uplink reference signals:

Primary synchronisation signal Random Access Preamble

Secondary synchronisation signal Uplink demodulation reference signal

Cell specific reference signals Sounding reference signal

UE specific reference signals = based on pseudo random bit sequences

= based on Zhadoff-Chu sequences MBMS specific reference signals = only used for special applications


Downlink Reference Signals Cell-specific reference signal

R 0 R 0

One antenna port R 0 R 0 freque

ncy

R 0 R 0

R 0 R 0

l = 0 l = 6 l = 0 l = 6

time

Cell specific reference signals Pseudo random bit sequence, based on physical cell ID

Staggered in frequency + time

Distributed over channel bandwidth, always sent


MIMO channel estimation due to reference signals

Estimate h 11 h 11

Estimate h 21 h 12

h 21 Estimate h 22 h 22

Estimate h 12

Antenna 1 Antenna 2 November 2012 | LTE Introduction | 116

MIMO in LTE (DL) Reference Symbols / Pilots Antenna 0 R0

R1 Antenna 1 R1 R3 R0 R1 R2 R0

R2 Antenna 2

R3 Antenna 3 R0 R2 R1 R0 R3 R1

12 subcarriers Different Tx antennas

R1 R3 R0 R1 R2 R0 Can be recognized

separately

R0 R2 R1 R0 R3 R1

1 subframe


Cell recognition due to physical cell identity Cell specific reference signals depend on N cell ID

ce en refer Cell fic spe pec i cific s eNodeB 2 Cell r efer enc e Physical Cell

eNodeB 1, identity B

Physical Cell Neighbour cells should have different

identity A physical layer cell identities to be distinguished


LTE Uplink: Reference Signals

2 different purposes:

1. Uplink channel estimation for uplink coherent demodulation/detection (reference symbol on 4th SC-FDMA symbol)

2. Channel sounding: uplink channel-quality estimation for better scheduling decisions (position tbd)


LTE Uplink: Reference Signals when PUSCH

time 0123456 0123456 0123456 0123456

Allocated bandwidth

Example structure

SRS bandwidth configuration frequency

Allocation for PUSCH

Demodulation Reference Signal: Uplink channel estimation for uplink coherent demodulation/detection

Sounding Reference Signal SRS: Channel sounding: uplink channel-quality estimation for better scheduling decisions


Sounding reference signal Frequency selective channel

allcoated bandwidth

eNodeB configures the UE when and where to send sounding reference signals

Sounding reference signals in uplink may assist the eNodeB to investigate frequency selectivity

=> Maybe change frequency scheduling


Security aspects power control random access Handover aspects


LTE security aspects: USIM

Modell of UMTS Subscriber Identity Module, USIM

Statements from TS 33.401:

A Rel-99 or later USIM shall be sufficient for accessing E-UTRAN

Access to E-UTRAN with a 2G SIM shall not be granted.


LTE fundamentals Downlink power allocation (1 RB)

For PDSCH power in same PDSCH power to RS, where NO reference Cell-specific PDCCH power symbol as reference signal an signals are present, is UE specific and reference signal depending additional cell specific offset signaled by higher layers as P A ( ? A ). power (RS power), on ? B / ? A

is applied, that is signaled by signaled in SIB Type 2 higher layers as P B ( ? B ).

[Power]

-50.00 dBm

P A = -4.77 dB 2011 ¸ Rohde&Schwarz y] -54.77 dBm c en

qu P B = 3 (-3.98 dB) re

[F -58.75 dBm

r rie ar

bc Su

[Time] 13 11 12 7 9 10 3 5 6 8 1 2 4 0

OFDM symbols

PDSCH - Physical Downlink Shared Channel PDCCH - Physical Downlink Control Channel


RACH Preamble (RAP) l RACH Preamble consists of

- CAZAC (Zadoff / Chu Sequence) in TDD/FDD -> orthogonality

- Cyclic Prefix Easy processing in frequency domain

- Guard Time Avoids Interference by no UL-Synchronization

l Different formats for different cell sizes: 0-3 (FDD: 1,2,3 Subframes), 4 (TDD: 1 Symbol)


LTE Protocol Architecture


EUTRAN stack: protocol layers overview MM ESM User plane

Radio Resource Control RRC

Packet Data Convergence PDCP

Control & Measurements

Radio Bearer

Radio Link Control RLC

Logical channels

Medium Access Control MAC

Transport channels

PHYSICAL LAYER


LTE - channels


Control plane

Broadcast Paging

RRC connection setup Radio Bearer Control

Mobility functions UE measurement control >

EPS bearer management Authentication

ECM_IDLE mobility handling Paging origination in ECM_IDLE

Security control >

EPS = Evolved packet system RRC = Radio Resource Control

NAS = Non Access Stratum ECM = EPS Connection Management


EPS Bearer Service Architecture

E-UTRAN EPC Internet

UE eNB S-GW P-GW Peer Entity

End-to-end Service

EPS Bearer External Bearer

Radio Bearer S1 Bearer S5/S8 Bearer

Radio S1 S5/S8 Gi


LTE TDD and FDD mode of operation


TDD versus FDD

Downlink

Guard band needed

Uplink

Independent resources in uplink +

downlink

Down- and Uplink

No duplexer Timing and UL/DL needed configuration

needed


Paired spectrum not always available -> use TDD mode


General comments What is called "Advantages of TDD vs. FDD mode" l Data traffic,

l Asymmetric setting between downlink and uplink possible, depending on the situation,

See interference aspects: UL - DL and inter-cell

l Channel estimation, l Channel characteristic for downlink and uplink same,

In principle yes: But hardware influence!

And: Timing delay UL and DL l Design,

l No duplexer required, simplifies RF design and reduce costs.

But most UEs will be dual- mode: FDD and TDD!


LTE TDD mode - overview 7 different UL/DL configurations are defined

Characteristics + differences of UL/DL configurations: Number of subframes dedicated to Tx and Rx Number of Hybrid Automatic Repeat Request, HARQ processes HARQ process timing: time between first transmission and retransmission Scheduling timing: What is the time between PDCCH and PUSCH?

9 different configurations for the "special subframe" are defined

Definition of how long are the DL and UL pilot signals and how much control information can be sent on it. -> also has an impact on cell size

Differences between Uplink and Downlink in TD-LTE

Characteristic of HARQ: Synchronuous or asynchronuous Number of Hybrid Automatic Repeat Request, HARQ processes HARQ process timing: time between first transmission and retransmission


LTE TDD: frame structure type 2

Used Always Always Optionally Always for UL used as DL UL DL or DL special

subframe

Subframe# 0 Subframe# 2 Subframe # 3 Subframe#4 Subframe #5 Subframe #7 Subframe #8 Subframe #9

One subframe ,

DwPTS GP UpPTS DwPTS GP UpPTS

DwPTS = PDCCH, P-Sync, Reference symbol, User Data GP = main Guard Period for TDD operation UpPTS = PRACH, sounding reference signal


LTE Rel9 / LTE-Rel 10 (= LTE-Advanced) Technology Outlook

Reiner Stuhlfauth [email protected] Training Centre Rohde & Schwarz, Germany

Technology evolution path 2005/2006 2009/2010 2011/2012 2007/2008 2013/2014

EDGE, 200 kHz EDGEevo VAMOS GSM/ DL: 473 kbps DL: 1.9 Mbps Double Speech GPRS UL: 473 kbps UL: 947 kbps Capacity

HSDPA, 5 MHz UMTS HSPA+, R7 HSPA+, R8 HSPA+, R9 HSPA+, R10 DL: 14.4 Mbps DL: 2.0 Mbps DL: 28.0 Mbps DL: 42.0 Mbps DL: 84 Mbps DL: 84 Mbps UL: 2.0 Mbps UL: 2.0 Mbps UL: 11.5 Mbps UL: 11.5 Mbps UL: 23 Mbps UL: 23 Mbps

HSPA, 5 MHz DL: 14.4 Mbps UL: 5.76 Mbps

LTE (4x4), R8+R9, 20MHz LTE-Advanced R10 DL: 300 Mbps DL: 1 Gbps (low mobility) UL: 75 Mbps UL: 500 Mbps

1xEV-DO, Rev. 0 1xEV-DO, Rev. A 1xEV-DO, Rev. B DO-Advanced cdma 1.25 MHz 1.25 MHz 5.0 MHz DL: 32 Mbps and beyond 2000 DL: 2.4 Mbps DL: 3.1 Mbps DL: 14.7 Mbps UL: 12.4 Mbps and beyond

UL: 153 kbps UL: 1.8 Mbps UL: 4.9 Mbps

Fixed WiMAX Mobile WiMAX, 802.16e Advanced Mobile scalable bandwidth Up to 20 MHz WiMAX, 802.16m 1.25 > 28 MHz DL: 75 Mbps (2x2) DL: up to 1 Gbps (low mobility) typical up to 15 Mbps UL: 28 Mbps (1x2) UL: up to 100 Mbps


The LTE evolution Rel-9

eICIC enhancements

Relaying Rel-10 In-device

Diverse Data co-existence Application CoMP

Rel-11 Relaying

eICIC eMBMS

SON enhancements enhancements

MIMO 8x8 MIMO 4x4 Carrier Enhanced Aggregation SC-FDMA

Public Warning Positioning Home eNodeB System

Self Organizing Networks eMBMS

UL DL Multi carrier /

DL UL Dual Layer Multi-RAT Beamforming Base Stations

LTE Release 8 FDD / TDD


Location based services

The idea is not new, > so what to discuss?

Satellite based services

Location controller

Network based services

Who will do the measurements? The UE or the network? = "assisted"

Who will do the calculation? The UE or the network? = "based"

So what is new? Several ideas are defined and hybrid mode is possible as well,

Various methods can be combined.


Measurements for positioning l l UE-assisted measurements. eNB-assisted measurements.

l l Reference Signal Received eNB Rx - Tx time difference. Power l TADV - Timing Advance. (RSRP) and Reference Signal - For positioning Type 1 is of Received Quality (RSRQ). relevance.

l RSTD - Reference Signal Time l AoA - Angle of Arrival. Difference. l UTDOA - Uplink Time Difference

l UE Rx-Tx time difference. of Arrival. TADV (Timing Advance) = eNB Rx-Tx time difference + UE Rx-Tx time difference

Neighbor cell j = (T eNB-RX - T eNB-TX ) + (T UE-RX - T UE-TX )

UL radio frame #i RSTD - Relative time difference

between a subframe received from neighbor cell j and corresponding

subframe from serving cell i: T SubframeRxj - T SubframeRxi DL radio frame #i UL radio frame #i

DL radio frame #i

Serving cell i

eNB Rx-Tx time difference is defined UE Rx-Tx time difference is defined as T eNB-RX - T eNB-TX , where T eNB-RX is

the RSRP, RSRQ are

as T UE-RX - T UE-TX , where T UE-RX is the

received timing of uplink radio frame #i measured on reference received timing of downlink radio frame and T eNB-TX the transmit timing of signals of serving cell i #i from the serving cell i and T UE-TX the downlink radio frame #i.

transmit timing of uplink radio frame #i.

Source: see TS 36.214 Physical Layer measurements for detailed definitions


E-UTRAN UE Positioning Architecture l In contrast to GERAN and UTRAN, the E-UTRAN positioning

capabilities are intended to be forward compatible to other access types (e.g. WLAN) and other positioning methods (e.g. RAT uplink measurements).

l Supports user plane solutions, e.g. OMA SUPL 2.0

UE = User Equipment SUPL* = Secure User Plane Location OMA* = Open Mobile Alliance SET = SUPL enabled terminal SLP = SUPL locaiton platform E-SMLC = Evolved Serving Mobile

Location Center MME = Mobility Management Entity RAT = Radio Access Technology

*www.openmobilealliance.org/technical/release_program/supl_v2_0.aspx

Source: 3GPP TS 36.305 November 2012 | LTE Introduction | 171

GNSS positioning methods supported l Autonomeous GNSS

l Assisted GNSS (A-GNSS) l The network assists the UE GNSS receiver to

improve the performance in several aspects: - Reduce UE GNSS start-up and acquisition times

- Increase UE GNSS sensitivity

- Allow UE to consume less handset power

l UE Assisted - UE transmits GNSS measurement results to E-SMLC where the position calculation

takes place

l UE Based - UE performs GNSS measurements and position calculation, suppported by data >

- > assisting the measurements, e.g. with reference time, visible satellite list etc.

- > providing means for position calculation, e.g. reference position, satellite ephemeris, etc.

Source: 3GPP TS 36.305 November 2012 | LTE Introduction | 172

GPS and GLONASS satellite orbits

GPS: 26 Satellites Orbital radius 26560 km

GLONASS: 26 Satellites Orbital radius 25510 km


Why is GNSS not sufficent?

Critical scenario Very critical scenario GPS Satellites visibility (Urban)

l Global navigation satellite systems (GNSSs) have restricted performance in certain environments

l Often less than four satellites visible: critical situation for GNSS positioning

support required (Assisted GNSS) alternative required (Mobile radio positioning)

Reference [DLR]


Cell ID

l Not new, other definition: Cell of Origin (COO). l UE position is estimated with the knowledge of the geographical

coordinates of its serving eNB. l Position accuracy = One whole cell .


Enhanced-Cell ID (E-CID) l UE positioning compared to CID is specified more

accurately using additional UE and/or E UTRAN radio measurements: l E-CID with distance from serving eNB position accuracy: a circle.

- Distance calculated by measuring RSRP / TOA / TADV (RTT).

l E-CID with distances from 3 eNB-s position accuracy: a point. - Distance calculated by measuring RSRP / TOA / TADV (RTT).

l E-CID with Angels of Arrival position accuracy: a point. - AOA are measured for at least 2, better 3 eNB's.

RSRP - Reference Signal Received Power TOA - Time of Arrival

November 2012 | LTE Introduction | 176 TADV - Timing Advance RTT - Round Trip Time

Angle of Arrival (AOA) l AoA = Estimated angle of a UE with respect to a reference

direction (= geographical North), positive in a counter- clockwise direction, as seen from an eNB. l Determined at eNB antenna based

on a received UL signal (SRS). l Measurement at eNB:

l eNB uses antenna array to estimate direction i.e. Angle of Arrival (AOA).

l The larger the array, the more accurate is the estimated AOA.

l eNB reports AOA to LS. l Advantage: No synchronization

between eNB's. l Drawback: costly antenna arrays.


OTDOA - Observed Time Difference of Arrival

l UE position is estimated based on measuring TDOA of Positioning Reference Signals (PRS) embedded into overall DL signal received from different eNB's. l Each TDOA measurement describes a hyperbola (line of constant

difference 2a), the two focus points of which (F1, F2) are the two measured eNB-s (PRS sources), and along which the UE may be located.

l UE's position = intersection of hyperbolas for at least 3 pairs of eNB's.


Positioning Reference Signals (PRS) for OTDOA Definition

l Cell-specific reference signals (CRS) are not sufficient for positioning, introduction of positioning reference signals (PRS) for antenna port 6. l SINR for synchronization

and reference signals of neighboring cells needs to be at least -6 dB.

l PRS is a pseudo-random QPSK sequence similar to CRS; PRS pattern: l Diagonal pattern with time

varying frequency shift. l PRS mapped around CRS to avoid collisions;

never overlaps with PDCCH; example shows CRS mapping for usage of 4 antenna ports.


Observed Time difference

Observed Time Difference of Arrival OTDOA

If network is synchronised, UE can measure time difference


Public Warning System (PWS) l Extend the Warning System support of the E-UTRA/E-UTRAN

beyond that introduced in the Release 8 ETWS (Earthquake and Tsunami Warning System) by providing l E-UTRA/E-UTRAN support for multiple parallel Warning Notifications l E-UTRAN support for replacing and canceling a Warning Notification l E-UTRAN support for repeating the Warning Notification with a repetition

period as short as 2 seconds and as long as 24 hours l E-UTRA support for more generic "PWS" indication in the Paging

Indication l The requirement is to extend the UE RRC ETWS broadcast

reception mechanism and the associated paging mechanism to accommodate reception of CMAS (Commercial Mobile Alert System) alerts contained in a CBS message.

l New: TS 22.268 Public Warning System (PWS) Requirements (Release 9)


IMT - International Mobile Communication l IMT-2000

l Was the framework for the third Generation mobile communication systems, i.e. 3GPP-UMTS and 3GPP2-C2K

l Focus was on high performance transmission schemes: Link Level Efficiency

l Originally created to harmonize 3G mobile systems and to increase opportunities for worldwide interoperability, the IMT-2000 family of standards now supports four different access technologies, including OFDMA (WiMAX), FDMA, TDMA and CDMA (WCDMA).

l IMT-Advanced l Basis of (really) broadband mobile communication l Focus on System Level Efficiency (e.g. cognitive network

systems) l Vision 2010 - 2015


IMT Spectrum

MHz

MHz

Next possible spectrum allocation at WRC 2015! MHz

MHz


LTE-Advanced Possible technology features

Relaying Wider bandwidth technology support

Cooperative Enhanced MIMO base stations schemes for DL and UL

Interference management Cognitive radio methods methods

Radio network evolution Further enhanced MBMS


Bandwidth extension with Carrier aggregation


LTE-Advanced Carrier Aggregation

Contiguous carrier aggregation

Non-contiguous carrier aggregation


Aggregation l Contiguous

l Intra-Band

l Non-Contiguous l Intra (Single) -Band

l Inter (Multi) -Band

l Combination

l Up to 5 Rel-8 CC and 100 MHz l Theoretically all CC-BW combinations possible (e.g. 5+10+20 etc)


Overview l Carrier Aggregation (CA)

enables to aggregate up to 5 different cells (component carriers CC), so that a maximum system bandwidth of 100 MHz can be supported (LTE-Advanced requirement). l Each CC = Rel-8 autonomous cell

Cell 2 Cell 1 - Backwards compatibility

l CC-Set is UE specific - Registration Primary (P)CC UE1 UE4 UE3 U3 UE4 U2

- Additional BW Secondary (S)CC-s 1-4 l CC2

Network perspective CC1

- Same single RLC-connection for one UE (independent on the CC-s)

UE1 UE2 CC2 CC1

- Many CC (starting at MAC scheduler) UE3

operating the UE l For TDD

- Same UL/DL configuration for all CC-s UE4


Deployment scenarios 3) Improve coverage

l #1: Contiguous frequency aggregation - Co-located & Same coverage - Same f

l #2: Discontiguous frequency aggregation - Co-located & Similar coverage - Different f

l #3: Discontiguous frequency aggregation - Co-Located & Different coverage - Different f - Antenna direction for CC2 to cover blank spots

l #4: Remote radio heads - Not co-located - Intelligence in central eNB, radio heads = only transmission

antennas - Cover spots with more traffic - Is the transmission of each radio head within the cell the

same?

l #5:Frequency-selective repeaters - Combination #2 & #4 - Different f - Extend the coverage of the 2nd CC with Relays


Physical channel arrangement in downlink

Each component carrier transmits P- Each component SCH and S-SCH, carrier transmits

Like Rel.8 PBCH, Like Rel.8


Carrier aggregation: control signals + scheduling

Each CC has its own control channels, like Rel.8

Femto cells: Risk of interference! -> main component carrier will send all control information.


LTE-Advanced Carrier Aggregation - Scheduling Non-Contiguous spectrum allocation Contiguous l There is one transport block

RLC transmission buffer (in absence of spatial

Dynamic multiplexing) and one HARQ switching

entity per scheduled component carrier (from the Channel Channel Channel Channel

coding coding coding coding UE perspective), l A UE may receive multiple HARQ HARQ HARQ HARQ

component carriers simultaneously, Data Data Data Data

mod. mod. mod. mod. l Two different approaches are

discussed how to inform the Mapping Mapping Mapping Mapping

UE about the scheduling for each band, e.g. 20 MHz

l Separate PDCCH for each carrier, l Common PDCCH for multiple carrier,

[frequency in MHz]


LTE-Advanced Carrier Aggregation - Common and Separate PDCCH?

l Based on RAN WG1#58 the following is up to 3 (4) symbols 1 subframe = 1 ms per subframe

considered being supported for LTE- Time 1 slot = 0.5 ms

Advanced, Frequency l Variant I PDCCH on a component carrier

PDCCH PDCCH PDCCH PDCCH assigns PDSCH resources on the same

PDSCH PDSCH PDSCH PDSCH component carrier (and PUSCH resources on a single linked UL component carrier) - No carrier indicator field, i.e. Rel-8 PDCCH

structure (same coding, same CCE-based PDSCH PDSCH PDSCH PDSCH

resource mapping) and DCI formats PDCCH PDCCH PDCCH PDCCH

l Variant II PDCCH on a component carrier can assign PDSCH or PUSCH resources in one of multiple component carriers using the carrier indicator field

PDSCH PDSCH PDSCH PDSCH - Rel-8 DCI formats extended with 1 to 3 bit carrier PDCCH PDCCH PDCCH PDCCH

indicator field - Reusing Rel-8 PDCCH structure (same coding, same

CCE-based resource mapping)

- Solutions to PCFICH detection errors on the component

Variant (I) Variant (II) Variant (III) PDSCH to be studied Variant (IV) carrier carrying

l In both cases, limiting the number of blind decoding is desirable,


Carrier aggregation activation

1. Establish SRB

3. Network Activates PCC =UL + DL

2. UE sends Capability information to the network

4.Network Add secondary CC


Carrier aggregation activation - mobility 1. UE has

EUTRAN connection active

2. Secondary CC is added

3. Secondary CC is removed

4. UE and network perform Handover on primary CC

3. Secondary CC is Added in target cell


DL MIMO Extension up to 8x8 Codeword to layer mapping for spatial multiplexing

l Max number of transport blocks: 2 Number Number Codeword-to-layer mapping

of code l Number of MCS fields of layers i = 0 , 1 , K M symb layer 1 words l one for each transport block

x ( 0 ) ( i ) = d ( 0 ) ( 2 i ) l ACK/NACK feedback x ( 1 ) ( i ) = d ( 0 ) ( 2 i + 1 )

l 1 bit per transport block for evaluation M symb = M symb 2 = M symb 3 layer ( 0 ) ( 1 ) 5 2

as a baseline x ( i ) = d ( 3 i ) ( 2 ) ( 1 )

x ( 3 ) ( i ) = d ( 1 ) ( 3 i + 1 ) l x ( 4 ) ( i ) = d ( 1 ) ( 3 i + 2 ) Closed-loop precoding supported

l Rely on precoded dedicated x ( 0 ) ( i ) = d ( 0 ) ( 3 i ) x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1 ) demodulation RS (decision on DL RS) x ( 2 ) ( i ) = d ( 0 ) ( 3 i + 2 ) l M symb = M symb 3 = M symb 3 layer ( 0 ) ( 1 )

Conclusion on the codeword-to- 6 2

x ( i ) = d ( 3 i ) ( 3 ) ( 1 )

layer mapping: x ( 4 ) ( i ) = d ( 1 ) ( 3 i + 1 ) x ( 5 ) ( i ) = d ( 1 ) ( 3 i + 2 ) l DL spatial multiplexing of up to eight x ( 0 ) ( i ) = d ( 0 ) ( 3 i ) layers is considered for LTE-Advanced, x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1 ) l x ( 2 ) ( i ) = d ( 0 ) ( 3 i + 2 ) Up to 4 layers, reuse LTE codeword-to-

M symb = M symb 3 = M symb 4 layer ( 0 ) ( 1 ) 7 2

layer mapping, x ( 3 ) ( i ) = d ( 1 ) ( 4 i ) x ( 4 ) ( i ) = d ( 1 ) ( 4 i + 1 )

l Above 4 layers mapping - see table x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 2 ) x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 3 )

l Discussion on control signaling x ( 0 ) ( i ) = d ( 0 ) ( 4 i )

details ongoing x ( 1 ) ( i ) = d ( 0 ) ( 4 i + 1 ) x ( 2 ) ( i ) = d ( 0 ) ( 4 i + 2 ) x ( 3 ) ( i ) = d ( 0 ) ( 4 i + 3 ) M symb = M symb 4 = M symb 4 layer ( 0 ) ( 1 )

8 2 x ( 4 ) ( i ) = d ( 1 ) ( 4 i ) x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 1 ) x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 2 ) x ( 7 ) ( i ) = d ( 1 ) ( 4 i + 3 )


LTE-Advanced Enhanced uplink SC-FDMA l The uplink

transmission scheme remains SC-FDMA.

l The transmission of the physical uplink shared channel (PUSCH) uses DFT precoding.

l Two enhancements: l Control-data

decoupling l Non-contiguous

data transmission


Significant step towards 4G: Relaying ?

Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008


Radio Relaying approach

No Improvement of SNR resp. CINR



L1/L2 Relaying approach



LTE-Advanced Coordinated Multipoint Tx/Rx (CoMP)

CoMP

Coordination between cells


Present Thrust- Spectrum Efficiency

Momentary snapshot of frequency spectrum allocation

Why not use this part of the spectrum?

l FCC Measurements:- Temporal and geographical variations in the utilization of the assigned spectrum range from 15% to 85%.


ODMA - some ideas.

BTS

Mobile devices behave as relay station


There will be enough topics

for future trainings

Thank you for your attention!

Comments and questions welcome!


Lte presentation

Technology

maximum ratio

tx time difference

discontiguous

positioning

schwarz gmbh

rx fft operation

uplink channel

reference