04 lte and beyond

8/11/2019 04 LTE and Beyond

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LTE, WiMAX and 4G

Mobile Communication and Mobile Computing

Prof. Dr. Alexander Schill

http://www.rn.inf.tu-dresden.de

Department of Computer Science Institute for System Architecture, Chair for Computer Networks
http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/http://www.rn.inf.tu-dresden.de/


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LTE: Characteristics

LTE = Long Term Evolution

European implementation of IMT (International MobileTelecommunications) by ETSI (European TelecommunicationStandards Institute)

Packet oriented propagation only

High data rates Up to 300 Mbit/s Downlink

Up to 75 Mbit/s Uplink

Flexible frequency assignment

About 40 frequency ranges

Varying frequency blocks (1.4, 3, 5, 10 and 20 MHz)

small latency of 5ms between mobile phone and conventionaltelephone network

optimized for travelling speeds of up to 15 km/h (up to500km/h possible)

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LTE Reference Architecture

UE eNodeB S-GW P-GW

MME

LTE - Uu S1-U S5/S8

S1-MME S11

HSSS6a

PCRF

Gx

SGi PSTN

eUTRAN Core Network

NodeB + RNC (3G) merged into evolved NodeB (eNodeB)

Core network Serving Gateway (S-GW)

Mobility Management Entity (MME)

PDN Gateway (P-GW)

Home Subscriber Server (HSS)

Policy Control and Charging Rules Function (PCRF)3


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LTE User Equipment

Examples of LTE-enabled devices

iPhone 5, Samsung Galaxy S3 LTE,Samsung LTE Stick

Five device categories

Category 1 2 3 4 5

Peak data rate

Mbit/s

DL 10 50 100 150 300

UL 5 25 50 50 75

RF bandwidth 20 MHz

Modulation QPSK, 16QAM QPSK, 16QAM,64QAM

2 Rx diversity Assumed in performance requirements

2x2 MIMONot

supported

Mandatory

4x4 MIMO Not supported Mandatory4


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LTE: Frequency bands

Germany (currently)

5 bands: 800 MHz, 900 MHz, 1800 MHz, 2000 MHz, 2600MHz

Rural Areas

800 MHz (Vodafone and Telecom)

Urban Areas

800 MHz (Vodafone)

1800 MHz (Telecom) -> reassignment from GSM

2600 MHz planned for crowded areas in cities (stations,shopping malls, etc.)

O2 and E-Plus cover currently only few areas

USA: 700MHz, 1700MHz and 2100 MHz

Europe: 800 MHz

Bands 700, 800, 1800 and 2600 MHz will potentiallyallow world wide roaming in the future

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LTE: German frequency bands

frequency spectrum of the digital dividend:

better building penetration & propagation features > higher range

frequency spectrum of the IMT extension band:Enough blocks for 20 MHz bandwidth > Higher data rate

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Duplex gap*12 MHz820 MHz 832 MHz

5 MHzfrequencyblock

(72 Mhz)790 MHz 862 MHz

10 x 5 MHzblocks uncoupled2570

MHz2620MHz

5 MHzfrequencyblock

(190 Mhz)2500MHz

2690MHz

* The Duplex gap is meant as a fallback position for wireless production technology.


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LTE: Modulation basics OFDM

LTE Modulation techniques are based on OFDM(Orthogonal frequency-

division multiplexing) in OFDM data is distributed over a large number of closely spaced

orthogonalsubcarriers

(two subcarriers are orthogonal if the maximum amplitude of onesubcarrier is reached while the other subcarriers amplitude is zero)

Subcarriers modulated with conventional modulation scheme (QAM)

Pro: robust against interference because interference on subcarrier doesnot influence the whole frequency band, Improved spectrum efficiencyand lower bandwidth demand W with OFDM

Con: expense for coding and decoding and therefore the powerconsumption increases with the number of subcarriers

8

OFDM with 3 subcarriers

f f

FDM with 3 subcarriers


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LTE: Modulation techniques

LTEs modulation techniques used for Downlink and Uplinkare based on OFDM with a special focus on simultaneousaccess of multiple users

*OFDMA(Orthogonal frequency-division multiple access)for Down Link

subsets of subcarriers are assigned to individual users >simultaneous (low data rate) transmission for severalusers

*SC-FDMA(Single Carrier FDMA) for Up Link multiple access realized by insertion of coefficients on the

transmitter side before Fourier transformation, andremoving on the receiver side. Different users areassigned to different coefficients (subcarriers). More

energy-efficient for battery-driven mobile devices. 9


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LTE E-UTRAN Architecture

Flat architecture:

eNodeBs form E-UTRAN NodeB + RNC (3G)

merged into evolvedNodeB (eNodeB)

eNodeB manages one orseveral cells

Responsibilities

IP header compression

Encryption

Radio resource

management Connectivity to core

network

Bearer management

UE mobility

Core Network

E-UTRAN

eNodeB

eNodeB

eNodeB

MME S-GW MME S-GW

comm. between

eNodeBs

signaling to

MMEs bearer path

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LTE Bearer

UE P-GWeNodeB S-GW

UL-TFT

Application/service layer

UL-TFT

DL-TFT

DL-TFT

Radio bearer S1 bearer S5/S8 bearer

RB-ID S1-TEID S1-TEID S5/S8-TEID

Different QoS requirements of applications (VoIP, browsing, filedownload) are mapped to bearers

Bearers cross multiple interfaces, each part is individually mapped tolower layer bearer with own bearer id

Each node manages binding between bearer ids

Packet filters (Traffic Flow Templates (TFT)) assign IP packets to bearers

(e.g. based on IP header information and TCP port numbers) 11


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LTE Interworking

UE E-UTRAN S-GW P-GW

MME

LTE - Uu S1-U S5/S8

S1-MMES11

3G-SGSN

S3 S4

non-3GPP networks

(CDMA2000, WiMAX,)

UTRAN

(GSM, UMTS)

Interworking and mobility with other 3GPP defined networks as

well as non-3GPP defined networks

Service Gateway (S-GW) is mobility anchor for other 3GPPnetworks

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LTE Advanced

Specified as LTE Release 10

Improved performance

Data rate up to 1 GBit/s

End-to-end delay 20 30 ms

Enhancements

Carrier aggregation up to 5 * 20 MHz -> 100MHz

Possible in contiguous and non-contiguous spectrum allocations

Multiple Input, Multiple Output (MIMO)

Up to 4 LTE antennas in LTE devices to use MIMO also for Uplink

Base stations can be equipped with up to 8 antennas

Support for relay node base stations

Connected to base station only

Improve signal quality at cell borders

Support of low power nodes such as picocells and femtocellsfor crowded areas

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WiMAX / IEEE802.16

WiMAX: Worldwide Interoperability for Microwave

Access, standardized by IEEE 802.16 and WiMAX-Forum(more than 230 members, including AOL, DeutscheTelekom, Intel, Microsoft, Nokia)

IEEE 802.16 FBWA (Fixed Broadband Wireless Access) is

an alternative for broadband cable services like DSL;frequency range: initially 10-66 GHz, in assumption ofLOS (line of sight)

Enhancement IEEE 802.16a; frequency band: 2-11 GHz,

NLOS (non line of sight)

Enhancement IEEE 802.16efor MBWA (MobileBroadband Wireless Access); frequency band: 2-6 GHz,NLOS

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WiMAX/IEEE 802.16: overview

Standard 802.16 802.16a 802.16e

Spectrum, GHz 10-66 2-11 2-6

LOS-condition LOS NLOS NLOS

Bit rate, MBit/s 32-134


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WiMAX: Frequencies worldwide

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For Germany especially: 3,41-3,452 GHz and 3,51-3,552 GHz


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802.16 Physical Layer

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Specification Frequency

band

Channel

bandwidth

Duplex

method

Modulatio

n

Line-of-

Sight

WirelessMAN-SC 10-66 GHz

Licensed

bandwidth

20, 25,

28 MHz

TDD, FDD Single

carrier

LOS

WirelessMAN-

SCa

2-11 GHz

Licensed

bandwidth

3,5, 7, 10,

20 MHz

TDD, FDD Single

carrier

NLOS

WirelessMAN-

OFDM

2-11 GHz

Licensed

bandwidth

variable

1,25-20

MHz

TDD, FDD OFDM NLOS

WirelessMAN-

OFDMA

2-11 GHz

Licensedbandwidth

variable

1,25-28MHz

TDD, FDD OFDMA

(multipleaccess)

NLOS

WirelessHUMAN 2-11 GHz

License-

free

10, 20 MHz TDD OFDM,

OFDMA

NLOS


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WiMAX: Modulation

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WiMAX: strong dependency

of effective channelcapacity, spectrumefficiency, range, signal-noise-ratio etc. on usedmodulation method:

BPSK Binary Phase Shift

Keying QPSK Quadrature Phase

Shift Keying

16QAM QuadratureAmplitude Modulation

64QAM Quadrature

Amplitude Modulation

(typical example distribution (percentage)of users in different coverage areas)


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802.16 Medium Access

TDMA (Time Division Multiple Access)

Each communication channel gets fixed slot for datatransmission

DAMA (Demand Assigned Multiple Access)

2 Phases:

Reservation: every station tries to acquire slot foreach transmission phase (collision possible)

Data transmission: within reserved slot guaranteedcollision free transmission

Duplex connection

FDD (Frequency Division Duplex): simultaneous use ofdifferent frequencies

TDD (Time Division Duplex): Switching between up-and downlink on the same frequency

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WiMAX: Cellular backbone

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Network

Point to PointBackbone

Point to Multipoint

WiMAX cell

UMTS cell

802.16

PHY 802.16OFDM-PHYe.g Gigabit

Ethernet


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1) Last Mile or

2) Point to Multipoint (PMP) network (see bellow) Base Station (BS) is the central point for the

Mobile Stations (MS)

Sending in Downlink-direction: Broad-, Multi-, Unicast

Connection of a MS to BS is characterized via Channel ID (CID),

Channel id gives the possibility for the BS to receive multicastmessages

802.16 Network topologies (1&2)

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MS/BS

MS/BS

BS

MS

MSMS MS

Network


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802.16 Network topologies (3)

3) Mesh network

MS can communicate directly

Mesh BS: connected with a network outside the mesh

other differentiation

neighbor: direct connection to a node

neighborhood: all other neighbors

extended neighborhood: remote neighborhoods

23Mesh MS

Mesh BS

Mesh MSMesh MS

Mesh MS

Mesh MSMesh MS

Network


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MBWA (Mobile Broadband Wireless Access);802.20 (1)

Working Group 802.20 originated from 802.16 goal: Specification of PHY and MAC for Packet-based MBWA-

System

Should close the gap between WLAN and slower but highlymobile networks (UMTS)

features variable cell size Handover- and Roaming-mechanism Velocity up to 250 km/h Transport of IP-data traffic

QoS on transport layer

Licensed bands below 3,5 GHz, variable bandwidth NLOS, for in- and outdoor TDD, FDD, Half-Duplex FDD More than 100 simultaneous sessions per cell End to End Security, AES

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Goals

Peak data rates

802.20 (2)

characteristic goal

User data rate Downlink > 1 MBit/s

User data rate Uplink > 300 KBit/s

Data rate Downlink per cell > 4 MBit/s

Data rate Uplink per cell > 800 KBit/sCell size Correspond. to all modern MANs, with ability to

use the existing infrastructure

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Data rates 1.25 MHz 5 MHzDownlink Uplink Downlink Uplink

Peak data rate

per user

4.5 MBit/s 2.25

MBit/s

18 MBit/s 9 MBit/s


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UMTS/HSPA/HSPA+ WiMAX MBWA LTE

Mobility Handover, Roaming ---------------- Handover, Roaming, Mobile IP ---

Max Speed 300 km/h 120 km/h 250 km/h 500 km/h

Switching type circuit and packet ---------------- Packet switching ----------------

Peak datarates Down

Link

2/14,4/28 Mbit/s(5MHz channel)

365 Mbit/s(2x 20MHzchannel,variations)

100 - 300 Mbit/s(1.4-20 MHzchannel)

Cell sizespico(1)-, micro(2)-,macro(3)-cells

variablepico(1)-,micro(2)-,macro(3)-cells

pico(1)-, micro(2)-,macro(3)-cells

QoSEnd-to-end QoSDifferent classes

End-to-endQoSDifferentclasses

End-to-endQoS

End-to-end QoSDifferent classes

Scalability ---------------- variable data rate ~ Multiple users per BS --------------

Air InterfaceCDMAadaptive ModulationMIMO

OFDM(A),adaptiveModulationMIMO

OFDMAdaptiveModulation

OFDM, SC-FDMAadaptiveModulationMIMO

Security AES AES, X.509 AES SNOW 3G

Technology comparison pre-4G

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(1)

1km


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4G requirements

high mobility Handover, Roaming,

velocity up to 300 km/h

switching technique pure packet switching

integrated multi-media-services VoIP, TVoIP, VoD,Streaming

high data rate (1Gbit/s)

even at high mobility shouldbe like DSL

Size of cell variable and scalable

QoS prioritization of specific data packages

scalability available and reliable with many users

air interface OFDM (better spectrum efficiency) security up to date standards (e.g. AES)

Extension / integration of UMTS and WLAN approaches

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Technology comparison 3G to 4G

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LTE (3G) LTE Advanced (4G)

Peak data rateDown Link (DL)

300 Mbit/s 1 Gbit/s

Peak data rateUp Link (UL)

75 Mbit/s 500 Mbit/s

Transmissionbandwidth DL

20 Mhz (max.) 100 Mhz

Transmissionbandwidth UL

20 Mhz (max.) 40 Mhz (requirements asdefined by ITU)

CoverageFull performance up to5km

Same as LTE requirement.Should be optimized ordeployed in local areas/microcell environments.

Scalablebandwidths

1.4, 3, 5, 10 and 20 MHz 20-100 MHz

Scalabilityvariable data rateMultiple users per BS

variable data rateMultiple users per BS

Capacity200 active participantsper cell at 5 MHz

3 times higher than that inLTE


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Summary: Data rates and mobility

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High-speed

/Wide-area

Medium-speed

/Urban area

Walking

/Local area

Standing

/Indoors

2G

Source:www.3g.co.uk

Mobility

0.1 1 10 100 200 1000Bitrate, MBit/s


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Some further readings

Eds.: Sesia, S., Toufik, I., Baker, M.: LTE The UMTS

Long Term Evolution From Theory to Practice, Whiley,2009

LTE:

www.gsmworld.com

www.ltemobile.dewww.apwpt.org

WiMAX technology:

www.wimaxforum.org

IEEE web sites for 802.16 and 802.20:grouper.ieee.org/groups/802/16/ and /802/20

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