Long Term Evolution (LTE) Technology

Presented by GHANSHYAM MISHRA 11EC63R22M.Tech,RF & Microwave EngineeringIIT KHARAGPUR.

OUTLINE:Generation of wireless mobile technologies

Targets for LTE

LTE architecture

LTE enabling technologies: OFDM MIMO antenna technology

Continued….Spectrum for LTE deployments

Comparative study of 3GPP LTE and Wi-MAX

LTE network performance

LTE- Advanced

References

GENERATION OF WIRELESS MOBILE COMMUNICATION

GENERATION FEATURES THROUGHPUT TECHNOLOGY

1 G Analog 14.4 Kbps(peak) AMPS

2 G Digital , Narrowband, Circuit switched data

9.6/14.4 Kbps TDMA(IS-136), GSM, CDMA (IS-95)

2.5 G Packet switched data

171.2 Kbps(peak)20-40 Kbps

GPRS

3 G Digital, broadband and packet data

3.1Mbps(peak)500-700Kbps

CDMA 2000, UMTSEDGE

3.5 G > 2 Mbps Upto 3.6/7.2/14.4 Mbps(peak)1-3 Mbps

HSPA

4 G Digital broadband packet , all IP , very high throughput

100-300Mbps (peak)3.5 Mbps

WIMAX,LTE-A

Beyond 3GEvolutionary path beyond 3G

◦– Mobile class targets 100 Mbps with high mobility

◦– Local area class targets 1 Gbps with low mobility

3GPP is currently developing evolutionary/ revolutionary systems beyond 3G◦– 3GPP Long Term Evolution (LTE)

IEEE 802.16-based WiMAX is also evolving towards 4G through 802.16m

MOTIVATION FOR 3G EVOLUTION

CURRENT GENERATION SUPER 3G

Voice communication VoIP, high quality video conferencing

SMS, MMS Video messaging

Internet browsing Super-fast internet

Downloadable games Online gaming with mobility

Downloadable video High quality audio & video streaming

No TV service Broadcast TV on-demand

Peer-to-peer messaging Wide-scale distribution of video clips

Mobile payment

File transfer

Many other innovative ideas

LTE TargetsPeak 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. Spectrum flexibility: 1.25 ~ 20 MHzReduced capex/opex via simple architecture

LTE ARCHITECTURE Radio Interfaces

Higher Data Throughput

Lower Latency

More Spectrum Flexibility

Improved CAPEX and OPEX IP Core Network

Support of non-3GPP Accesses

Packet Only Support

Improved Security

Greater Device Diversity Service Layer

More IMS Applications (MBMS, PSS, mobile TV now IMS enabled)

Greater session continuity

LTE ARCHITECTURE:

LTE ARCHITECTURE Main logical nodes in EPC are:

PDN Gateway (P-GW)

Serving Gateway (S-GW)

Mobility Management Entity (MME) EPC also includes other nodes and functions, such:

Home Subscriber Server (HSS)

Policy Control and Charging Rules Function (PCRF) EPS only provides a bearer path of a certain QoS, control of

multimedia applications is provided by the IP Multimedia

Subsystem (IMS), which considered outside of EPS E-UTRAN solely contains the evolved base stations, called

eNodeB or eNB

LTE Enabling Technologies

Two main technologies1.Orthogonal Frequency Division

Multiplexing (OFDM)

2.Multiple-Input Multiple-Output (MIMO) Antenna technology

OFDM We have a high rate (hence, large bandwidth)

stream of modulation symbols Xk (ex. QAM)

Needs to be transmitted on a frequency selective fading channel

Stream Xk is divided into N low rate parallel sub-streams

Bandwidth of each sub-stream is N times narrower

Each sub-stream is carried by one subcarrier

Received must restore each Xk without interference from current or previously transmitted sub-streams

OFDM ConceptTransmitted OFDM Signal

Received OFDM Signal

OFDM Concept

1

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knx X

N N

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Ser

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IFFT

Add Guard

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X1

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X1 XN-1

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k = 2k/N

TbTg

time

frequencyOFDM Symbol

Ts =Tb+ Tg

01

N-1

Unused subcarriersXk = 0

OFDM Concept:OFDM modulation using IFFTGuard time (cyclic prefix) is

added to protect against inter-symbol interference

Guard subcarriers to protect against neighbor channels at both sides

Some subcarriers are used as pilots for channel estimation

After equalization, receiver performs FFT to retrieve back the stream Xk

OFDM ADVANTAGES OFDM is spectrally efficient

IFFT/FFT operation ensures that sub-carriers do not interfere with each other.

OFDM has an inherent robustness against narrowband interference. Narrowband interference will affect at

most a couple of sub channels. Information from the affected sub

channels can be erased and recovered via the forward error

correction (FEC) codes.

Equalization is very simple compared to Single-Carrier systems

OFDM ADVANTAGES

OFDM has excellent robustness in multi-path environments. Cyclic prefix preserves orthogonality between sub-

carriers. Cyclic prefix allows the receiver to capture multi- path energy more efficiently.

Ability to comply with world-wide regulations: Bands and tones can be dynamically turned on/off to comply with changing regulations.

Coexistence with current and future systems: Bands and tones can be dynamically turned on/off for enhanced coexistence with the other devices.

MIMOSignal transmitted from multiple antennas (Multiple

In)Signal received by multiple antennas (Multiple Out)

• Receiver combines the received signals and optimally combine energy from MxN channels

• Two main types of MIMO Transmit Diversity Spatial Multiplexing

TX RX

M antennas

N antennas

MIMO 2X2, Transmit Diversity

Take M=2 and N=2Diversity order 4

MIMO 2x2, Spatial Multiplexing

Purpose is to increase data rate (2x2 gives twice data rate)

The 4 gains must be known at receiver Spatial multiplexing is a transmission technique in MIMO

to transmit independent and separately encoded data signals from each of the multiple transmit antenna .

1 2 1 3or s g s g

1 1o o or s g s g

Spectrum for LTE deployments An operator may introduce LTE in ‘new’ bands where it

is easier to deploy 10 MHz or 20 MHz carriers.

e.g. 2.6 GHz band(IMT Extension band) or Digital Dividend spectrum700, 800 MHz Or in re-farmed existing mobile bands e.g. 850, 900, 1700, 1800, 1900, 2100 MHz

Eventually LTE may be deployed in all of these bands –and others later

2.6 GHz (for capacity) and 700/800 MHz (wider coverage, improved in-building) is a good combination

LTE offers a choice of carrier bandwidths: 1.4 MHz to 20 MHz; the widest bandwidth will be needed for the highest speeds

Comparative study of 3GPP LTE and Wi-MAX

WiMAX (Worldwide Interoperability for Microwave

Access), is a wireless communication system that can provide broadband access on a large-scale coverage.

It enhances the WLAN (IEEE 802.11) by extending the wireless access to Wide Area Networks and Metropolitan Area Networks.

Parameter WiMAX LTE

Duplex method TDD FDD and TDD

Bandwidth 5 and 10 MHz 1.25, 3, 5, 10, 15 & 20 MHz

Frame size 5 ms 10 ms with 10 sub-frames

Multiplex Access DL OFDMA OFDMA

Multiplex Access UL OFDMA SC-FDMA

Scheduling speed Every frame (5 ms) Every sub-frame (1 ms)

Subcarrier spacing 10.9 kHz 15 kHz

Maximum DL Data rate (SISO)

46 Mbps (10 MHz band) 50 Mbps (10 MHz band)

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

Diversity MIMO up to 2x2TD & SM

MIMO up to 4x4TD & SM

Advantages/disadvantages for WiMAX and LTE

Parameter/Criterion WiMAX(+/-) LTE (+/-)

Availability ++ -

Migration costs - ++

Frequency band options + ++

Peak data rates + ++

Adaptive antenna systems + ++

UL performances + ++

DL performances + ++

Mobility + ++

Radio access modes(TDD&FDD)

+ ++

QoS provisioning ++ ++

LTE network deployments

April 7, 2010: The number of mobile operators who have committed to deploy LTE advanced mobile broadband systems has more than doubled in the past year. There are now 64 operators committed to LTE network deployments in 31 countries, according to the Global mobile Suppliers Association (GSA)

LTE commercial networks -performance

Signals Research Group conducted the first ever extensive independent drive test evaluation of a commercial LTE network, assessing the performance of the Telia SoneraLTE networks in Stockholm and Oslo, and reported to GSA:

“While still in its infancy, commercial LTE networks in Stockholm and Oslo already outperform many fixed broadband connections, offering average data rates of 16.8Mbps (peak = 50Mbps) and 32.1Mbps (peak = 85Mbps) in 10MHz and 20MHz, respectively. Measured data rates would have been even higher if it had not been for the stringent test methodology, which focused almost entirely on vehicular testing.”

Signals Research Group, LLC “Signals Ahead,” March 2010

LTE: some industry forecasts

Maravedis: The number of LTE subscribers worldwide will pass 200 million in 2015

Strategy Analytics: the global LTE handset market will reach 150 million sales units by 2013

ABI Research: by 2013 operators will spend over $8.6 billion on LTE base stations infrastructure

IDC: Spending on LTE equipment will exceed WiMAXequipment spend by end 2011, with worldwide LTE infrastructure revenues approaching USD 8 billion by 2014

Global mobile Suppliers Association (GSA): up to 22 LTE networks are anticipated to be in commercial service by end 2010, and at least 45 by end 2012

Gartner: long Term Evolution will be the dominant next-generation mobile broadband technology

FUTURE OF LTE LTE-Advanced (LTE-A)

LTE-A shall have same or better performance than LTE

Peak data rate (peak spectrum efficiency)Downlink: 1 Gbps, Uplink: 500 Mbps

Peak spectrum efficiencyDownlink: 30 bps/Hz, Uplink: 15

bps/Hz Same requirements as LTE for

mobility, coverage, synchronization, spectrum flexibility etc

References:

[1] Erik Dahlman, Stefan Parkvall, Johan Sköld, Per Beming, "3G Evolution – HSPA and LTE for Mobile Broadband", 2nd edition, Academic Press, 2008, ISBN 978-0-12-374538-5.

[2] K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE and WiMAX, 2nd Edition, John Wiley & Sons, 2008, ISBN 978-0-470-99821-2.

[3] H. Ekström, A. Furuskär, J. Karlsson, M. Meyer, S. Parkvall, J. Torsner, and M. Wahlqvist, "Technical Solutions for the 3G Long-Term Evolution," IEEE Commun. Mag., vol. 44, no. 3, March 2006, pp. 38–45.

[4] “The Long Term Evolution of 3G” on Ericsson Review no.2, 2005.

[5] www.3gpp.org

THANK YOU