20 Introduction Frequency spectrum for LTE Flexible spectrum - - PowerPoint PPT Presentation

Rev 1

Vanja Plicanic vanja.plicanic@eit.lth.se Department of Electrical and Information Technology

3G Evolution

Chapter:

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20

Flexible bandwidth in LTE

2009-05-28 3G Evolution - HSPA and LTE for Mobile Broadband 1

Rev 2

Outline

• Introduction
• Frequency spectrum for LTE
• Flexible spectrum use
• Flexible channel bandwidth use
• RF requirements for LTE

– BS transmitter – BS receiver – UE transmitter – UE receiver

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Introduction

Spectrum flexibility – key feature of LTE

• Deployment in various frequency spectra (paired and unpaired)
• Deployment in various sizes of frequency spectra

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Rev 4

Allocated frequency bands in paired and unpaired spectra

Frequency spectrum for LTE 1 (4)

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• Ex. WCDMA/HSPA
• Ex. TD-CDMA/TD-SCDMA

LTE

Rev 5

Frequency spectrum for LTE 2(4)

• Reuse of frequency spectra for GSM and IMT-2000
• Additional ”new” frequency bands
• 450-470 MHz
• 698-806 MHz
• 2300-2400 MHz
• 2500-2690 MHz
• 3400-3600 MHz

Wide frequency operation range 450 MHz 3600MHz

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Rev 6

Frequency spectrum for LTE 3(4)

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Paired spectrum Unpaired spectrum

Rev 7

Frequency spectrum for LTE 4(4)

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450 MHz band 3500 MHz band 806-960 MHz band

Rev 8

Flexible spectrum use

Flexibility achieved if following considered:

• Coexistence between operators in the same geographical area in the

band

• Co-location of BS equipment between operators
• Coexistence with services in adjecent frequency bands and across

country

• Release independent frequency band principle

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Solution in RF requirements

Rev 9

Flexibility achieved with scalable bandwidth

Flexible channel bandwidth use 1(2)

Pure OFDM signal 90% of the channel bandwidth (78% for 1.4 MHz case) Set of bandwidths frequency band dependent

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Rev 10

Flexible channel bandwidth use 2(2)

Solves the problem of spectrum availability and migration into currently used spectra (GSM, CDMA2000 etc.)

• Bandwidths 1.4 MHz and 3 MHz used

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Rev 11

RF requirements for LTE

• BS and UE requirements for transmit and receive

performance

– Transmitter characteristics: maximum output power, output power

dynamics, transmitted signal quality, unwanted emissionstranmitter intermodulation

– Receiver characteristics: reference sensitivity level, receiver dynamic

range , Adjecent Channel Selectivity, receiver blocking, receiver intermodulation, receiver spurious emissions

• Flexibility in bandwidth considered
• Regional regulation

– Network signaling of RF requirements for UE – Europe: ETSI, ECC, US:FCC

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Rev 12

BS transmitter requirements 1(2)

Unwanted emissions:

• Out-of-band (OOB) emissions
• Spurious emissions

Concept of operating band unwanted emissions

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Rev 13

Adjacent Channel Leakage Ratio (ACLR)

• For analysis of coexistence between two systems that operate on

adjacent channels (OOB domain)

• Unwanted emissions from components at adjacent channel (PAs)

BS transmitter requirements 2(2)

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Rev 14

BS receiver requirements 1(3)

• Reference sensitivity

– How much receiver degrades the SNR of the receiver signal – Defined over 25 resource blocks (5 MHz)

• Receiver dynamic range

– To ensure high throughput when receive signal is increased due to increased interference

From book “LTE, The UMTS Long Term Evolution”

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Rev 15

Receiver susceptibility to interfering signals

BS receiver requirements 2(3)

+ Receiver intermodulation

ICS=In-channel selectivity ACS=Adjacent channel selectivity

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Rev 16

BS receiver requirements 3(3)

Adjacent Channel Selectivity (ACS)

Adjacent Channel Interference Ratio (ACIR)

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Rev 17

UE transmitter requirements 1(2)

• UE power level

– Terminal power classes (23dBm) – Maximum Power Reduction (MRP) – Additional Maximum Power Reduction (A-MRP)

• Unwanted emission limits

– In-band emissions – OOB emissions

• Spectrum Emissions Mask (SEM)
• ACLR

– Spurious emissions

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Rev 18

UE transmitter requirements 2(2)

Spectrum Emissions Mask (SEM)

From book “LTE, The UMTS Long Term Evolution”

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Rev 19

UE receiver requirements

• Assumptions:

– 2 Rx antennas assumed, 0 dBi gain each – Requirements on MRC combined signal

• Requirements

– Similar to BS but different levels – Exception: no in-channel selectivity

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Rev 20

Summary

Various paired & unpaired frequency bands + Flexibel transmission bandwidth due to OFDM Spectrum flexibility in LTE

…if considered properly in the physical layer and RF requirements

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