LTE PHY Overview - Electrical and Computer · PDF fileLTE PHY Overview Gwanmo Ku Adaptive...

LTE PHY Overview

Gwanmo Ku

Adaptive Signal Processing and Information Theory Research Group

Nov. 4, 2011

Outline

LTE Introduction

LTE PHY Standard Descriptions

Protocol Architecture

Standard Docs.

Parameters

Frame Structures

PHY Resources

Modulation, Channel Coding, and Physical Channels

References

2/25

LTE Introduction

2/11

Why LTE?

4/25

Higher Data Rate

QoS

Packet Switch

Optimized System

Continuity of

Competitiveness

of 3G System

High Spectral Efficiency

Very Low Latency

Support of Variable Bandwidth

LTE

(Reference: http://www.3gpp.org/LTE)

LTE Multiple Access

DL (Downlink), UL (Uplink), CP (Cyclic Prefix)

eNB (e Node B), UE (User Equipment)

DFTS-OFDMA (DFT Spread OFDMA) : also called as SC-FDMA (Single Carrier FDMA)

5/25

Base Station

(eNB)

Mobile

(UE)

DL : OFDMA with CP

UL : DFTS-OFDMA with CP

(Reference : p7, 3GPP TS 36.201 V8.3.0 (2009-03))

OFDMA & SC-FDMA

S/P (Serial to Parallel Conversion), P/S (Parallel to Serial Conversion)

𝑵𝒖 : Used Subcarriers

𝑵 : Total Subcarriers

7/25

Constellation Mapping

&

S/P

𝑵𝒖 - DFT Subcarrier

Mapping 𝑵 - IFFT

Add CP

&

P/S

Bits

OFDMA

SC-FDMA (DFT Spread OFDMA) +

DFT Spread

(Reference : p. 71, 3GPP TR 25.814 V7.1.0 (2006-09))

LTE PHY Standard Descriptions

2/11

LTE Protocol Architecture

LTE Protocol Architecture around PHY

Logical Channels : Type of information transferred

Transport Channels : How the information is transferred

9/25

Radio Resource Control (RRC)

Medium Access Control (MAC)

Physical Layer (PHY)

Logical Channels

Transport Channels

Control /

Measurements

Layer 3

Layer 2

Layer 1

(Reference : p. 7, 3GPP TS 36.201 V8.3.0 (2009-03))

LTE PHY Standard Docs.10/25

Rel-8 36 Series : LTE

Rel-9 36 Series : LTE with Enhancement

Rel-10, 11, … 36 Series : LTE Advanced

Rel-8 362XX : LTE PHY Technical Spec.

36201 : LTE PHY General Descriptions

36211 : Physical channels and modulation

36.212 : Multiplexing and channel coding

36.213 : Physical layer procedures

36.214 : Physical layer Measurements

Layer 1

Layer 2 & 3

Requirements

PHY Parameters

DL/UL Parameters

Subcarrier Spacing ∆𝑓 = 15 𝑘𝐻𝑧 UL/DL, ∆𝑓∗ = 7.5 𝑘𝐻𝑧 DL only

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System BW [MHz] 1.4 3 5 10 15 20

# Resource Blocks 𝑵𝑹𝑩 6 15 25 50 75 100

FFT Size 𝑵

∆𝒇 = 𝟏𝟓𝑲𝑯𝒛 2048

∆𝒇 = 𝟕. 𝟓𝑲𝑯𝒛 - 4096*

# Subcarriers per RB 𝑵𝒔𝒄

∆𝒇 = 𝟏𝟓𝑲𝑯𝒛 12

∆𝒇 = 𝟕. 𝟓𝑲𝑯𝒛 - 24*

# Used Subcarriers 𝑵𝒖

∆𝒇 = 𝟏𝟓𝑲𝑯𝒛 72 180 300 600 900 1200

∆𝒇 = 𝟕. 𝟓𝑲𝑯𝒛 - 2400*

Sampling Rate [MHz] 1.92 3.84 7.68 15.36 23.04 30.72

(Reference : 3GPP TS 36.101 V8.15.0 (2011-09))

PHY Parameters – CP Length

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5.2083 𝝁𝒔 4.6875 𝝁𝒔

66.6667 𝝁𝒔

0 Symbol 0 1 Symbol 1 2 Symbol 2 3 Symbol 3 4 Symbol 4 5 Symbol 5 6 Symbol 6

cp0 Symbol 0 CP1 Symbol 1 CP2 Symbol 2 CP3 Symbol 3 CP4 Symbol 4 CP5 Symbol 5

16.6666 𝝁𝒔

66.6667 𝝁𝒔

133.33 𝝁𝒔

33.333 𝝁𝒔

cp0 Symbol 0 CP1 Symbol 1 CP2 Symbol 2

One Slot

0.5 ms (500 𝝁s)

DL/UL Normal CP

DL/UL Extended CP with Freq. Spacing 15 KHz

DL Extended CP with Freq. Spacing 7.5 KHz


Operating Bands (700 MHz) 13/25

MHz 699 716 729 746 756 758 768 777 787 788 798

700 800 750

Band 12 Band 12 Band 13 Band 14 Band 13 Band 14

Band 17 Band 17

704 716

Verizon LTE Plan in US

FCC Upper 700 MHz Band C

FDD Uplink FDD Downlink

LTE Recommendation

FCC Band in US

C C

757 776

References : [1] 3GPP TS 36.101 V8.15.0 (2011-09)

[2] FCC Doc. : http://transition.fcc.gov/Daily_Releases/Daily_Business/2011/db0630/FCC-11-103A1.pdf

TDD

Operating Bands (800 MHz)14/25

MHz 824 849 869 894 960

800 950 750

Band 6 Band 6

Band 5 Band 5

830 840 875 885

FCC Cellular Band


850 900

880 915 925

Band 8 Band 8

Cellular Cellular

LTE Recommendation

But unavailable for LTE



TDD

Operating Bands (1700-2200 MHz)15/25

MHz 1710 1785 1805 1880 1920 1980 2010 2025 2110 2170

1700 2200


1749.9 1784.9 1844.9 1879.9

1900 1800 2000 2100

1770 1850 1910 1930 1990

1755 2155

Band 3 Band 3 Band 39 Band 1 Band 34 Band 1

Band 10 Band 35 Band 37 Band 36 Band 10

Band 4 Band 2 Band 2 Band 4

Band 9 Band 9 Band33

AWS1 PCS Broadband PCS Broadband AWS1

LTE Recommendation

FCC

PCS Broadband and

Advanced Wireless Services (AWS)

AT&T LTE Plan : AWS band



TDD

Operating Bands (1400 & 2300-2700 MHz)16/25

MHz 1427.9 1447.9 1475.9 1495.9 2570 2620 2690

1400 2700

FCC

Broadband Radio Service (BRS) and

Educational Broadband Service (EBS)


1500 2600 2500 2400 2300

Band11 Band11 Band 40 Band 7 Band38 Band 7

BRS

EBS

BRS + EBS

2502 2602 2673.5 2690

But

LTE available

BW upto 5MHz

LTE Recommendation



TDD

Frame Structure

Frame Structure Type 1 : FDD

Frame Structure Type 2 : TDD

17/25

5ms

Switch

10ms

Switch


Frame Structure – TDD (Cont.)

UL/DL Configurations

Subframe Index : D (Downlink), U (Uplink), S (Special)

18/25

UL-DL

Configuration

DL to UL

Switch Point

Periodicity

Sub-frame Number

0 1 2 3 4 5 6 7 8 9

0 5 ms D S U U U D S U U U

1 5 ms D S U U D D S U U D

2 5 ms D S U D D D S U D D

3 10 ms D S U U U D D D D D

4 10 ms D S U U D D D D D D

5 10 ms D S U D D D D D D D

6 5 ms D S U U U D S U U D


PHY Resources

Resources in LTE

Resources : # Usable Subcarriers

Resource Block & Slot

19/25

Frequency

time

180 kHz

0.5 ms Slot Time

Resourcce Block

BW


PHY Resources – UL Slot Structure20/25

Configuration 𝑵𝒔𝒄𝑹𝑩 𝑵𝒔𝒚𝒎𝒃

𝑼𝑳

Normal CP 12 7

Extended CP 12 6

Configuration CP Length

Normal CP 160 for 0th Symbol

144 for 1~6th Symbol

Extended CP 512 for 0~5th Symbol

𝑁𝑠𝑐𝑅𝐵

𝑁𝑅𝐵𝑈𝐿 ∙ 𝑁𝑠𝑐

𝑅𝐵

𝑁𝑠𝑦𝑚𝑏𝑈𝐿 SC-FDMA Symbols

Nullities

Nullities

𝑁

1 Slot time

Frequency

…

…

BW [MHz] 1.4 3 5 10 15 20

𝑵𝑹𝑩𝑼𝑳 6 15 25 50 75 100

𝑵 128 256 512 1024 1536 2048


PHY Resources – DL Slot Structure21/25

Configuration 𝑵𝒔𝒄𝑹𝑩 𝑵𝒔𝒚𝒎𝒃

𝑫𝑳

Normal CP ∆𝑓 = 15 𝑘𝐻𝑧 12 7

Extended CP ∆𝑓 = 15 𝑘𝐻𝑧 12 6

∆𝑓 = 7.5 𝑘𝐻𝑧 24 3

Configuration CP Length

Normal CP ∆𝑓 = 15 𝑘𝐻𝑧 160 for 0th Symbol

144 for 1~6th Symbol

Extended CP ∆𝑓 = 15 𝑘𝐻𝑧 512 for 0~5th Symbol

∆𝑓 = 7.5 𝑘𝐻𝑧 1024 for 0-2nd Symbol

𝑁𝑠𝑐𝑅𝐵

𝑁𝑅𝐵𝐷𝐿 ∙ 𝑁𝑠𝑐

𝑅𝐵

𝑵𝒔𝒚𝒎𝒃𝑫𝑳 OFDMA Symbols

Nullities

Nullities

𝑁

1 Slot time

Frequency

…

…

BW [MHz] 1.4 3 5 10 15 20

𝑵𝑹𝑩𝑫𝑳 6 15 25 50 75 100

𝑵 128 256 512 1024 1536 2048


Modulations, Coding, Physical Channels

Modulations

QPSK, 16QAM, 64QAM

Channel Coding

Turbo Coding

Physical Channels

DL Physical Channels

PDSCH, PDCCH, PCFICH, PBCH, PMCH, PHICH

UL Physical Channels

PUSCH, PUCCH, PRACH

22/25


Future Work (Next Talk)23/25

Resource Allocation

AMC (Adaptive Modulation and Coding)

LTE

References

2/11

References

• LTE related Webpages

http://www.3gpp.org : 3GPP Standard Web

http://www.fcc.gov/ : FCC

http://wireless.fcc.gov/uls/ : FCC Band License Search

• LTE Standard Docs. – Release 8 Technical Specs.

http://www.3gpp.org/ftp/Specs/latest/Rel-8/36_series/

• FCC Useful Doc. – 15th Report

http://transition.fcc.gov/Daily_Releases/Daily_Business/2011/db0630/FCC-11-103A1.pdf

• DFTS-OFDMA (SC-FDMA)

http://sites.google.com/site/hgmyung/scfdma

25/25

LTE PHY Overview - Electrical and Computer · PDF fileLTE PHY Overview Gwanmo Ku Adaptive...

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