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ETRI연구개발지원사업 연차 평가 (2차년도) 11

- COOC2017 단기 강좌 -

2017년 6월 7일


5G & C‐RAN

전송용량저감기술

광액세스기술

Indoor Analog RoF기술

5G 를위한광액세스기술

3

5G 광액세스망 관계 ?

광통신?

5G ?

5

5G Key Services

5

Enhanced Mobile Broadband

High data rate

Massive Internet of Things

Massive connectivity(Ultra-high reliability/low latency

Low Latency Services

5G

IoT

Demanding conditions

6

5G Vision & Key Capabilities

6

Key capabilities of IMT-2020Inter‐relation between the three usage scenarios & Key capabilities

PeakData Rate

Area TrafficCapacity

Network EnergyEfficiency

ConnectionDensity

Latency

Mobility

SpectrumEfficiency

User ExperiencedData RateGbps

20Mbps100

Times3

Mbps/m210

Times100

km/h500

per km2

(1 per m2)

106msec

(Radio Interface)

1

[Note] Each of the three usage scenarios does not need to meet all the Key Capabilities

7

2.54.2

6.8

10.7

16.1

24.3

0

5

10

15

20

25

30

2014 2015 2016 2017 2018 2019

EXABYTES PER

MONTH

GLOBAL MOBILE TRAFFIC GROWTH

57% CAGR 2014‐

(Ref: Cisco, “Cisco VNI Global Mobile Data Traffic Forecast, 2014-2019”)

1,182 8,417 32,577 107,463

203,268 336,210

591,951

912,027

1,201,670

1,517,479

1,812,817

0

500,000

1,000,000

1,500,000

2,000,000

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

Subsc

riber

s in

tho

usad

s

Number of 4G mobile subscribers worldwide

from 2010 to 2020 (in 1,000)

(ref: Jefferies & Company, Statistics 2015)

모바일 네트워크 현안

Mobile traffic Growth: 57% CAGR (compound annual growth rate)

2015: 4.2 EB (Exa bytes), 2019: 24.3 EB (exa bytes)

10x traffic growth in next 5 years

worldwide 4G LTE subscriber: ~$1.8 billion in 2020 (25% of world population)

5x growth in 5 years

5G prototype service in 2018, commercial service in 2020

8

(ref: Infonetics, “2014 Market Size and Forecasts: WW, NA, EMEA, APAC, CALA”)

(ref: Infonetics, “2014 Market Size and Forecasts: WW, NA, EMEA, APAC, CALA”)

Capex Revenue

Mobile network Capex

average Capex $35 billion (Y2014~Y2018)

Revenue growth: 2%

Big gap between traffic growth and revenue growth

사업자의 수익 정체

C-RAN

10

Standard BS

BBU Remoted

BBU Centralized Intra BBU Pooling+CoMP Inter BBU Pooling+CoMP

Possible future Products

Cloud RAN ArchitecturesConventional Architectures

Future C-RAN

Virtualized or vRAN

Multiple site per

BBU

Multiple site per

BBU

Multiple site per

BBU

BBU1 BBU2 BBU3

Switching Layer

BBU1 BBU2 BBU3

Fiber Fiber Fiber

Central Office

BackhaulFiber

BackhaulFiber

BackhaulFiber

Phase 2 C-RAN

Multiple site per

BBU

Multiple site per

BBU

Multiple site per

BBU

Fiber Fiber Fiber

Central Office

BackhaulFiber

BackhaulFiber

BackhaulFiber

Phase 1 C-RAN

3 cells (1 site)

per BBU

3 cells (1 site)

per BBU

Radio

Site 1

Radio

Site 2

BS BS

BBU1 BBU2

BackhaulCopperM-wave

Fiber

FiberFiber


Fiber

Traditional Site

Remote Head Site

(RRU)

Radio

BS

BBU

Fiber

Site


Fiber

Radio

BS

BBU

Site


Fiber

Coaxial

참고: OFC2015 Workshop “Access Networks for High Speed Applications and Mobile Xhaul”

기지국의 진화


Radio Access Network: Traditional Architecture


Radio Access Network: C-RAN

13

Advantage of C-RAN(ref: http://www.fiercewireless.com/)

Capex/Opex Reduction

14

• 인도어 DAS 정의: 건물내 무선 서비스 제공을 위해 호스트장치에 접속된 공간적으로 분리된 다수의 안테나 네트워크

• 인도어 DAS 역할: 다수의 안테나를 공간적으로 분산시켜 실내 환경의 높은 트래픽 용량 문제와 음영지역 해소

• 인도어 DAS 기술현황: 국내 4G망은 디지털 샘플링 방식 기반의 광전송 기술을 적용한 사업자별로 독립된 망을 운용

• Fronthaul 정의: C-RAN 구조의 이동통신 기지국에서 BBU (DU) 와 RRH (RU)를 연결하는 광 전송망을 지칭

• Fronthaul 역할: 모바일 가입자의 음성 및 데이터를 RRU에서 모아 BBU가 위치하는 전화국으로 전달

• Fronthaul 기술현황: 현재 국내 LTE 기반의 4G망에서는 CPRI & OBSAI 와 같은 디지털 방식의 광전송 기술을 적용

In-building DAS network

DAS(distributed antenna system)

모바일용 광인프라 기술

국내 4G LTE 망에서는 C-RAN 구조의 이동통신기지국이 활용되고 있으며, 인

도어 DAS/Fronthaul 구간은 디지털 방식의 광전송 기술이 주로 사용

BackhaulFronthaulIn-building DAS

network

인도어 DAS

프론트홀

5G Key Technologies


The Coming 5G

17

Mobile fronthaul

Speed Limitation of Fronthaul

17

Type Data-rate Required data-traffic (CPRI-formatted)

LTE (20MHz)2x2 MIMO

0.15 Gb/s[1]2(antenna) x 30.72 Msps(sample rate) x 16 (bit/sample) x 2 (IQ) x 1.25 (8B/10B) = 2.45 Gb/s

5G (125MHz)2x2 MIMO, 8FA

5 Gb/s2(antenna) x 8(FA) x 184.3 Msps(sample rate) x 16 (bit/sample) x 2 (IQ) x 1.25 (8B/10B) = 117.95 Gb/s





C-RAN

Required data-traffics

* [1] S. Cho et al, “Cost‐effective Next Generation Mobile Fronthaul Architecture with Multi‐IF Carrier Transmission Scheme, OFC 2014

Digital Units

Radio units

Core network

18

5G 를 위한 광액세스 기술

5G Vision from IMT-2020

Quadruple x1000

Capacity1000X

（Capacity/km2

)

Speed1000X

（20Gbps)

LatencyLess than

1ms

Energy 1000X

Reduce

1990 2000 2010 2011 2014 2020

GSM GPRS

EDGE

UMTSHSPA

HSPA+

LTE LTE-A

3GPP Family Technology Evolution

Centralized (cloud)-RAN

Distributed-RANDistributed-RANDigitized RoF

(CPRI, OBSAI, ORI)Digitized RoF

(CPRI, OBSAI, ORI) ??Cost-effective approaches for infrastructure will be very important


5G & C‐RAN


광액세스기술



5G Field Test 1

21

Requirement Approach Solution

Bandwidth

Latency

Capacity Increase

Data Reduction

New Technology

Large Capacity Transmission

Data Compression

Analog RoF

Function Split

Fast Signal Processing

5G 를 위한 광액세스 후보 기술

22[CPRI Interface] [CPRI Protocol]

CRPI 규격은 현재 버전 7까지 완료되었으며, 24.3Gbps (option 10) 까지 정의

광링크의 전송속도를 줄이기 위해 IQ data 압축기술이 연구 되고 있으며, 전체의 93.75%

를 차지하는 IQ data sample 을 대상으로 함.

무선 장비 제어기(Radio Equipment Controller, REC)에서 무선 장비(Radio Equipment, RE)

사이의 기지국간 디지털 접속을 정의한 규격

REC

REC

CPRI 기반 모바일 프론트홀

23

CPRI frame: IQ data (93.7% of total data), control, timing sync

Requirement of IQ data compression

Compression ratio: ~ 50%

delay: < 20 s

EVM degradation: < 3 %

[CPRI Protocol Overview]

Original IQ data

time

I/Q b

it w

idth

Compressed IQ data

2nd step: IQ bit width reduction

Down-sampled IQ data

1st step: IQ Data Down-sampling

Data Compression Ratio: ~50%

<IQ Data Compression>BBU RRH

IQ Data Compression

2424

CPRI Compression Algorithms

Algorithm Concept Pros & Cons

1st

StepDown

sampling

+ : high compressionquaulity & relatively low EVM degradation

2nd

Step

Non-linearquantization

+ : best in EVM degradation

- : worst in FPGAlogic utilization

Block scaling

+ : good in EVM degradation

- : need a time for processing time

Partial bit sampling

+ : best performance for latency & FPGA logic utilization,relatively good in EVM degradation

b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0

MSB LSB

Original signal

Lower-bit decimation

Compress signal

Decompress signal

b14 b13 b12 b11 b10 b9 b8 b7 b6 b5

b14 b13 b12 b11 b10 b9 b8 b7 b6 b5

b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 1 0 1 0 1

25

CPRI Compression Requirements

Requirements Standardization (ORI)Real Field

(Telco needs)

Compression Ratio > 50 %( based I/Q data)

50 %( based CPRI )

EVM degradation < 3 % < 0.5 % *

One-way latency< 100 sec

(preferably 20 sec)< 10 sec

26

CPRI Compression System

VSG

VSA 20km of SMFSFP+ #1, #2

Software Developement Kit& Integrated Logic Analyzer

[ Photograph test-bed for IQ data compression/decompression ]

FPGA board #1, #2

27

EVM degradation

(PB: partial bit sampling, BS: block scaling, NL: non-linear quantization)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 1 2 3

EVM = 0.70%,∆EVM = 0.55%

Up/down+PBUp/down+BSUp/down+NL

SimulationExperimental

EVM of input signal (%)

EV

M d

egra

datio

n (%

)

EVM = 1.64%,∆EVM = 0.16% EVM = 2.89%,

∆EVM = 0.08%

[ Measured EVM degradation versus EVM of input signal, and constellation of 64QAM ]

28

One-way latency

Transmission distance (km)

One

-way

late

ncy

(µs)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 5 10 15 20 25

Up/down+PBUp/down+NLUp/down+BS

Speed OptimizedArea Optimized

[ One-way latency of additional compression+decompression ]

29

Function Split & Virtual Access Network

30

Digital Signal Analog Signal

Upper Layer MAC

OFDMPHY

CPRI Framer/Deframer

CPRI Framer/Deframer

ADC

BBU (DU) RRH (RU)

상대적 데이터율 1612 121

1.2~1.5

-Extraction of User Data -Header Removal-8B/10B coding

-MAC layer overhead

참고: Keiji Tanaka et al., “Next-Generation Optical Access Networks for C-RAN”, OFC 2015, LA

MAC/PHY 기능 재분리를 통한 데이터 저감

31

DU Function Split 및 종류

Trade off

32

Antenna Configuration and RAN Split


5G & C‐RAN


광액세스기술



5G Field Test 2

35

5G Access Options (BH/FH)

Transport Options for new 5G Access Points

Always use the available and lowest cost option if possible

IP connection

Dedicated optical fiber

Optical PON

XG_fast

XG-cable

mmWave point-to-point systems

36

Passive Optical Network (PON)

• No needs to use electrical power btw. central office and subscriber

• PON consists with OLT, ONT, and power splitter or WDM filter at Remote node

37

Sub-Channel CWDM Technology

38

Dual Sub-Channel/Multi Sub-Channel

39

Colorless Operation

40

NG-PON2

41

Incremental Upgrade (Pay-as-you-grow)

42

FSAN Standard Roadmap

43

100G-EPON timeline

44

100G-EPON

45

NG-PON2 vs 100G EPON

NG-PON2 100G EPON

Standard body ITU-T SG15 IEEE 802

Standard G.989.1,2,3 IEEE802.3ca

PON capacityDn: 4x10G (8x10G)Up: 4x2.5G (8x10G)

Dn: 4x25GUp: 4x25G (or 10G)

PtP WDM-PON Included Maybe not

Max Capacity of ONU 10G / 2.5G 100G / 100G

Channel bonding No Yes

Wavelength Plan Dn: L+band, Up: C-band Not yet

Tunable Yes No

Co-existence G-PON, XG-PON 10G-EPON

46

100G EPON Homepage

47

25G PON 프로토타입 시험

OE 실험 구성도

상하향 성능 QoS


5G & C‐RAN

전송 용량 저감 기술

광액세스 기술

Indoor Analog RoF 기술

5G 를 위한광액세스

기술

4949

* 참조: A global leader in infrastructure solutions for communications networks, CommScope

전체 Mobile Traffic의 80%가 Indoor 환경에서 발생

모바일 서비스(SNS 등)은 의사전달 수단에서 개인의 사회적 행동의 도구로 발전

현재는 Data 속도 저하 및 음영지역 해소 필요

Indoor 환경에서 25년 이상 사용되어 검증되고, 급격한 발전이 예상되는 solution은 DAS.

현재 DAS가 적용된 site는 수 만 국소 이상이며, 향후 2023년까지 약 1억 site로 증가 예상

Indoor 5G 기술

50

현재의 디지털 DAS 기술 현황

디지털 DAS의 광전송 용량 증가

호스트 장치 Radio 장치

광트랜시버 광트랜시버

광케이블

디지털 DAS 구조

51

Bandwidth Efficient IFoF based Optical Access

51

Digital Units

Type Properties

Radio frequency over Fiber (RFoF)

Transmission of mobile signal on the RF frequency as air interface through fronthaul link+ Low implementation cost and complexity in RU- Requires many wavelength for increasing data-rate

Intermediate Frequency over Fiber (IFoF)

Transmission of mobile signal on intermediate frequency through fronthaul link+ Bandwidth efficient transmission+ Flexible bandwidth allocation- Increases implementation cost and complexity in RU

Digital Units

Radio Units

ƒc

Radio Units

ƒc

~ƒc

ƒ1 ƒ2 ƒn

IFoF

RFoF Mobile fronthaul

Mobile fronthaul…

52

기지국 최대 20Gbps

단말 1 Gbps

최대 32 FA, 8x8 MIMO 지원

최대 전송거리 5km, 최대 8 분기 수용

5G 이동통신 서비스 음영지역 해소

125 MHz

125 MHz x 8FA = 1GHz

1.7GHz 2.7G

Air:

D-I/F

27.5GHz 28.5GHz

밀리미터파 5G 이동통신시스템 신호 사양

밀리미터파 5G 이동통신 시스템 아날로그 IFoF기반 Indoor DAS

Millimeter wave 5G & indoor

53

5G 프로트타입 성능 시험

54

1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7-30

-25

-20

-15

-10

-5

0

Frequency (GHz)

Recieved optical power : 0 dBm

S21

(d

B)

S21

Analog Optical Transceiver

[Analog optical transceiver]

[Frequency response]

< ±1 dBLD

LNA

PD

LD Driver

[Block diagram]

55

Supporting giga-bit mobile service with 28 GHz mmWave 5G prototypeAchieving peak data-rate up to 1.5 Gb/s per each user

Measured Throughput per User @ UE

55

56

1. 모바일 네트워크 현안

- 트래픽 폭증, 셀 소형화에 따라 비용 절감을 위한 새로운 망 구축/운용 기술 필요

2. 광 기반 모바일 인프라 기술

- 4G까지는 CPRI/OBSAI/ORI 표준 기반 전송 기술 및 기존 유선 인프라 활용

3. 5G 를 위한 광액세스망 기술

- 5G를 위한 다양한 프론트홀 후보 기술 대두, 대역폭 및 지연 성능 개선이 중요

- 100G PON, Analog RoF 기술등 새로운 기술 대두

Summary

- 광통신이 무한대의 대역폭을 제공한다는 선입관의 변화: 광액세스망 제한조건

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