ITU Kaleidoscope 2015
Trust in the Information Society
5G Transport and Broadband
Access Networks: The Need for
New Technologies and Standards
Pham Tien Dat1, Atsushi Kanno1, Naokatsu
Yamamoto1, and Tetsuya Kawanishi1,2
1National Institute of Information and Communication
Technology (NICT), Japan
2Waseda University, Tokyo, Japan
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Outline
• Motivations
• 5G transport challenges
• Proposed technologies:
– Analog radio over fiber (ARoF)
– Intermediate frequency over fiber (IFoF)
– Radio on radio (RoR)
– Seamless convergence of fiber and millimeter-wave
• Standardization activities
• Conclusion and outlook
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Motivations
ITU Connect 2020
5G mobile networks
. 1000x capacity/km2
Higher system
capacity
Higher data
rate
Reduced
Latency
. 100x typical data rate
(Even for high mobility)
5G
Massive device
connectivity
. 100x connected devices
(Even in crowded areas)
• ICTs: key enabler
for social, and
sustainable
growth.
. RAN latency: < 1ms
• 2020: 90%
broadband
Energy saving &
coverage for rural
cost reduction
. Energy saving for NW & terminals worldwide
. Reduced NW cost incl. backhaul
Source: NTT Docomo While paper 2014
Needs for new transport
technologies and standards
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5G transport network challenges
Ubiquitous
things
communicating
Best
experience
follows you
simple devices,
coverage
Accessibility,
mobility
Amazing
speed
bit-rate,
delay
Great
service in a
crowd
Accessibility,
dense crowds
Super realtime and
reliable
connections
delay,
reliability
• Transport: different requirements, low cost, simple,
high data rate, flexible
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Analog radio over fiber systems-1
Digitized transmission
Remote
Center
IQ
signals
Optical Rx
(Digital)
Optical Tx
(Digital)
D/A
IQ Mod
BB to RF
• Very high data rate; long latency; synchronization and
jitter problems; high–speed D/A and A/D (high cost).
Analog transmission
Center
IQ
signals
Remote
D/A
IQ Mod
Optical Tx
(Analog)
Optical Rx
(Analog)
• Low bandwidth; low latency; no synchronization and
jitter; co-transmission; better co-operation.
D/A: Digital to Analog
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IQ: In-phase/Quadrature
BB to RF: Baseband to Radio Frequency
IQ Mod: IQ modulation
Tx/Rx: Transmitter/Receiver
5
Analog radio over fiber systems-2
-28
Carrier fre. at 5 GHz
10
Required
Carrier fre. at 10 Ghz
8
Carrier fre. at 15 GHz
EVM (%)
EVM (dB)
-32
Required
-36
Carrier at 2 GHz
Carrier at 6 GHz
Carrier at 12 GHz
6
4
-40
2
-44
-2
0
2
4
6
RF Tx. Power (dBm)
8
10
WLAN 802.11 ac signal
12
0
-15
-10
-5
0
5
Tx. RF. Power (dBm)
10
15
LTE-A signal
• Satisfactory performance; degradation at high fre.
• Further studies: improvement methods
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EVM: Error Vector Magnitude
6
Intermediate frequency over fiber-1
Radio over fiber
MMW
HSPD
• Low spectral efficiency, high cost
Intermediate frequency over fiber
PD
PD
• High spectral efficiency, low cost, matured technology
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PD: Photodiode; MMW: Millimeter-wave
7
Intermediate frequency over fiber-2
Centre
10
LD
Laser
Required
Attenuator Amplifier
LTE-A
20-m SMF
20-km SMF
Mod.
8
40-km SMF
Amplifier
Laser
EVM (%)
12 GHz
Local
Oscillator
Mod.
PD
Remote
Filter
4
X4
Amplifier
LTE-A
6
Attenuator
Down.
Mixer
PD
Filter
2
-19
-17
-15
-13
-11
-9
-7
Rx. Opt. Power (dBm)
Experiment setup
LTE-A signal
• Satisfactory performance, low fiber dispersion
• Other issues: LO signal delivery; improved methods
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Mod: Modulator; PD: Photodiode
8
Radio on radio-1
Millimeter-wave and terahertz wave:
• Digitized transmission: high data
rate, high cost
• Analog transmission (Radio on
Radio): low required data rate,
cost effective
96 GHz
Center
Remote
Local
Oscillator
3m
Amplifier
LTE-A
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Amplifier
Amplifier
Down.
LTE-A
Down: down-converter
9
Radio on radio-2
Required
8
QPSK signal
7
QPSK signal
8
16-QAM signal
16-QAM signal
7
64-QAM signal
6
EVM (%)
Required
9
64-QAM signal
6
5
5
4
4
3
2
-35
3
(b)
-30
-25
-20
-15
Tx. RF. Power (dBm)
Received LTE-A
-10
2
-21
-19
-17
-15
-13
Vs Tx. Power (LTE-A)
Vs Tx. Power (MMW)
• Satisfied performance, MMW link up to 1.5 km
• Some signal degradation because of distortions
• Issues: compensation methods, device integration,
standardizations
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Tx. MMW. Power (dBm)
EVM: Error Vector Magnitude
10
Convergence of fiber and radio-1
High-speed radio
Optical fiber
×
• Protection link against fiber being cut at disaster
• Temporal link to at disaster recovery
• “Last mile” solution until optical fiber deployment
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Convergence of fiber and radio-2
Conventional system
Local
Oscillator
E/O conv.
DSP
Radio FE
Radio FE
Opt. sig.
DSP
Optical
Tx
O/E conv.
Radio access unit
Opt. Sig.
Optical
Rx
Local
Oscillator
Large latency
Large power consumption
E/O conv.
Radio FE
RoF sig.
Radio FE
Optical
Tx
O/E conv.
RoF-based convergence
RoF sig.
Optical
coherent
Rx
Opt. LO
• Simple, low latency, low power consumption, simple
operation and management
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Convergence of fiber and radio-3
Center
Mod.
92.5 GHz
3m
Amplifier
16-QAM, 30-km SMF
64-QAM, 30-km SMF
16-QAM, 50-km SMF
64-QAM, 50-km SMF
8
PD
Remote
Access
LTE-A
Remote
cells
LTE-A
20 km
Amplifier
EVM (%)
Two-tone
Gen.
DEMUX
10
Required
6
4
Amplifier
Down.
2
-10
-5
0
5
10
15
Tx. RF. Power (dBm)
Experiment setup
LTE-A signal performance
• High performance, possible high-capacity trans.
Issues: high-speed real-time, standardizations
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PD: Photodiode
Two-tone Gen.: Optical two tone signal generator
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Standardization activities
Activities:
• ITU-T SG15 Q2: Passive Optical Network with RoF
Publication: ITU-T G.Suppl.55 “Radio-over-fiber (RoF)
technologies and their applications”
• ASTAP EG-SACS: RoF systems for Asian pacific countries
• IEC TC103: Precise measurement techniques for RoF
components
• IEEE802: .15.3d, .15 IG THz
Possible issues in standardization:
• Interfaces between RoF and digital networks
• RoF network architecture, and requirements
• Control of cells and networks
• Measurement techniques for RoF components
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Conclusions
• 5G and broadband access networks poses many
challenges to the transport networks.
• The need for a variety of technologies and standards to
serve different use cases
• Proposed technologies for flexible, cost effective solutions:
– Analog radio over fiber
– Intermediate frequency over fiber
– Radio on Radio (RoR)
– Seamless convergence of fiber and radio
Other issues:
• Convergence of fixed and mobile networks
• Co-design, co-operation/optimization of optical and radio
• Standardization activities
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Acknowledgement
This work was conducted as a part of the “Research and
development for expansion of radio wave resources," supported
by the Ministry of Internal Affairs and Communications (MIC),
Japan.
Thank you for your attention!
ptdat@nict.go.jp
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