Three techniques for generating millimeter-wave signals for high-capacity wireless links are discussed: 1) Direct intensity modulation with direct detection, which is difficult to scale to high frequencies. 2) Photonic generation and RF heterodyning, which requires stringent laser linewidth requirements but is scalable to high frequencies. 3) Experimental generation of a 100Gbps wireless signal using optical baseband 16-QAM generation, photonic upconversion with a free-running laser, and double-stage downconversion.

1. DWDM Fiber-Wireless
Access Systems
Antonio Caballero Jambrina
acaj@fotonik.dtu.dkacaj@fotonik.dtu.dk

2. Thanks to
Idelfonso Tafur Monroy
Darko Zibar
Valeria Arlunno
Xiaodan Pang
Neil Guerrero Gonzalez
Lei Deng
…
And the whole metro-access group
28th May 20132 DWDM Fiber-Wireless Access Systems
And the whole metro-access group
(past and present)

3. Outline
• Motivation: wireless and optics convergence
• High capacity wireless links: how to achieve them
• Photonic technologies for wireless signal generation and detection
• RoF for access networks
• Wireless detection & transport
• Phase-modulated optical link assisted with coherent detection
28th May 20133 DWDM Fiber-Wireless Access Systems
• Phase-modulated optical link assisted with coherent detection
• Application scenarios
• Wireless generation
• mm-wave photonic generation towards 100 Gbps wireless links
• Wireless generation and detection
• Transparent all photonic mm-wave
• Conclusion

4. Motivation: wireless and
optics convergence
28th May 20134 DWDM Fiber-Wireless Access Systems
optics convergence

5. Telecommunication Network Hierarchy
Long Haul Networks
Metropolitan
Networks
Metro-access
Networks
• Optical fiber getting closer to the
customer premises
• Wireless brings flexibility to the
28th May 20135 DWDM Fiber-Wireless Access Systems
5
In-Home
Networks
PC
Corporate LAN
Residential
PON
Rural Area
Network
Hybrid
Optical-Wireless
Metro-access
Networks
• Wireless brings flexibility to the
communications

6. High capacity wireless
links
28th May 20136 DWDM Fiber-Wireless Access Systems
links

7. Applications of high speed wireless links
Optical fiber
28th May 20137 DWDM Fiber-Wireless Access Systems
• Sync and go
• All wireless connectivity at business and home
• HD video streaming (uncompressed)
• Cloud computing
• Video-calls
http://wirelessgigabitalliance.org/
• Beyond LTE Cellular networks
• Disaster recovery links
• Fast deployment wireless networks
• Extension of optical fiber links
Optical fiber
Optical fiber

8. How to achieve multi gigabit wireless links I
Higher RF carrier frequencies
• GHz of bandwidth available
• Higher Air attenuation
28th May 20138 DWDM Fiber-Wireless Access Systems
Advanced modulation techniques
• High spectral efficiency
• Stringent requirements on
linearity and SNR
E.E. Altshuler et al.,
IEEE TAP 1988

9. 100Mbps
1Gbps
10Gbps
100Gbps
W
ireless
links
(standard
W
LAN)
W
ireless links (research)
Optical serial interface (products)
Bitrate
Optical serial interface (research)
How to achieve multi gigabit wireless links II
28th May 20139 DWDM Fiber-Wireless Access Systems
1988 1992 1996 2000 2004 2008 2012
10Mbps
100Mbps
W
ireless
links
(standard
W
LAN)
W
ireless links (research)
Year
Bring the capacity of baseband optical links to wireless links
Multi-gigabit wireless links
Sources
P. Winzer, IEEE Comm. Mag. July 2010
G. Fettweis, IEEE VTC Fall 2007
A. Stöhr, OFC/NFOC 2011

10. Photonic technologies for
wireless signal generation
28th May 201310 DWDM Fiber-Wireless Access Systems
wireless signal generation
and detection

11. Concept and requirements
28th May 201311 DWDM Fiber-Wireless Access Systems
Photonic Generation (Downlink)
• Capable to generate high speed RF
signals
• High bandwidth of E-O components
Transport (optical fiber)
• Long reach links
• High bandwidth
• Shared architecture with PON
Photonic Detection (Uplink)
• High bandwidth
• Requires high linearity
• Digital Coherent receivers

12. Radio-over-fiber links for access networks
•Hybrid optical-wireless networks
• IM-DD schemes with SSB or DSB for longer reach (downlink only) [1,2]
• Ultra-dense WDM-PON architecture ([3,4]
• Converged PON [5,6]
• Baseband: QPSK
• Radio-over-fiber: UWB, Wimax, OFDM
28th May 201312 DWDM Fiber-Wireless Access Systems
[1] C. Lim et al., JON 2009
[2] D. Wake et al., JLT 2010
[3] Z. Jia et al., JLT 2007
[4] G.-K. Chang et al., JON 2009
[5] K. Prince et al., PTL 2009
[6] N. Guerrero, OFC 2011

13. Photonic Digital Coherent Receiver
• Combining the received optical signal (Ein) with a local oscillator
28th May 201313 DWDM Fiber-Wireless Access Systems
• Combining the received optical signal (Ein) with a local oscillator
(ELO) in a 90o optical hybrid
• Digital signal processing
• Demodulation of different types of signals
• Baseband: BPSK, QPSK, 16QAM, OFDM
• Radio-over-fiber: Phase Modulated, Intensity Modulated
• Compensation of link impairments
• Fiber chromatic dispersion
• Laser free-running beating
• Transmitter and receiver imbalances

14. Wireless detection &
transport:
28th May 201314 DWDM Fiber-Wireless Access Systems
transport:
Phase-modulated optical link
assisted with coherent detection

15. Photonic technologies for wireless detection I
•Mature technology (90s)
•RF power fading by chromatic
dispersion
• SSB, DSB
•Linearity limited
• Techniques for linearization
Intensity Modulation Direct Detection (IM-DD) [1,2]
28th May 201315 DWDM Fiber-Wireless Access Systems
•Higher linearity than IM-DD
•Limited bandwidth of operation
•Phase information recovery
• Interferometric detection [4]
• PM to IM [5]
Phase Modulation Direct Detection (PM-DD) [3,4,5]
[1] C. Cox et al., MTT 2006
[2] J. Yao, JLT 2009
[3] R. Kalman et al., JLT 1994
[4] V. Urick et al., JLT 2007[6]
[5] H. Chi et al., JLT 2009

16. Photonic technologies for wireless detection II
•PLL for phase tracking
•Optical domain (OPLL)
• Difficult to implement
• Limited bandwidth
•Digital Domain (DPLL)
• Homodyne detection
• Independent light source transport
Phase Modulation Phase Tracking Receiver (PM-PLL) [6,7]
28th May 201316 DWDM Fiber-Wireless Access Systems
• Independent light source transport
•Independent and free-running
Local Oscillator
•Digital Signal Processing
•Scalability to higher RF
•Easy integration with PON
Phase Modulation Digital Coherent Receiver (PM-Coh) [8,9]
[6] Y. Li et al., JLT 2009
[7] T. Clark et. al., MTT 2010
[8] D. Zibar et. al., PTL 2009
[9] A. Caballero et. al., JLT 2011

17. PM-Coh link with photonic downconversion1,2
28th May 201317 DWDM Fiber-Wireless Access Systems
1549.5 1550.0 1550.5
-80
-60
-40
-20
0
Power[dBm]
Wavelength [nm]
38.4 GHz
1549.5 1550.0 1550.5
-80
-60
-40
-20
0
Power[dBm]
Wavelength [nm]
40 GHz
[1] A. Caballero et al., ECOC’10 PDP3.4
[2] A. Caballero et. al., JLT 2011

18. PM-Coh link with photonic downconversion1,2
3
2
UFEC Limit
-log(BER)
B2B
40 km Tx
3
2
-log10(BER)
1 Gbaud
800 Mbaud
28th May 201318 DWDM Fiber-Wireless Access Systems
22 23 24 25 26 27 28 29 30 31 32 33
4
40 km Tx
OSNR [dB/0.1 nm]
1,5 2,0 2,5 3,0 3,5 4,0 4,5
4
-log10(BER)
Bitrate [Gbps]
625 Mbaud
500 Mbaud
• Pioneering results on high-capacity wireless detection
• Up to 3.2 Gbps at 40 GHz below FEC limit
• Electrical bandwidth of only 4 GHz
[1] A. Caballero et al., ECOC’09 PDP3.4
[2] A. Caballero et. al., JLT 2011

19. Wireless detection &
transport:
28th May 201319 DWDM Fiber-Wireless Access Systems
transport:
Application scenarios

20. PM-Coh link for DAS I
• Next generation cellular access
networks (LTE+) will require
Distributed Antenna Systems for
high throughput
• Current digitized RF transport
interface demands high bitrate
backhaul link
28th May 201320 DWDM Fiber-Wireless Access Systems
backhaul link
• Digital Coherent Radio-over-fiber
technology as solution
• Scalable
• Transparent
• High capacity

21. PM-Coh link for DAS II
Subcarrier multiplexing
28th May 201321 DWDM Fiber-Wireless Access Systems
3 Cell system x 4 Antennas/cell
Total 12 different channels
Same frequency allocation
Subcarrier multiplexing
Higher spectral efficiency
PM-Coh RoF Link
Transparent transport of the
wireless signals

22. PM-Coh link for DAS III
12 subcarriers, 100 Mbaud 16QAM
1 2 3 4 5
4
3
2
-log10(BER)
Modulation Index (%)
2 3 4 5
8
12
16
20
24
EVMRMS(%)
Modulation Index (%)
100 kHz
Experiment
28th May 201322 DWDM Fiber-Wireless Access Systems
6 subcarriers, 200 Mbaud 16QAM
2 3 4 5 6 7
4
3
2
-log10(BER)
Modulation Index (%)
Modulation Index (%)
2 3 4 5 6 7 8
8
12
16
20
24
EVMRMS(%)
Modulation Index (%)
100 kHz
Experiment
Modulation Index (%)

23. Converged wireless-baseband access I
28th May 201323 DWDM Fiber-Wireless Access Systems
Reconfigurable
Digital Coherent
Receiver

24. 5
4
3
2
B2B single channel
78km single channel
78km all wavelengths
-log(BER)
Coherent VCSEL(a)
4
3
2
B2B single channel
B2B all wavelengths
78km single channel
78km all wavelengths
-log(BER)
(c) IR-UWB
IR-UWBCoherent VCSEL
Single reconfigurable DSP enabled
coherent receiver
•Heterogeneous hybrid access networks
Converged wireless-baseband access II
28th May 201324 DWDM Fiber-Wireless Access Systems
-30 -29 -28 -27 -26
4
3
2
B2B single channel
B2B all wavelengths
78km single channel
78km all wavelengths
-log(BER)
Received Power [dBm]
(b) QPSK
-26 -25 -24 -23 -22 -21 -20
5
Received Power [dBm]
-26 -24 -22 -20 -18
Received Power [dBm]
-32 -31 -30 -29 -28 -27
5
4
3
2
B2B single channel
B2B all wavelengths
78 km single channel
78 km all wavelengths
-log(BER)
Received Power [dBm]
(d) OFDM RoF
QPSK OFDM RoF
•Heterogeneous hybrid access networks
•Mix modulation formats
•Mix bit rates

25. Hybrid Wireless-Optical Broadband-Access
Network (WOBAN)
Advantages of two
technologies
Ring - PON
• High capacity
• Transparency
• Multi-channel
28th May 201325 DWDM Fiber-Wireless Access Systems
• Multi-channel
• Upgrading
Wireless network
• Flexibility
• Cost-savings
• Centralize control
• Frequency re-use

26. WOBAN II: Experimental setup
• PM-Coh for RoF transport
• Passive Antenna Base Stations
• Raman amplification
High OSNR
Possible centralize pump location
Wide spectral gain range
Optical+Wireless
28th May 201326 DWDM Fiber-Wireless Access Systems
-39 -38 -37 -36 -35 -34 -33 -32 -31 -30
4
3
2
B2B single λ
B2B 2 neigh.
B2B 4 neigh.
Optical+Wireless
4 neighbours
Optical single λ
Optical 2 neigh.
Optical 4 neigh.
-log(BER)
Received Power [dBm]

27. Wireless generation:
Millimeter-wave generation
28th May 201327 DWDM Fiber-Wireless Access Systems
Millimeter-wave generation
towards 100 Gbps wireless links

28. 100Mbps
1Gbps
10Gbps
100Gbps
W
ireless
links
(standard
W
LAN)
W
ireless links (research)
Optical serial interface (products)
Bitrate
Optical serial interface (research)
Motivation
28th May 201328 DWDM Fiber-Wireless Access Systems
1988 1992 1996 2000 2004 2008 2012
10Mbps
100Mbps
W
ireless
links
(standard
W
LAN)
W
ireless links (research)
Year
Bring the capacity of baseband optical links to wireless links
100 Gbps wireless links
Sources
P. Winzer, IEEE Comm. Mag. July 2010
G. Fettweis, IEEE VTC Fall 2007
A. Stöhr, OFC/NFOC 2011

29. Photonic technologies for wireless generation
•Coherent beating at the PD
•Electrical signal and RF carrier
generation
• Frequency doubling and quadrupling
techniques
•Difficult to scale at high RF
frequencies
Direct Intensity Modulation with Direct Detection [1,2,3]
28th May 201329 DWDM Fiber-Wireless Access Systems
frequencies
•High capacity optical baseband
generation
•Incoherent beating at the PD
•Stringent requirement on laser
linewidth
•Scalable to high RF frequencies
Photonic generation and RF heterodyning [4,5]
[1] C. Cox et al., MTT 2006
[2] J. Yao, JLT 2009
[3] C. Lim et al., JON 2009
[4] U. Gliese et al., MTT 1998
[5] X. Pang et al., OE 2012

30. State of the art on mm-wave links
Data rate (Gb/s)
70
90
110 [6]
[1]
[10]
[11
]
[12]
[1] X. Pang, Opt. Exp. (2011)
[2] A. Kanno, Opt. Exp. (2011)
[3] W. Jiang, OFC’12
[4] A. Hirata, MTT, (2012)
[5] T. Kosugi, SRiF’13
[6] S. Koenig, OFC’13 PDP
[7] H.-J. Song, EL. (2012)
[8] A. Kanno, MWP’12
[9] C.-H. Ho, OFC’12
[10] A. Kanno, ECOC’12
[11] Z. Dong, OFC’13
[12] J. Zhang, PTL’13
28th May 201330 DWDM Fiber-Wireless Access Systems
Frequency
band
10
30
50
60
GHz
75-110
GHz
120
GHz
237.5
GHz
300
GHz
[3] [2]
[1]
[4]
[5] [7]
[8]
[9]
[12] J. Zhang, PTL’13

31. 100Gbps wireless: Experimental Setup I
28th May 201331 DWDM Fiber-Wireless Access Systems
•Optical baseband 16-QAM generation using binary signal generator
•Free running ECL (100 kHz linewidth) as LO for photonic up-conversion
•Double-stage down-conversion:
1. Electrically W-band to 1-26GHz;
2. Digitally from 1-26 GHz to baseband

32. 100Gbps wireless: Experiment Setup II
28th May 201332 DWDM Fiber-Wireless Access Systems
X branch Y branch

33. 100Gbps wireless: Experiment Setup III
W-band
Antenna
100 GHz
W1-WR10
Adaptor
28th May 201333 DWDM Fiber-Wireless Access Systems
100 GHz
PDW-band
Antenna
W-band
LNA
W-band
Mixer
LO
IF

34. 100Gbps wireless: Experiment results
2
1
Wireless d = 50cm
Wireless d = 150cm
Wireless d = 200cm
-log(BER)
50 Gbit/s
50 Gbit/s SP 16-QAM
2
1
Wireless d = 50 cm
Wireless d = 75 cm
Wireless d = 120 cm
-log(BER)
100 Gbit/s
100 Gbit/s PolMux 16-QAM
28th May 201334 DWDM Fiber-Wireless Access Systems
-1 0 1 2 3 4 5 6 7 8 9 10
5
4
3
2
-log(BER)
Optical power into PD (dBm)
FEC
-1 0 1 2 3 4 5 6 7 8 9
5
4
3
2
-log(BER) Optical power into PD (dBm)
FEC

35. Multi-band OFDM signal transmission in the
W-band I
28th May 201335 DWDM Fiber-Wireless Access Systems

36. Multi-band OFDM signal transmission in the
W-band II
28th May 201336 DWDM Fiber-Wireless Access Systems

37. Wireless generation and
detection:
28th May 201337 DWDM Fiber-Wireless Access Systems
detection:
Transparent all-photonic mm-
wave

38. Motivation
Photonic generation and RF heterodyning
•High capacity optical baseband
generation
•Incoherent beating at the PD
•Stringent requirement on laser
linewidth
•Scalable to high RF frequencies
28th May 201338 DWDM Fiber-Wireless Access Systems
Intensity Modulation Direct Detection (IM-DD)
•Mature technology (90s)
•RF power fading by chromatic
dispersion
• SSB, DSB
•Linearity limited
• Techniques for linearization
• Optical OFDM generation
• Baseband fiber transmission
• Digital coherent detection

39. Principle of photonic generation and detection
(a) Multicarrier generation
(b) O-OFDM baseband signal
(c) Optical signals for RF
optical heterodyning
(d) mm-wave RF signal
generated
28th May 201339 DWDM Fiber-Wireless Access Systems
(e) Optically modulated RF signal
(f) SSB baseband signal containing
the transmitted O-OFDM signal

40. Experimental Setup
0
w OFDM QPSK
•Baseband electrical signal
generation
•Optical heterodyning mm-wave
generation
•Free running lasers
28th May 201340 DWDM Fiber-Wireless Access Systems
•Complete transparency in carrier frequency and modulation format
•Digital coherent receiver as for baseband optical communications
1548,4 1548,8 1549,2 1549,6 1550,0
-70
-60
-50
-40
-30
-20
-10
Power[dBm]
Wavelength [nm]
w OFDM QPSK
w/o OFDM QPSK
82 GHz
10 GHz

41. Experimental results
3
2
1
Single carrier:
5Gbaud@60GHz
10Gbaud@100GHz
OFDM,2 subcarriers:
5Gbaud,sc1@60GHz
5Gbaud,sc2@60GHz
5Gbaud,sc1@100GHz
5Gbaud,sc2@100GHz
-log(BER)
3
2
O-OFDM,2SC,10Gbaud@100GHz
O-OFDM,2SC,8Gbaud@100GHz
O-OFDM,3SC,4Gbaud@60 GHz
-log10[BER]
O-OFDM,2SC,5Baud@60 GHz
UFEC
-2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0
-2,0
-1,5
-1,0
-0,5
0,0
0,5
1,0
1,5
2,0
Quadrature
Inphase
Single carrier and 2 Subcarriers Maximum experimental bitrates
40 Gbps at
28th May 201341 DWDM Fiber-Wireless Access Systems
-53 -52 -51 -50 -49 -48 -47 -46
5
4
3
Received optical power [dBm]
8 12 16 20 24 28 32 36 40 44
4
Bit Rate [Gb/s]
5Gbaud@60GHz
40 Gbps at
100 GHz
First experimental demonstration of 40 Gbps photonic
generation and detection of mm-wave signals

42. Conclusion
28th May 201342 DWDM Fiber-Wireless Access Systems

43. Conclusion
•Photonic technologies enable high capacity wireless links:
• 100 Gbps wireless transmission
• Generate and detect 40 Gbps at 100 GHz
• High linearity analogue links based on phase-modulation and coherent
detection
• Compatible for DWDM PON
28th May 201343 DWDM Fiber-Wireless Access Systems
•Future work
• Move to sub-terahertz frequencies (200 GHz- 2000 GHz)
• Integration of photonic and wireless devices
• Incorporate into DWDM-PON

44. Acknowledgements
OPSCODER project
http://www.opscoder.fotonik.dtu.dk/
28th May 201344 DWDM Fiber-Wireless Access Systems

45. You can find us at
MetroAccessGroup
Metro Access Photonics Engineering
28th May 201345 DWDM Fiber-Wireless Access Systems
www.fotonik.dtu.dk/English.aspx
MetroAccess DTU Fotonik