Gee-Kung Chang
Byers Eminent Scholar Chair ProfessorSchool of Electrical and Computer Engineering
Georgia Institute of TechnologyAtlanta, GA 30332-0250
OFC 2008 WorkshopSan Diego, California
February 25, 2008
Convergence of Optical and Wireless Convergence of Optical and Wireless Access NetworksAccess Networks
2
Outline
• Convergence of Broadband Networking • Integrated Optical Wireless Access Networks• Optical Wireless Signal Generation
– Up-conversion of optical wireless signal– Multi-band wireless signals
• Optical Wireless Network Architecture– Dual Services: Wired and Wireless – Wavelength Reuse for Full-duplex Connection
• Technology Challenges• Conclusions
3
Broadband Networking Trends
Meet the needs of future end-to-end, dynamic and flexible Internet services
Convergence of Voice, Data, Video and Interactive Multimedia ServicesConvergence of Voice, Data, Video and Interactive Multimedia Services
Convergence of Wireless and Wired NetworksConvergence of Wireless and Wired Networks
Convergence of High Speed DWDM Metro and WAN NetworksConvergence of High Speed DWDM Metro and WAN Networks
4
Opportunities of using 60GHz mm-Wave for Wireless Services
56 57 58 59 60 61 62 63 64 65 66 56 57 58 59 60 61 62 63 64 65 66 GHzGHz
ProhibitedProhibitedUnlicensedUnlicensed
Wireless LANWireless LAN
Wireless LANWireless LAN
II SS MM
UnlicensedUnlicensedPt.Pt.--toto--Pt.Pt.
Space and fixed & m
obile apps.Space and fixed &
mobile apps.
Japan
E.U.
U.S.
There is a license free band near There is a license free band near 60GHz. There is up to 8 GHz antenna 60GHz. There is up to 8 GHz antenna resonant bandwidth available for resonant bandwidth available for wireless communicationswireless communications. .
It can provide super broadband It can provide super broadband wireless data links at > 1Gb/s.wireless data links at > 1Gb/s.
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Convergence of Broadband Access NetworksW
irelin
e
Time
Next GenerationOptical WirelessAccess Networks
Capa
city Data Rate
Mobility
ADSL/CableADSL/Cable
APONAPON
BPONBPONEPONEPON
GPONGPON
<10Mb/s
155Mb/s
622Mb/s
1.25Gb/s
2.5Gb/s
TDMTDM--PONPON WDM PONWDM WDM PONPON
CopperCopper
FiberFiber
1Gb/s --- 10 Gb/s10Mb/s --- 100Mb/s
WiFi2.4GHz (802.11b/g)
5GHz (802.11a)
WiMAX2.5, 3.5GHz10, 26GHz
MVDS40GHz
MBS60GHz
MMDS2-3GHz
LMDS26-29GHz
Frequency
Wire
less
10G TDM10G TDM--PONPON
UWB3-10GHz
Millimeter Region
6
Optical Wireless Network Applications
Emerging applications requiring super broadband optical-wireless access:
• HDTV distribution
• Interactive multimedia games
• High-speed wireless (>1Gb/s) data access
• High Mobility Communications - Base Station handoff- vehicle speed, bandwidth, and packet length
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PassiveOpticalnetwork
PassiveOpticalnetwork
Optical networking, transmission and integration
with WDM PON
Optical mm-wave generation, modulation
and up-conversion
RF Data/optical
interface
RF Data/optical
interface
Central Office Remote Node
Data/Video Source Center
Optical Metro
Network
Wireless Network
Optical/RF Data Interface
Optical/RF Data Interface
Base Station
Radio air interfaceBidirectional transmission
Wired and wireless service delivery
UsersUsers
• Bandwidth>1 Gb/s for both directions
• MobilityRF wireless for roaming connection
• CoverageOptical fiber links for long distance
• Multi-channel CapacitySeamless integration with WDM PONAll-optical methods for architecture design
Wireless over Optical Transport Technologies
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2.5Gbit/s
20GHz
DFB-LDMOD
PD
0 20 40 60Frequency (GHz)
Pow
er (d
Bm)
RF at 40GHzBaseband
There are two components of electrical signals after all-optical up-conversion:
one part occupies the baseband, the other occupies high-frequency band near 40 to 60GHz.
Dual Stage Modulation using Optical carrier suppression
DC: Vπ
Spectrum of Optical Wireless Signals
Optical Wireless
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Up-Conversion Based on External Modulation
DC Bias: 0.5
2.5 Gb/s 40GHz
1 5 5 4 .0 1 5 5 4 .5 1 5 5 5 .0 1 5 5 5 .5-7 0-6 0-5 0-4 0-3 0-2 0-1 0
01 0
4 0 G H z 4 0 G H z
Opt
ical
pow
er (d
Bm
)
W a v e le n g th (n m )
B-T-B
2km
Vπ
40GHz
Dual-arm MZM
2π
Shift2.5 Gb/s
DC: 0.5Vπ1554.0 1554.5 1555.0 1555.5
-70-60-50-40-30-20-10
010 40GHz
Opt
ical
pow
er (d
Bm)
W avelength (nm)
B-T-B
40km
20GHz
DC: Dual –arm MZM
Shift
Vπ
π
1554.0 1554.5 1555.0 1555.5-60
-50
-40
-30
-20
-10
0
1040GHz
Opt
ical
pow
er (d
Bm)
Wavelength (nm)
40km
B-T-B
DSB
SSB
OCS 2.5 Gb/s
MZM1DFB LD
MZM1DFB LD
MZM2
MZM1DFB LD
DSB: Double sideband; SSB: Single sideband; OCS: Optical carrier suppression
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32-Channel DWDM ROF Transmissionbased on OCS external modulation
Dual–arm MZM
2.5 Gb/sDFB LD 1
DFB LD 32AWG
40km SMF 20GHz40km SMF
(i) (ii)
1 5 3 5 1 5 4 0 1 5 4 5 1 5 5 0 1 5 5 5 1 5 6 0- 7 0
- 6 0
- 5 0
- 4 0
- 3 0
- 2 0
- 1 0
0
Rel
ativ
e op
tical
pow
er
W a v e le n g th ( n m ) 1 5 3 6 1 5 4 4 1 5 5 2 1 5 6 0- 7 0
- 6 0
- 5 0
- 4 0
- 3 0
- 2 0
- 1 0
Rel
ativ
e op
tical
pow
er
W a v e le n g th ( n m )
EDFA Vπ
ShiftπTOF2
EA
MUX
Mixer
1:4
10GHz Clock
50GHz PIN
BERT
Demux
1ns/div
100ps/div
Core or Metro network Central OfficeRemote Node
Base Station
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Transmission of 32-Channel ROF Signals
1 5 3 5 1 5 4 0 1 5 4 5 1 5 5 0 1 5 5 5 1 5 6 0-4 4
-4 2
-4 0
-3 8
-3 6
-3 4 B -T -B A fte r 4 0 k m
Rec
eive
r sen
sitiv
ity (d
Bm)
W a v e le n g th (n m )Power penalty is less 2dB
for all channels.
32 DWDM ROF channels
J. Yu, Z. Jia and G. K. Chang, ECOC 2005, Post Deadline, 2005, Th 4.5.4.
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Key Technologies for RoF Signal Generation
Multiple Bands RF Signal Multiple Bands RF Signal Generation: Generation:
Microwave and MillimeterMicrowave and Millimeter--WaveWave
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Multiple RF Signal Generation
DC: Vpi
18GHz 6GHz
750Mb/s750Mb/s
36GHz
Data 1
LPF
IL
TOF
0.3nm
1nm
Received power
12GHz
Data 2
LPF
EA20km SMF-28
LN-MODDFB-LD
Coupler
Mixer
0.3nm
1nm
Data 1 Data 2
EDFA
O/E
1539 1540 1541-80
-60
-40
-20
0
Rel
ativ
e O
ptic
al P
ower
(dB
m)
Wavelength (nm)1539 1540 1541
-80
-60
-40
-20
0
Rel
ativ
e O
ptic
al P
ower
(dBm
)
Wavelength (nm)
1539 1540 1541-80
-60
-40
-20
0
Rel
ativ
e O
ptic
al P
ower
(dBm
)(i)
(iii)
(ii)Microwave
mm-wave
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Optical Wireless Access Network Architecture Design
FullFull--Duplex Operation Based on Duplex Operation Based on Wavelength Reuse for UpstreamWavelength Reuse for Upstream
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Full-Duplex Colorless Transmission for Uplink
At CS, Phase modulation and the subsequent interleaver for optical mm-wave generation.At BS, FBG is used to reflect the optical carrier while pass the downlink mm-wave signal.At BS, SOA performs the function of both amplification and modulation.
OC
ƒmm-wave
CW
Downlink
DownlinkData
PM SMF
Receiver
Uplink
ƒmm-wave
RFMZM
Uplink
DataSOA
PIN Duplexer
Antenna
Mixer
EA
Uplink
PSƒcarrier
Interleaver
FBG
TD
CS BS
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• Various wireless services can share common fiber infrastructure.• A testbed setup consisting of four wireless standards were
simultaneously transmitted to stress the ROF distribution network.• 802.11g, WCDMA, GSM and PHS were combined electrically and
distributed via 300m of MMF ROF system.
Multi-Standards Wireless Transmission
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Wireless over fiber systems using ROF technologies operating in the 0.8-2.5GHz band have been demonstrated
• Moving from RF and microwave to mm-wave carriers for high bandwidth services
• Moving from point-to-point links to point to multiple points network architectures
• Moving from low mobility wireless over fiber systems to high speed moving trains and planes
- Howl’s Moving Castle?
• Facilitating new system architecture and new applications
What’s Next?
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Future Considerations and Challenges (1)
• Optical technology– Improve efficiency, simplicity and stability of signal
generation and up-conversion for the optical wireless systems;
– Increase the wavelength utilization efficiency in full-duplex operation when integration with WDM PON;
– Mitigating the optical mm-wave signals transmission impairment, particularly for the dispersion tolerance.
19
Future Considerations and Challenges (2)
• Electrical components and interfaces– Low profile, high gain, high frequency antenna and mixer design;– 40GHz, 60GHz and beyond optical millimeter carrier wave characteristics;– Improvement for wireless signals synchronization, interference and
stability.
• O/E and E/O Interfaces– Requirement for power, noise, bandwidth and coding methods;– Standardization issues.
mm-wave bands
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Conclusions
• Optical wireless signal generation and up-conversion techniques play key roles in realizing RoF network.
• A novel architecture is developed for bidirectional wireless and optical access network integrated with WDM-PON with wavelength reuse in base stations.– Demo of uncompressed HDTV over both wireline and wireless links
• Technology challenges are ahead of us:
– low-cost optical and RF components,
– optical wireless system interface,
– optical wireless protocols, and standardization.