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Digital Signal Processing for 100G/400G Optical Fiber Connectivity Links
Eiselt, Nicklas; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso
Publication date:2016
Document VersionPublisher's PDF, also known as Version of record
Link back to DTU Orbit
Citation (APA):Eiselt, N., Vegas Olmos, J. J., & Tafur Monroy, I. (2016). Digital Signal Processing for 100G/400G Optical FiberConnectivity Links. Poster session presented at Big Data Photonics Workshop 2016, Los Angeles, California,United States.
Digital Signal Processing for 100G/400G Optical Fiber Connectivity Links
Nicklas Eiselt1,2, J. J. Vegas Olmos1 and Idelfonso T. Monroy1
(1) Technical University of Denmark (DTU), Department of Photonics Engineering, Ørsteds Plads, Build. 343, DK-2800
(2) ADVA Optical Networking SE, Märzenquelle 1-3, 98617 Meiningen, Germany
Experimental Setup
Acknolowledgement
Conclusion
Experimental Results @ 56 Gbit/s
Optical b2b performance Transmission over 80 km SSMF
Parameter Setup
Data Rate 56 Gb/s
Frequency 194.25 THz
DAC/ADC 84 GS/s
MZM LiNbO3, > 35 GHz bw
PIN/TIA 30 GHz bw
MUX/DEMUX 39 GHz bw
SSMF (80 km)
EDFA
VOA
OSA
MZM
DCF MUX DEMUX
DAC 84 GS/s
Noise Loading
ADC 84 GS/s
PIN/TIA
VOA
EDFA
Tx DSP PAM4/DMT
(offline)
VOA DCF
Rx DSP PAM4/DMT
(offline)
Four-level pulse amplitude modulation (PAM-4)
Discrete Multitone (DMT)
DSP
Data S/P
TS Mapping
P/S Cyclic Prefix
IFFT
Quantization Clipping
BER P/S
Equalizer Demapping
CP Remove FFT
TS Remove
Synchronisation S/P
Transmitter Receiver
deBruijn Mapping
Oversampling Level Adjust
Quantization Pre-EQ Shaping
FFE BER
Resampling Clock-Rec.
Normalization
Transmitter Receiver
1
2
3
4
5
6
1
22 24 26 28 30 32 34 36 38 40
- B
ER
OSNR [dB]
DSB-DMT
VSB-DMT
PAM-4
HD-FEC
Motivation – DWDM InterconnectionsLow-Cost Approach (Scale up from short reach)
• 400G direct detection
• 8x50G DWDM/ 4x100G WDM
8 x DMT @ 56 Gb/s
8 x PAM-4 @ 56 Gb/s
Several Tb/s link capacity, reach up to 100 km RX Low cost Low power consumption (Some) dispersion tolerance
TX Low cost Low power consumption
Wavelength range C-band, EDFA amplification Optical dispersion
compensation
Data rates multiples of 400G
DWDM
Estimated SNR of double sidband DMT (DSB-DMT) and vestigial sideband DMT (VSB-DMT) at optical b2b
Residual Dispersion & PAM-4
22
24
26
28
30
32
-250-200-150-100 -50 0 50 100 150 200 250 300
RO
SNR
@ B
ER=3
.8e
-3
CD [ps]
FFE 3 FFE 7 FFE 11
FFE 21 FFE 31
Required OSNR at the FEC-limit of 3.8e-3 vs. residual dispersion with different FFE tap count
Launch Power
Optimum launch power into 80 km SSMF using PAM-4: Where to put the DCF?
Optimum launch power into 80 km SSMF using DSB-DMT; DCF is not required!
2
3
4
5
6
7 28
30
32
34
36
38
40
422
-8 -6 -4 -2 0 2 4 6 8 10
OSN
R [
dB
]
- B
ER
Launch Power per Channel [dBm]
DCF Tx
DCF Rx
2
3
4 28
30
32
34
36
38
40
421
-4 -2 0 2 4 6 8 10
OSN
R [
dB
]
- B
ER
Launch Power per Channel [dBm]
DSB-DMT - 80 km
BER vs. OSNR for b2b-mode
1
2
3
4
5 6
1
22 24 26 28 30 32 34 36 38 40
- B
ER
OSNR [dB]
PAM-4 - 80 km
DSB-DMT - 80 km
VSB-DMT - 80 km
OSNR Performance
Estimated SNR of double sidband DMT (DSB-DMT) and vestigial sideband DMT (VSB-DMT) at 80 km SSMF
BER vs. OSNR at 80 km SSMF
• PAM-4 and vestigial sideband DMT show a lot of potential for a low-cost solution for next generation of inter-data center interconnections
• PAM-4 outperforms DSB-DMT and VSB-DMT in terms of required OSNR at the FEC-threshold for the b2b-case and even for 80 km SSMF
• DMT does not require any DCF 5 dB higher power margin for DMT compared to PAM-4
The work was in part funded by the European Commission in the Marie Curie projects ABACUS and FENDOI and by the German ministry of education and research (BMBF) in projects SASER-ADVAntage_NET and SpeeD under contracts 16BP12400 and 13N13744
PAM-4 Eye Diagrams used for transmission
After DAC After MZM
DMT Parameters
FFT length 1024
Oversampling 1.05
Max. used subcarriers 486
OFDC Frame 123 Symbols + 5 training symbols
Equalizer 1-tap, Decision-Directed
Bit & Powerloading Chow’s & Cioffi’s algorithm
Format HD-FEC OSNR b2b OSNR 80 km
PAM-4 3.8e-3 ~ 23.8 dB ~ 24.8 dB
DSB-DMT 3.8e-3 ~ 25.7 dB ~ 27.2 dB
VSB-DMT 3.8e-3 ~ 27 dB ~ 31 dB
Results
References [1] N. Eiselt, et al., „Experimental Comparison of 56 Gbit/s PAM-4 and DMT for Data Center Interconnect Applications“, Photonische Netze, 17. ITG Fachtagung, 2016, Leipzig
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