Ultra Dense WDM System

[Ranjeet Kumar]

Hi Everyone,
I want to design Ultra Dense Wavelength Division Multiplexing System using different advanced modulation formats like CSRZ, DRZ, MDRZ and DPSK and DQPSK.
My aim to design above system with channel spacing 50GHZ and 25GHZ.
I have design the above networks for 100GHZ channel spacing using symmetrical compensation technique and at a bit rate of 40gbps and for long haul communication i.e upto 1200 Km.
Here i am uploading 32 channel WDM system with 100ghz channel spacing system at 40 gbps bit rate and using symmetrical compensation technique. But when i decease the channel spacing upto 50ghz and 25 ghz, we doesn’t find results at BER analyzer, although it works for channel spacing of 75ghz.
So, I request you to suggest some techniques or steps to get it.
Here I am uploading an osd file of 100 ghz channel spacing CSRZ DWDM system.

Seeking your response.

Attachments:

1. 8channelCSRZ.osd

[Dr. Dhiman Kakati]

I tried to simulate this design for 25 and 50 GHz spacing but could not get a better result as you have mentioned because the output sidelobes has sufficient power so going more denser in multiplexing results i overlapping of information, I got least power at side lobes while designing MSK transmitter but still work is going on that project. Looking for response from people who have done extensive work on WDM.

Regards,
Dhiman

[love kumar]

hi ranjeet.. i guess it may be due to nonlinerilty in DWDM system .. you can try nonlinerilty control for better results..

[Ranjeet Kumar]

Hi,
I would suggest you to
apply dense wavelength division multiplexing
(DWDM) to the system will be a strong candidate
in order to support all of BS’s for fiiture fiber-optic
access network infrastructure. There have been
several reports on such DWDM radio-on-fiber
systems [I]-[3]. To increase the spectral efficiency
of the system, the concept of optical frequency
interleaving was first proposed by Schaffer et al.
by simultaneous upconversion scheme with an
electro-optic modulator [4]. Recently, a simple
method to increase the spectral efficiency by
optical frequency interleaving was proposed in
which the modulation format could be either
optical double side band (DSB) or optical single
side band (SSB).The transmitted signal (A) is fed to a
high-Finesse Fabry-Perot etalon (FP) through an
optical circulator (OC). Thc free spcctral range of
the FP is adjusted to cqual to the channel spacing.

Thanks,

[Rajguru M. Mohan]

Hi Ranjeet,
I agree with your points of using optical single
side band (SSB).The transmitted signal (A) is fed to a
high-Finesse Fabry-Perot etalon (FP) through an
optical circulator (OC).
Use cascaded amplifiers, the performance of the system can be enhanced. EDFA when combined with Raman to
form hybrid amplifier it have advantages over individual amplifiers, designed hybrid
Raman/EDFA for yielding closed form analysis by considering the fiber non-linearities. observed by
combining the Raman/EDFA, maximum repeater-less transmission distance increases compared to individual
amplifier.
Use Parameters of laser source are: line-width =
10MHz and power = 10dBm. Mach-Zehander modulator with extinction ratio = 15dB is used as the external
modulator to modulate data source signals using laser.
Transmitted signals are multiplexed and launched in to optical fiber, where YDFA is used to amplify the signals.
Results are evaluated by varying the length of optical fiber from 40-160km. Parameters of optical fiber are:
attenuation = 0.2dB/km, dispersion slope = 0.07ps/nm2
/km and dispersion = 6ps/nm/km. Parameters of YDFA are:
length = 5m, ytterbium ion density = 1×1025m-3
, ytterbium doping radius = 3.4µm and numerical aperture = 0.2.

[Hamza Ali Abbas Khan]

Hello Ranjeet
i agree with rajguru that The transmitted signal (A) is fed to a high-Finesse Fabry-Perot etalon (FP) through an optical circulator (OC). you should try to Use cascaded amplifiers, the performance of the system can be enhanced. EDFA when combined with Raman to
form hybrid amplifier it have advantages over individual amplifiers, designed hybrid Raman/EDFA for yielding closed form analysis by considering the fiber non-linearities. observed by combining the Raman/EDFA, maximum repeater-less transmission distance increases compared to individual amplifier.
Try this and see if there is some substantial change in your design.
I hope it will work for you.
Thank you

[Karan Ahuja]

Hi Ranjeet.
as far as DWDM is concerned , Dense Wavelength Division Multiplexing (DWDM) is a technology that allows multiple information streams to be transmitted simultaneously over a single fiber. This provides a cost effective method to increase the capacity of the existing networks without the need to add additional fiber. This application note explains capabilities of the OptiSystem software to explore different design structures (e.g. modulation format, linear and nonlinear impairment compensation) to optimize the performance of these networks for access and long-haul application.
It has few applications:
Long-haul optical networks either in point-to-point or ring topology, Expanding the capacity of an existing optical network and Capacity leasing for network wholesalers.

Hope it helps
Regards

[Rajguru M. Mohan]

Hi Ranjeet,
Meanwhile, companies such as Wave-Splitter Technologies are pursuing the development of 25-GHz channel demultiplexing using arrayed-waveguide-grating routing technology and interleavers. Interleaving is frequently used in 50-GHz channel spacing. Basically, one set of 100-GHz-spaced channels or wavelengths is going in one direction and another set of wavelengths is going in the opposite direction.
The fiber Bragg grating technology that supports 25-GHz and 12.5-GHz channel spacing will allow carriers to increase the number of channels in the C-band without requiring other major component upgrades in the network, such as additional amplifiers, according to Ciena. The same technology could also be used in the L-band and S-band.

i would suggest you to please refer to following links:
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6013167&abstractAccess=no&userType=inst
http://www.ijarcsse.com/docs/papers/Volume_4/6_June2014/V4I6-0319.pdf
http://www.fiberoptic.com/adt_dwdm.html
http://www.ncbi.nlm.nih.gov/pubmed/21716338
https://www1.doshisha.ac.jp/~toda/Publications/2-37.pdf
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1158853
http://www.cisco.com/c/en/us/td/docs/optical/15000r7_0/dwdm/planning/guide/70epg/d7ovw.html

thanks,

[Karan Ahuja]

hi ranjeet
i am attaching a link which can be very helpful to you. It is a paper which should help you in getting some idea.
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6013167&abstractAccess=no&userType=inst
In this paper a new structure of PON system based on coherent heterodyne receivers is presented. The coherent detection enables a filterless ultra-dense WDM system. here they have simulated a 64 channel system with 10GHz channel spacing, offering symmetrical 1 Gbit/s sustained data rate per user both downlink and uplink by single fiber. The quadrature phase-shift keying (QPSK) modulation format is applied to downstream data for higher spectrum efficiency, while use of Amplitude Modulation (AM) on upstream data to reduce the system cost. Hope it helps you.
Regards

[Karan Ahuja]

i want to also mention that to meet growing demands for bandwidth, a technology called Dense Wavelength Division Multiplexing (DWDM)
has been developed that multiplies the capacity of a single fiber. DWDM systems being deployed today can increase a single fiber’s capacity sixteen fold, to a throughput of 40 Gb/s! Which is still not enough to manage the current bandwidth requirements of the corporate, which is up to 1Tb/s? So in this paper we are going to discuss how this enormously high bandwidth and speed could be achieved. This cutting edge technology—when combined with network management systems and add-drop multiplexers— enables carriers to adopt optically-based transmission networks that will meet the next generation of bandwidth demand at a significantly lower cost than installing new fiber.The potential bandwidth of single mode fiber is 50 Tb/s, so we are going to demonstrate how to achieve less than 1/10th of this enormous speed which is still quite a lot taking into consideration today’s scenario. We are going to show the techniques to achieve the high bandwidth of 1 Tb/s.
regards

[Karan Ahuja]

i am providing you with a link of another paper which introduces an “ultra-dense” concept into next-generation WDM-PON systems, which transmits a Nyquist-WDM uplink with centralized uplink optical carriers and digital coherent detection for the future access network requiring both high capacity and high spectral efficiency. 80-km standard single mode fiber (SSMF) transmission of Nyquist-WDM signal with 13 coherent 25-GHz spaced wavelength shaped optical carriers individually carrying 100-Gbit/s polarization-multiplexing quadrature phase-shift keying (PM-QPSK) upstream data has been experimentally demonstrated with negligible transmission penalty. The 13 frequency-locked wavelengths with a uniform optical power level of -10 dBm and OSNR of more than 50 dB are generated from a single lightwave via a multi-carrier generator consists of an optical phase modulator (PM), a Mach-Zehnder modulator (MZM), and a WSS. Following spacing the carriers at the baud rate, sub-carriers are individually spectral shaped to form Nyquist-WDM. The Nyquist-WDM channels have less than 1-dB crosstalk penalty of optical signal-to-noise ratio (OSNR) at 2 × 10(-3) bit-error rate (BER). Performance of a traditional coherent optical OFDM scheme and its restrictions on symbol synchronization and power difference are also experimentally compared and studied.
Here is the link of the paper. Hope this is helpful
http://www.ncbi.nlm.nih.gov/pubmed/21716338

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