how to design code shift keying OCDMA ??

[amritesh ojha]

Hi,i am a beginner.here i am trying to design a OCDMA system based on code shift keying.so there is i use a switch which separate 1 and 0. so how to design that switch.

[Karan Ahuja]

Hi.

The system designed in project SAC OCDMA.osd is a spectral-amplitude- coding OCDMA. It has three users, where in this setup two users are transmitting data, while one user is off. The FBGs in the system are working as encoders/decoders for the incoherent optical signal. Here is the link for the same you may find it useful for your case.

Optical Code-Division Multiple-Access System (OCDMA)

The above design illustrates a 3-user spectral-amplitude-coded OCDMA with two users transmitting data and the other user offline. The FBGs in the system are working as encoders/decoders for the incoherent optical signal.In an SAC-OCDMA system based on FBGs, each user has bits of information that are modulating the broadband incoherent optical carrier to fulfill the E/O conversion (OOK modulation format). A series of FBGs are introduced to control the amplitude spectra of the broadband incoherent optical signals.

I hope this will help you.
Thanks

[Karan Ahuja]

I want to add that the spectral frequency pattern, with spectral chips centered about the grating frequencies, is determined by signature code properly written in the FBGs. The receiver end applies a matched series of FBGs and a balanced detector for computing correlation difference. The user’s bit stream can now be extracted.The diagram below shows the receiver-end for one of the users, where the received signal is split into an upper branch (FBGs are the same as the encoder) and lower branch (FBGs are the complement of the encoder).

You may go through these links for further study. These will surely help

OCDMA Network Design

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwjThfSJttnNAhVDj5QKHSDzA-EQFgg-MAQ&url=http%3A%2F%2Flink.springer.com%2Fbook%2F10.1007%252F978-3-540-68468-8&usg=AFQjCNGM6rS90qgsECK6XlcHwLLp3Nxrlg&bvm=bv.126130881,d.dGo

Optical Code-Division Multiple-Access System (OCDMA)

Thanks

[Karan Ahuja]

Further i would like to mention that Optical code division multiple accessm(OCDMA) technique, which allows multiplemusers share the same transmission mediamby assigning different optical codes (OCs)mto different users, is an attractive candidatemfor next generation broadband access networks . The basic architecture and the working principle of an OCDMA passive optical network (PON) network. Partricularly，coherent OCDMA technique is receiving much attention for the overall superior performance over incoherent OCDMA and the development of compact and reliable en/decoders (E/D) like spatial light phase modulator (SLPM), superstructured fiber Bragg grating (SSFBG) and multi-port array waveguide grating (AWG)-type E/D . Previously, on-off-key (OOK) is mostly used as modulation format for payload data in OCDMA system, which is refered as OOKOCDMA. In a multi-user asynchronous coherent OOK-OCDMA system, the major noise sources are the coherent signalinterference (SI) beat noise (coherent noise) and the incoherent MAI (incoherent noise), which limit the number of active users in a network. Therefore, it is essential to combat the SI beat and MAI noises in such a network. Time gating and optical thresholding techniques can be used to suppress the MAI enabling data-rate detection.
Here i am providing with various papers you may consult. These will be very helpful.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4290311&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F35%2F4290299%2F04290311
http://file.scirp.org/pdf/JEMAA_2013022815384836.pdf
https://optics.synopsys.com/rsoft/application-gallery/optsim-optical-code-division-multiple-access.html
https://www.eng.tau.ac.il/~tur/pdfs/112.pdf
http://home.eps.hw.ac.uk/~xw66/News%20and%20highlights_files/AOE-invited-xw.pdf

The last paper is about different modulation schemes used in OCDMA. It may be very helpful to you.
Thanks

[dinesh chauhan]

@karan
Hi, in SAC_OCDMA why we use fiber grating ,how it select the frequency if you have any document which give proper understanding of SAC-OCDMA

[Marcelo santos]

Hello,

First of all I would like to congratulate OOK-OCDMA. I worked a period with this modulation and was challenged to apply such coding (OCDMA) on a BPSK system. Could anyone help with this theme? I have had serious difficulties. Thank you!

[Author]

Posts