SAC-OCDMA system

[GURINDER SINGH]

I have simulated spectral amplitude coded optical code division multiple access system for three users where third user is off. The detection technique i have chosen is single photodiode detection (SPD) technique. The BER for user 1 and user 2 are 0.00923 and 0.00621 respectively. I have attached the file. Please let me know how to improve the BER.
Thankyou.

[Ashu verma]

Hello Gurinder Singh,

Please specify the coding you are using in SAC OCDMA . I have seen your system and found that you are using same system of SAC OCDMA present in optisystem samples library. I liked the concept that you are using LED in order to replace the white light source also you have used a single photo detector to detect the specific coded signal. Here i want to discuss the coding used in the optisystem samples that is hadamard coding
with subtraction technique.
In sample the code used is
0 1 0 1
0 0 1 1
1 0 1 0
Four different wavelengths has been used to code the data coming from PRBS generator and with subtraction detector at every respective user you would get encoded signal. In your system i have found that you are using transmitting signal of FBG instead of reflective one and you are using only three different wavelengths on the each encoder side you reflect two wavelengths but on decoder side you add third wavelength and the eye diagram analyzer clearly shows the cross-talk of signals. It is very important to mention on which paper you are working or which specific coding you are using because there are many schemes to encode a signal. You can also find the discussion on SAC OCDMA from forum archives. I have given link of some important discussions in which seven user SAC OCMA with hadamard coding also discussed. Here are the links ↓

FTTH using OCDMA

Bipolar Encoding

SCM OCDMA with ZCC code

optiwave

Optical CDMA System

↑ I think i have make my point clear. Hope you will get to know better about SAC OCDMA.
Feel free to ask anytime , if you will have any doubts , also i will try to make this system using single single photo detector detection.
Regards.

[GURINDER SINGH]

Thankyou so much…I am also using Hadamard coding. If i consider the transmitted signal of FBG then BER comes out to be very poor. I have attached the paper on which I am working.

[Taiwo Ambali Abiola]

I would have suggested you use reflected spectrum from FBG rather than transmission. However, you may still need to consider using attenuator at the lower arm of your balance subtraction detection for proper MAI cancellation. at times the power carried by the FBG at lower arm may be higher than what you have at the upper arm. As a result, you need to use attenuator to suppress the power

[Harold ADEGNANDJOU]

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