PRBS word length

[Gokul Boro .]

Hi everybody,
In some papers I found that “PRBS has word length of (2^14)-1. Can a anybody tell me what does this mean and how can I set this config in OPTISYSTEM PRBS component?

Thank you in advance.

[alistu]

Hi Gokul,

Word length is the number of bits transmitted in the system. In OptiSystem, it is the same as the sequence length component which is available in layout parameters. By the way, it should be set as 2^x so I don’t think you can set it as (2^x)-1 in OptiSystem; it automatically changes to 2^x.

Regards

[Dr. Dhiman Kakati]

Hi Alistu,
are you sure that the word length is same as that of sequence length, because as Gokul said I also found this in most of the papers. Can you give some reference for the same. Thanks.

Regards,
Dhiman

[alistu]

Hi Dhiman,

I very much think so, and we have had many discussions in the forums when we have used “word length” instead of “sequence length”. I really don’t know what type of reference I can give regarding this, as “sequence length” is the name that OptiSystem has used for the word length (since it uses “sequence” to recognize digital vectors I think). Maybe asking Optiwave team about this would clear your doubt.

Regards

[Dr. Dhiman Kakati]

Thanks Alistu for the reply, actually i am asking for confirmation because the papers I am talking about is implemented using optisystem. The authors could have mentioned as sequence length instead of word length. Hope to get response from optiwave team regarding this.

Regards,
Dhiman

[alistu]

Maybe the reason for the authors using “word length” instead of “sequence length” is the fact that “word length” is the conventional phrase. Using “sequence length” might be unclear to many who read the paper yet don’t use the certain simulation software whose phrase has been used. If you consider any other meaning for “word length”, I would be grateful if you share.

Regards

[Dr. Dhiman Kakati]

Hi Alistu, that may be the reason as you mentioned “Maybe the reason for the authors using “word length” instead of “sequence length” is the fact that “word length” is the conventional phrase. Using “sequence length” might be unclear to many who read the paper yet don’t use the certain simulation software whose phrase has been used”. I also think that way. Thanks for making me clear.

Regards,
Dhiman

[alistu]

You’re welcome. So you agree with my GIVEN REASON.

Regards

[Md. Mahfuzul Azam Ghuri]

But in some paper they used PRBS of word length “2^31-1”, what we will do then because if it means the “sequence length” it exceed the maximum capacity of optisystem when i tries to write (2^31-1) and shows “Sequence length not valid Please enter a numerical value between 1 and 1.07374e+009” . Can you help me solving this rather i am also a new user in optisystem . thank u

[SAHIL SINGH]

hi.
by changing the length of sequence is there any betterment in the results. will my quality factor increase or decrease if i increase or decrease the word length and the sequence length. i am designing a simple transmitter and receiver system where i need 10 Gbps for 100km with good quality factor. will it increase the quality factor in my simulation.

[Ranjeet Kumar]

Hi,
Word length is same as sequence length of layout. It is equal to 2^n-1. n is bits e.g n=16 then 2^16-1= 65535

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