Re: [dtn-interest] Re : Re: Question

Dear All,

If it might be of interest, a similar activity is also carried out within CCSDS, where DLR is writing an orange book for erasure codes in near-earth and deep-space scenarios. The orange book is mostly on the code (encoding and decoding) design, but it gives also some notes on the implementation within the DTN architecture, namely around the LTP protocol.

Best Regards,

Tomaso

------------------------ 
Deutsches Zentrum für Luft- und Raumfahrt (DLR) 
German Aerospace Center 
Institute of Communications and Navigation | Satellite Networks | Oberpfaffenhofen | 82234 Wessling | Germany 
Tomaso de Cola, Ph.D. 
Telefon +49 8153 28-2156 | Telefax  +49 8153 28-2844 | tomaso.decola@dlr.de 
http://www.dlr.de/kn/institut/abteilungen/san 

-----Original Message-----
From: dtn-interest-bounces@irtf.org [mailto:dtn-interest-bounces@irtf.org] On Behalf Of Emmanuel Lochin
Sent: Thursday, January 31, 2013 11:56 AM
To: sitaraman@nmsworks.co.in
Cc: Dubois Emmanuel; dtn-interest@irtf.org; Gelard Patrick
Subject: Re: [dtn-interest] Re : Re: Question

Hi Sitaraman

Thanks for your interest. We are currently working on these aspects for deep space communication on top of a DTN architecture with CNES (the French space agency).
In particular, we seek to integrate erasure coding inside the DTN architecture.
Note that there is also an IETF draft on this subject : http://www.ietf.org/id/draft-zinky-dtnrg-erasure-coding-objects-00.txt

Emmanuel

On 31/01/2013 02:34, sitaraman@nmsworks.co.in wrote:
> I should rather say "in addition to" instead of "as opposed to" in the 
> below
>> Hi Emmanuel,
>>   This looks great to me, thanks for this pointer. Only one scenario 
>> comes to mind, if it so happens that the expected bundle loss rate, 
>> even if for brief periods, is underestimated. Such scenarios could 
>> perhaps be relevant in space as intense disturbances for brief period 
>> is more likely than a steady noise, and with Tetrys, it would be 
>> inefficient to have the expected bundle loss rate set at its peak.
>>   I am tending to think while Tetrys could be a default scheme 
>> running in the DTN, DSN, there is needed a scheme that can put out 
>> fires occasionally?
>> Sitaraman
>>> Hi Sitaraman
>>>
>>>> Thanks much for this pointer, it will help me learn this aspect.
>>>> In general a question remains that i have, for the group as  whole.
>>>> A lot seems to have already been done  and literature and code 
>>>> available in FEC and Erasure Codes as has been made available from  
>>>> the discussion on this group  Do these complement or can they 
>>>> replace loss (chunks of data compeletely lost so that there is not 
>>>> anything to decode from) handling mechansims?
>>> Concerning this point, you'll find a study that uses such scheme to 
>>> rebuild lost chunks in "Robust streaming in delay tolerant networks":
>>> see http://oatao.univ-toulouse.fr/4111/
>>> The erasure coding scheme is a specific elastic-window encoding 
>>> scheme named Tetrys: see http://websites.isae.fr/tetrys/
>>>
>>> Emmanuel
>>>
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>>
>>
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>

-- 
Emmanuel Lochin
Professeur ISAE - OSSI
Institut Supérieur de l'Aéronautique et de l'Espace (ISAE)
Issu du rapprochement SUPAERO et ENSICA
10 avenue Edouard Belin - BP 54032 - 31055 Toulouse cedex 4
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