Antwort: Re: Antwort: IP over DVB-RCS

[Torsten.Jaekel@FTK.rohde-schwarz.com]

The 32 bit CRC is just used to recognize transmission (packet) errors. No way to
correct missing or incorrect bits (is not a redundancy
part or Reed Solomon code). The whole packet (many ATM cells) is discarded if
the CRC is not matching.

tj
|+----------------+-------------------------------------|
||   Lloyd Wood   |                                     |
||   <l.wood@eim.s|           An:                       |
||   urrey.ac.uk> |   ip-dvb@erg.abdn.ac.uk             |
||                |           Kopie:        (Blindkopie:|
||   03.04.2002   |   Torsten Jaekel/FTK)               |
||   16:47        |           Thema:        Re: Antwort:|
||   Bitte        |   IP over DVB-RCS                   |
||   antworten an |                                     |
||   ip-dvb       |                                     |
||                |                                     |
|+----------------+-------------------------------------|







On Wed, 3 Apr 2002 Torsten.Jaekel@FTK.rohde-schwarz.com wrote:

> I am not (yet) so familiar with RCS but a bit with ATM.
> There are different ATM Adaption Layers (AAL). AAL5 (using jumbo frames) has
> just a 32 bit CRC, no approaches for data integrity (issue of
> higher layers).

??? that's what the 32-bit CRC is for...

L.

> But if you use AAL1 (I do not know if intended for RCS, perhaps because this
is
> also used for MPEG-2 via ATM),
> there is an ATM based FEC algorythm (Reed Solomon), in addition to MPEG-2 FEC.
>
> Is this similar to CableModems (DOCSIS) where the Uplink is also ATM-like ?

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>