RE: ULE over DVB-H

[<Rod.Walsh@nokia.com>]

Hi All

DVB-H is (like DVB-T) specifically intended to be a unidirectional
system with any ancillary point-to-point data occurring over IP (and
none-MPEG2) bearers (i.e. GPRS and friends).

As such, the original mandate to use ULE (2-way links) does not apply.
So please, please, please check the ULE design assumptions. E.g. the
time slicing and MPE-FEC frames may interfere with your packing and
timing assumptions.

Also, the DVB-H and ULE design assumptions because the intended
applications - hence I feel it has no bearing on the viability of ULE
whether it is every used over DVB-H. conversely, use over 2-way DVB-S
links seems to be essential to prove ULE's viability.

DVB operates on a process of commercial requirements -> technical
requirements -> technical proposals and specifications -> technical
standards and guidelines. A commercial requirement within DVB-CM
demonstrating the need for something other-than-MPE would be needed for
ULE to be viable over DVB-H. (Assuming, you share my opinion that
without DVB and thus ETSI adoption of a DVB-H bearer technology, it has
no viability in anycase).

MPE-FEC was created through a design process I was not involved in.
However it would be prudent to try and get an understanding of it's
design selections and assumptions if you were to attempt a ULE-FEC. For
academic purposes it would be interesting to merely copy the MPE-FEC
approach with R-S and the same framing parameters.

For the "delta-t", I came to the conclusion that (c) a header extension
would be the best approach (a few years ago when I was curious about the
feasibility of ULE for DVB-H - another lifetime :)

I think it would be interesting to check the feasibility of ULE over
DVB-H, but am not currently optimistic about it's uptake potential.

Cheers, Rod.



>-----Original Message-----
>From: owner-ipdvb@erg.abdn.ac.uk 
>[mailto:owner-ipdvb@erg.abdn.ac.uk] On Behalf Of ext Georgios Gardikis
>Sent: 11 November, 2005 14:36
>To: ipdvb@erg.abdn.ac.uk
>Subject: ULE over DVB-H
>
>Dear all,
>
>Regarding ULE, I think it is important for its viability to 
>study the issue of its migration to DVB-H. It is unfortunately 
>true that ULE cannot be applied to DVB-H ploatforms "as-is", because:
>
>i) DVB-H "steals" four bytes from MAC address field of MPE to 
>use in time slicing signalling. These bytes convey the 
>"delta-t" time i.e. the time interval until the next burst 
>containing data from the same stream. 
>Of course the whole process is a hack, and stems from the fact 
>that DVB recognised that the MAC bytes are almost never used 
>for what they were initially designed to.
>Possible solutions: a) using the NPA field in ULE (and destroy 
>its initial purpose, i.e. hack ULE itself), b) adding extra 
>bytes in DVB-H header (i.e. altering the candidate standard), 
>c) using and standardizing an extension header
>
>ii) DVB-H uses the "MPE-FEC" structure, which is built upon 
>MPE, and uses the table_id (first byte in MPE header) to 
>discriminate between data bytes and FEC overhead bytes.
>Possible solution: directly port ULE to carry FEC frames (no action
>needed) and use of a new Typefield value to declare FEC data.
>
>What do you think?
>
>G.Gardikis
>-------
>Dr. Georgios J. Gardikis
>Associate Researcher
>NCSR "Demokritos", Institute of Informatics and 
>Telecommunications Athens 153 10, Greece
>Tel: +30 210 650 3108
>Fax: +30 210 653 2175
>
>
>