Subject: Re: [MMUSIC] Use of TIAS as alt-group-subtype in 3GPP PSS R6 media alternative s framework

From: Magnus Westerlund <[email-masked]>
Date: Thu, 07 Jul 2005 13:44:48 +0200

Hi,

Yes, you are correct only the grouped TIAS bandwidth value will be 
possible to provide as currently defined. It will miss the transport 
dependent part of required bit-rate for an grouping.

It is possible to fix as I see it. However it will require action from 
3GPP SA4 to update their specification with an clarification.

One alternative to fix it would be:

Define that for TIAS the value token shall be "<bit-rate>/<packet-rate>"

Cheers

Magnus

Cristovao DaSilva wrote:
> 
> In Release 6 3GPP PSS  (TS 26.234) the use of the transport independent bw
> modifier (TIAS) (RFC 3890) is recommended instead of AS.
> 
> However R6 PSS also introduces the media alternative framework by which the
> session level grouping attribute, 'alt-group' is used to inform the PSS
> client of which possible alternative media combinations are available for
> the same content.
> 
> When AS is used as the alt-group-subtype (alt-group-type=BW obviously) then
> the grouping value i.e. session level AS bandwidth for each combination is
> enough to compute the UMTS/3G bandwidth required to carry each combination
> 
> However if TIAS is used then the grouping value, i.e the session level TIAS
> bandwidth for each combination is not enough because the UMTS bandwidth also
> depends on the session level maxprate (max packet rate over all media
> components that compose the session) for which no alternative values can be
> provided.
> 
> Is this interpretation correct or am I missing something?
> 
> 
> Cris

-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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