Re: [tcmtf] [tsvwg] New version (v7) of TCM-TF draft

"Jose Saldana" <> Tue, 10 June 2014 14:23 UTC

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From: "Jose Saldana" <>
To: "=?iso-8859-1?Q?'Juli=E1n_Fern=E1ndez-Navajas'?=" <>, "'Eggert, Lars'" <>
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Date: Tue, 10 Jun 2014 16:23:43 +0200
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Subject: Re: [tcmtf] [tsvwg] New version (v7) of TCM-TF draft
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Thanks, Julián.
Just a brief summary:
a) VoIP
- The bandwidth savings for VoIP could be up to 57%, if RTP and G729a with 2
samples per packet are used. ECRTP was used for header compression.
- pps can be reduced in the same factor as the number of flows. Up to 40
flows can be grouped together.
- in this case, the additional latency would be 20ms (inter-packet time).
This was translated into a 1% reduction of R-Factor (ranging from 1 to 100).

- ITU’s R-factor [1] is calculated from delay and packet loss
- If background traffic appears, optimized traffic can even increase
subjective quality, since the overall traffic gets reduced and so does
packet loss rate. So optimization increases delay but may reduce packet
Another paper about multiplexing VoIP is [3]
b) UDP-based online games
- The bandwidth savings for 8 games were obtained. For IPv4, 30 or 35% of
the bandwidth was saved. For IPv6 the reduction was between 50 and 55%.
- pps were reduced by a factor of 5 or 10
- the additional latency tested was between 5 and 50 ms. The jitter has to
be taken into account, since multiplexing adds jitter (the first packets are
delayed more than the last ones)
- A subjective quality estimator for “Quake IV” was used [2]. It is based on
delay and jitter. Packet loss does not matter, because these games implement
very good methods for concealing it.
- The MOS could be above 3.5 when multiplexing was on.
[1] ITU-T Recommendation G.107 (2011) The E-model, a computational model for
use in transmission planning.
[2] Wattimena A.F, Kooij R.E, van Vugt J.M, Ahmed O.K (2006) Predicting the
perceived quality of a first person shooter: the Quake IV G-model. In
Proceedings 5th SIGCOMM workshop on Network and system support for games
(NetGames '06), ACM, New York, NY, USA
[3] Pereira R.M, Tarouco L.M (2009) Adaptive Multiplexing Based on E-model
for Reducing Network Overhead in Voice over IP Security Ensuring
Conversation Quality. In Proceedings Fourth international Conference on
Digital Telecommunications, Washington DC, pp. 53-58
De: Julián Fernández-Navajas [] 
Enviado el: martes, 10 de junio de 2014 13:02
Para: Eggert, Lars; Jose Saldana
CC:; Martin Stiemerling;;
Asunto: Re: [tsvwg] New version (v7) of TCM-TF draft
Hello Lars,

I send you some publications that quantify the benefits (in terms of
bandwidth) and drawbacks (in terms of latency and loss).
VoIP: this paper evaluates the bandwidth savings and also the influence of
multiplexing on VoIP subjective quality (using ITU’s E-Model):
df> Evaluating the Influence of Multiplexing Schemes and Buffer
Implementation on Perceived VoIP Conversation Quality," Computer Networks
<>  (Elsevier), Volume
56, Issue 7, Pages 1893-1919, May 2012.
<> doi
Online games: This paper also calculates bandwidth savings:
 <> First Person Shooters: Can
a Smarter Network Save Bandwidth without Annoying the Players?," IEEE
Communications Magazine, vol. 49, no.11, pp. 190-198, November 2011. doi:
And this one is focused on the effect on subjective quality (using a
subjective quality estimator for a FPS game):
 <> "Online FPS Games: Effect of
Router Buffer and Multiplexing Techniques on Subjective Quality Estimators,"
Multimedia Tools and Applications, Springer. doi 10.1007/s11042-012-1309-4
 El 10/06/2014 10:59, Eggert, Lars escribió:
are there any measurements or simulations that would quantify the benefits
(in terms of bandwidth) and drawbacks (in terms of latency)?