Subject: [AVTCORE] Gains from using Report Groups (draft-ietf-avtcore-rtp-multi-stream-optimisation)

From: Magnus Westerlund <[email-masked]>
Date: Mon, 12 May 2014 14:46:01 +0200

WG,
(As individual)

As part of my work to perform some simulations I took the opportunity to
determine how big the gain is when using the report group extension as
well as the aggregate scheduling.

Below you find the statistical simulation results for the intervals
between regular RTCP packets achieved over 10000 RTCP packets in an
WebRTC like situation with X number of SSRCs per endpoint between two
endpoints, all SSRC are active senders. The RTCP bandwidths are
configured as RR: 15000 bps, RS: 10000 bps and T-rr-int = 0, and IP MTU
=1400 bytes

AVPF is base line AVPF

AVPF-AGG-ADJ is the scheduling aggregation that is being specified in
draft-ietf-avtcore-rtp-multi-stream

AVPF-RG is with the report group extension and the removal of cross
reporting specified in draft-ietf-avtcore-rtp-multi-stream-optimisation
but without aggregating reports from multiple local SSRC in same RTCP
packet.

AVPF-RG-AGG is with the report group extension and the removal of cross
reporting specified in draft-ietf-avtcore-rtp-multi-stream-optimisation

Average transmission interval (s) from using the different solutions:

SSRCs		1	2	3	4	5	8	12	

AVPF		1.045	1.127	1.243	1.402	1.594	2.442	4.852	
AVPF-AGG-ADJ	1.042	1.110	1.216	1.368	1.541	2.239	4.687	
AVPF-RG		1.048	1.102	1.144	1.188	1.244	1.385	1.573	
AVPF-RG-AGG	1.054	1.082	1.117	1.154	1.184	1.293	1.435	

Change of average inter reporting interval from using the different
solutions compared with AVPF:

SSRCs		1	2	3	4	5	8	12	
AVPF-AGG-ADJ	-0.33%	-1.50%	-2.14%	-2.38%	-3.33%	-8.30%	-3.39%	
AVPF-RG		0.28%	-2.23%	-7.93%	-15.27%	-21.94%	-43.26%	-67.57%
AVPF-RG-AGG	0.89%	-3.96%	-10.16%	-17.70%	-25.76%	-47.04%	-70.41%

As can be seen the significant gain for the report group extension
(except with single SSRC per endpoint),
especially as the SSRCs per end point increases.

The figures for the higher number of SSRC looks like these.

SSRCs		16	24	31	32	64	128	256

AVPF		8.411	12.638	16.282	16.846	33.548	66.533	131.993
AVPF-AGG-ADJ	8.451	12.661	16.288	16.826	33.563	66.476	131.607
AVPF-RG		1.774	2.176	2.591	2.707	5.371	11.136	24.534
AVPF-RG-AGG	1.287	1.586	2.065	2.254	4.819	10.397	23.311

SSRCs		16	24	31	32	64	128	256

AVPF-AGG-ADJ	0.48%	0.18%	0.04%	-0.12%	0.04%	-0.09%	-0.29%
AVPF-RG		-78.91%	-82.78%	-84.09%	-83.93%	-83.99%	-83.26%	-81.41%
AVPF-RG-AGG	-84.69%	-87.45%	-87.32%	-86.62%	-85.63%	-84.37%	-82.34%

Cheers

Magnus Westerlund

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