ISSN : 1796-2056
Volume : 3    Issue : 3    Date : March 2008

Large-Scale RTCP Feedback Optimization
Vít Novotný and Dan Komosný
Page(s): 1-10
Full Text:
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Nowadays, multimedia streaming is a common service on the Internet including both fixed and
mobile networks. The RTP protocol is usually used to transfer the media. The RTCP protocol is an
accompanying protocol for the RTP and it is used for feedback transmission in order to control
multimedia session behaviour. The issue is the bandwidth dedicated for the RTCP protocol. As
defined in the RTP specification, it is limited to 5 % of the total allowed bandwidth. This is a limiting
factor for large-scale media streaming services based on Source-Specific Multicast (SSM) since the
RTCP bandwidth is shared among all the receivers. It causes large delays in sending feedback
data from each receiver. For the purpose of solving this issue, a hierarchical structure of receivers
with summarisation nodes has been proposed. The paper introduces an optimization of this
hierarchical structure in order to achieve the lowest feedback transmission intervals. The proposal
is supported by a simulation in Matlab environment. Furthermore, the paper deals with a design of a
new protocol called Tree Transmission Protocol (TTP) that was proposed to organize session
nodes into a hierarchical tree structure.

Index Terms
streaming services, RTP, RTCP, ASM, SSM, hierarchical feedback