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Table of Contents
NC-MPRTP (Network Coded Multipath Realtime Transport Protocol)
We propose the use of MPRTP (MultiPath Real-time Transport Protocol) [1] to support multimedia high-bandwidth applications. The core idea is quite simple: multiple links are used at the same time to deliver the multimedia content to a remote destination. In a similar way to RAID (Redundant Array of Independent Disks) storage technology, multiple low-cost links can be aggregated, in order to provide an efficient, reliable and cost-effective high-bandwidth logical channel, composed of several physical channels. Having more than one channels available at any time, the better performing channel (or channels subset) can be used, excluding (or limiting the use of) bad performing ones. The use of MPRTP opens to the aforementioned behavior, providing the possibility to schedule the transmission of the multimedia flow over multiple links, according to implemented policies.
Scheduler Implementation
The scheduler implementation available at [2] estimates the overall available bandwidth, and splits the multimedia flow accordingly. The source video bitrate is then set, in order to provide the maximum achievable video quality, according to the available bandwidth. Anyway, the current implementation does not provide a way to reduce the load on lossy and/or high-delay su-links, thus causing corrupted video at the receiver. As analysed in [3], the scheduler should be able to quickly adapt to bandwidth changes, to overcome packet skew due to different RTTs, and to choose an optimal subset of sub-links, in order to provide the desired Quality of Service and Quality of Experience.
ORIGINAL SCHEDULER
Corruption on a single link makes the whole stream unusable.
PROPOSED MODIFIED SCHEDULER
Corruption on a single link does not make the whole stream unusable, because the bad link is quickly excluded from the subset of the links in use.
REFERENCES
[1] An IETF draft is available at https://tools.ietf.org/html/draft-ietf-avtcore-mprtp-03, which describes MPRTP protocol.
[2] MP-RTP implementation available at: https://github.com/multipath-rtp/gst-mprtp
[3] Singh V, Ahsan S, Ott J. MPRTP: multipath considerations for real-time media. Proceedings of the 4th ACM Multimedia Systems Conference 2013 Feb 28 (pp. 190-201).
