4 research outputs found
Online Versus Offline Rate in Streaming Codes for Variable-Size Messages
Providing high quality-of-service for live communication is a pervasive
challenge which is plagued by packet losses during transmission. Streaming
codes are a class of erasure codes specifically designed for such low-latency
streaming communication settings. We consider the recently proposed setting of
streaming codes under variable-size messages which reflects the requirements of
applications such as live video streaming. In practice, streaming codes often
need to operate in an "online" setting where the sizes of the future messages
are unknown. Yet, previously studied upper bounds on the rate apply to
"offline" coding schemes with access to all (including future) message sizes.
In this paper, we evaluate whether the optimal offline rate is a feasible
goal for online streaming codes when communicating over a burst-only packet
loss channel. We identify two broad parameter regimes where, perhaps
surprisingly, online streaming codes can, in fact, match the optimal offline
rate. For both of these settings, we present rate-optimal online code
constructions. For all remaining parameter settings, we establish that it is
impossible for online coding schemes to attain the optimal offline rate.Comment: 16 pages, 2 figures, this is an extended version of the IEEE ISIT
2020 paper with the same titl