ARQ for network coding

Abstract

A new coding and queue management algorithm is proposed for communication networks that employ linear network coding. The algorithm has the feature that the encoding process is truly online, as opposed to a block-by-block approach. The setup assumes a packet erasure broadcast channel with stochastic arrivals and full feedback, but the proposed scheme is potentially applicable to more general lossy networks with linkby-link feedback. The algorithm guarantees that the physical queue size at the sender tracks the backlog in degrees of freedom (also called the virtual queue size). The new notion of a node "seeing" a packet is introduced. In terms of this idea, our algorithm may be viewed as a natural extension of ARQ schemes to coded networks. Our approach, known as the drop-when-seen algorithm, is compared with a baseline queuing approach called drop-when-decoded. It is shown that the expected queue size for our approach is O 1 1−ρ as opposed to Ω 1 (1−ρ) 2 for the baseline approach, where ρ is the load factor.

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“…This will allow to receiver the decode substrings after a small number of blocks. Similar approaches are proposed for broadcast channels in [24] and in [25].…”

Adaptive Network Coding Scheme for TCP over Wireless Sensor Networks

“…The source transmits random linear combinations of packets currently in the congestion window, and the receiver acknowledges every innovative linear combination it receives, even if it cannot decode an original packet immediately. This scheme gives a new interpretation of ACKs, and brings a new concept that "seen packet" which is defined in [7] as an abstraction for the case in which a packet cannot yet be decoded but can be safely removed from the coding buffer at the sender. TCP-Vegas is chosen for the transport layer protocol in TCP/NC, as it is more compatible with their modifications.…”

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“…In [1], authors exploits the use of generation-based network coding to further improve the performance [2]. A sliding-window network coding scheme was introduced in [25], [3].…”