Network coding permits to deploy distributed packet delivery algorithms that locally adapt to the network availability in media streaming applications. However, it may also increase delay and computational complexity if it is not implemented efficiently. We address here the effective placement of a limited number of nodes that implement randomized network coding in overlay networks, so that the goodput is kept high while the delay for decoding stays small in streaming applications. We first estimate the decoding delay at each client, which depends on the innovative rate in the network. This estimation permits to identify the nodes that have to perform coding in order to reduce the decoding delay. We then propose two iterative algorithms for selecting the nodes that should perform network coding. The first algorithm relies on the knowledge of the full network statistics. The second algorithm uses only local network statistics at each node. Simulation results show that large performance gains can be achieved with the selection of only a few network coding nodes. Moreover, the second algorithm performs very closely to the central estimation strategy, which demonstrates that the network coding nodes can be selected efficiently with help of a distributed innovative flow rate estimation solution. Our solution provides large gains in terms of throughput, delay, and video quality in realistic overlay networks when compared to methods that employ traditional streaming strategies as well as random network coding nodes selection algorithms.
Finally, game theoretic concepts are adopted in a recent work @cite_7 for developing socially optimal distributed algorithms that decide on the nodes that should combine packets. Specifically, incentives such as extra download bandwidth are given to network nodes in order to change their status to network coding and indirectly minimize the delays in the system. However, this algorithm does not offer any guarantee that limited resources will be used efficiently, since all the nodes may potentially desire to become network coding nodes. It is not appropriate when a certain number of network coding nodes shall be placed effectively in a network.
@cite_7
2130155168
Network coding has been recently proposed as an efficient method to improve throughput, minimize delays and remove the need for reconciliation between network nodes in distributed streaming systems. It permits to take advantage of the path and node diversity in the network when the network coding nodes are placed efficiently. In this paper, we investigate networks consisting of nodes that autonomously determine whether they should perform network coding or not as well as their set of parent nodes. Each node makes its decisions that maximize its quality of service. The decisions include the selection of operation mode (i.e., network coding mode, simple data forwarding mode) and the selection of extra connections. The resulting interactions among the nodes are modeled as a congestion game, thereby ensuring an equilibrium, i.e., stable multimedia stream flow. The experimental results show that the proposed scheme is appropriate for distributed multimedia transmission since it provides a stable quality without imposing centralized control.