An Efficient Network Coding based Retransmission Algorithm for Wireless Multicasts

Retransmission based on packet acknowledgement (ACK/NAK) is a fundamental error control technique employed in IEEE 802.11-2007 unicast network. However the 802.11-2007 standard falls short of proposing a reliable MAC-level recovery protocol for multicast frames. In this paper we propose a latency and bandwidth efficient coding algorithm based on the principles of network coding for retransmitting lost packets in a singlehop wireless multicast network and demonstrate its effectiveness over previously proposed network coding based retransmission algorithms.Comment: 5 pages, 5 figure

Network Coding for WDM All-Optical Multicast

Network coding has become a useful means for achieving efficient multicast, and the optical community has started to examine its application to optical networks. However, a number of challenges, including limited processing capability and coarse bandwidth granularity, need to be overcome before network coding can be effectively used in optical networks. In this paper, we address some of these problems. We consider the problem of finding efficient routes to use with coding, and we study the effectiveness of using network coding for optical-layer dedicated protection of multicast traffic. We also propose architectures for all-optical circuits capable of performing the processing required for network coding. Our experiments show that network coding provides a moderate improvement in bandwidth efficiency for unprotected multicast while significantly outperforming existing approaches for dedicated multicast protection

Survivability and performance optimization in communication networks using network coding

The benefits of network coding are investigated in two types of communication networks: optical backbone networks and wireless networks. In backbone networks, network coding is used to improve survivability of the network against failures. In particular, network coding-based protection schemes are presented for unicast and multicast traffic models. In the unicast case, network coding was previously shown to offer near-instantaneous failure recovery at the bandwidth cost of shared backup path protection. Here, cost-effective polynomial-time heuristic algorithms are proposed for online provisioning and protection of unicast traffic. In the multicast case, network coding is used to extend the traditional live backup (1+1) unicast protection to multicast protection; hence called multicast 1+1 protection. It provides instantaneous recovery for single failures in any bi-connected network with the minimum bandwidth cost. Optimal formulation and efficient heuristic algorithms are proposed and experimentally evaluated. In wireless networks, performance benefits of network coding in multicast transmission are studied. Joint scheduling and performance optimization formulations are presented for rate, energy, and delay under routing and network coding assumptions. The scheduling component of the problem is simplified by timesharing over randomly-selected sets of non-interfering wireless links. Selecting only a linear number of such sets is shown to be rate and energy effective. While routing performs very close to network coding in terms of rate, the solution convergence time is around 1000-fold compared to network coding. It is shown that energy benefit of network coding increases as the multicast rate demand is increased. Investigation of energy-rate and delay-rate relationships shows both parameters increase non-linearly as the multicast rate is increased

Wireless Broadcast with Network Coding in Mobile Ad-Hoc Networks: DRAGONCAST

Network coding is a recently proposed method for transmitting data, which has been shown to have potential to improve wireless network performance. We study network coding for one specific case of multicast, broadcasting, from one source to all nodes of the network. We use network coding as a loss tolerant, energy-efficient, method for broadcast. Our emphasis is on mobile networks. Our contribution is the proposal of DRAGONCAST, a protocol to perform network coding in such a dynamically evolving environment. It is based on three building blocks: a method to permit real-time decoding of network coding, a method to adjust the network coding transmission rates, and a method for ensuring the termination of the broadcast. The performance and behavior of the method are explored experimentally by simulations; they illustrate the excellent performance of the protocol

On the utility of network coding in dynamic environments

Many wireless applications, such as ad-hoc networks and sensor networks, require decentralized operation in dynamically varying environments. We consider a distributed randomized network coding approach that enables efficient decentralized operation of multi-source multicast networks. We show that this approach provides substantial benefits over traditional routing methods in dynamically varying environments. We present a set of empirical trials measuring the performance of network coding versus an approximate online Steiner tree routing approach when connections vary dynamically. The results show that network coding achieves superior performance in a significant fraction of our randomly generated network examples. Such dynamic settings represent a substantially broader class of networking problems than previously recognized for which network coding shows promise of significant practical benefits compared to routing

Optimization Based Rate Control for Multicast with Network Coding

Recent advances in network coding have shown great potential for efficient information multicasting in communication networks, in terms of both network throughput and network management. In this paper, we address the problem of rate control at end-systems for network coding based multicast flows. We develop two adaptive rate control algorithms for the networks with given coding subgraphs and without given coding subgraphs, respectively. With random network coding, both algorithms can be implemented in a distributed manner, and work at transport layer to adjust source rates and at network layer to carry out network coding. We prove that the proposed algorithms converge to the globally optimal solutions for intrasession network coding. Some related issues are discussed, and numerical examples are provided to complement our theoretical analysis

Optimization based rate control for multicast with network coding: A multipath formulation

Network coding offers new capabilities for efficient information multicasting in communication networks. In this paper, we study rate control for multicast with network coding. We propose a path-based multicasting scheme, where each source has multiple paths to each receiver in the multicast group. One advantage of this approach over a tree-based approach is that it is easier to find a minimum cost set of paths as compared to trees. We present three end-to-end rate control algorithms which operate over the set of paths supplied by the network layer. With random network coding, all algorithms can be implemented in a distributed manner. Our algorithms can also be generalized to solve other optimization problems with non-strictly concave objection function

Classifying Networks For Network Coding

Network coding is a relatively recent development in the realm of maximizing information transfer in communications and computer networks. Traditional networks operate by simply storing and forwarding data along. Network coding, however, allows intermediate network nodes to combine data using arithmetic operations. In many instances, this can lead to more efficient use of network resources. Since there is a significant throughput input in some networks, some studies have been done on what kinds of networks will benefit from coding. A coding advantage is defined as a situation where a network coded graph has a lower cost to send given information per unit time session than the same un-coded graph. It has been proven that for two simple single-sender-single-receiver communication sessions that a graph must have one of two special graph-theoretic structures called the butterfly and grail in order to yield a coding advantage. We decided to focus our efforts on a different traffic scenario: a multicast session with a single sender and multiple receivers. Through our research we proved that a multicast-version of the butterfly network structure is needed within a single session multicast with two sinks and one source in order to gain a coding advantage. We also performed a simulation-based study in order to study the structures of multicast sessions with a larger number of receivers. The study involved the random generation of networks using several graph generation techniques. We also considered a variety of different edge-weighting constraints. Given a particular graph with set edge weights, the coding advantage problem was modeled as a linear program and run through the simulator to determine if a coding advantage was gained. Based on visual inspection of these results, it appears that variations of the multicast butterfly are ultimately the dominant structure allowing for a coding advantage. We also found that many types of random networks only very rarely resulted in a coding advantage. Only the graphs generated using the rectangular grid method showed a coding advantage, with a coding advantage percentage of 0.005% for 4 sinks in a 30 node network, with the coding advantage percentage going up as the number of sinks within the network increased