Effective Delay Control in Online Network Coding

Motivated by streaming applications with stringent delay constraints, we consider the design of online network coding algorithms with timely delivery guarantees. Assuming that the sender is providing the same data to multiple receivers over independent packet erasure channels, we focus on the case of perfect feedback and heterogeneous erasure probabilities. Based on a general analytical framework for evaluating the decoding delay, we show that existing ARQ schemes fail to ensure that receivers with weak channels are able to recover from packet losses within reasonable time. To overcome this problem, we re-define the encoding rules in order to break the chains of linear combinations that cannot be decoded after one of the packets is lost. Our results show that sending uncoded packets at key times ensures that all the receivers are able to meet specific delay requirements with very high probability.Comment: 9 pages, IEEE Infocom 200

Informed Network Coding for Minimum Decoding Delay

Network coding is a highly efficient data dissemination mechanism for wireless networks. Since network coded information can only be recovered after delivering a sufficient number of coded packets, the resulting decoding delay can become problematic for delay-sensitive applications such as real-time media streaming. Motivated by this observation, we consider several algorithms that minimize the decoding delay and analyze their performance by means of simulation. The algorithms differ both in the required information about the state of the neighbors' buffers and in the way this knowledge is used to decide which packets to combine through coding operations. Our results show that a greedy algorithm, whose encodings maximize the number of nodes at which a coded packet is immediately decodable significantly outperforms existing network coding protocols.Comment: Proc. of the IEEE International Conference on Mobile Ad-hoc and Sensor Systems (IEEE MASS 2008), Atlanta, USA, September 200

Estudo de mercado de redes AD-HOC como plataforma colaborativa para jogos de telemóveis.

Tese de mestrado. Mestrado em Inovação e Empreendedorismo Tecnológico. Faculdade de Engenharia. Universidade do Porto. 201

Network Coding for Delay Constrained Wireless Systems with Feedback

Rousseau Pierre. Une base de colonne découverte dans l'église de Saint-Germain-des-Prés à Paris. In: Bulletin de la Société Nationale des Antiquaires de France, 1975, 1977. pp. 47-48

Resilient Coding Algorithms for Sensor Network Data Persistence

Storing and disseminating coded information instead of the original data can bring significant performance improvements to sensor network protocols. Such methods reduce the risk of having some data replicated at many nodes, whereas other data is very scarce. This is of particular importance for data persistence in sensor networks. While coding is generally beneficial, coding over all available packets can be detrimental to performance, since coded information might not be decodable after a network failure. In this paper we investigate the suitability of different codeword degree distributions with respect to the dynamics of the underlying wireless network and design a corresponding data management algorithm. We further propose a simple buffer management scheme for continuous data gathering. The performance of the protocols is demonstrated by means of simulation, as well as experiments with an implementation on MICAz motes