A media access and feedback protocol for reliable multicast over wireless channel

A link level reliable multicast requires a channel access protocol to resolve the collision of feedback messages sent by multicast data receivers. Several deterministic media access control protocols have been proposed to attain high reliability, but with large delay. Besides, there are also protocols which can only give probabilistic guarantee about reliability, but have the least delay. In this paper, we propose a virtual token-based channel access and feedback protocol (VTCAF) for link level reliable multicasting. The VTCAF protocol introduces a virtual (implicit) token passing mechanism based on carrier sensing to avoid the collision between feedback messages. The delay performance is improved in VTCAF protocol by reducing the number of feedback messages. Besides, the VTCAF protocol is parametric in nature and can easily trade off reliability with the delay as per the requirement of the underlying application. Such a cross layer design approach would be useful for a variety of multicast applications which require reliable communication with different levels of reliability and delay performance. We have analyzed our protocol to evaluate various performance parameters at different packet loss rate and compared its performance with those of others. Our protocol has also been simulated using Castalia network simulator to evaluate the same performance parameters. Simulation and analytical results together show that the VTCAF protocol is able to considerably reduce average access delay while ensuring very high reliability at the same time.

A TDMA-based Energy Aware MAC (TEA-MAC) Protocol for Reliable Multicast in WSNs

Multicast in wireless sensor networks (WSNs) is an efficient way to spread the same data to multiple sensor nodes. It becomes more effective due to the broadcast nature of wireless link, where a message transmitted from one source is inherently received by all one-hop receivers, and therefore, there is no need to transmit the message one by one. Reliable multicast in WSNs is desirable for critical tasks like code updation and query based data collection. The erroneous nature of wireless medium coupled with limited resource of sensor nodes, makes the design of reliable multicast protocol a challenging task. In this work, we propose a time division multiple access (TDMA) based energy aware media access and control (TEA-MAC) protocol for reliable multicast in WSNs. The TDMA eliminates collisions, overhearing and idle listening, which are the main sources of reliability degradation and energy consumption. Furthermore, the proposed protocol is parametric in the sense that it can be used to trade-off reliability with energy and delay as per the requirement of the underlying applications. The performance of TEA-MAC has been evaluated by simulating it using Castalia network simulator. Simulation results show that TEA-MAC is able to considerably improve the performance of multicast communication in WSNs.

Adaptive Reliable Multicast

An increasing number of applications, such as distributed interactive simulation, live auctions, distributed games and collaborative systems, require the network to provide a reliable multicast service. This service enables one sender to reliably transmit data to multiple receivers. Reliability is traditionally achieved by having receivers send negative acknowledgments (NACKs) to request from the sender the retransmission of lost (or missing) data packets. However, this Automatic Repeat reQuest (ARQ) approach results in the well-known NACK implosion problem at the sender. Many reliable multicast protocols have been recently proposed to reduce NACK implosion. But, the message overhead due to NACK requests remains significant. Another approach, based on Forward Error Correction (FEC), requires the sender to encode additional redundant information so that a receiver can independently recover from losses. However, due to the lack of feedback from receivers, it is impossible for the sender to determine how much redundancy is needed. In this paper, we propose a new reliable multicast protocol, called ARM for Adaptive Reliable Multicast. Our protocol integrates ARQ and FEC techniques. The objectives of ARM are (1) reduce the message overhead due to NACK requests, (2) reduce the amount of data transmission, and (3) reduce the time it takes for all receivers to receive the data intact (without loss). During data transmission, the sender periodically informs the receivers of the number of packets that are yet to be transmitted. Based on this information, each receiver predicts whether this amount is enough to recover its losses. Only if it is not enough, that the receiver requests the sender to encode additional redundant packets. Using ns simulations, we show the superiority of our hybrid ARQ-FEC protocol over the well-known Scalable Reliable Multicast (SRM) protocol.

SomeCast: A Paradigm for Real-Time Adaptive Reliable Multicast

SomeCast is a novel paradigm for the reliable multicast of real-time data to a large set of receivers over the Internet. SomeCast is receiver-initiated and thus scalable in the number of receivers, the diverse characteristics of paths between senders and receivers (e.g. maximum bandwidth and round-trip-time), and the dynamic conditions of such paths (e.g. congestion-induced delays and losses). SomeCast enables receivers to dynamically adjust the rate at which they receive multicast information to enable the satisfaction of real-time QoS constraints (e.g. rate, deadlines, or jitter). This is done by enabling a receiver to join SOME number of concurrent multiCAST sessions, whereby each session delivers a portion of an encoding of the real-time data. By adjusting the number of such sessions dynamically, client-specific QoS constraints can be met independently. The SomeCast paradigm can be thought of as a generalization of the AnyCast (e.g. Dynamic Server Selection) and ManyCast (e.g. Digital Fountain) paradigms, which have been proposed in the literature to address issues of scalability of UniCast and MultiCast environments, respectively. In this paper we overview the SomeCast paradigm, describe an instance of a SomeCast protocol, and present simulation results that quantify the significant advantages gained from adopting such a protocol for the reliable multicast of data to a diverse set of receivers subject to real-time QoS constraints.

CodePipe : an opportunistic feeding and routing protocol for reliable multicast with pipelined network coding

Multicast is an important mechanism in modern wireless networks and has attracted significant efforts to improve its performance with different metrics including throughput, delay, energy efficiency, etc. Traditionally, an ideal loss-free channel model is widely used to facilitate routing protocol design. However, the quality of wireless links would be affected or even jeopardized by many factors like collisions, fading or the noise of environment. In this paper, we propose a reliable multicast protocol, called CodePipe, with advanced performance in terms of energy-efficiency, throughput and fairness in lossy wireless networks. Built upon opportunistic routing and random linear network coding, CodePipe not only simplifies transmission coordination between nodes, but also improves the multicast throughput significantly by exploiting both intra-batch and inter-batch coding opportunities. In particular, four key techniques, namely, LP-based opportunistic routing structure, opportunistic feeding, fast batch moving and inter-batch coding, are proposed to offer substantial improvement in throughput, energy-efficiency and fairness. We evaluate CodePipe on ns2 simulator by comparing with other two state-of-art multicast protocols, MORE and Pacifier. Simulation results show that CodePipe significantly outperforms both of them.

Reliable multicast with pipelined network coding using opportunistic feeding and routing

Multicast is an important mechanism in modern wireless networks and has attracted significant efforts to improve its performance with different metrics including throughput, delay, energy efficiency, etc. Traditionally, an ideal loss-free channel model is widely used to facilitate routing protocol design. However, the quality of wireless links is affected or even jeopardized resulting in transmission failures by many factors like collisions, fading or the noise of environment. In this paper, we propose a reliable multicast protocol, called CodePipe, with energy-efficiency, high throughput and fairness in lossy wireless networks. Building upon opportunistic routing and random linear network coding, CodePipe can not only eliminate coordination between nodes, but also improve the multicast throughput significantly by exploiting both intra-batch and inter-batch coding opportunities. In particular, four key techniques, namely, LP-based opportunistic routing structure, opportunistic feeding, fast batch moving and inter-batch coding, are proposed to offer significant improvement in throughput, energy-efficiency and fairness.Moreover, we design an efficient online extension of CodePipe such that it can work in a dynamic network where nodes join and leave the network as time progresses. We evaluate CodePipe on ns2 simulator by comparing with other two state-of-art multicast protocols,MORE and Pacifier. Simulation results show that CodePipe significantly outperforms both of them.

Fine-Grained Layered Multicast

Traditional approaches to receiver-driven layered multicast have advocated the benefits of cumulative layering, which can enable coarse-grained congestion control that complies with TCP-friendliness equations over large time scales. In this paper, we quantify the costs and benefits of using non-cumulative layering and present a new, scalable multicast congestion control scheme which provides a fine-grained approximation to the behavior of TCP additive increase/multiplicative decrease (AIMD). In contrast to the conventional wisdom, we demonstrate that fine-grained rate adjustment can be achieved with only modest increases in the number of layers and aggregate bandwidth consumption, while using only a small constant number of control messages to perform either additive increase or multiplicative decrease.

Multicast lifetime maximization using network coding in lossy wireless ad-hoc networks

In traditional stop-and-wait strategy for reliable communications, such as ARQ, retransmission for the packet loss problem would incur a great number of packet transmissions in lossy wireless ad-hoc networks. We study the reliable multicast lifetime maximization problem by alternatively exploring the random linear network coding in this paper. We formulate such problem as a min-max problem and propose a heuristic algorithm, called maximum lifetime tree (MLT), to build a multicast tree that maximizes the network lifetime. Simulation results show that the proposed algorithms can significantly increase the network lifetime when compared with the traditional algorithms under various distributions of error probability on lossy wireless links.

Soporte de redes activas para un servicio integrado de multipunto fiable con control de congestión

Las limitaciones de las tecnologías de red actuales, identificadas en la Agencia de Proyectos de Investigación Avanzados para la Defensa (DARPA) durante 1995, han originado recientemente una propuesta de modelo de red denominado Redes Activas. En este modelo, los nodos proporcionan un entorno de ejecución sobre el que se ejecuta el código asociado a cada paquete. El objetivo es disponer de una tecnología de red que permita que nuevos servicios de red sean desarrollados e instalados rápidamente sin modificar los nodos de la red. Un servicio de red que se puede beneficiar de esta tecnología es la transmisión de datos en multipunto con diferentes grados fiabilidad. Las propuestas actuales de servicios de multipunto fiable proporcionan una solución específica para cada clase de aplicaciones, y los protocolos existentes extremo a extremo sufren de limitaciones técnicas relacionadas con una fiabilidad limitada, y con la ausencia de mecanismos de control de congestión efectivos. Esta tesis realiza propuestas originales conducentes a solucionar parte de las limitaciones actuales en el ámbito de Redes Activas y multipunto fiable con control de congestión. En primer lugar, se especificará un servicio genérico de multipunto fiable que, basándose en los requisitos de una serie de aplicaciones consideradas relevantes, proporcione diferentes clases de sesiones y grados de fiabilidad. Partiendo de la definición del servicio genérico especificado, se diseñará un protocolo de comunicaciones sobre la tecnología de Redes Activas que proporcione dicho servicio. El protocolo diseñado estará dotado de un mecanismo de control de congestión para que la fuente ajuste dinámicamente el tráfico inyectado a las condiciones de carga de la red. En esta tesis se pretende también profundizar en el estudio y análisis de la tecnología de Redes Activas, experimentando con dicha tecnología para proporcionar una realimentación a sus diseñadores. Dicha experimentación se realizará en tres ámbitos: el de los servicios y protocolos que puede soportar, el del modelo y arquitectura de las Redes Activas y el de las plataformas de ejecución disponibles. Como aportación adicional de este trabajo, se validarán los objetivos anteriores mediante una implementación piloto de las entidades de protocolo y de su interfaz de servicio sobre uno de los entornos de ejecución disponibles. Abstract The limitations of current networking technologies identified in the Defense Advance Research Projects Agency (DARPA) along 1995 have led to a recent proposal of a new network model called Active Networks. In this model, the nodes provide an execution environment over which the code used to process each packet is executed. The objective is a network technology that allows the fast design and deployment of new network services without requiring the modification of the network nodes. One network service that could benefit from this technology is the transmission of multicast data with different types of loss tolerance. The current proposals for reliable multicast services provide specific solutions for each application class, and existing end-to-end protocols suffer from technical drawbacks related to limited reliability and lack of an effective congestion control mechanism. This thesis contains original proposals that aim to solve part of the current drawbacks in the scope of Active Networks and reliable multicast with congestion control. Firstly, a generic reliable multicast network service will be specified. This service will be designed from the requirements of a relevant set of applications, and will provide different session classes and different types of reliability. Then, a network protocol based on Active Network technology will be designed such that it provides the specified network service. This protocol will incorporate a congestion control mechanism capable of performing an automatic adjustment of the traffic injected by the source to the available network capacity. This thesis will also contribute to a deeper study and analysis of Active Network technology, by experimenting with the technology in order to provide feedback to its designers. This experimentation will be done attending to three different scopes: support of Active Network for services and protocols, Active Network model and architecture, and currently available Active Network execution environments. As an additional contribution of this work, the previous objectives will be validated through a prototype implementation of the protocol entities and the service interface based on one of the current execution environments.

Unificación de los protocolos de multipunto fiable optimizando la escalabilidad y el retardo

Las aplicaciones distribuidas que precisan de un servicio multipunto fiable son muy numerosas, y entre otras es posible citar las siguientes: bases de datos distribuidas, sistemas operativos distribuidos, sistemas de simulación interactiva distribuida y aplicaciones de distribución de software, publicaciones o noticias. Aunque en sus orígenes el dominio de aplicación de tales sistemas distribuidos estaba reducido a una única subred (por ejemplo una Red de Área Local) posteriormente ha surgido la necesidad de ampliar su aplicabilidad a interredes. La aproximación tradicional al problema del multipunto fiable en interredes se ha basado principalmente en los dos siguientes puntos: (1) proporcionar en un mismo protocolo muchas garantías de servicio (por ejemplo fiabilidad, atomicidad y ordenación) y a su vez algunas de éstas en distintos grados, sin tener en cuenta que muchas aplicaciones multipunto que precisan fiabilidad no necesitan otras garantías; y (2) extender al entorno multipunto las soluciones ya adoptadas en el entorno punto a punto sin considerar las características diferenciadoras; y de aquí, que se haya tratado de resolver el problema de la fiabilidad multipunto con protocolos extremo a extremo (protocolos de transporte) y utilizando esquemas de recuperación de errores, centralizados (las retransmisiones se hacen desde un único punto, normalmente la fuente) y globales (los paquetes solicitados se vuelven a enviar al grupo completo). En general, estos planteamientos han dado como resultado protocolos que son ineficientes en tiempo de ejecución, tienen problemas de escalabilidad, no hacen un uso óptimo de los recursos de red y no son adecuados para aplicaciones sensibles al retardo. En esta Tesis se investiga el problema de la fiabilidad multipunto en interredes operando en modo datagrama y se presenta una forma novedosa de enfocar el problema: es más óptimo resolver el problema de la fiabilidad multipunto a nivel de red y separar la fiabilidad de otras garantías de servicio, que pueden ser proporcionadas por un protocolo de nivel superior o por la propia aplicación. Siguiendo este nuevo enfoque se ha diseñado un protocolo multipunto fiable que opera a nivel de red (denominado RMNP). Las características más representativas del RMNP son las siguientes; (1) sigue una aproximación orientada al emisor, lo cual permite lograr un grado muy alto de fiabilidad; (2) plantea un esquema de recuperación de errores distribuido (las retransmisiones se hacen desde ciertos encaminadores intermedios que siempre estarán más cercanos a los miembros que la propia fuente) y de ámbito restringido (el alcance de las retransmisiones está restringido a un cierto número de miembros). Este esquema hace posible optimizar el retardo medio de distribución y disminuir la sobrecarga introducida por las retransmisiones; (3) incorpora en ciertos encaminadores funciones de agregación y filtrado de paquetes de control, que evitan problemas de implosión y reducen el tráfico que fluye hacia la fuente. Con el fin de evaluar el comportamiento del protocolo diseñado, se han realizado pruebas de simulación obteniéndose como principales conclusiones que, el RMNP escala correctamente con el tamaño del grupo, hace un uso óptimo de los recursos de red y es adecuado para aplicaciones sensibles al retardo.---ABSTRACT---There are many distributed applications that require a reliable multicast service, including: distributed databases, distributed operating systems, distributed interactive simulation systems and distribution applications of software, publications or news. Although the application domain of distributed systems of this type was originally confíned to a single subnetwork (for example, a Local Área Network), it later became necessary extend their applicability to internetworks. The traditional approach to the reliable multicast problem in internetworks is based mainly on the following two points: (1) provide a lot of service guarantees in one and the same protocol (for example, reliability, atomicity and ordering) and different levéis of guarantee in some cases, without taking into account that many multicast applications that require reliability do not need other guarantees, and (2) extend solutions adopted in the unicast environment to the multicast environment without taking into account their distinctive characteristics. So, the attempted solutions to the multicast reliability problem were end-to-end protocols (transport protocols) and centralized error recovery schemata (retransmissions made from a single point, normally the source) and global error retrieval schemata (the requested packets are retransmitted to the whole group). Generally, these approaches have resulted in protocols that are inefficient in execution time, have scaling problems, do not make optimum use of network resources and are not suitable for delay-sensitive applications. Here, the multicast reliability problem is investigated in internetworks operating in datagram mode and a new way of approaching the problem is presented: it is better to solve to the multicast reliability problem at network level and sepárate reliability from other service guarantees that can be supplied by a higher protocol or the application itself. A reliable multicast protocol that operates at network level (called RMNP) has been designed on the basis of this new approach. The most representative characteristics of the RMNP are as follows: (1) it takes a transmitter-oriented approach, which provides for a very high reliability level; (2) it provides for an error retrieval schema that is distributed (the retransmissions are made from given intermedíate routers that will always be closer to the members than the source itself) and of restricted scope (the scope of the retransmissions is confined to a given number of members), and this schema makes it possible to optimize the mean distribution delay and reduce the overload caused by retransmissions; (3) some routers include control packet aggregation and filtering functions that prevent implosión problems and reduce the traffic flowing towards the source. Simulation test have been performed in order to evalúate the behaviour of the protocol designed. The main conclusions are that the RMNP scales correctly with group size, makes optimum use of network resources and is suitable for delay-sensitive applications.

ROMA: Reliable Overlay Multicast with Loosely Coupled TCP Connections

We consider the problem of architecting a reliable content delivery system across an overlay network using TCP connections as the transport primitive. We first argue that natural designs based on store-and-forward principles that tightly couple TCP connections at intermediate end-systems impose fundamental performance limitations, such as dragging down all transfer rates in the system to the rate of the slowest receiver. In contrast, the ROMA architecture we propose incorporates the use of loosely coupled TCP connections together with fast forward error correction techniques to deliver a scalable solution that better accommodates a set of heterogeneous receivers. The methods we develop establish chains of TCP connections, whose expected performance we analyze through equation-based methods. We validate our analytical findings and evaluate the performance of our ROMA architecture using a prototype implementation via extensive Internet experimentation across the PlanetLab distributed testbed.