Optimal transmission radius for energy efficient broadcasting protocols in ad hoc and sensor networks

We investigate the problem of minimum energy broadcasting in ad hoc networks where nodes have capability to adjust their transmission range. The minimal transmission energy needed for correct reception by neighbor at distance r is proportional to r/sup /spl alpha//+c/sub e/, /spl alpha/ and c/sub e/ being two environment-dependent constants. We demonstrate the existence of an optimal transmission radius, computed with a hexagonal tiling of the network area, that minimizes the total power consumption for a broadcasting task. This theoretically computed value is experimentally confirmed. The existing localized protocols are inferior to existing centralized protocols for dense networks. We present two localized broadcasting protocols, based on derived "target" radius, that remain competitive for all network densities. The first one, TR-LBOP, computes the minimal radius needed for connectivity and increases it up to the target one after having applied a neighbor elimination scheme on a reduced subset of direct neighbors. In the second one, TRDS, each node first considers only neighbors whose distance is no greater than the target radius (which depends on the power consumption model used), and neighbors in a localized connected topological structure such as RNG or LMST. Then, a connected dominating set is constructed using this subgraph. Nodes not selected for the set may be sent to sleep mode. Nodes in selected dominating set apply TR-LBOP. This protocol is the first one to consider both activity scheduling and minimum energy consumption as one combined problem. Finally, some experimental results for both protocols are given, as well as comparisons with other existing protocols. Our analysis and protocols remain valid if energy needed for packet receptions is charged.     

Toward integrating IP multicasting in internet network management protocols

Supporting multi-point group communications in network management platforms is essential for improving scalability and responsiveness of management applications. With the deployment of IP multicasting as the standard infrastructure for multi-point group communications in the Internet, the integration of IP multicasting in SNMP becomes significantly important to achieve these goals. This paper presents a highly flexible, efficient and easy-to-integrate framework for integrating IP Multicast in standard SNMP agents. The proposed framework enables managers to re-configure the agents’ group membership and the communication model (e.g. one-to-many, many-to-one and many-to-many) dynamically based on the application requirements. This framework exploits the advantages of IP multicasting without requiring any significant changes or performance overhead in the protocol or the agent architecture. The resulting framework can be easily adopted by exiting SNMP agents of various network management platforms. Although the other approaches provide group communications through broker agents in the management platform, integrating IP multicasting in SNMP agents is more efficient and a simpler approach. Our ultimate goal is to promote the integration of IP multicasting as a standard service in SNMP agents.     

Demand-scalable geographic multicasting in wireless sensor networks

In this paper, we focus on the challenge of demand-scalable multicast routing in wireless sensor networks. Due to the ad-hoc nature of the placement of the sensor nodes as well as the variations in the available power of the nodes, centralized or stateful routing schemes are not applicable. Thus, in this paper, we first introduce a Geographic Multicast routing Protocol (GMP) for wireless sensor networks.¹ The protocol is fully distributed and stateless. Given a set of the destinations, the transmitting node first constructs a virtual Euclidean Steiner tree rooted at itself and including the destinations, using a novel and highly efficient reduction ratio heuristic (called rrSTR). The simulation results on NS2 show that GMP requires 25% less hops and energy than the existing Position Based Multicasting, PBM, Location-Guided Steiner trees, LGS, approaches. The GMP algorithm as well as LGS and PBM all assume that each recipient receives the same copy of the multicast message. In reality, however, especially when the transmission includes streamed media, different recipients have different demands (in terms of the frequency of packets or the quality of media). Thus, in this paper, we investigate the suitability of the geographic multicasting schemes for situations where scalable transmission paths can save power. In particular, we propose intuitive mechanisms to extend the three schemes to cases where the data transmission can scale based on the demand. This leads to three new weighted multicast routing algorithms: wGMP, wLGS, and wPBM. The results show that the wGMP algorithm provides the best opportunities for scalability due to its flexible self-correcting decision making process, while other schemes, such as wLGS and wPBM are not directly suitable for scalable multicasting, due to their naively greedy structures.     

Circuit-switched broadcasting in torus networks

In this paper we present three broadcast algorithms and lower bounds on the three main components of the broadcast time for 2-dimensional torus networks (wrap-around meshes) that use synchronous circuit-switched routing. The first algorithm is based on a recursive tiling of a torus and is optimal in terms of both phases and intermediate switch settings when the start-up time to initiate message transmissions is the dominant cost. It is the first broadcast algorithm to match the lower bound of log₅ N on number of phases (where N is the number of nodes). The second and third algorithms are hybrids which combine circuit-switching with the pipelining and arc-disjoint spanning trees techniques that are commonly used to speed up store-and-forward routing. When the propagation time of messages through the network is significant, our hybrid algorithms achieve close to optimal performance in terms of phases, intermediate switch settings, and total transmission time. They are the first algorithms to achieve this performance in terms of all three parameters simultaneously     

Dual partitioning multicasting for high-performance on-chip networks

As the number of cores integrated onto a single chip increases, power dissipation and network latency become ever-increasingly stringent. On-chip network provides an efficient and scalable interconnection paradigm for chip multiprocessors (CMPs), wherein one-to-many (multicast) communication is universal for such platforms. Without efficient multicasting support, traditional unicasting on-chip networks will be low efficiency in tackling such multicast communication. In this paper, we propose Dual Partitioning Multicasting (DPM) to reduce packet latency and balance network resource utilization. Specifically, DPM scheme adaptively makes routing decisions based on the network load-balance level as well as the link sharing patterns characterized by the distribution of the multicasting destinations. Extensive experimental results for synthetic traffic as well as real applications show that compared with the recently proposed RPM scheme, DPM significantly reduces the average packet latency and mitigates the network power consumption. More importantly, DPM is highly scalable for future on-chip networks with heavy traffic load and varieties of traffic patterns.     

Circuit-switched broadcasting in torus and mesh networks

We consider the problem of broadcasting on torus and mesh networks using circuit-switched, half-duplex, and link-bound communication. In this paper, we obtain an optimal broadcasting algorithm that uses pd time steps for a d-dimensional torus with (2d+1)^p nodes in each side of the torus. Using this algorithm, we show that a broadcasting on a d-dimensional mesh with the same size can be done in pd+p+d-1 time steps     

A trip-based multicasting model in wormhole-routed networks withvirtual channels

This paper focuses on efficient multicasting in wormhole-routed networks. A trip-based model is proposed to support adaptive, distributed, and deadlock-free multiple multicast on any network with arbitrary topology using at most two virtual channels per physical channel. This model significantly generalizes the path-based model proposed earlier which works only for Hamiltonian networks and cannot be applicable to networks with arbitrary topology resulted due to system faults. Fundamentals of the trip-based model, including the necessary and sufficient condition to be deadlock-free, and the use of appropriate number of virtual channels to avoid deadlock are investigated. The potential of this model is illustrated by applying it to hypercubes with faulty nodes. Simulation results indicate that the proposed model can implement multiple multicast on faulty hypercubes with negligible performance degradation     

Rapid almost-complete broadcasting in faulty networks

This paper studies the problem of broadcasting in synchronous point-to-point networks, where one initiator owns a piece of information that has to be transmitted to all other vertices as fast as possible. The model of fractional dynamic faults with threshold is considered: in every step either a fixed number c(G)−1$c\left(G\right)-1$, where c(G)$c\left(G\right)$ is the edge connectivity of the communication graph, or a fraction α$\alpha$ of sent messages can be lost depending on which quantity is larger.     

Scheduling support for multicasting sessions in broadband communication networks

Multimedia applications require support from the underlying broadband network at the end-to-end communication level. Multicasting is an important paradigm of end-to-end communication. The root node of a multicasting session is responsible for controlling the session including monitoring, maintenance, and the implementation of the multicasting protocol. The job that controls the multicasting session executes as a group of tasks at the root node of a multicasting tree. The scheduling scheme at the root node should give support to a multicasting session by improving the completion time of the jobs controlling the multicasting session, hence increasing throughput and the probability of admitting new multicast sessions into the system. In this paper, we model the tasks that carry out the multicasting session monitoring and maintenance as a fork-join job executing on a multiprocessor system. We assume that an executing task blocks for device I/O as a part of the activities associated with sending and receiving data packets. We develop two analytic models for scheduling a session control job on a multiprocessor system. The first model allows incoming job tasks to multiplex processors with existing tasks of another multicasting session, while the other model schedules a task of the incoming job to an idle processor. We assume that the overhead of rescheduling a task to another processor is large. We compare the performance of both models and show the range of conditions under which a model outperforms the other. We point out how the results can be used in the design of an adaptive scheduler that uses both models to improve throughput and consequently the probability of admitting new multicast sessions.     

Efficient architectures and algorithms for multicasting data in computer communication networks

This paper presents two network architectures with associated routing and multicast algorithms for improved performance under multicasting traffic conditions. A conditionally nonblocking network, referred to as a Clos network, forms the basis for the development of efficient multicast communication networks. The Clos network is first analyzed under multicast traffic conditions for blocking and multicast overflow probability. The analysis determines the overflow probability under two different multicast distribution assumptions. The first distribution assumes all packets request the same number of copies and the second distribution uses a random number of requested copies. An analysis of an extension of the presented network to multiplexed parallel planes of a network shows a significant improvement on the network performance and particularly on the carried traffic load when compared with previously published multicast architectures using different buffering strategies.     

Acknowledged broadcasting in ad hoc radio networks

We consider ad hoc radio networks in which each node knows only its own identity but is unaware of the topology of the network, or of any bound on its size or diameter. Acknowledged broadcasting (AB) is a communication task consisting in transmitting a message from a distinguished source to all other nodes of the network and making this fact common knowledge among all nodes. To do this, the underlying directed graph must be strongly connected. Working in a model allowing all nodes to transmit spontaneously even before getting the source message, Chlebus et al. [B. Chlebus, L. Ga?sieniec, A. Gibbons, A. Pelc, W. Rytter, Deterministic broadcasting in unknown radio networks, Distrib. Comput. 15 (2002) 27-38] proved that AB is impossible, if collision detection is not available, and gave an AB algorithm using collision detection that works in time O(nD) where n is the number of nodes and D is the eccentricity of the source. Uchida et al. [J. Uchida, W. Chen, K. Wada, Acknowledged broadcasting and gossiping in ad hoc radio networks, Theoret. Comput. Sci. 377 (2007) 43-54] showed an AB algorithm without collision detection working in time O(n4/3log10/3n) for all strongly connected networks of size at least 2. In particular, it follows that the impossibility result from [B. Chlebus, L. Ga?sieniec, A. Gibbons, A. Pelc, W. Rytter, Deterministic broadcasting in unknown radio networks, Distrib. Comput. 15 (2002) 27-38] is really caused by the singleton network for which AB amounts to realize that the source is alone. We improve those two results by presenting two generic AB algorithms using a broadcasting algorithm without acknowledgement, as a procedure. For a large class of broadcasting algorithms the resulting AB algorithm has the same time complexity. Using the currently best known broadcasting algorithms, we obtain an AB algorithm with collision detection working in time O(min{nlog²D,nlognloglogn}), for arbitrary strongly connected networks, and an AB algorithm without collision detection working in time O(nlognloglogn) for all strongly connected networks of size n?2. Moreover, we show that in the model in which only nodes that already got the source message can transmit, AB is infeasible in a strong sense: for any AB algorithm there exists an infinite family of networks for which this algorithm is incorrect.     

Deterministic broadcasting in ad hoc radio networks

We consider the problem of distributed deterministic broadcasting in radio networks of unknown topology and size. The network is synchronous. If a node u can be reached from two nodes which send messages in the same round, none of the messages is received by u. Such messages block each other and node u either hears the noise of interference of messages, enabling it to detect a collision, or does not hear anything at all, depending on the model. We assume that nodes know neither the topology nor the size of the network, nor even their immediate neighborhood. The initial knowledge of every node is limited to its own label. Such networks are called ad hoc multi-hop networks. We study the time of deterministic broadcasting under this scenario. For the model without collision detection, we develop a linear-time broadcasting algorithm for symmetric graphs, which is optimal, and an algorithm for arbitrary n-node graphs, working in time . Next we show that broadcasting with acknowledgement is not possible in this model at all. For the model with collision detection, we develop efficient algorithms for broadcasting and for acknowledged broadcasting in strongly connected graphs. Received: January 2000 / Accepted: June 2001     

An approach to support IP multicasting in networks with mobile hosts

It is an efficient way for a mobile host to obtain multicast service via a local multicast router on the visited network.However,there is a possibility for a temporary disruption of multicast service due to the join latency and other issues in handoff procedure.This paper proposes a scheme to solve such a problem. A smooth handoff mechanism is introduced to avoid unnecessary data loss.Besides,any mobility agent capable of multicast can be appointed to provide service to mobile hosts,which makes it possible to deploy the protocol widely.Discrete-event simulations were conducted to survey the performance of the proposed scheme.The simulation results show that the scheme has better performance than the compared approaches.     

Context-aware broadcasting approaches in mobile ad hoc networks

The aim of this paper is to compare different context-aware broadcasting approaches in mobile ad hoc networks (MANETs) and to evaluate their respective performances. Message broadcasting is one of the core challenges brought up by distributed systems and has therefore largely been studied in the context of traditional network structures, such as the Internet. With the emergence of MANETs, new broadcasting algorithms especially geared at these networks have been introduced. The goal of these broadcasting algorithms is to ensure that a maximum number of nodes deliver the broadcasted message (reliability), while ensuring that the minimum number of nodes retransmit the broadcasted message (efficiency), in order to save their resources, such as bandwidth or battery. In recent years, as more and more mobile devices have become context-aware, several broadcasting algorithms have been introduced that take advantage of contextual information in order to improve their performance. We distinguish four approaches with respect to context: (1) context-oblivious approaches, (2) network traffic-aware approaches, (3) power-aware approaches, and (4) location-aware approaches. This paper precisely aims at presenting these four different broadcasting approaches and at measuring the performance of algorithms built upon them.     

Dynamic IP configuration of terminals in broadcasting networks

The concept of synergy between broadcasting and telecommunication networks has been strengthened by the emergence of multi-modal terminals, which are used in a broadcast environment (mainly in DTV-Digital Television networks) to provide IP-based multimedia services. The migration of IPv4/IPv6 applications, either interactive or not, in a broadcasting network, requires that certain parameters, such as Host, Gateway and DNS IP addresses are configured in the terminals, either statically or dynamically. This paper discusses issues of dynamic configuration of IP parameters for DTV terminals, based on an overview of relevant mechanisms usually used in access networks. It proposes an IP-based auto-configuration protocol tailored to the needs of an IP/DTV access platform, describes its implementation and evaluates its behaviour in a laboratory-based DVB-T network.     

Information delivery through broadcasting in satellite communication networks

Satellite broadcast is an important candidate for large-scale multimedia information distribution due to the inherent wide-range multicasting capability of satellites and the asymmetry of satellite communications (high bandwidth downlink, limited bandwidth uplink) that matches nicely the information flow asymmetry in multimedia applications. We consider a data broadcasting model that is encountered in most asymmetric satellite communication environments. The problem of scheduling the data broadcast such that average response time experienced by the users is low is considered. In a push-based system, where the users cannot place requests directly to the server and the broadcast schedule should be determined based solely on the access probabilities, we formulate a deterministic dynamic optimization problem, the solution of which provides the optimal broadcast schedule. Properties of the optimal solution are obtained and then we propose a suboptimal dynamic policy which achieves average response time close to the lower bound. In a pull-based system where the users may place requests about information items directly to the server, the scheduling can be based on the number of pending requests for each item. Suboptimal policies with good performance are obtained in this case as well. If a user has local memory, it can alleviate its access latency by selectively prefetching the items from the broadcast and storing them in the memory. A good memory management strategy can substantially reduce the user's access latency. An optimal memory management policy is identified, that minimizes the expected aggregate latency. Memory update strategies with limited look-ahead are presented as implementable approximations of the optimal policy as well. We also consider the problem of joint broadcast scheduling and user's cache management and propos a joint optimization scheme which can achieve the performance up to 40% better than the existing non-joint approach.     

Efficient broadcasting in radio networks with long-range interference

We study broadcasting, also known as one-to-all communication, in synchronous radio networks with known topology modeled by undirected (symmetric) graphs, where the interference range of a node is likely exceeding its transmission range. In this model, if two nodes are connected by a transmission edge they can communicate directly. On the other hand, if two nodes are connected by an interference edge they cannot communicate directly and transmission of one node disables recipience of any message at the other node. For a network $G,$ we term the smallest integer $d$ , s.t., for any interference edge $e$ there exists a simple path formed of at most $d$ transmission edges connecting the endpoints of $e$ as its interference distance $d_I$ . In this model the schedule of transmissions is precomputed in advance. It is based on the full knowledge of the size and the topology (including location of transmission and interference edges) of the network. We are interested in the design of fast broadcasting schedules that are energy efficient, i.e., based on a bounded number of transmissions executed at each node. We adopt $n$ as the number of nodes, $D_T$ is the diameter of the subnetwork induced by the transmission edges, and $\varDelta $ refers to the maximum combined degree (formed of transmission and interference edges) of the network. We contribute the following new results: (1) We prove that for networks with the interference distance $d_I\ge 2$ any broadcasting schedule requires at least $D_T+\varOmega (\varDelta \cdot \frac{\log {n}}{\log {\varDelta }})$ rounds. (2) We provide for networks modeled by bipartite graphs an algorithm that computes $1$ -shot (each node transmits at most once) broadcasting schedules of length $O(\varDelta \cdot \log {n})$ . (3) The main result of the paper is an algorithm that computes a $1$ -shot broadcasting schedule of length at most $4 \cdot D_T + O(\varDelta \cdot d_I \cdot \log ^4{n})$ for networks with arbitrary topology. Note that in view of the lower bound from (1) if $d_I$ is poly-logarithmic in $n$ this broadcast schedule is a poly-logarithmic factor away from the optimal solution.     

Repetition-based cooperative broadcasting for vehicular ad-hoc networks

In vehicular ad hoc networks, most of critical applications involved with safety rely on reliable broadcast communications with low latency. Recently, repetition-based protocols have been proposed to meet the requirements of timeliness and reliability for broadcasting. In these protocols, a sender repeatedly retransmits the broadcast message during the lifetime of the message. However, existing protocols face serious problems such as deterioration of the signal quality caused by wireless fading. In particular, since excessive repetitions might cause network congestion and waste channel resources, reliability of broadcasting should be achieved with as small a number of repetitions as possible. In this paper, we therefore propose a novel repetition-based broadcast protocol which exploits a cooperative diversity technique (called RB-CD) making a small number of repetitions robust for wireless fading. To support this cooperative diversity, neighboring nodes transmit the same message almost simultaneously (that is, using the same repetition pattern for each other) in order to form a virtual antenna array. The virtual antenna array achieves a diversity gain at the receivers. In the RB-CD protocol, the virtual antenna array consists of the source and some of its neighbors (called relays) which participate in repeating the transmission of a broadcast message. In addition, a new distributed relay selection algorithm is introduced in the RB-CD protocol. From the ns-2 simulation results, we verified that RB-CD provides a more reliable broadcasting service due to its capability of exploiting cooperative diversity.     

A novel adaptive protocol for lightweight efficient multicasting in ad hoc networks

In group communications, we find that current multicast protocols are far from “one size fits all”: they are typically geared towards and optimized for particular scenarios. As a result, when deployed in different scenarios, their performance and overhead often degrades significantly. A common problem is that most of these protocols incur high overheads with a high density of group members and in high mobility. Our objective is to design a protocol that adapts in response to the dynamics of the network. In particular, our objective is to provide efficient and lightweight multicast data dissemination irrespective of the density of group members and node density. Our work is motivated by two observations. First, broadcasting in some cases is more efficient than multicasting. Second, member and node layout distributions are not necessarily homogeneous. For example, many MANET applications result in a topological clustering of group members that move together. Thus, we develop Fireworks, an adaptive approach for group communications in mobile ad hoc networks. Fireworks is a hybrid 2-tier multicast/broadcast protocol that adapts to maintain performance given the dynamics of the network topology and group density. In a nutshell, our protocol creates pockets of broadcast distribution in areas with many members, while it develops a multicast backbone to interconnect these dense pockets. Fireworks offers packet delivery statistics comparable to that of a pure multicast scheme but with significantly lower overheads.