Efficient Broadcast Algorithm Research Articles

Infrastructure-assisted joint power adaptation and routing for heterogeneous vehicular networks

In vehicular networks, protocols and algorithms rely on the in-network status information and its delivery via control messages for their operations. Using the same wireless channel for data and control message transmissions consume significant channel capacity and time, thus resulting in performance degradation. In this paper, a multi-tiered, heterogeneous vehicular network architecture is considered consisting of mainly two radio access technologies, i.e., ad hoc and cellular. Based on the concept of infrastructure-assistance, we suggested offloading control messages over the cellular network and data over the ad hoc network. Next, an efficient broadcast algorithm is proposed that exploits predicted connectivity information to decide on transmit power levels for each vehicle. Finally, a joint transmit power adaptation, and routing algorithm is implemented to disseminate data over a multi-hop network. Through extensive simulations, we reported significant performance gains in terms of delay, collision rate, and packet delivery ratio while maintaining lower communication overhead.

Bloom filter–based efficient broadcast algorithm for the Internet of things

In the Internet of things, a large number of objects can be embedded over a region of interest where almost every device is connected to the Internet. This work scrutinizes the broadcast overhead problem in an Internet of things network, containing a very large number of objects. The work proposes a probabilistic structure (bloom filter)-based technique, which uses a new broadcast structure that attempts to reduce the number of duplicate copies of a packet at every node. This article utilizes a clustering concept to make the broadcast efficient in terms of memory space, broadcast overhead, and energy usage. The unique idea of a bloom-based network uses a filter to incorporate neighbor information when taking a forwarding decision to reduce broadcast overhead. The simulation results show that parallel broadcasting among different clusters and the use of a bloom filter can achieve a reduction in broadcast overhead from hundreds to ones and tens, when compared with a conventional non-bloom-based broadcast al...

Broadcast Wormhole-Routed 3-D Mesh Networks

In a network, one-to-all broadcasting is the process of disseminating messages from a source node to all the nodes existing in the network through successive data transmissions between pairs of nodes. Broadcasting is the most primary communication process in a network. In this paper, we study on multiport wormhole-routed multicomputers where nodes are able to send multiple messages into the network at a time. We propose efficient broadcast algorithms in multi-port wormhole-routed multicomputers which are characterized by 3D mesh topology. The proposed algorithm Three-Dimension Broadcast Layers (3-DBl) is designed such that can send messages to destinations within two start-up communication phases for each 2-D mesh. The second proposed algorithm Three-Dimension Broadcast Surfaces (3-DBS) is designed such that can send messages to destinations within six start-up communication phases. The performance study in this paper clearly shows the advantage of the proposed algorithm.

Network coding and competitive approach for gradient based routing in wireless sensor networks

Energy efficiency is a key design criterion for routing protocols in wireless sensor networks since sensor nodes are strongly constrained in terms of energy supply. Gradient-Based Routing (GBR) is a well known energy efficient routing protocol that is used in WSNs. However, there exist shortcomings in the GBR scheme such as: (1) sinks make use of flooding to broadcast interest messages which leads to a lot of duplication packets which are transmitted. This leads to the waste of a lot of energy in the network and (2) nodes deliver messages in a point to point manner. As a result, the potential of data retransmissions in the network is high due to the unstable network environment in WSNs. In this study, network coding and a competitive approach are proposed to solve the above two problems. Firstly, an energy efficient broadcast algorithm using network coding for GBR (GBR-NC) is proposed. This algorithm aims to reduce network traffic, and furthermore, reduce the energy consumption and prolong the lifetime of the network. Secondly, two competing algorithms (GBR-C and auto-adaptable GBR-C) are proposed for GBR. The basic idea of the proposed competing algorithms is to reduce the retransmission attempts and save the energy by considering two forward candidates. Simulation results show that the proposed schemes give better results when compared to the traditional GBR in terms of energy efficiency.

Information dissemination in VANETs based upon a tree topology

In this work, we focus on vehicular ad hoc networks, also called VANETs, which are communication networks that devices (in this case vehicles) use to exchange messages in a decentralized fashion, i.e., using no preexisting infrastructure. We first assess the feasibility of relying on a tree-based topology management structure for mobile ad hoc networks and in particular for VANETs. Next, we enhance DAGRS, an existing decentralized model for enabling distributed tree management and build BODYF on it, an efficient broadcast algorithm. Several broadcasting algorithms of the state of the art are implemented in order to compare the performance of BODYF. The approach is validated by simulation through three realistic scenarios located in Luxembourg city: the city center for both pedestrian and vehicles, and a highway environment. The comparison is made in terms of the coverage achieved by the broadcasting process as well as the complexity of the messages. DAGRS/BODYF approach outperforms other existing protocols in terms of both the number of devices reached and the network use.

Neighborhood tracking for mobile ad hoc networks

In mobile ad hoc networks (MANETs), node mobility causes network topologies to change dynamically over time, which complicates such important tasks as broadcasting and routing. In a typical efficient localized approach, each node makes forwarding decisions based on a neighborhood local view constructed simply by collecting received ''Hello'' messages. That kind of neighborhood local view can become outdated and inconsistent, which induces a low-coverage problem for efficient broadcasting tasks and a low-delivery ratio problem for efficient routing tasks. In this paper, we propose a neighborhood tracking scheme to guarantee the accuracy of forwarding decisions. Based on historical location information, nodes predict the positions of neighbors when making a forwarding decision, and then construct an updated and consistent neighborhood local view to help derive more precise forwarding decisions. The inaccuracy factors of our scheme are also discussed and an accessory method is provided for possible usage. Simulation results illustrate the accuracy of our proposed tracking scheme. To verify the effectiveness of our scheme, we apply it to existing efficient broadcast algorithms. Simulation results indicate that our neighborhood tracking scheme can improve the protocols coverage ratio greatly.

A Generic Localized Broadcast Framework in Mobile Ad Hoc Ubiquitous Sensor Networks

In this paper, we investigate the critical low coverage problem of position aware localized efficient broadcast in mobile ad hoc ubiquitous sensor networks and propose a generic framework for it. The framework is to determine a small subset of nodes and minimum transmission radiuses based on snapshots of network state (local views) along the broadcast process. To guarantee the accuracy of forward decisions, based on historical location information nodes will predict neighbors' positions at future actual transmission time and then construct predicted and synchronized local views rather than simply collect received Hello messages. Several enhancement technologies are also proposed to compensate the inaccuracy of prediction and forward decisions. To verify the effectiveness of our framework we apply existing efficient broadcast algorithms to it. Simulation results show that new algorithms, which are derived from the generic framework, can greatly increase the broadcast coverage ratio.

Tree-Based Data Broadcast in IEEE 802.15.4 and ZigBee Networks

This paper studies efficient and simple data broadcast in IEEE 802.15.4-based ad hoc networks (e.g., ZigBee). Since finding the minimum number of rebroadcast nodes in general ad hoc networks is NP-hard, current broadcast protocols either employ heuristic algorithms or assume extra knowledge such as position or two-hop neighbor table. However, the ZigBee network is characterized as low data rate and low cost. It cannot provide position or two-hop neighbor information, but it still requires an efficient broadcast algorithm that can reduce the number of rebroadcast nodes with limited computation complexity and storage space. To this end, this paper proposes self-pruning and forward node selection algorithms that exploit the hierarchical address space in ZigBee networks. Only one-hop neighbor information is needed; a partial list of two-hop neighbors is derived without exchanging messages between neighboring nodes. The ZigBee forward node selection algorithm finds the minimum rebroadcast nodes set with polynomial computation time and memory space. Using the proposed localized algorithms, it is proven that the entire network is covered. Simulations are conducted to evaluate the performance improvement in terms of the number of rebroadcast nodes, number of duplicated receivings, coverage time, and communication overhead.

Improved schemes for power-efficient broadcast in ad hoc networks

Ad hoc wireless networks are a special type of wireless network in which a collection of mobile hosts (nodes) with wireless network interfaces may form a temporary network without base-stations. How to design an energy efficient broadcast algorithm is very important. In this paper, we propose scalable broadcast algorithms based on reducing the number of forwarding nodes and the transmission range. Simulations show that our schemes use the least energy so far. Furthermore, the two aspects can be combined for less energy consumption and by considering the residue energy in each host, the lifetime of the network can be prolonged.

A plane-based broadcast algorithm for multicomputer networks

Maximising the performance of parallel systems requires matching message-passing algorithms and application characteristics with a suitable underling interconnection network. Broadcast algorithms for wormhole-switched meshes have been widely reported in the literature. However, most of these algorithms handle broadcast in a sequential manner and do not scale well with the network size. As a consequence, many parallel applications cannot be efficiently supported using existing techniques. Motivated by these observations, this paper presents a new efficient broadcast algorithm for the mesh, called the Plane-Based (PB) algorithm. The main feature of this approach is its ability to perform broadcast operation with a high degree of scalability and parallelism. Furthermore, performance is insensitive to the network size, i.e., only three message-passing steps are required to implement a broadcast operation irrespective of the network size. Results from a comparative analysis demonstrate that the PB algorithm exhibits superior performance characteristics over those of the well-known Recursive Doubling and Extending Dominating Node algorithms.

A new scalable broadcast algorithm for multiport meshes with minimum communication steps

Many broadcast algorithms have been proposed for the mesh in the literature. However, most of these algorithms do not exhibit good scalability properties as the network size increases. As a consequence, most existing broadcast algorithms cannot support real-world parallel applications that require large-scale system sizes due to their high computational demands. Motivated by this observation, this paper makes two contributions. Firstly, in an effort to minimise the effects of network size on communication performance, this study proposes a new routing approach that enables the development of efficient broadcast algorithms that can maintain good performance levels for various mesh sizes. Secondly, based on the new routing approach, we propose a new adaptive broadcast algorithm for the mesh. The main feature of the proposed algorithm is its ability to handle broadcast operations with a fixed number of message-passing steps irrespective of the network size. Results from extensive comparative analysis reveal that our algorithm exhibits superior performance characteristics over those of the well-known Recursive Doubling and Extending Dominating Node algorithms.

EFFICIENT SOLUTION TO UNIFORM ATOMIC BROADCAST

Chandra and Toueg proposed in 1993 a new approach to overcome the impossibility of reaching deterministically Consensus — and by corollary Atomic Broadcast — in asynchronous systems subject to crash failures. They augment the asynchronous system with a possibly Unreliable Failure Detector which provides some information about the operational state of processes. In this paper, we present an extension of the Consensus problem that we call Uniform Prefix Agreement. This extension enables all the processes to propose a flow of messages during an execution — instead of one as in the Consensus problem — and uses all these proposed messages to compose the decision value. Prefix Agreement is based on an Unreliable Failure Detector. We use repeated executions of Prefix Agreement to build an efficient Uniform Atomic Broadcast algorithm. This paper describes the Uniform Prefix Agreement and Uniform Atomic Broadcast algorithms, and provides proofs of their correctness.

OPTIMAL SNAP-STABILIZING NEIGHBORHOOD SYNCHRONIZER IN TREE NETWORKS

We propose a snap-stabilizing synchronization technique, called the Neighborhood Synchronizer[Formula: see text] that synchronizes nodes with their neighbors in a tree network. The [Formula: see text] scheme has optimal memory requirement — only one bit per processor. [Formula: see text] is snap-stabilizing [11], meaning that it always behaves according to its specification. The proposed synchronizer being snap-stabilizing is optimal in terms of stabilization time. We show an application of the synchronizer by designing an efficient broadcast algorithm [Formula: see text] in tree networks. [Formula: see text] is also snap-stabilizing and needs only 2h + 2m - 1 rounds to broadcast m messages, where h is the height of the tree.

Support for broadcast communication in multicomputer networks

A general-purpose multicomputer network must be able to efficiently handle broadcast communication because it is required by many parallel applications. Previous studies have focused mainly on the design of efficient broadcast algorithms. As a result, there has been hardly any work that assesses the performance of existing networks to handle this kind of communication. In an effort to fill this gap, this paper examines the relative performance merits of the low-dimensional k-ary n-cube and the hypermesh in the presence of broadcast traffic. The former network has been one of the widely popular networks in current practical multicomputers, while the latter has recently been proposed, and shown to exhibit attractive topological properties. The results reveal that owing to its hypergraph topology, the hypermesh represents a potential candidate as a high-performance network for future multicomputers as it provides better support for broadcast communication than the k-ary n-cube.

Scalable and efficient broadcasting algorithms for very large internetworks

Broadcast is a special case of routing in which a packet is to be delivered to a set that includes all the network nodes. While dynamic and distributed broadcast techniques have been proposed and used in the Internet, unfortunately they suffer from scalability problems, i.e. they are not efficient with respect to the tremendous size of today's networks. Moreover, it has been observed that the cost of routing and the broadcast time are two conflicting performance measures as far as optimization is concerned, especially in large networks. Also, many of the current techniques are not robust enough and give low performance under events of link failure. First, we show that in order to achieve universal reachability, internets have naturally acquired a multi-level hierarchical structure. Second, utilizing this existing hierarchy, we propose scalable broadcasting protocols which achieve near-optimal cost and time measures. Because of the hierarchy, our proposed algorithm only maintains information of links connected to direct neighbors, thereby making it scalable to future growth in size of the network. We show that time-optimal broadcast in point-to-point networks can be achieved by formulating the problem as finding maximum marching in bipartite graphs. Several heuristics based on matchings are presented. Performance bounds are derived along with numerical and simulation results obtained that prove the validity and feasibility of the scheme.

On the design and implementation of broadcast and global combine operations using the postal model

There are a number of models that were proposed in recent years for message passing parallel systems. Examples are the postal model and its generalization the LogP model. In the postal model a parameter /spl lambda/ is used to model the communication latency of the message-passing system. Each node during each round can send a fixed-size message and, simultaneously, receive a message of the same size. Furthermore, a message sent out during round r will incur a latency of /spl lambda/ and will arrive at the receiving node at round r+/spl lambda/-1. Our goal in this paper is to bridge the gap between the theoretical modeling and the practical implementation. In particular, we investigate a number of practical issues related to the design and implementation of two collective communication operations, namely, the broadcast operation and the global combine operation. Those practical issues include, for example, (1) techniques for measurement of the value of /spl lambda/ on a given machine, (2) creating efficient broadcast algorithms that get the latency h and the number of nodes n as parameters and (3) creating efficient global combine algorithms for parallel machines with /spl lambda/ which is not an integer. We propose solutions that address those practical issues and present results of an experimental study of the new algorithms on the Inter Delta machine. Our main conclusion is that the postal model can help in performance prediction and tuning, for example, a properly tuned broadcast improves the known implementation by more than 20%.

The Mobius cubes

The Mobius cubes are hypercube variants that give better performance with the same number of links and processors. We show that the diameter of the Mobius cubes is about one half the diameter of the equivalent hypercube, and that the average number of steps between processors for a Mobius cube is about two-thirds of the average for a hypercube. We give an efficient routing algorithm for the Mobius cubes. This routing algorithm finds a shortest path and operates in time proportional to the dimension of the cube. We also give efficient broadcast algorithms for the Mobius cubes. We show that the Mobius cubes contain ring networks and other networks. We report results of simulation studies on the dynamic message-passing performance of the hypercube, the Twisted Cube of P.A.J. Hilbers et al. (1987), and the Mobius cubes. Our results are in agreement with S. Abraham (1990), showing that the Twisted Cube has worse dynamic performance than the hypercube, but our results show that the 1-Mobius cube has dynamic performance superior to that of the hypercube. This contradicts current literature, which implies that twisted cube variants will have worse dynamic performance. >

A star-based I/O-bounded network for massively parallel systems

The paper describes a new interconnection network for massively parallel systems, referred to as star-connected cycles (SCC). The SCC graph presents an I/O-bounded structure that results in several advantages over variable degree graphs like the star and the hypercube. The description of the SCC graph includes issues such as labelling of nodes, degree, diameter and symmetry. The paper also presents an optimal routeing algorithm for the SCC and efficient broadcasting algorithms with O(n) running time, with n being the dimensionality of the graph. A comparison with the cube-connected cycles (CCC) and other interconnection networks is included, indicating that, for even n, an n-SCC and a CCC of similar sizes have about the same diameter. In addition, it is shown that one-port broadcasting in an n-SCC graph can be accomplished with a running time better than or equal to that required by an n-star containing (n-1) times fewer nodes.

A routing and broadcasting scheme on faulty star graphs

The authors present a routing algorithm that uses the depth first search approach combined with a backtracking technique to route messages on the star graph in the presence of faulty links. The algorithm is distributed and requires no global knowledge of faults. The only knowledge required at a node is the state of its incident links. The routed message carries information about the followed path and the visited nodes. The algorithm routes messages along the optimal, i.e., the shortest path if no faults are encountered or if the faults are such that an optimal path still exists. In the absence of an optimal path, the algorithm always finds a path between two nodes within a bounded number of hops if the two nodes are connected. Otherwise, it returns the message to the originating node. The authors provide a performance analysis for the case where an optimal path does not exist. They prove that for a maximum of n-2 faults on a graph with N=n! nodes, at most 2i+2 steps are added to the path, where i is O( square root n). Finally, they use the routing algorithm to present an efficient broadcast algorithm on the star graph in the presence of faults. >

Enhanced hypercubes

A hypercube with extra connections added between pairs of nodes through otherwise unused links is investigated. The extra connections are made in a way that maximizes the improvement of the performance measure of interest under various traffic distributions. The resulting hypercube, called the enhanced hypercube, requires a simple routing algorithm and is guaranteed not to create any traffic-congested points or links. The enhanced hypercube achieves noticeable improvement in diameter, mean internode distance, and traffic density, and it also is more cost effective than a regular hypercube. An efficient broadcast algorithm that can considerably speed up the broadcast process in enhanced hypercubes is provided. >