Search results

Multicasting is a necessity for a broadband metro‐area‐network. Discusses the security problems with current multicast protocols. To make the multicast delivery infrastructure more secure and reliable, a stateful multicast access control mechanism, based on MAPE, is proposed. This mechanism expands the current forwarding procedure of a layer 2 switch so that stateful multicast access control can be carried out at the very edge of the metro area network. The architecture of MAPE is discussed in detail, as well as the states maintained and messages exchanged. Further explains that the scheme is flexible and scalable.

The purpose of this paper is to introduce a resource allocation mechanism for Multimedia Broadcast/Multicast Service (MBMS) in a wireless cellular system and to obtain a rapid and efficient transmission scheme over various types' services. The proposed algorithm is evaluated by simulation results.

A big problem for wireless communication is the limited time/frequency resources. Therefore, the most important issue is how to utilize these limited resources to transmit various services over a wireless broadband network, especially for MBMS services. In this paper, resource allocation mechanism in a full unicast system is first analyzed with three classical methods, then improved modulation and coding schemes (MCS) methods are proposed in a full multicast system to improve system throughput and spectral efficiency. Based on the foregoing discussions, research on resource allocation mechanism for mixed multicast and unicast traffic is developed in single‐cell and multi‐cell system (MBSFN, MBMS over single frequency network), respectively. Different transmission proportions between multicast and unicast are analyzed and a multiplexing scenario is also considered.

Resource allocation is a hot topic in wireless communication and there are many investigations on it. However, resource allocation for multicast system, especially for mixed multicast and unicast traffic system, is still a problem worthy of further study. Under same transmission condition in a single cell scenario, system throughput in multicast mode is worse than in unicast mode, which is partly because the number of valid date in multicast resource block (RB) is less than the one in unicast in 3GPP LTE/LTE‐A, on the other hand, because that multicast need to select a relative low MCS to satisfy most MBMS users, even the users with a very poor transmission condition. Fortunately, multicast in MBSFN (MBMS over single frequency network) transfer mode can largely improve system performance.

Improved MCS selection schemes are proposed for full multicast transmission and three transmission scenarios for mixed multicast and unicast traffic are presented to discuss resource allocation mechanism over various types' services. Simulation results show that system performance of multicast system can be greatly enhanced in MBSFN transmission mode, especially with MIMO technology.

The purpose of this paper is to propose a multi-objective differential evolution algorithm named as MOMR-DE to resolve multicast routing problem. In mobile ad hoc network (MANET), multicast routing is a non-deterministic polynomial -complete problem that deals with the various objectives and constraints. Quality of service (QoS) in the multicast routing problem mainly depends on cost, delay, jitter and bandwidth. So the cost, delay, jitter and bandwidth are always considered as multi-objective for designing multicast routing protocols. However, mobile node battery energy is finite and the network lifetime depends on node battery energy. If the battery power consumption is high in any one of the nodes, the chances of network’s life reduction due to path breaks are also more. On the other hand, node’s battery energy had to be consumed to guarantee high-level QoS in multicast routing to transmit correct data anywhere and at any time. Hence, the network lifetime should be considered as one objective of the multi-objective in the multicast routing problem.

Recently, many metaheuristic algorithms formulate the multicast routing problem as a single-objective problem, although it obviously is a multi-objective optimization problem. In the MOMR-DE, the network lifetime, cost, delay, jitter and bandwidth are considered as five objectives. Furthermore, three QoS constraints which are maximum allowed delay, maximum allowed jitter and minimum requested bandwidth are included. In addition, we modify the crossover and mutation operators to build the shortest-path multicast tree to maximize network lifetime and bandwidth, minimize cost, delay and jitter.

Two sets of experiments are conducted and compared with other algorithms for these problems. The simulation results show that our proposed method is capable of achieving faster convergence and is more preferable for multicast routing in MANET.

In MANET, most metaheuristic algorithms formulate the multicast routing problem as a single-objective problem. However, this paper proposes a multi-objective differential evolution algorithm to resolve multicast routing problem, and the proposed algorithm is capable of achieving faster convergence and more preferable for multicast routing.

This paper aims to discuss problems, requirements and current trends for deploying group communication in real‐world scenarios from an integrated perspective.

The Hybrid Shared Tree is introduced – a new architecture and routing approach to combine network – and subnetwork‐layer multicast services in end‐system domains with transparent, structured overlays on the inter‐domain level.

The paper finds that The Hybrid Shared Tree solution is highly scalable and robust and offers provider‐oriented features to stimulate deployment.

A straightforward perspective is indicated in the paper for a mobility‐agnostic routing layer for future use.

Online auctions on the Internet have become popular. However, the communication techniques currently used in the online auction industry are primarily based on unicast technology. Unicast‐based online auctions suffer from unbearable delay of the communication between the auctioneer and bidders. Recently, multicast is changing the Internet environment, and is penetrating to the online auction field. This study describes a model for multicast‐based online auctions. The laboratory experiments demonstrate that the communication performance of multicast‐based online auctions is significantly better than that of traditional unicast‐based auctions.

Coexistence of various wireless access networks and the ability of mobile terminals to switch between them make an optimal selection of serving networks for multicast groups a challenging problem. Since optimal network selection requires large dimensions of data to be collected from several network locations and sent between several network components, the scalability can easily become a bottleneck in large-scale systems. Therefore, reducing data exchange within heterogeneous wireless networks is important. The paper aims to discuss these issues.

The authors study the decision-making process and the data that need to be sent between different network components. To analyze the operation of the wireless heterogeneous network, the authors built a mathematical model of the network. The objective is defined as a minimization of multicast streams in the system. To evaluate the heuristic solutions, the authors define the upper and lower bounds to their operation.

The proposed heuristic solutions substantially reduce the usage of bandwidth in mobile networks and exchange of information between the network components.

The authors proposed the approach that allows network selection in a decentralized manner with only limited information shared among the decision makers. The authors studied how different sets of information available to decision makers influenced the performance of the system. The work also investigates the usage of multiple paths for multicast in heterogeneous mobile environments.

Group communication has become increasing important in mobile ad hoc networks (MANET). Current multicast routing protocols in MANET have been shown to incur large overheads due to dynamic network topology. To this end, this paper proposes an overlay multicast scheme in MANET that is more efficient.

The approach is to construct an overlay multicast tree based on the locations of the group nodes. The paper proposes several tree construction algorithms, namely, location‐guided k‐ary (LGK) tree, location‐guided directional (LGD) tree and location‐guided Steiner (LGS) tree. All of them rely on the geometric locations of the nodes as heuristics to construct the tree. The paper also introduces several mechanisms to enhance the proposed algorithms.

The simulation results show that the location‐guided heuristics is very effective in constructing low bandwidth cost overlay multicast trees in MANET. When location information is up‐to‐date, the bandwidth cost of a LGS tree is similar to that of an optimal router‐assisted Steiner multicast tree. When location information is out‐dated, LGD tree has the lowest cost.

This paper demonstrates the effectiveness of location‐guided heuristics in constructing overlay multicast trees in MANET. This study strongly suggests that location‐guided heuristics can be used to design many other algorithms in a mobile network.

In this paper, a Web portal is presented for multicast communication management, providing fully automatic service management with integrated provisioning of hardware equipment. The portal is based on an open and configurable object‐oriented framework, that allows self‐provisioning by the user and the seamless integration with all types of multicast application software. As its topological structure is ideally suited for multicasting, and it allows the accurate control of the transmission bandwidth, the portal focuses currently on satellite as a delivery medium. The software architecture, the implementation, and the application usage of the Web portal for multicast delivery are described.

Presence of innumerable sensors, complex deduction of contexts from sensor data, and reusability of contextual information impose the requirement of middleware for context aware computing. Smart applications, hosted in myriad devices (e.g. PDA, mobile, PCs), acquire different contexts from the middleware and act intelligently based on the available contexts in a context‐aware computing environment. As the system grows larger, scalable delivery of contexts from the middleware to numerous context‐aware applications will be inevitable. However, pure unicast based or pure broadcast‐based dissemination cannot provide high scalability as well as low‐average latency. The purpose of this paper is to present a scalable context delivery mechanism for the middlewares to facilitate the development of larger context‐aware computing systems.

The proposed scheme is based on hybrid data dissemination technique where the most frequently requested data (e.g. HOT contexts) are delivered through multicast and the rest (e.g. COLD contexts) are delivered through unicast to reduce network traffic. The paper dynamically prioritizes and classifies the HOT and COLD context data depending on the number of requests and longest waiting time. Moreover, the division of bandwidth between the delivery of HOT and COLD contexts reduces average latency. Polling traffic is decreased by incorporating leasing mechanism. Extensive simulation is conducted to evaluate the proposed scheme.

The mechanism dynamically prioritizes and classifies the hot and cold context data depending on the request rate and longest waiting time. The solution addresses the push popularity problem that occurs in the passive as the passive clients access data without sending explicit requests. The leasing mechanism is incorporated to reduce the periodical requests (polling) for better performance.

The paper is of value in presenting a scalable context delivery mechanism for the middlewares to facilitate the development of larger context‐aware computing systems and also in presenting implementation details of a prototype that is developed using Jini framework and Java reliable multicast service (JRMS) library.

This article focuses on Brazil’s migration to digital television. It shows how, in the case of Brazil, unicasting solely reflected the interests of commercial broadcasters. Comparing Brazil to France and the United Kingdom, it explains why the European choice for multicasting is one of the reasons for the success of digital television penetration in these two countries.

By analyzing viewing shares and the financial relevance of the public broadcasters, BBC, and France Televisions, to the national broadcasting spaces, the study concludes that these European traditional broadcasters profited from digital television, despite their exposure to a more competitive environment.

As I will discuss, the model chosen in Brazil continues to hamper Public Service Broadcasting (PSB) and national audiovisual industries’ developments, as well as slowing digital take-up. In Brazil, public broadcasting continued to play a marginal role in the national broadcasting space and the audiovisual market, concentrated in a few local companies.

The findings of this comparative study, developed from a political economy perspective, provide important insights into both Brazilian and European telecommunications policy.