Dewan Tanvir Ahmed

A survey of application-layer multicast protocols

In light of the slow deployment of IP Multicast technology on the global Internet and the explosive popularity of peer-to-peer (P2P) file-sharing applications, there has been a flurry of research activities investigating the feasibility of implementing multicasting capability at the application layer, referred to as Application Layer Multicasting (ALM), and numerous algorithms and protocols have been proposed. This article aims to provide researchers in the field with an understanding of ALM protocols by identifying significant characteristics, from both application requirements and networking points of view, and by using those characteristics as a basis for organizing the protocols into an integrated and well-structured format. Current trends and directions for further research are also presented. This article surveys the literature over the period 1995¿2005 on different application layer multicasting approaches.

A Visibility-Driven Approach to Managing Interest in Distributed Simulations with Dynamic Load Balancing

Distributed simulations that support a massive number of users typically divide the virtual world into zones that are managed by separate servers to evenly distribute resources and achieve scalability. However, such zoning restricts cross-zonal interactions and exposes the division of the world to the participating parties. Problems such as crowding one zone among others defeats the very purpose of interest management and makes geographic partitioning inefficient for modeling interactions. In this work, we have designed and implemented a visibility-driven approach to make the partitioning transparent to users. The effectiveness of this distributed architecture is tested through a prototype implementation. We also introduce a novel idea to dynamic load balancing that can be achieved in real-time without modifying the communication architecture. By increasing the granularity of the partitioning and providing a layered approach to zoning, transient crowding can be handled by adoptively dispersing parts of the crowded zone to adjacent servers.

A Dynamic Area of Interest Management and Collaboration Model for P2P MMOGs

In this paper, we present a dynamic area of interest management for massively multiplayer online games (MMOG). Instead of mapping the virtual space to the area of interest (AOI), we scheme AOIs to the virtual space. This zoneless MMOG is the consequence of dynamic AOI that redeems the necessity of inter-AOI communication. In addition, the AOI maintenance cost is reduced significantly by assigning the maintenance responsibility to a subset of players for each AOI. Due to the integration of peer-to-peer communication model to the system, the scalability has improved. To satisfy the timing constraints, the projection of the underling network topology to the overlay network is more fruitful than building the overlay on the fly unintelligently. In response to this fact, the proposed communication model adapts a geometric algorithm which is usually used for minimax problem. The model is evaluated and justified through proper simulation.

A microcell oriented load balancing model for collaborative virtual environments

In this paper, we present a microcell oriented load balancing mechanism in the context of a hybrid MMOG (massively multiplayer online game) architecture. The objective of the proposed approach is to define a fair load balancing model for peer-to-peer MMOGs and virtual environments that minimizes peer-to-peer distortions in the overlays. In the case of an overloaded server, the proposed approach identifies appropriate microcell(s) that reduces overlay maintenance cost and minimizes inter-server communications. The load is relieved by devolving these microcells to the other less loaded servers. The model is justified through extensive simulation.

A hybrid P2P communications architecture for zonal MMOGs

Distributed Virtual Environments are becoming more popular in today’s computing and communications among people. Perhaps the most widely used form of such environments is Massively Multiplayer Online Games (MMOG), which are in the form of client/server architecture that requires considerable server resources to manage a large number of distributed players. Peer-to-peer communication can achieve scalability at lower cost but may introduce other difficulties. Synchronous communication is a prime concern for multi-user collaborative applications like MMOGs where players need frequently interaction with each other to share their game states. In this article, we present a hybrid MMOG architecture called MM-VISA (Massively Multiuser VIrtual Simulation Architecture). In this architecture, servers and peers are coupled together to take the inherent advantages of the centralized architecture and the scalability of distributed systems. As the virtual world is decomposed into smaller manageable zones, the players’ random movement causes reorganization at the P2P overlay structure. The frequent nature of movements along with unintelligent zone crossing approaches, currently implemented in MMOGs, breaks synchronous communication. To limit such problem, we consider players’ gaming characteristics to intelligently define routing paths. A graph-theoretic framework is incorporated for overlay oriented real-time distributed virtual environments. We shall show that interest-driven zone crossing, dynamic shared region between adjacent zones, and clustering of entities based on their attributes significantly decrease unstable overlay situations. The effectiveness of the presented system is justified through simulation.

Multi-level Hashing for Peer-to-Peer System in Wireless Ad Hoc Environment

Peer-to-peer is a popular distributed system. With the advancement in mobile technologies, mobile P2P has revealed its attraction. But, the resource constraints such as bandwidth, computing power, energy, etc. and nodes mobility give hard challenges to the researchers. Smart content distribution and efficient content discovery are the heart of P2P protocols. Routing is associated with every task but it is expensive in ad hoc environment. In this paper, we address these issues and present a peer-to-peer system for wireless ad-hoc networks using multi-level hashing to reduce routing overhead. The necessity of multilevel hashing is justified through extensive simulation

A cloud-based serious games framework for obesity

Obesity is becoming an outstanding public health issue in most countries of the world. One innovative approach to address this problem is utilizing serious games which combine exercise and gaming in more attractive manners. While attempts have been made to use gaming to tackle obesity, existing work generally fail to provide the full potential of pervasive exergaming (i.e. anywhere, anytime and from any device) with activity recommendation, evaluation, and in many cases even a suitable context (i.e. temporal, spatial, and vital sign parameters) tracking mechanism. In this paper, we propose a cloud computing-based pervasive serious games framework that can address above issues effectively and thus augments current obesity treatment methods and empower therapists and patients with a comprehensive process of continuous treatment and long-term management of obesity. The design and implementation of the proposed platform for obesity is described and illustrated through the description of a sample serious game.

A Visibility-Driven Approach for Zone Management in Simulations

Massively multi-user simulations aim to support a large number of users while keeping the communication among the parties synchronous and highly interactive. In this paper, we present a collaborative virtual architecture that supports a large number of users by dividing the virtual environment into multiple adjacent hexagonal regions in order to manage the interest of the entities. A master node, called a hybrid node, constructs a Peer-to-Peer (P2P) overlay network to connect and manage nodes that lie in its region. Messaging is done at the application layer rather than the network layer, and a node-joining algorithm is proposed to reflect the underlying network physical topology onto the data distribution pathways among the end hosts to enhance the system performance. In addition, the introduction of a buffer zone between adjacent zones reduces the number of connections and disconnections that occur when a node frequently moves at the boundary of the two zones and provides more resilience to the system. We also attempt to shift the messaging among parties in one region from a zone-based method to a visibility-driven method to refine their interest by enabling message filtering. The effectiveness of this collaboration architecture is tested through a prototype implementation and a high level application.

Zone Based Messaging in Collaborative Virtual Environments

Massively multi-user simulation requires synchronous communication among the parties. In this paper, we present a multiuser collaboration architecture that divides the virtual world in multiple adjacent hexagonal regions in order to properly organize the entities and efficiently manage their liaison. An especial node, named hybrid node, be in charge of each hexagonal region and constructs a data distribution tree at the application layer rather at the network layer. While constructing the data distribution pathways among the end-hosts, protocol focuses to reflect the physical topology onto the overlay network to enhance the system performance. To control the excessive message overhead, necessary messages of a foreign region are only imported when needed to a particular region through a hybrid node. Dynamic adjustment of cheek-in and check-out marks reduces frequent connections and disconnections between a hybrid and an ordinary node, and provides resilience to the system. The effectiveness of this collaboration architecture is tested through the implementation

VeDi: A vehicular crowd-sourced video social network for VANETs

As one of the important members of Internet of Things (IoT), vehicles have seen steep advancement in communication technology.With the advent of Vehicular Ad-Hoc Networks (VANETs), vehicles now can evolve into social interactions to share safety, efficiency, and comfort related messages with other vehicles. In this paper, we study vehicular social network from Social Internet of Things (SIoT) perspective and propose VeDi, a vehicular crowd-sourced video social network for VANETs.When a user shares a video in the VeDi, it can be accessed by other surrounding vehicles. Any social interaction (e.g. view, comment, like) with the video on the roadway are stored in the social network cloud along with the video itself. In VeDi, every vehicle maintains a list of video related metadata (e.g. blur and shakiness) of available videos which are used to selectively retrieve quality videos by surrounding vehicles. We also present a method to determine representative quality scores for an entire video clip using blur and shakiness values. The prototype implementations and experimental results denote that the proposed system can be a viable option to create video social networks such as youtube, vine, and vimeo by employing vehicular crowd.