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Journal of Mobile Multimedia

Editor-in-Chief: Pavlos Lazaridis, University of Huddersfield, UK


ISSN: 1550-4646 (Print Version),

ISSN: 1550-4654 (Online Version)
Vol: 5   Issue: 2

Published In:   June 2009

Publication Frequency: Quarterly


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Analysis of Connectivity and Session Management for Mobile Peer-to-Peer Applications


Otso Kassinen, Timo Koskela, Erkki Harjula, Jukka Riekki, and Mika Ylianttila

University of Oulu, Oulu, Finland

Abstract: [+]    |    Download File [ 475KB ]

Abstract: Mobile applications utilizing wireless networks are growing in popularity as increasingly capable terminals and advanced networking technologies emerge. In order to provide a seamless user experience, applications must be able to rely on an intelligent mobile middleware that hides the complexity of underlying technologies and allows developers to solve application-specific problems instead. A middleware should take care of generic networking functionality such as management of user communities, signalling for sessions, interaction with content-licensing services, and management of the terminal’s networking resources. This paper focuses on two major components of a prototype peer-to-peer networking middleware: a solution for connectivity management and another for session management. First, the connectivity management solution is discussed. The solution formalizes cross-layer resource optimization and employs upgradeable state machines to make connectivity selections based on context data and user preference, aiming to always provide the best connection for different communications and keep the system extensible. Second, the session management solution is discussed. The solution enables installation of missing software dynamically on a terminal when another user proposes a mutual application session. This greatly increases users’ possibilities to initiate sessions with each other. In this paper, design principles behind each of the novel solutions are studied, their prototype implementations are evaluated on the Symbian smartphone platform, and they are contrasted with existing technologies. A lightweight Session Initiation Protocol (SIP) stack has also been implemented as a component for the middleware. Future work concerning the connectivity and session management solutions includes evaluation of the technologies in more realistic settings than was possible within the work for this paper.

Keywords: Mobile middleware, cross-layer optimization, state machines, content distribution

Fault Tolerance in the Mobile Environment


Daniel C. Doolan1, Sabin Tabirca2 and Laurence T. Yang3

1School of Computing, Robert Gordon University Aberdeen, AB25 1HG, United Kingdom
2Department of Computer Science, University College Cork
3Department of Computer Science, St. Francis Xavier University Antigonish, NS B2G 2W5, Canada Cork, Ireland

Abstract: [+]    |    Download File [ 237KB ]

Abstract: In general it is assumed that a parallel program will execute on reliable hardware. A fault tolerant program and underlying infrastructure should be capable of surviving fail- ures such as system crashes and network failures. At the highest level the application should be capable of automatically recovering from a set of faults without any change to the apparent behaviour of the program. The process of checkpointing may be used to allow a program to save its state to persistent storage, abort and restart from the checkpoint. Several fault tolerant MPI implementations are currently in existence, for example MPICH-V is considered to be one of the most complete, featuring checkpointing and message logs to allow aborted processes to be replaced. No matter how sophisti- cated a fault tolerant system may be, it can never be completely relied upon, as there is always the possibility of a complete system failure. It is one thing to develop fault toler- ant applications on high end dedicated clusters and supercomputers, however applying fault tolerance to the realm of mobile parallel computing presents an entire new series of challenges that are inexorably linked with the unpredictable nature of wireless com- munication systems. Two differing strategies for fault tolerance in the mobile Bluetooth wireless environment will be presented and compared to see which should be adopted over another.

Keywords: Fault Tolerance, Mobile Message Passing, Bluetooth

A New Lossy and Lossless Image Representation by using Non-symmetry and Anti-packing Model with Rectangles for Gray Images


Mudar Sarem1, Yun-Ping Zheng2 and Chuan-Bo Chen2

1School of Software Engineering,HuazhongUniversity of Science and Technology, China
2School of Computer Science and Technology,HuazhongUniversity of Science and Technology, China

Abstract: [+]    |    Download File [ 623KB ]

Abstract: With the rapid development of mobile communication systems, demands for the transmission of multimedia information are increasing day by day. The effective transmission of images can be increased by getting smaller image file that is obtained by compression. However, image quality is often sacrificed in the compression process. Therefore, there is a need to represent images with less data storage without sacrificing the image quality. In this paper, inspired by the concept of the packing problem, we present a new Non-symmetry and Anti-packing Model with Rectangles (NAMR) for lossy and lossless image representation in order to represent the pattern more effectively and flexiblely. Also, in this paper, we propose an algorithm of NAMR and analyze the data amount of this algorithm. The theoretical analyses and experimental results presented in this paper show that when the representation method of NAMR is compared with that of the popular linear quadtree, not only can the former reduce the data storage much more effectively than the latter in lossless case, but also the former has a better reconstruction quality than the latter in lossy case.

Keywords: Image representation, anti-packing problem, linear quadtree, non-symmetry and anti-packing model, rectangle subpattern

An Event-Driven Wearable System for Supporting Pit-crew and Audiences on Motorbike Races


Tsutomu Terada1, Masakazu Miyamae2, Yasue Kishino3, Takahito Fukuda2 and Masahiko Tsukamoto1

1Graduate School of Engineering, Kobe University 1-1 Rokkodai, Nada Ward, Kobe, Hyogo 657-8501, Japan
22-4-6 Funakoshi, Chuoh Ward, Osaka, Osaka 540-0036, Japan
3NTT Communication Science Laboratories 2-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237, Japan

Abstract: [+]    |    Download File [ 953KB ]

Abstract: Motorbike racing is one of the most popular motorsports and many fans visit circuits to watch races. However, since audiences and pit crews can only obtain limited information, it is difficult for them to get detailed information about teams except for high ranking teams and few popular teams. To solve this problem, we propose an information browsing system for pit crews and audiences who use wearable computers. This system allows pit crew to browse for various race information easily and effortlessly, and it can entertain audiences much more.

Keywords: Wearable Computing, Motorbike Race

Distributed Information Management and Publish/Subscribe in VANETs


Vivian Prinz, Michele Brocco, and Wolfgang Woerndl

Department of Informatics, Technische Universit¨at M¨unchen, Boltzmannstr. 3 85748 Garching, Germany

Abstract: [+]    |    Download File [ 1338KB ]

Abstract: Wireless communication is particularly powerful in vehicular ad hoc networks (VANETs) as it implies important possibilities to enhance traffic safety. For this purpose, a car-to- car (C2C) communication system should provide distributed information management. For example, it should guarantee the availability of a black ice warning for the duration of its validity. In addition, the Publish/Subscribe (Pub/Sub) paradigm allows for infor- mation filtering and tracking of changes in the information environment. Thus, vehicles could monitor traffic changes, for example.

This article introduces the application of structured peer-to-peer (P2P) algorithms and P2P/Distributed Hash Table (DHT)-based Pub/Sub for the named functionalities. To allow for their application given high mobilities and to provide location-awareness, the vehicular network is segmented into separate, interacting P2P networks. Cars man- age information of their own segment and exchange them between adjacent segments if necessary. The Pub/Sub functionality is built on top of the P2P segments’ DHTs. This way, Pub/Sub can be applied as there is no need to maintain a vehicular broker tree. The proposed solution enables C2C applications to publish information referring to certain areas or validity durations. In addition, they can request, modify and delete this information and solely interested vehicles can be notified about these events.

Keywords: vehicular ad hoc networks, peer-to-peer algorithms, distributed hash tables, publish/subscribe, wireless communication systems, car-to-car communication, car-to- car applications

River Publishers: Journal of Mobile Multimedia