JMM Abstracts 

Vol.3 No.2 June 15, 2007   

Editorial (101-102)
        A. Hafid, P. Dini, and K. Liu

 Research articles:

Efficient JPEG2000 Image Transmission Using RCPT Codes Based on Channel Operating Regions (103-117)  
W.-L. Liu and D.G. Daut   
The latest wavelet-based image compression standard, JPEG2000, provides five different progressive modes. Due to the embedded structure used in the codestream syntax, the received bits after transmitting over noisy channels exhibit severe error sensitivity and experience error propagation. In this paper, we propose an efficient JPEG2000 transmission system with separate design methods for image header and data packets. First, two hybrid FEC/ARQ schemes operating over an AWGN channel to realize near error-free transmission of the image header are studied. Second, compressed data packets for different quality layers are protected using an unequal error protection (UEP) method. A set of rate compatible punctured turbo codes (RCPT) is used for forward error correction. In addition to the rate-distortion based rate allocation models, a practical channel segmentation method, which avoids the complicated optimization computation, is presented for code rate selection based on channel operating regions. Using simulation methods, it has been found that the choice of code rates is best guided by segmentation of the SNR into operating regions of the AWGN channel. Experimental results show that the proposed system outperforms systems using equal error protection (EEP) up to $9~dB$ while significantly reducing the computation complexity compared to other UEP systems. One major contribution of the system developed in this paper is the separate treatments of the compressed data in the JPEG2000 codestream. Another contribution is that of a rate selection method for practical channel codes. The resulting system design approach yields improved overall image transmission quality with minimal bandwidth expansion.

Inter-Domain SLS Negotiation for End-to-End UMTS/IMS QoS  (118-130)  
Q.T. Nguyen-Vuong and N. Agoulmine  
The Third Generation Partnership Project (3GPP) has defined an IP Multimedia Subsystem (IMS) for Third Generation (3G) networks. IMS offers services for any type of IP communication that can be provided by third parties independently of underlying access technology. The main challenge for IMS in the future is to support proper interworking with underlying resource management in order to provide the end-to-end QoS assurance. This problem has been addressed by the 3GPP as well as within several projects. However, the proposed solutions have concerned mainly the UMTS Radio Access Network (RAN) and core network domains while the resources at the border with the external IP domains are considered as static. In this paper, we introduce an enhancement of the 3GPP QoS architecture that allows a dynamic and automatic resource provisioning between the UMTS network and the external IP core network to respond to the variable demands of end users. This new mechanism provides the operators a more efficient resource utilization to support a larger number of IMS sessions in a cost-effective manner.

Development of an Open Source IMS Core for Emerging IMS Testbeds, the Academia and Beyond (131-149)  
D. Vingarzan, P. Weik, and T. Magedanz  
The IP Multimedia Subsystem (IMS) as defined by the 3GPP emerges as blueprint for a central architecture to provide Next Generation Network (NGN) services. As an overlay architecture for IP based access networks, it provides standardized interfaces to services which will merge the advantages of traditional telephony networks with the benefits of Internet services.   The {\it Open IMS Core} project of the Fraunhofer Institute FOKUS which is described in this article will start in 2006 as an Open Source initiative targeted at all parties interested in the research development of NGN services and IMS testbeds. The Open IMS Core consists of Call Session Control Functions and a Home Subscriber Server and aims to fill the void in the Open Source software landscape with flexible solutions that have proved their conformance and performance in several national and international R\& D projects.   This article highlights the challenges in the development of the components and provides insights on major implementation details as well as for their performance. Examples of the usage of the Open IMS Core will illustrate how IMS Open Source software helps not only rapid, but also efficient, flexible and powerful design, development and testing of NGN components and services.

Modeling IMS services (150-167)  
E. Bertin, I. Ben Yahia, and N. Crespi  
The IMS offers telecom operators and service providers with the architecture and the procedures to build an open IP-based service infrastructure for deployment of innovative multimedia communication services that integrate telecom and data services. IMS services should be network agnostic and user-centric. This implies a design of IMS services with reusable service enablers. This service design should rely on a common IMS service modeling to ensure interoperability and coherence in the service portfolio of service providers. The article proposes a definition of IMS services and an IMS service modeling that takes into account the user perception of the service and the technical functions carrying out the service.

Resource Management at Connection Level for Multimedia in Wireless/Mobile Cellular Networks (168-178)  
M. Sanabani, S. Shamala, M. Othman, and Z. Zukarnain  
Quality of Service (QoS) guaranteed for multimedia services in next generation wireless/mobile cellular networks poses great challenges due to the scarce radio bandwidth. Therefore, the demand for effective and careful resource allocation is immensely needed. In this paper, we combine Call Admission Control (CAC) and Adaptive Resource Allocation (ARA) algorithm into a novel framework, which we call Connection-Level Resource Controller (CLRC) for provisioning connection-level QoS in Multimedia wireless/mobile cellular networks.  Simulation results show that the framework is able to reduce Handoff Connection Dropping Probability (HCDP) for active users of real time services to zero level. Thus, it satisfies mobile users’ needs resulting in a stable performance levels during heavy load periods. Furthermore, the framework provides a low New Connection Blocking Probability (NCBP), which is translated into high resource utilization. This is a highly desirable property from the service provider point of view.

A Constraint-Based Approach to Dynamically Adapt Multimedia Interfaces (179-196)
J.M. Oliveira and E.M. Carrapatoso    
The concept of the Virtual Home Environment~(VHE) was introduced in mobile networks focusing on the issues surrounding the support of non-standard services for roaming users. This paper presents a proposal to solve the problem of the dynamic adaptation of multimedia services provided by a telecommunications operator in the context of the VHE concept. The paper discusses how the development of multimedia services can be facilitated in this context, how these services can be provided in a heterogeneous world of networks and terminals and how they can be used in a personalized and adaptable way.} {The paper defines a solution for the adaptation of multimedia services based on the real-time generation of user interfaces conditioned by the user context. The solution is mainly characterized by the approach used for resolving the existing dependencies among user interface variables, which is based on the constraints theory, and by the mechanism for acquiring the user context information, which uses the Parlay/OSA interfaces.

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