Jean-Charles Grégoire

IMS Application Servers: Roles, Requirements, and Implementation Technologies

The IP multimedia subsystem (IMS) defines a generic architecture to support communication services over a Session Initiation Protocol (SIP) infrastructure. In the IMS architecture, application servers host and execute the IMS service logic. These servers can be SIP application servers, open services architecture (OSA) application servers, or a customized applications for mobile networks using enhanced logic (Camel) service environment. Some technologies used in telephony and voice-over-IP (VoIP) application servers are also applicable to IMS application servers, but such servers have some unique requirements that could limit the extent to which these technologies can meet them.

Giving users an edge: A flexible Cloud model and its application for multimedia

We present the Edge Cloud architecture and explore how the users experience of the Internet is enhanced through its use, by moving desktop functionality within the network, in the Void environment. We explore how this model allows us to expand the range of benefits of using the Internet Cloud model, especially when it comes to media processing and user customization. A prototype that transcodes audio/video stream inside the Cloud has been implemented and presented. The prototype is deployed in two different environments: in a local lab and in the Amazon EC2 public Cloud. We also study the performance of the prototype by analyzing the inter-arrival jitter.

A framework to use SIP in ad-hoc networks

A rapid increase in wireless communication services has occurred during the last years. Infrastructure-less ad-hoc networks emerge as an interesting option to provide pervasive wireless services, although several challenges must be resolved first. Our paper focuses on issues related to signalling and presence management in mobile wireless ad-hoc networks. We present a framework to use SIP in this kind of networks. The objective of this framework is to allow the users of ad-hoc networks to communicate with each other and exchange instant messages. This framework permits the discovery of participants, the establishment, the publishing and the ending of two-party or multiparty sessions by providing SIP (session initiation protocol) extensions. To cope with the bandwidth limitation problem, it is proposed to unify the network layer routing protocols and the application layer SIP REGISTER methods. Scalability of the framework is improved by introducing a clustering approach that group nodes together into clusters.

IMS for Enterprises

We discuss how the IMS architecture is applicable to the enterprise environment, the relevance it has for enterprise users, different options for integrating private and public IMS infrastructures, and the impact of those options on enterprises and IMS service providers. Similarly, we review IMS architecture, discuss the requirements of enterprise communications systems, and present four possible architectures for the use of IMS by enterprises. We also discuss the possibility of using the service oriented architecture (SOA) to integrate IMS-based enterprise communications systems within enterprise information technology (IT) infrastructure. We have built a softswitch prototype based on the IMS architecture. We describe the implementation and the lessons we learned from this experience.

Low-complexity offline and online clock skew estimation and removal

Packet delay traces are important sources of measurements for analyzing end-to-end performance of computer networks. Due to the lack of tight synchronization between the clocks of end systems, these measurements can be quite inaccurate. Therefore, detection, estimation and removal of clock skew from delay traces is a critical operation to obtain precise measurements of network latencies. In this paper, we propose two new techniques to detect, estimate and remove the clock skew in delay traces. The first technique, named average technique, derives the clock skew estimate by calculating the average of the difference between consecutive packets delay. The second technique, named direct skew removal technique, proceeds by iteratively evaluating a set of possible skew values until the best value is reached.Compared with existing techniques such as linear programming and Convex_Hull, the average technique reduces the complexity of the skew estimation operation. The direct skew removal is more accurate and allows us to obtain delay after skew removal with the same precision as the original traces. Applied to traces that contain clock resets, the direct skew removal also reduces the time complexity of the operation.Clock skew is also present in online delay measurements that are used by real-time endpoints such as audio and video terminals, to determine the buffering delay of received packets and to synchronize streams from different sources. The problem is more obvious when communication sessions last for a long time. Contrary to the offline skew removal, little work has been done on the online skew removal problem. In this paper, we propose two simple algorithms to remove the clock skew from online delay measurements. The first algorithm, named sliding window algorithm, tracks the skew by continually evaluating the variation of the minimum measured delay. The second algorithm, named the combined algorithm, is a mixed approach of the sliding window and the Convex_Hull algorithm proposed elsewhere.

Network Edge Intelligence for the Emerging Next-Generation Internet

Author to whom correspondence should be addressed; E-Mail: islam@emt.inrs.ca;Tel.: (514) 875 1266 ext. 2013; Fax: (514) 875-0344.Received: 9 October 2010; in revised form: 2 November 2010 / Accepted: 3 November 2010 /Published: 5 November 2010Abstract: The success of the Content Delivery Networks (CDN) in the recent years hasdemonstrated the increased benefits of the deployment of some form of “intelligence” withinthe network. Cloud computing, on the other hand, has shown the benefits of economiesof scale and the use of a generic infrastructure to support a variety of services. Followingthat trend, we propose to move away from the smart terminal-dumb network dichotomy toa model where some degree of intelligence is put back into the network, specifically at theedge, with the support of Cloud technology. In this paper, we propose the deployment of anEdge Cloud, which integrates a variety of user-side and server-side services. On the user side,surrogate, an application running on top of the Cloud, supports a virtual client. The surrogatehides the underlying network infrastructure from the user, thus allowing for simpler, moreeasily managed terminals. Network side services supporting delivery of and exploitingcontent are also deployed on this infrastructure, giving the Internet Service Providers (ISP)many opportunities to become directly involved in content and service delivery.Keywords: next-generation Internet; edge network intelligence; Cloud computing;Edge Cloud; overlay; virtualization1. IntroductionOver the past two decades, the Internet has steadily evolved from a closed, research-focused networkthat was primarily used for mail and data transfer to an Internet of things, where services and content

A secure mobile multimedia system to assist emergency response teams

Long wait times after injury and greater distances to travel between accident scenes and medical facilities contribute to increased, possibly unnecessary deaths. This paper describes a mobile emergency system aimed at reducing mortality by improving the readiness of hospital personnel, therefore allowing for more efficient treatment procedures to be performed when the victim arrives. The system is designed to provide a secure transmission of voice, medical data, and video in real-time over third-generation cellular networks. Test results obtained on a commercial network under real-life conditions demonstrate the ability to effectively transmit medical data over 3G networks, making them a viable option available to healthcare professionals.

Feature interaction detection contest of the Fifth International Workshop on feature interactions

Abstract A feature interaction detection contest was held for the Fifth International Workshop on Feature Interactions. The contest had two phases. The first phase required the contestants to analyze interactions among ten features, which were published on 15 February 1998, and to submit their results by 15 July 1998. The second phase, begun on 15 July 1988, required analysis of the interactions among two new features and the original 10, to be submitted by 1 August 1988. Six contestants submitted entries, to be judged in August and September, with the winner to be announced at the workshop. This body of this paper outlines the contest instructions.

SYN Flooding Attack Detection Based on Entropy Computing

We present an original approach to detect SYN flooding attacks from the victims side, by monitoring unusual handshake sequences. Detection is done in real-time to allow quick protection and help guarantee a proper defence. Our detection system uses an entropy measure to detect changes in the balance of TCP handshakes. Experiment results show that our method can detect SYN flooding attacks with better accuracy and robustness than traditional stateless methods, and with manageable overhead.

A feature interaction benchmark for the first feature interaction detection contest

Abstract The feature interaction problem is an inherently difficult problem that affects the entire software life cycle for development of new features for reactive systems. A considerable body of work has been created over the last 10 years addressing this problem. To encourage testing and comparing different approaches to the problem, a feature interaction detection contest was held for the Fifth International Workshop on Feature Interactions in Telecommunications and Software Systems. The contest required the participants to use automated tools to address the feature interaction problem in the requirements phase of feature development. The participants were required to discover the pair-wise feature interactions inherent in the requirements for a collection of features. This special issue of COMNET contains the best papers from the participants in that contest. Although there could be only one winner of the contest, all of the approaches represented here provide useful insight into how to approach the feature interaction problem as it affects the requirements phase of feature development. We hope that subsequent contests will provide opportunities to refine these approaches and to address other phases of feature development.