P. Demeester

Co-operative Proxy Caching Algorithms for Time-Shifted IPTV Services

The increasing popularity of multimedia streaming applications introduces new challenges in content distribution networks. Streaming services such as video on demand (VoD) or digital television over the Internet (IPTV) are very bandwidth-intensive and cannot tolerate the high delays and poor loss properties of todays Internet. To solve these problems, caching (a sliding segment of popular streams at proxies could be envisaged. This paper presents a novel caching algorithm and architecture for time-shifted television (tsTV) and its implementation using the IETFs real-time streaming protocol (RTSP). The algorithm uses sliding caching windows with sizes depending on content popularity and/or distance metrics. The caches can work in stand-alone mode as well as in co-operative mode. This paper shows that the network load can already be reduced considerably using small diskless caches, especially when using cooperative caching. A brief overview of the functionality of a prototype proxy implementation is presented as well

Synchronized Interactive Services for Mobile Devices over IPDC/DVB-H and UMTS

DVB-H (digital video broadcasting - handheld) is a technical specification for bringing broadcast services to handheld receivers. IP datacast integrates DVB-H in a hybrid network structure consisting of both a mobile communications network such as GPRS or UMTS and an additional DVB-H downstream. This paper introduces two different approaches for providing interactive services to DVB-H terminals. It is assumed that the terminals dispose of a MIDP compliant runtime environment. The mobile information device profile (MIDP) is a J2ME profile for the use of Java on embedded devices such as mobile phones and PDAs. It is shown how these services can be synchronized with the multimedia data that is broadcasted over the DVB-H channel. A first approach will only use the DVB-H broadcast channel as bearer of both the audiovisual data and the interactivity-related data. The second approach combines the broadcast path with a bidirectional unicast channel in order to implement the interactive services.

A Scalable Low-Power WSAN Solution for Large-Scale Building Automation

Nowadays, wireless sensor and actuator networks are a hot issue because they can enable the Internet of things at little expense. Research activities mainly focus on one aspect of these networks (e.g. energy consumption) neglecting others (e.g. latency, scalability). Aspects like energy reduction, scalability, quality-of-service, and reliability are key requirements in our envisaged heterogeneous applications for sensor and actuator networks in commercial/residential buildings consisting of 1000+ nodes. In this paper, a stack which meets these requirements is proposed. We found that simulations only are not sufficient when developing WSAN solutions. We showed that it is possible to combine low-power with low-latency on large-scale QoS-aware networks.

On the design and implementation of a hierarchical, generic and scalable open architecture for the network management layer

In this paper we address the design and implementation aspects of a generic architecture for the NML (network management layer). The focus in this paper will be on SNMP manageable ADSL/ATM networks. SNMP (simple network management protocol) is a standardized protocol which is supported by almost all current computer network devices. The architecture is compliant with the TINA (Telecommunication Information Network Architecture) recommendations and is implemented based on the CORBA (Common Object Request Broker Architecture) standard. During the design and implementation process, a lot of effort has been devoted to the performance, robustness, persistence and consistence of the distributed software under various load and fault scenarios. The most suitable distributed software techniques, like object transactions, concurrency control, event notification and naming service were used and thoroughly tested on their usability. It is also indicated how the core of the described architecture can be extended towards next-generation IP-based networks.

Enabling Java-based VoIP backend platforms through JVM performance tuning

Software backend platforms are increasingly important in voice over IP (VoIP) service offering. Java, currently the most popular language, and the J2EE platform have evolved toward one of the important software frameworks for designing and implementing business logic on a telecom backend platform. Considering the popularity of Java, the question arises whether Java-based backend platforms can meet the requirements imposed by VoIP applications. SIP is an important example of a signaling protocol often used for VoIP. The SIP Servlet technology was developed for building Java based VoIP services. Therefore, we evaluated both the functionality and performance of the SIP Servlet specification and implementations. The evaluation procedure and the obtained results are reported upon. The influence of the Java virtual machine (JVM) tuning has been investigated and will be detailed in this paper. Moreover, performance of techniques based on the obtained results to optimize the garbage collector tuning of the JVM in general, and more specifically for VoIP related applications, will be presented.

CAM03-4: Management of Time-Shifted IPTV Services through Transparent Proxy Deployment

A recent important evolution in broadband access network design is the deployment of IP aware access network elements, which allow to introduce access network services beyond basic triple-play. The focus of this paper is on the management of time-shifted television (tsTV), an IPTV service which allows for watching the broadcast content at real-time or with a (small) time shift. An architecture for a large-scale tsTV service deployment is presented, using co-operating transparent diskless proxy caches in broadband access networks, with an implementation based on the IETFs real-time streaming protocol (RTSP). Caching algorithms have been designed to take into account content popularity and distance metrics. The algorithms make use of the sliding window concept and calculate the optimal trade-off between bandwidth usage efficiency and storage cost. A prototype implementation of a transparent tsTV proxy is presented and evaluated through performance measurements.

Design of a scalable its architecture based on IP datacast over DVB-H/SH

Intelligent transport systems (ITS) are ICT systems that enable a more efficient and safer traffic through the use of a wide range of diverse technologies. In this paper we present a scalable ITS architecture by making use of the upcoming broadcast standards for mobile television, more specifically DVB-H (digital video broadcasting-handheld) and DVB-SH (satellite services to handhelds). Our integration of ITS services into these broadcast technologies is based on the use of the DVB-IPDC (IP Datacast) specification. This paper presents the challenges for fully deploying ITS data distribution and details how DVB-IPDC mechanisms can be used for the delivery of ITS services.

Efficient management of synchronised interactive services through the design of MCDP middleware

As the variety in network service platforms and end user devices grows rapidly, content providers must constantly adapt their production system to support these new technologies. A factor that highly complicates this process is the need for interactivity. In the Multimedia Content Distribution Platform (MCDP) project, an architecture for deploying highly interactive and synchronised television programs over a diverse collection of broadcast networks and end user devices was developed. It consists of a middleware platform with pluggable support for new broadcast networks and end-user devices. One of the main contributions is the preservation of the synchronisation between the interactive services and the multimedia broadcasts, defined once by the content provider and delivered to a multitude of endusers. The MCDP middleware is currently used as the main platform for the delivery of synchronised, interactive services in a IP Datacast system combining DVB-H and UMTS.