This paper presents the QoS management for an enhanced VoIP platform based on H.323/MGCP interwor... more This paper presents the QoS management for an enhanced VoIP platform based on H.323/MGCP interworking. This enhanced VoIP platform bears a call agent/gatekeeper that centrally controls one or more media gateways. The QoS management is based on a software module that resides on the call agent, terminates and processes the RTCP stream of each connection and extracts the appropriate results. These results trigger the QoS management software module to instruct the call agent to take the appropriate actions in order to retain or to improve a certain voice quality for the connections. This is achieved by using the MGCP commands of the call agent and by changing the voice codec used on the connection so that the compression used for the voice packets is bigger and the bandwidth consumption is lower. The algorithm proposed for the QoS management is based on the E-model and the R-factor recommended by the ITU-T. This paper presents the structure of the QoS management module, the algorithm itself and outlines the architecture of the enhanced VoIP platform that uses this QoS module.
This paper presents the architecture and design of an enhanced VoIP gateway based on the H.323 pr... more This paper presents the architecture and design of an enhanced VoIP gateway based on the H.323 protocol. The key characteristics of this gateway include: scalability by separating signaling from media transformation and use of media gateway control protocols such as MGCP/MEGACO for communication between the signaling part and the media gateway; lightweight property by using the transport protocol SCTP (stream control transmission protocol) to convey H.323 and MGCP/MEGACO signaling; QoS support through the control of the voice encoding of the VoIP connections. This control is accomplished by estimating the network load and enforces the voice connections to modify the encoding scheme according to the estimated network load.
Abstract This article presents a middleware architecture to support multimedia services across in... more Abstract This article presents a middleware architecture to support multimedia services across intertechnology radio access networks in a secure and seamless manner. The proposed architecture uses the media-independent handover framework, where the handover decision function is based on triggering/collecting statistics from the physical, network, and application layers so that an ongoing multimedia session (video) can be transferred seamlessly and securely (using context transfer) across intertechnology radio ...
Abstract Real-time rate control techniques are necessary to applications such as video streaming ... more Abstract Real-time rate control techniques are necessary to applications such as video streaming in order to adapt video sending rate to network conditions so that the perceived video quality is optimised. In this paper two realtime rate control schemes, are presented. The first one uses the currently available bandwidth in order to perform rate control by selecting the optimum QP (Quantization Parameter).
Abstract The realization of the paradigm of Internet anywhere, anytime and any-device and the dif... more Abstract The realization of the paradigm of Internet anywhere, anytime and any-device and the diffusion of end-user multimedia devices with powerful and userfriendly capabilities, such as smartphones/PDAs, tablet PCs, mobile gaming terminals, and ebook readers, are leading to the proliferation of a wide range of emerging multimedia services, including immersive environments, mobile online gaming, 3D virtual world, book/newspaper consumption, social networking, and IPTV applications, just to cite a few.
This paper describes the design and prototype implementation of a communication platform aiming t... more This paper describes the design and prototype implementation of a communication platform aiming to provide voice and video communication in a distributed networking environment. Performance considerations and network characteristics have also been taken into account in order to provide the set of properties dictated by the sensitive nature and the real-time characteristics of the targeted application scenarios.
Abstract: This document determines the exploitation and marketing strategy of EVOLUTE system and ... more Abstract: This document determines the exploitation and marketing strategy of EVOLUTE system and its components through the analysis of current market opportunities and potential future market opportunities. Furthermore, it performs an initial analysis of the competition in the area and a risk/SWOT analysis for the potential EVOLUTE system and applications. Finally, it presents the dissemination strategy and activities of the EVOLUTE consortium. Keyword list: WLAN, mobility, 3G, SIP, all-IP networks, multimedia services
Abstract This document proposes security extensions that are applicable to P2PSIP overlays that f... more Abstract This document proposes security extensions that are applicable to P2PSIP overlays that follow the base protocol described in the WG leading drafts. The proposed extensions exploit symmetric/asymmetric cryptography and a key refresh mechanism to protect the signaling exchanged between the participating peers in order to enhance the robustness of the system against several types of attacks that are common to peer-to-peer networks.
Abstract The transition to next generation networks is often coupled with the vision of innovativ... more Abstract The transition to next generation networks is often coupled with the vision of innovative services providing personalized and customisable services over an all-IP infrastructure. To enable a smooth transition, next generation all-IP networks need not only support more services but also support emergency services.
Abstract This article presents a multilayer mobility management scheme for all-IP networks where ... more Abstract This article presents a multilayer mobility management scheme for all-IP networks where local mobility movements (micro-mobility) are handled separately from global movements (macro-mobility). Furthermore, a hybrid scheme is proposed to handle macro-mobility (mobile IP for non-real-time services and SIP for real-time services). The internetworking between micromobility and macro-mobility is implemented at an entity called the enhanced mobility gateway.
Abstract—This paper describes the methods devised for cross layer optimisation in ROMEO architect... more Abstract—This paper describes the methods devised for cross layer optimisation in ROMEO architecture. The goal is to provide a top to bottom design taking advantage of the methods developed at each layer. By utilising a network topology leveraging the video coding techniques, ROMEO aims to create a robust and fully optimised delivery system. In addition, novel chunk scheduling techniques that take advantage of both topology and video coding, which are also supported by network monitoring mechanisms, are developed.
Abstract—Cloud Computing is an extremely sophisticated and innovative information system architec... more Abstract—Cloud Computing is an extremely sophisticated and innovative information system architecture often considered to be the future of computing. It allows shared services to become dominant over isolated products and this approach enables corporations to focus on their primary business goals based on a much more efficient usage-based cost model.
Next generation wireless and wireline communication technologies for healthcare applications and ... more Next generation wireless and wireline communication technologies for healthcare applications and services is a new and growing field to facilitate reliable, innovative, personalized, and high-quality healthcare applications and services. Advances in networking infrastructures (eg, HSxPA/WiMax/LTE) are important in order to deliver healthcare applications and services regardless of the patient's physical location.
Abstract Future Media Internet has been designed to overcome current limitations and address emer... more Abstract Future Media Internet has been designed to overcome current limitations and address emerging trends including: network architecture, content and service delivery across heterogeneous networks, diffusion of heterogeneous nodes and devices, mass digitisation, new forms of (3D) user centric/user generated content provisioning, emergence of software as a service and interaction with improved security, trustworthiness and privacy.
Abstract-A key role of IP in next generation mobile networks will be the efficient and cost-effec... more Abstract-A key role of IP in next generation mobile networks will be the efficient and cost-effective interworking between different wireless technologies for the seamless provisioning of current and future applications and services. Various mobility management schemes have been developed for commercial IP-based networks ranging from networklayer solutions (Mobile IP), to application-layer ones (Session Initiation Protocol), and micro-mobility approaches (Cellular IP, HAWAII).
ABSTRACT This paper studies the performance of different packetization schemes (single NAL Unit, ... more ABSTRACT This paper studies the performance of different packetization schemes (single NAL Unit, aggregation packet and Fragmentation Unit) for the emerging H. 264/MVC standard, in terms of overhead, number of decoded frames, error propagation and PSNR using different network conditions (MTU size, packet loss). The experimentation test-bed platform, utilizes the Multi Session Transmission approach for various video packetization options in terms of the number of NAL Units per frame.
Abstract This paper presents a novel chunk-based resource allocation scheme for MIMO-OFDMA multiu... more Abstract This paper presents a novel chunk-based resource allocation scheme for MIMO-OFDMA multiuser downlink channel. In chunk-based resource allocation, a number of contiguous subcarriers of each OFDM symbol are considered as a chunk and resource allocation is performed on chunk-by-chunk basis.
Abstract Telecommunication market today is defined by a plethora of innovative products and techn... more Abstract Telecommunication market today is defined by a plethora of innovative products and technologies that constantly raising the bar of technical feasibility in both hardware and software. Meanwhile users constantly demand better quality and improved attributes for all applications, becoming less and less tolerant in errors or inconsistencies.
This paper presents the QoS management for an enhanced VoIP platform based on H.323/MGCP interwor... more This paper presents the QoS management for an enhanced VoIP platform based on H.323/MGCP interworking. This enhanced VoIP platform bears a call agent/gatekeeper that centrally controls one or more media gateways. The QoS management is based on a software module that resides on the call agent, terminates and processes the RTCP stream of each connection and extracts the appropriate results. These results trigger the QoS management software module to instruct the call agent to take the appropriate actions in order to retain or to improve a certain voice quality for the connections. This is achieved by using the MGCP commands of the call agent and by changing the voice codec used on the connection so that the compression used for the voice packets is bigger and the bandwidth consumption is lower. The algorithm proposed for the QoS management is based on the E-model and the R-factor recommended by the ITU-T. This paper presents the structure of the QoS management module, the algorithm itself and outlines the architecture of the enhanced VoIP platform that uses this QoS module.
This paper presents the architecture and design of an enhanced VoIP gateway based on the H.323 pr... more This paper presents the architecture and design of an enhanced VoIP gateway based on the H.323 protocol. The key characteristics of this gateway include: scalability by separating signaling from media transformation and use of media gateway control protocols such as MGCP/MEGACO for communication between the signaling part and the media gateway; lightweight property by using the transport protocol SCTP (stream control transmission protocol) to convey H.323 and MGCP/MEGACO signaling; QoS support through the control of the voice encoding of the VoIP connections. This control is accomplished by estimating the network load and enforces the voice connections to modify the encoding scheme according to the estimated network load.
Abstract This article presents a middleware architecture to support multimedia services across in... more Abstract This article presents a middleware architecture to support multimedia services across intertechnology radio access networks in a secure and seamless manner. The proposed architecture uses the media-independent handover framework, where the handover decision function is based on triggering/collecting statistics from the physical, network, and application layers so that an ongoing multimedia session (video) can be transferred seamlessly and securely (using context transfer) across intertechnology radio ...
Abstract Real-time rate control techniques are necessary to applications such as video streaming ... more Abstract Real-time rate control techniques are necessary to applications such as video streaming in order to adapt video sending rate to network conditions so that the perceived video quality is optimised. In this paper two realtime rate control schemes, are presented. The first one uses the currently available bandwidth in order to perform rate control by selecting the optimum QP (Quantization Parameter).
Abstract The realization of the paradigm of Internet anywhere, anytime and any-device and the dif... more Abstract The realization of the paradigm of Internet anywhere, anytime and any-device and the diffusion of end-user multimedia devices with powerful and userfriendly capabilities, such as smartphones/PDAs, tablet PCs, mobile gaming terminals, and ebook readers, are leading to the proliferation of a wide range of emerging multimedia services, including immersive environments, mobile online gaming, 3D virtual world, book/newspaper consumption, social networking, and IPTV applications, just to cite a few.
This paper describes the design and prototype implementation of a communication platform aiming t... more This paper describes the design and prototype implementation of a communication platform aiming to provide voice and video communication in a distributed networking environment. Performance considerations and network characteristics have also been taken into account in order to provide the set of properties dictated by the sensitive nature and the real-time characteristics of the targeted application scenarios.
Abstract: This document determines the exploitation and marketing strategy of EVOLUTE system and ... more Abstract: This document determines the exploitation and marketing strategy of EVOLUTE system and its components through the analysis of current market opportunities and potential future market opportunities. Furthermore, it performs an initial analysis of the competition in the area and a risk/SWOT analysis for the potential EVOLUTE system and applications. Finally, it presents the dissemination strategy and activities of the EVOLUTE consortium. Keyword list: WLAN, mobility, 3G, SIP, all-IP networks, multimedia services
Abstract This document proposes security extensions that are applicable to P2PSIP overlays that f... more Abstract This document proposes security extensions that are applicable to P2PSIP overlays that follow the base protocol described in the WG leading drafts. The proposed extensions exploit symmetric/asymmetric cryptography and a key refresh mechanism to protect the signaling exchanged between the participating peers in order to enhance the robustness of the system against several types of attacks that are common to peer-to-peer networks.
Abstract The transition to next generation networks is often coupled with the vision of innovativ... more Abstract The transition to next generation networks is often coupled with the vision of innovative services providing personalized and customisable services over an all-IP infrastructure. To enable a smooth transition, next generation all-IP networks need not only support more services but also support emergency services.
Abstract This article presents a multilayer mobility management scheme for all-IP networks where ... more Abstract This article presents a multilayer mobility management scheme for all-IP networks where local mobility movements (micro-mobility) are handled separately from global movements (macro-mobility). Furthermore, a hybrid scheme is proposed to handle macro-mobility (mobile IP for non-real-time services and SIP for real-time services). The internetworking between micromobility and macro-mobility is implemented at an entity called the enhanced mobility gateway.
Abstract—This paper describes the methods devised for cross layer optimisation in ROMEO architect... more Abstract—This paper describes the methods devised for cross layer optimisation in ROMEO architecture. The goal is to provide a top to bottom design taking advantage of the methods developed at each layer. By utilising a network topology leveraging the video coding techniques, ROMEO aims to create a robust and fully optimised delivery system. In addition, novel chunk scheduling techniques that take advantage of both topology and video coding, which are also supported by network monitoring mechanisms, are developed.
Abstract—Cloud Computing is an extremely sophisticated and innovative information system architec... more Abstract—Cloud Computing is an extremely sophisticated and innovative information system architecture often considered to be the future of computing. It allows shared services to become dominant over isolated products and this approach enables corporations to focus on their primary business goals based on a much more efficient usage-based cost model.
Next generation wireless and wireline communication technologies for healthcare applications and ... more Next generation wireless and wireline communication technologies for healthcare applications and services is a new and growing field to facilitate reliable, innovative, personalized, and high-quality healthcare applications and services. Advances in networking infrastructures (eg, HSxPA/WiMax/LTE) are important in order to deliver healthcare applications and services regardless of the patient's physical location.
Abstract Future Media Internet has been designed to overcome current limitations and address emer... more Abstract Future Media Internet has been designed to overcome current limitations and address emerging trends including: network architecture, content and service delivery across heterogeneous networks, diffusion of heterogeneous nodes and devices, mass digitisation, new forms of (3D) user centric/user generated content provisioning, emergence of software as a service and interaction with improved security, trustworthiness and privacy.
Abstract-A key role of IP in next generation mobile networks will be the efficient and cost-effec... more Abstract-A key role of IP in next generation mobile networks will be the efficient and cost-effective interworking between different wireless technologies for the seamless provisioning of current and future applications and services. Various mobility management schemes have been developed for commercial IP-based networks ranging from networklayer solutions (Mobile IP), to application-layer ones (Session Initiation Protocol), and micro-mobility approaches (Cellular IP, HAWAII).
ABSTRACT This paper studies the performance of different packetization schemes (single NAL Unit, ... more ABSTRACT This paper studies the performance of different packetization schemes (single NAL Unit, aggregation packet and Fragmentation Unit) for the emerging H. 264/MVC standard, in terms of overhead, number of decoded frames, error propagation and PSNR using different network conditions (MTU size, packet loss). The experimentation test-bed platform, utilizes the Multi Session Transmission approach for various video packetization options in terms of the number of NAL Units per frame.
Abstract This paper presents a novel chunk-based resource allocation scheme for MIMO-OFDMA multiu... more Abstract This paper presents a novel chunk-based resource allocation scheme for MIMO-OFDMA multiuser downlink channel. In chunk-based resource allocation, a number of contiguous subcarriers of each OFDM symbol are considered as a chunk and resource allocation is performed on chunk-by-chunk basis.
Abstract Telecommunication market today is defined by a plethora of innovative products and techn... more Abstract Telecommunication market today is defined by a plethora of innovative products and technologies that constantly raising the bar of technical feasibility in both hardware and software. Meanwhile users constantly demand better quality and improved attributes for all applications, becoming less and less tolerant in errors or inconsistencies.
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Papers by Tasos Dagiuklas