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‘Always Best Connected’ (ABC) is considered one of the main requirements for next generation networks. The ABC concept allows a person to have access to applications using the devices and network technologies that best suits his or her needs or profile at any time. Clearly, this requires the combination of a set of existing and new technologies, at all levels of the protocol stack, into one integrated system. In this paper, a considerable set of the technologies, that are expected to play a key role towards the ABC vision, are presented. Starting from a reference architecture, the paper describes the required enhancements at certain levels of a traditional protocol stack, as well as technologies for mobility and end-to-end Quality of Service (QoS) support. The paper concludes with a case study that reveals the advantages of the ABC concept. This article replaces a previously published version (Wireless Communications and Mobile Computing; 5(2): 175-191. [DOI: 10.1002/wcm.207]). Retraction notice DOI: 10.1002/wcm.426. Copyright © 2006 John Wiley & Sons, Ltd.

The need for real-time services support over the Internet drives research efforts toward the provisioning of quality of service (QoS) guarantees in IP networks. Among the various aspects of QoS provisioning, QoS state establishment and maintenance in intermediate routers is a major factor, responsible for dynamic resource allocation. The dynamic manipulation of QoS state is possible through the utilization of appropriate QoS signaling that triggers the respective resource allocation in QoS-capable network elements. At first, protocol design assumed a homogeneous underlying network and resulted in end-to-end QoS protocols that applied a specific QoS configuration in all routers along the path. However, the need for accommodating network heterogeneity and flexibility led to a two-tier resource management model that utilizes separate signaling for intra- and inter-domain reservations and requires different signaling processing in domain interior and border routers. This article gives an overview of the QoS signaling protocols designed for the Internet and describes their characteristics. Moreover, the identified protocols are classified depending on their applicability for intra- or inter-domain usage. A comparison of the various protocols based on some common signaling elements is also provided, and future trends in the Internet QoS signaling area are identified.

During the past years, several attempts have been made to develop functionality for mobility management support and QoS provision in the realm of the IP networks. Since IP was not designed to support such functionality, new protocols have been specified and implemented to tackle these issues. Mobile IP is currently the dominant protocol that allows users to retain connectivity while roaming in IP networks. RSVP (Resource reSerVation Protocol) is a well established protocol for reserving network resources to support QoS requirements. These protocols, when deployed separately, can work quite efficiently. However, if their functionality is combined, several inefficiencies arise in terms of QoS deterioration and misuse of the network resources. To minimize these inefficiencies, we propose a new approach that limits mobility and QoS related network modifications inside the domain, in which a user moves. The deployment of our scheme enhances the network resource usage efficiency, while minimizing the duration of the QoS deterioration experienced after a terminal movement. To quantify the advantages of our proposal, we have developed an analytical and a simulation model that we also present in this paper.

The medium access control (MAC) protocol and the underlying traffic scheduling algorithm developed within project Magic WAND (Wireless ATM Network Demonstrator) are presented. Magic WAND is investigating wireless ATM technology for customer premises networks in the framework of the Advanced Communications Technologies and Services (ACTS) program funded by the European Union. The MAC protocol, known as MASCARA, is a hub-based, adaptive TDMA scheme which combines reservation- and contention-based access methods to provide multiple access efficiency and quality-of-service guarantees to wireless ATM terminal connections sharing a common radio channel. The traffic scheduling algorithm is delay-oriented to meet the requirements of the various traffic classes defined by the ATM architecture. The results of the simulation of a number of scenarios are presented to assess the performance of the proposed algorithm.

Researchers are trying to find viable means to support the quality of services for fixed IP users for quite some time. This is a difficult task and even up until today there is no universally accepted mechanism to assure the quality of an operational service from the one end to the other. As years were passing, the need of IP users to keep their network connectivity while on the move, introduced a family of mobility management protocols. However, it was soon noted that these mobility management protocols were inter-working rather inefficiently with the protocols for the quality of services’ support. Thus, new protocols are under design to tackle this issue. However, even with these new protocols there are important issues left unchallenged. This chapter provides all the necessary information for this research area and its current status.

Interactive digital TV is becoming a reality throughout the globe. The most essential aspect of TV broadcasting is enhancing the interaction experience for the viewer. To this end, we explore the potential of introducing semantics in the distribution, processing and usage of the media content. We propose a smart iTV receiver framework capable of collecting, extending and processing semantic metadata related to the broadcast multimedia content. A system architecture is presented along with examples of services to illustrate the combination of semantic metadata content, user preferences and external data sources.

Self-organized and ad hoc communications have many fundamental principles in common and also face similar problems in the domains of security and Quality of Service. Trust management, although still in its first steps, seems capable of dealing with such problems. In this paper we present an integrated trust management framework for self-organized networks. In addition, starting from our experience with the presented framework, we indicate and discuss important research challenges (among them interoperability and integration issues) for the future evolution of the trust-based autonomic computing paradigm. We argue that ontologies can address many of these issues through the semantics they convey.

Mobility and QoS provision are the two most important burdens to solve before IP becomes truly ubiquitous. Mobile IP and RSVP (resource reservation protocol) are the most visible proposals for those problems. Their interoperability, though, is inefficient. To ameliorate the compatibility problem and performance gap, we have proposed the introduction of the RSVP mobility proxy (see Paskalis, S. et al., "RSVP Mobility Proxy", Internet Draft, 2001; Workshop on Wireless Local Networks, 2001). We present a performance evaluation of our scheme versus the plain RSVP operation.

The Internet Protocol suite is emerging as the ubiquitous communication platform for almost every conceivable information exchange. Hence, a worldwide effort to support IP functionality over any existing link technology has started, including the booming wireless industry. DECT is a well-standardized wireless access network technology, supporting high bitrate digital communications. Moreover, IPv6, the emerging Internet Protocol version, extends support for mobility, QoS, wireless nodes and addressing issues. We propose a framework for mobility and QoS provisioning in IPv6 DECT networks. Mobile IPv6 is deployed, in conjunction with standard DECT mobility procedures to provide a suitable environment for Internet users on the move. Furthermore, RSVP is utilized to handle QoS signaling.

Mobile hosts utilize Mobile IP to retain connectivity, while roaming in various networks, and acquire new IP addresses through the mechanisms that Mobile IP supports. One of today's most demanding application requirements is QoS support. RSVP (resource reservation protocol), the protocol implementation of the IETF integrated services architecture (IntServ), cannot handle hosts that change their IP addresses during a connection lifetime, and thus, must re-establish any given reservation states. To overcome this limitation, we propose the adoption of a mobility management scheme, that maintains a single contact IP address throughout the mobility session. Furthermore, we introduce RSVP mobility proxy, an enhanced RSVP enabled border router to deal with QoS signaling at any mobility related network topology modification.

This article has been retracted and replaced. Retraction notice DOI: 10.1002/wcm.426 ‘Always Best Connected’ (ABC) is considered one of the main requirements for next generation networks. The ABC concept allows a person to have access to applications using the devices and network technologies that best suits his or her needs or profile at any time. Clearly, this requires the combination of a set of existing and new technologies, at all levels of the protocol stack, into one integrated system. In this paper, a considerable set of the technologies, that are expected to play a key role towards the ABC vision, are presented. Starting from a reference architecture, the paper describes the required enhancements at certain levels of a traditional protocol stack, as well as technologies for mobility and end-to-end Quality of Service (QoS) support. The paper concludes with a case study that reveals the advantages of the ABC concept. Copyright © 2004 John Wiley & Sons, Ltd.

The mobility management issue in IP access networks can be dealt with from various perspectives. A possible approach includes the use of the session initiation protocol (SIP) and its associate entities for mobility signaling. Following this approach, existing SIP functionality in a network can be reused for mobility management purposes, providing efficient utilization of resources. In this paper we propose the hierarchical mobile SIP (HMSIP) framework, a SIP-based intra-domain mobility management approach that builds upon the general framework of SIP mobility management. The HMSIP agent is introduced as a border network entity providing the necessary mobility functionality. Detailed location and mobility management procedures are presented. The scheme is further enhanced with additional functionality for the support of multiple HMSIP agents across the border of a domain, maintaining a unique contact address throughout a session within the domain.

SIP is evolving as the dominant protocol for multimedia call control in IP networks and is expected to be widely deployed in the near future. Using SIP for supporting mobility in SIP-based networks appears as a very attractive alternative to mobile IP, taking advantage of existing SIP infrastructure and signaling, while avoiding duplication of functionality. However, existing proposals for supporting mobility with SIP are not efficient in handling micro-mobility and do not cater for all types of traffic. In this paper, we introduce hierarchical mobile SIP (HMSIP), for efficient micro-mobility management in SIP environments. HMSIP is a SIP-based scheme that builds on existing IP mobility protocols, aiming at integrating their key concepts in the most beneficial way. Our proposed scheme minimizes the handoff latency and the backbone signaling overhead, while catering for all types of traffic. Moreover, HMSIP can be effectively combined with micro-mobility schemes for QoS flows, producing, thus, a complete micro-mobility solution for SIP flows with QoS guarantees.