Abstract
The users of telecommunications services are demanding access to their subscribed services in mobile contexts. This demand leads to the development of mechanisms that enable the transference of service sessions between networks, seamlessly to the user. These mechanisms allow the operator to jointly manage its networks resources, providing a better service to its customers and, simultaneously, increasing its revenue. Starting from the UMTS and WLAN interconnection architecture defined by 3GPP, this paper presents a new strategy for joint radio resource management, suitable for contexts where these networks are interconnected. This strategy bases its decisions on criteria related to user mobility characteristics. The algorithm also introduces the possibility of renegotiating new calls and reallocating running calls from one access network to another. The new radio resource management strategy is compared with two well-known strategies, the former based on coverage area and the later based on load balancing. The comparison studies show the proposed strategy outperforms the other strategies in what concerns call blocking probability and applications QoS support. Besides, the proposed strategy tends to reduce the handoffs between networks.

Abstract
Factors such as the growing number of multimedia terminals, the constant increase of bandwidth available per user, and the large number of existing data sharing applications, are compelling users to generate and distribute their own content to restricted groups of other users. Inorder to support such scenario, we present an IMS-based solution that enables content distribution, in multicast, to groups of users, where the source of the content is also an end-user The proposed solution allows the source of content to configure the service, indicating a list of authorized receivers and both the transmission date and duration. Moreover, the proposed solution also allows the operator to manage the registered user profiles, to impose access control and to validate the configurations submitted by the users.

Abstract

Abstract
The changes in the communication paradigm envisioned for future networks, with peer-to-peer/symmetric attachments gaining momentum and two IP (Internet Protocol) versions coexisting, will pose new challenges to mobile communication networks. Traditional IP auto-configuration mechanisms will not work properly, since they were designed mostly having in mind a client-server/asymmetric attachment model, they assume a single IP version paradigm, and they target the auto-configuration of devices only. The IST Ambient Networks project has introduced a new concept - the Ambient Network - that enables handling every communication entity, either a single device or an entire network, as an Ambient Network (AN). This paper describes a new efficient mechanism, named Basic Connectivity (BC) mechanism, for auto-configuring IP connectivity between attaching ANs. A proof-of-concept prototype, experimental results, and theoretical analysis show that BC suites the future networking paradigm and represents a solution more efficient than the current trial-and-error mechanism for auto-configuring IP connectivity.

Abstract
In beyond 3G networks the user will not be aware of the access network technology used to provide a telecommunications service. Heterogeneous network technologies will be seamlessly integrated in one "common" access network, enabling users to move around and continuously receive their subscribed services. In a commercial environment, this network evolution requires that a telecommunications operator jointly manages its networks resources to improve the service offered to the users and, at the same time, to increase its revenue. Starting from the UMTS and WLAN interconnection architecture defined by 3GPP, this paper analyzes the performance of a new joint radio resource management strategy, comparing it with two well-known strategies used in scenarios where both networks, the UMTS and the WLAN, are interconnected. The new strategy presented in the paper bases its decisions on criteria related to user mobility characteristics and the application characteristics. The strategy also introduces the possibility of renegotiating new calls and reallocating running calls from one access network to another. The performance analysis considers two traffic scenarios. One where only real-time applications are running and other which also introduces TCP applications. The comparison studies show the proposed strategy outperforms the other strategies in what concerns call blocking probability and applications QoS support. Besides, the proposed strategy tends to reduce the handoffs between networks.

Abstract
Header compression techniques such as robust header compression can be used to reduce the overhead of IP-based traffic. Voice over IP may replace voice circuits in the next generations of wireless networks, and it is the type of traffic that benefits most from header compression because its packets have small pay-loads, IEEE 802.11 is a technology that will play an important role in the next generations of wireless networks. The study reported in this article shows that the maximum gain of the RoHC's U-mode when applied to VoIP over IEEE 802.11. is about 23 percent for medium or better voice quality. Values for the RoHC U-mode parameters over IEEE 802.11 are also suggested.