Abstract
The 4th Generation of mobile communication networks will use heterogeneous wireless technologies. Voice and low quality video flows will consist of very small FP packets, for which the standard RTP/UDP/IP headers constitute a significant overhead. Considering that the radio resources are scarce, this overhead may be unacceptable and the adoption of header compression mechanisms is desirable. This paper presents a solution for including RoHC header compression mechanisms within 4G networks; the solution is combined with the mechanisms required to provide QoS to the real time flows. © 2005 IEEE.

Abstract
Real-time multimedia applications, such as VoIP, video conferencing or on-line gaming are key applications to the success of 4G. In today's Internet these applications are not subject to congestion control, therefore the growth of popularity of these applications may endanger the stability of the Internet. On the other hand, 4G networks will be much more dynamic due to mobility and multi-homing, and the network conditions may vary abruptly requiring a fast response from the control mechanism. In this article we compare the feedback-based to the reservation-based congestion control approach and focus on the first one, by evaluating some mechanisms with respect to Media Friendliness, Scalability and Dynamic Behaviour. We also present a set of requirements for the ideal congestion control mechanism of real-time flows in 4G networks. © 2005 IEEE.

Abstract
Foreseeing a future where IPv6 and mobile terminals play an important role in public access communication networks, this article introduces a monitoring system capable of identifying relevant traffic flows and tracking them while terminal equipment moves between network attachment points. The mobile flows are characterized and represented so that individual users and flows can perceive the quality of service they receive, and operators can have global traffic views of their heterogeneous access networks.

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Abstract
The development of communications systems demands testing. This paper presents a framework for testing on-the-fly, which relies on the definition of 3 types of tests and on their sequential execution. The ioco conformance relation was considered in order to assign verdicts. A tool prototype is also presented that supports the proposed framework. This tool, named PROFYT, was developed based on the SPIN verifier, and uses communicating FSMs to describe the specification. The test of Conference Protocol implementations was carried out on-the-fly with PROFYT and enabled us to conclude about the benefits of the test methodology proposed.

Abstract