Abstract
This paper proposes a new real-time communication scheme for IEEE 802.11e HCCA networks. The proposed communication scheme is called Group Sequential Communication (GSC) and it aims the reduction of the polling overhead associated to the real-time message transmission when using the HCCA function. The GSC scheme partially eliminates the polling inefficiency, by means of a virtual token passing procedure among polled stations. Thus, it reduces the number of exchanged messages between the HCCA controller and the polled stations. The GSC uses a real-time group concept, where the real-time members of the group are granted a sequential access to the communication medium.

Abstract
Due to the increased availability of low Cost network technology, the use of networks to interconnect sensors, actuators and controllers is now widely accepted for the implementation of feedback control systems. To ensure the correct behaviour of such a system, the communication network must provide a reliable and timely communication service. The components with the highest impact on the communication delays are the Medium Access Control (MAC) protocol and the local communication stack. Therefore, an adequate communication stack is of utmost importance to guarantee the timing correctness of the feedback control application. I n this paper, we propose the use of state-of-the-art scheduling algorithms to manage the outgoing queue of the local communication stacks. We demonstrate that it is possible to improve the responsiveness of applications supported by the CAN communication protocol, by using just a light scheduling middleware to adequately schedule each of the outgoing queues. We also show that implementing such middleware even on top of COTS communication hardware permits a substantial reduction in the occurrence of priority inversions in the communication medium, and therefore a decrease in the number of deadline misses for highly loaded network scenarios.

Abstract
The eagerness of Internet and Intranet computing applications has fueled the complexity of the network administration tasks. Nowadays, the network management tools have usually insufficient resources to monitor the complexity of computer networks. The majority of the agents used in computer networks are passive agents, i.e., they have no autonomy, nor participate in the decision-making procedures. We have assessed multiple artificial intelligence (AI) techniques to improve network management systems, according to the autonomic computing concept introduced by IBM. In this paper, we present a methodology for agent's development based on artificial intelligence techniques. The reported results show that the proposed methodology is adequate to support the development of active agents.

Abstract
In this paper we address the P-NET Medium Access Control (MAC) ability to schedule traffic according to its real-time requirements, in order to support real-time distributed applications. We provide a schedulability analysis based on the P-NET standard, and propose mechanisms to overcome priority inversion problems resulting from the use of FIFO outgoing buffers.

Abstract
In this paper, we analyse the ability of Profibus fieldbus to cope with the real-time requirements of a Distributed Computer Control System (DCCS), where messages associated to discrete events must be made available within a maximum bound time. Our methodology is based on the knowledge of real-time traffic characteristics, setting the network parameters in order to cope with timing requirements. Since non-real-time traffic characteristics are usually unknown at the design stage, we consider an operational profile where, constraining non-real-time traffic at the application level we assure that real-time requirements are met. Copyright (C) 1998 IFAC.

Abstract
The DEAR-COTS (Distributed Embedded ARchitecture using Commercial Off-The-Shelf components) architecture provides a COTS-based framework to execute reliable hard real-time applications. To ease the task of building reliable real-time applications on top of COTS components, a simple and transparent programming model is provided, in order that programmers abstract from the low-level implementation details of distribution and replication issues, These issues are only dealt with in a later configuration phase, where the system is configured and distributed over the DEAR-COTS nodes. This paper presents the proposed programming framework, and demonstrates how it can be used to support the transparent replication of software components.