| Crisis situations require fast regain of control. Data communications can aid tremendously. Emergency systems (C2000) hardly support data communications. Cellular systems (GPRS) are not reliable enough in emergency situations. Data communication requires significant radio spectrum, which today is divided into small pieces. Regulatory bodies (FCC) recognise that new services require a new approach. Cognitive radio is a paradigm shift in spectrum utilization. This project researches its key technical and legal aspects, and realises a working solution. - Emergency situations need reliable data communications. Large-scale emergencies like the disaster at SE Fireworks in Enschede and the crash of the C-130 Hercules at Eindhoven Airport have strong negative impacts on society. Such emergencies require rapid regain of control to prevent further escalation. This chance for de-escalation is often missed by lack in quality of available information and communication. Investigations into disasters show the critical importance of optimum communication in the minimisation of the human toll. - Future rescue teams use ad-hoc data networks. Large-scale emergencies require multi-disciplinary rescue teams consisting of fire brigade units, multiple ambulances and a significant police force. The unplanned nature prevents planning to ensure availability of communication. The emerging ad-hoc networking technology provides tremendous gains in effectiveness in these ad-hoc situations. The central command can act on near complete information of on-scene events and conditions through sensors, voice and video communication. Such future calamity attack teams form and dismantle networks in a highly dynamic way. Arrival, departure or movement of personnel or equipment will cause restructuring of the network when needed. Special measures ensure reliability of the network in case of malfunctioning of network elements. - The end of fixed spectrum allocation. Data communication requires a significant amount of radio spectrum, while spectrum is scarce. Today's approach divides the spectrum into small pieces, each for a specific purpose. The applications use their spectrum to a limited extent. This leads to the unwanted situation of under-utilization of this scarce public resource. Regulatory bodies (e.g. FCC) recognise the nearly-reached end to this approach, while radio-based communication grows constantly. - Cognitive radio addresses scarceness in spectrum. The FCC actively pursues cognitive radio as a new paradigm in spectrum utilization. A cognitive radio utilizes empty spectrum. It searches for under-utilised spectrum, and adapts its transmission without interfering other users. As spectrum use is by definition dynamic, it adapts very rapidly to changes in spectral usage. Adaptation to spectral utilisation can be in multiple ways. Primary the frequency domain but also the time and space domain are means. Adaptive loading of carriers in combination with adaptive power control can further optimise the communication. Finally interference cancellation and multi-user detection can be added. Cognitive radio is a new technology with both issues in technology and legislation. The FCC investigates rule-making aiming at cognitive radio. In Europe initiatives in this direction are still very premature. - Addressing cognitive radio challenges. This paradigm shift includes various intriguing challenges. First free spectrum, in frequency, time and space, must be identified. The project researches methods that characterize present signals, and integrates knowledge on legislation and sensitivity to interference of these signals. As cognitive radio is not allowed to impact legacy systems, the selection of spectrum will consider the sensitivity of the legacy systems to the transmitted signal. The project researches how adaptive OFDM with its huge freedom is best applied, considering interference, system stability, capacity and complexity. The project also addresses meta-communications, including neighbour discovery with beacons that fulfil the cognitive radio rules, and the communication of transmission parameters. - Experimental research in a heterogeneous reconfigurable platform. Cognitive radio is a complex system combining several non-trivial technologies. To tackle the risk of overlooking crucial details, the project addresses cognitive radio through experimental research. The project regularly realises proposals in a verification platform, and validates the performance of the solutions in experiments. Recent trends towards system-on-the-chip perfectly match cognitive radio, which requires such flexible heterogeneous system that can adapt its communication scheme rapidly to the new conditions. The verification platform consists of an RF front-end, a system-on-the-chip and an application running on an external device. Besides for verifying cognitive radio concepts, the operation system the heterogeneous system-on-the-chip requires is a research topic on its own this project addresses. |
