This paper proposes an efficient architecture of a smart public safety platform that involves public professional operators as well as citizens. The proposed system is compliant with the emerging paradigm of a smart city. Its main features are that of monitoring, forecasting and managing emergency situations, arising from environmental disasters or crimes. The proposed platform performs a smart and functional integration of heterogeneous components as a smart data gathering and analysis system, a novel professional communication system, wireless sensor networks and social networks. Each element acts not only as an information collector but has autonomous capabilities to cooperate with the others in order to increase the system efficiency and to reduce the need of human interactions. Finally, the paper highlights some open research issues that represent critical aspects and require additional investigations in order to further improve the performance of the proposed platform.City management, improving quality of offered services by reducing costs, introducing transparency and citizen participation. It has to give the citizens an appropriate, precise and clear information awareness about the correct use of the resources made available by the community and show the possibilities deriving from a direct involvement in civil life. Education, allowing the use of technology to increase access, improving the quality and experience, and reducing costs.Healthcare, allowing more accurate and rapid diagnosis and responses to emergency. Storage and communication platforms permit data to be stored and shared for diagnosis and research. Transportation, improving services, as traffic management in congested areas, and at the same time reducing costs. The goal is to reduce traffic congestion while encouraging the use of public transportation. Environment, improving the environmental conditions, limiting the sources of pollution, increasing the green areas, providing widespread health services, etc. Economy, promoting innovation, productivity, exportation, etc. Public safety, improving the capability of monitoring critical environments and forecasting disasters due to both natural causes or terrorist attacks. It uses real-time information to respond rapidly to emergencies and threats.Among these smart systems, this paper aims to identify an efficient architecture of a smart public safety platform. Indeed, with the huge increase of cities population density, public safety operators need to respond more quickly to emergency situations. It has made essential the need of effective and smart emergency management solutions. New and advanced systems and platforms have to be identified in order to guarantee the safety and well-being of citizens, properly protect services and critical infrastructures. Smart solutions for public safety involves to accomplish complex tasks related to the following:Monitoring and forecasting-adopting specific monitoring activities and analysis of results arising from the monitoring campaigns to prevent natural...
Long Term Evolution (LTE) is considered one of the main candidate to provide wireless broadband access to mobile users. Among main LTE characteristics, flexibility and efficiency can be guaranteed by resorting to suitable resource allocation schemes, in particular by adopting adaptive OFDM schemes. This paper proposes a novel solution to the subcarrier allocation problem for the LTE downlink that takes into account the queues length, the QoS constraints and the channel conditions. Each user has different queues, one for each QoS class, and can transmit with a different data rate depending on the propagation conditions. The proposed algorithm defines a value of each possible sub-carrier assignment as a linear combination of all the inputs following a cross-layer approach. The problem is formulated as a Multidimensional Multiplechoice Knapsack Problem (MMKP) whose optimal solution is not feasible for our purposes due to the too long computing time required to find it. Hence, a novel efficient heuristic has been proposed to solve the problem. Results shows good performance of the proposed resource allocation scheme both in terms of throughput and delay while guarantees fairness among the users. Performance has been compared also with fixed allocation scheme and round robin.
This paper deals with the performance evaluation of Decode and Forward Physical Layer Network Coding schemes under multipath fading channel propagation conditions. Physical Layer Network Coding in Two Way Relay Networks ideally allows to drastically increase the network throughput. However, under the assumption of actual channel propagation conditions, the performance quickly degrades due to high decoding error probability. With the aim of counteracting this drawback, the paper proposes a suitable approach for Orthogonal Frequency Division Multiplexing systems based on a signal pre-equalization technique. Furthermore, in order to lower the decoding error probability, three subcarriers suppression methods are introduced. These methods differ from each other for the performance achieved and the required amount of signaling that nodes have to exchange. An important result obtained here is that the combined use of channel inversion and subcarriers suppression allows to enhance the system reliability with a slight decrease of the throughput.Index Terms-Decode and forward, channel inversion, OFDM, physical layer network coding, subcarriers suppression, two way relay network.
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