A channel model is proposed for the purpose of Monte-Carlo simulation of the frequency-selective (wideband) vector channel between a subscriber and an array-enhanced base station. The model is defined in the baseband ...
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A channel model is proposed for the purpose of Monte-Carlo simulation of the frequency-selective (wideband) vector channel between a subscriber and an array-enhanced base station. The model is defined in the baseband equivalent, discrete-time domain and can therefore be represented as multiple tapped-delay lines (one per diversity branch). It is based on the wide-sense stationary, uncorrelated scattering (WSSUS) assumption and includes not only the radio channel itself but also the transmitting and receiving fixed filters. Each tap coefficient corresponds to a complex gaussian variate which is correlated with other taps at different branches and different delays. The ensemble of tap coefficients constitutes a complex multivariate gaussian process whose statistics can be entirely defined with an analytically-derived lag-delay correlation function (where the term lag denotes spatial separation between two elements).
This paper describes the core of the research work done by the ISR/IST team on cooperative autonomous marine vehicle (AMV) motion control in the scope of the EU Project GREX - coordination and control of cooperating h...
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This paper describes the core of the research work done by the ISR/IST team on cooperative autonomous marine vehicle (AMV) motion control in the scope of the EU Project GREX - coordination and control of cooperating heterogeneous unmanned systems in uncertain environments. The first part of the paper affords the reader a concise introduction to the general problem of cooperative motion control of fleets of AMVs by highlighting illustrative mission scenarios developed collectively by the GREX partners and summarizing the main challenges that they pose to system engineers. This is followed by the description of a general architecture for cooperative autonomous marine vehicle control in the presence of time-varying communication topologies and communication losses that is rooted in a solid control-theoretic framework. The results of simulations with the NetMar SyS - networked marine systems simulator - of ISR/IST are presented and show the efficacy of the algorithms developed for cooperative motion control. The last part of the paper focuses on practical issues and describes the results of tests at sea in the Azores, in the Summer of 2008. The paper concludes with a critical review of the work done and a discussion of theoretical and practical implementation issues that warrant further research and development effort.
Diversity has been used as an effective criteria to optimise test suites for cost-effective testing. Particularly, diversity-based (alternatively referred to as similarity-based) techniques have the benefit of being g...
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Low power wireless communication is essential for the realization of IoT devices connected because radio transceivers are one of the biggest sources of power drains. The low power Wake-up Receiver (WUR) is a promising...
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ISBN:
(纸本)9781538631706
Low power wireless communication is essential for the realization of IoT devices connected because radio transceivers are one of the biggest sources of power drains. The low power Wake-up Receiver (WUR) is a promising technology that can facilitate this by enabling an on-demand and asynchronous wake-up signal. Although the concept of WUR is not new, only recently it has attracted significant attention from industries due to the development of IoT and energy efficiency that has become a design concern in high performance devices. On the other side, there is a strong effort on the minimization of energy consumption and dissipation associated to the analog and digital circuitry. Therefore, the strategy of AC-clocked power supply follows this tendency. In this work, CPAL JK flip-flops are evaluated regarding time violation, either for frequency shifting or phase shifting, considering the evaluate/hold state of the four-phase power-clock.
As an unsupervised learning method, clustering methods plays an important role in quality data mining and various other applications. This work investigates them based on swarm intelligence, introduces a new intellige...
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As an unsupervised learning method, clustering methods plays an important role in quality data mining and various other applications. This work investigates them based on swarm intelligence, introduces a new intelligence algorithm called mussels wandering optimization (MWO) to the data clustering field, and proposes a new clustering algorithm by combining K-means clustering method and MWO. Tests on six standard data sets are performed. The results demonstrate the validity and superiority of the proposed method over some representative clustering ones.
It is well accepted that with even very simple tasks, a user's performance with a cursor control device improves substantially over some period of time before stabilizing. Although no systematic studies are availa...
It is well accepted that with even very simple tasks, a user's performance with a cursor control device improves substantially over some period of time before stabilizing. Although no systematic studies are available concerning how particular attributes of screen or device design affect the rate at which users learn to interact with a system, past studies with input devices have shown that the overall period of time required to learn to physically interact with a system is generally quite short. Hence the lack of attention paid to the “learning” phase with respect to physical interaction is probably justified. For users with mobility impairments, however, not only may the overall physical learning phase be significantly longer than for nondisabled users, but certain features of the interface design may require a longer learning period than others. Depending on how different “initial” performance is from “practiced” performance, systems meant for “walk up and use” or casual use may need to be designed differently to allow easy access for persons with mobility impairments. In addition, adaptive interfaces which change the physical design of features over time as a user becomes more proficient may facilitate access for individuals with impaired motor *** persons with impaired hand and arm function (as a result of spinal cord injury) performed a target acquisition task with five cursor control devices. The task required that the user select targets of different sizes and distances using both “point and click” and “drag” modes of interaction. Time and errors were recorded. The results indicate not only that some physical design attributes negatively effect performance, but that the magnitude of the effects differ for “initial” performance and “practiced” performance. In fact, in some cases attributes which had no effect once performance had asymptoted were shown to have a significant effect on novice performance. Also, some features required significantly long
A frequency domain correlator (FDC) with low-complexity architecture is proposed. This signal processing module is part of FFT-based acquisition stage of a global position system (GPS). The FDC is based on a single re...
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A frequency domain correlator (FDC) with low-complexity architecture is proposed. This signal processing module is part of FFT-based acquisition stage of a global position system (GPS). The FDC is based on a single reconfigurable core capable of computing both decimation in frequency radix-2 (DIF-2) fast Fourier transform (FFT) and decimation in time radix-2 (DIT-2) inverse fast Fourier transform (IFFT). The proposed FDC reuses the reconfigurable core together with appropriate decimation choice, providing an improvement in resource management while avoiding any additional reorder data hardware. Additionally, the FDC architecture shows a great flexibility due to three levels of parameterization which allows to fix the number of complex input samples, data width and word format. The architecture has been implemented in Altera Cyclone II and Xilinx Virtex II Pro for N-points correlation with different word lengths. The simulation and synthesis results shows that the FDC is suitable for performing acquisition stage in GPS, enabling its utilization in software define radios.
We define ’SPEM fragments’ of five methods for developing self-organising multi-agent systems. Self-organising traffic lights controllers provide an application scenario.
We define ’SPEM fragments’ of five methods for developing self-organising multi-agent systems. Self-organising traffic lights controllers provide an application scenario.
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