Parameter estimation and channel reconstruction based on compressive sensing for ultra-wideband MB-OFDM systems

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The urban geography of advanced producer service transaction links in Belgium

This paper aims to contribute to the literature on the geography of external relations of cities. Our overall purpose thereby is to tease out some of the basic principles of alternative approaches to the study of the spatiality of urban systems in the context of economic globalization. To this end, we present an empirical analysis of the urban geography of producer service procurement by 118 of the 300 largest companies in Belgium. The main features of this urban geography of service procurement include (i) the dominance of Brussels as a service city ; (ii) the existence of overlapping urban spheres of influence ; and (iii) the presence of transaction links with foreign cities. The results of our analysis also suggest that, in addition to space- and quality-related decision factors, the intra-firm distribution of decision-making power in multinational firms equally influences the spatiality of transaction links. The relevance of these results is discussed in the context of theorizations of urban systems.Dit artikel levert een bijdrage tot de literatuur die de geografie van externe stedelijke relaties bestudeert. Onze overkoepelende doelstelling is om enkele van de basisprincipes bloot te leggen van alternatieve benaderingen in de studie van de geografie van stedelijke systemen in de context van economische mondialisering. De empirische analyse die de basis vormt voor deze studie, bestudeert de stedelijke geografie van transactielinks tussen 118 van de de 300 grootste bedrijven in België en hun voornaamste zakenpartners voor een aantal “productieve diensten”. De belangrijkste kenmerken van deze stedelijke geografie van transactielinks zijn (i) de dominantie van Brussel als dienstenstad ; (ii) de aanwezigheid van overlappende stedelijke invloedssferen ; en (iii) de aanwezigheid van transactielinks met steden in het buitenland. De resultaten van onze analyse geven ook aan dat – naast ruimte- en kwaliteitsgerelateerde beslissingsfactoren – de verdeling van beslissingsbevoegdheden binnen multinationale firma’s eveneens een invloed heeft op de geografie van deze transactielinks. De relevantie van deze resultaten wordt besproken in de context van theorievorming rond stedelijke systemen

An indoor variance-based localization technique utilizing the UWB estimation of geometrical propagation parameters

A novel localization framework is presented based on ultra-wideband (UWB) channel sounding, employing a triangulation method using the geometrical properties of propagation paths, such as time delay of arrival, angle of departure, angle of arrival, and their estimated variances. In order to extract these parameters from the UWB sounding data, an extension to the high-resolution RiMAX algorithm was developed, facilitating the analysis of these frequency-dependent multipath parameters. This framework was then tested by performing indoor measurements with a vector network analyzer and virtual antenna arrays. The estimated means and variances of these geometrical parameters were utilized to generate multiple sample sets of input values for our localization framework. Next to that, we consider the existence of multiple possible target locations, which were subsequently clustered using a Kim-Parks algorithm, resulting in a more robust estimation of each target node. Measurements reveal that our newly proposed technique achieves an average accuracy of 0.26, 0.28, and 0.90 m in line-of-sight (LoS), obstructed-LoS, and non-LoS scenarios, respectively, and this with only one single beacon node. Moreover, utilizing the estimated variances of the multipath parameters proved to enhance the location estimation significantly compared to only utilizing their estimated mean values

Pathways of change : shifting connectivities in the world city network, 2000-08

This is an empirical paper that measures and interprets changes in intercity relations at the global scale in the period 2000-08. It draws on the network model devised by the Globalization and World Cities (GaWC) research group to measure global connectivities for 132 cities across the world in 2000 and 2008. The measurements for both years are adjusted so that a coherent set of services/cities is used. A range of statistical techniques is used to explore these changes at the city level and the regional scale. The most notable changes are: the general rise of connectivity in the world city network; the loss of global connectivity of US and sub-Saharan African cities (Los Angeles, San Francisco and Miami in particular); and, the gain in global connectivity of south Asian, Chinese and eastern European cities (Shanghai, Beijing and Moscow in particular)

The changing geography of globalized service provision, 2000-2008

This empirical paper maps changes in the global geography of advanced producer service provision across major cities in the 2000-2008 period. The analyses are based on a systematic assessment of geographical shifts in the office networks of leading firms in finance, management consultancy, accountancy, advertising and law, using measures of inter-city connectivity. It has been previously shown that there has been a general shift of these services from 'West to East'. In this paper, variations in the degree and pattern of this global shift among the different sectors are described and interpreted. The results point to an inherent complexity in economic globalization that is sometimes overlooked in general descriptions of the meta-process