Kuju/kwap, kide/too : La valence des coordonnées spatiales de la topographie Turkana

« […] les sociétés aménagent leur environnement en fonction de l’interprétation qu’elles en font, et réciproquement elles l’interprètent en fonction de l’aménagement qu’elles en font. »(Augustin Berque, 1995, p.15) Introduction Dans cette contribution, je m’attache à déterminer la valence « générique » que certaines composantes de l’espace (tel qu’il est vécu, appréhendé et conçu par les agents) acquièrent dans l’univers culturel turkana. Le terme de « valence » demande quelques éclaircisseme..

Impact of polarization diversity in massive MIMO for industry 4.0

The massive polarimetric radio channel is evaluated in an indoor industrial scenario at 3.5 GHz using a 10×10 uniform rectangular array (URA). The analysis is based on (1) propagation characteristics like the average received gain and the power to interference ratio from the Gram matrix and (2) system-oriented metrics such as sum-rate capacity with maximum-ratio transmitter (MRT). The results clearly show the impact of polarization diversity in an industrial scenario and how it can considerably improve different aspects of the system design. Results for sum-rate capacity are promising and show that the extra degree of freedom, provided by polarization diversity, can optimize the performance of a very simple precoder, the MRT

Polarization properties of specular and dense multipath components in a large industrial hall

This paper presents an analysis of the polarization characteristics of specular and dense multipath components (SMC & DMC) in a large industrial hall based on frequency-domain channel sounding experiments at 1.3 GHz with 22 MHz bandwidth. The RiMAX maximum-likelihood estimator is used to extract the full polarimetric SMC and DMC from the measurement data by taking into account the polarimetric radiating patterns of the dual-polarized antennas. Cross-polar discrimination (XPD) values are presented for the measured channels and for the SMC and DMC separately

Polarimetric distance-dependent models for large hall scenarios

A comprehensive polarimetric distance-dependent model of the power delay profile (PDP) and path gain is proposed. The model includes both specular multipath components (SMCs) and dense multipath components (DMC), the latter being modeled with an exponential and power law. The parameters of the model were estimated from polarimetric measurements of a large hall radio channel under line-of-sight (LOS) conditions at 1.3 GHz with a dedicated procedure. The validity and robustness of the proposed approach are provided by the good agreement between the polarimetric data and models for the investigated transmitter-receiver distance range. Furthermore, the description of the radio channel with path loss models is discussed for cases where the DMC is included, and a two-step method to compute the path loss characteristics directly from the measured data is developed. The results of this contribution highlight the fact that a complete polarimetric description of all propagation mechanisms and related path loss models is desired to design faithful polarimetric radio channel models

Flexible real-time MIMO channel sounder for multidimensional polarimetric parameter estimation

This paper describes the architecture of a fully parallel multiple-input multiple-output (MIMO) channel sounder. It has been designed to give in real-time the full polarimetric channel matrix which is then exploited to display, for example, the bi-directional channel characteristics as the angle of arrival (AoA) and angle of departure (AoD) of the multipath components. This 16x16 sounder, working at a center frequency of 1.35 GHz, uses an OFDM transmission scheme with an 80 MHz bandwidth. Applications of this sounder are then illustrated by studying the outdoor to indoor propagation characteristics

Dense multipath component polarization and wall attenuation at 1.35 GHz in an office environment

This paper presents an analysis of dense multipath components in office meeting rooms. Radio channel sounding measurements at 1.35 GHz were performed with transmitter and receiver in the same room (intra-room) and in adjacent rooms (inter-room). Specular and dense multipath components were estimated with the RiMAX maximum-likelihood algorithm. The dense multipath reverberation characteristics were found to be not significantly different between polarization subchannels for both the intra-room and the inter-room channels, supporting the validity of a scalar dense multipath model. The specular and dense multipath wall attenuation losses were found to be 12.0 and 5.4 dB, respectively

MIMO in tunnel : impact of polarization and array orientation on the channel characteristics

Polarimetric characteristics of the propagation channel in a straight tunnel and in a frequency band around 1.3 GHz, are deduced from measurements using a real-time MIMO channel sounder. Emphasis is on the cross-polarization discrimination factor and, for a MIMO configuration, on the correlation between transmitting and receiving array elements, depending on the array orientation and on the polarization of the transmitting elements

Hybrid virtual polarimetric massive MIMO measurements at 1.35 GHz

The polarimetric massive multiple-input multiple-output (MIMO) radio channel of an indoor line-of-sight scenario is investigated at 1.35 GHz using a real-time radio channel sounder. The 8 x 12 massive MIMO transmitter is constructed using a hybrid architecture including a vertical uniform linear array translated at different horizontal positions forming a virtual, yet realistic, uniform rectangular array. The performance of the system is evaluated with six users distributed in the room for different polarisation schemes and receiver orientations using propagation channel-based metrics (such as receiver spatial correlation and Rician factor) and system-oriented metrics such as sum-rate capacity and signal to interference and noise ratio. The results show a clear dependence of the performance to the polarisation schemes and receiver orientation and showing that when facing the array, cross-polarisation can be very beneficial. Furthermore, it is concluded that the additional degree of freedom brought by the polarisation diversity can contribute to improve spectral efficiency (similar to 20% depending on the configuration), paving the way for further capacity enhancements in massive MIMO systems. It was also found that the receiver spatial correlation can be modelled using a Burr distribution