EMR: A New Metric to Assess the Resilience of Directional mmWave Channels to Blockages

Millimeter-wave (mmWave) communication systems require narrow beams to increase communication range. If the dominant communication direction is blocked by an obstacle, an alternative and reliable spatial communication path should be quickly identified to maintain connectivity. In this paper, we introduce a new metric to quantify the effective multipath richness (EMR) of a directional communication channel by considering the strength and spatial diversity of the resolved paths, while also taking into account beamwidth and blockage characteristics. The metric is defined as a weighted sum of the number of multipath component (MPC) clusters, where clustering is performed based on the cosine-distance between the MPCs that have power above a certain threshold. This process returns a single scalar value for a transmitter (TX)/receiver (RX) location pair in a given environment. It is also possible to represent the EMR of the whole environment with a probability distribution function of the metric by considering a set of TX/RX locations. Using this proposed metric, one can assess the scattering richness of different communication environments to achieve a particular quality of service (QoS). This metric is especially informative and useful at higher frequencies, such as mmWave and terahertz (THz), where the propagation path loss and penetration loss are high, and directional non-light-of-sight (NLOS) communication is critical for the success of the network. We evaluate the proposed metric using our channel measurements at 28 GHz in a large indoor environment at a library setting for LOS and NLOS scenarios.Comment: This work has been submitted to the IEEE for possible publicatio

An experimental investigation into smart radio environments

The potential for dynamically manipulating the wireless channel introduces a revolutionary concept in wireless communication systems known as the smart radio environment (SRE). Recent works have suggested that SREs hold the promise of delivering unprecedented performance benefits to wireless networks. However, a notable gap exists as the overwhelming majority of published works on this subject lack a robust data-driven approach. This investigation into SREs sets out to bridge the chasm between theory and reality. Novel reconfigurable intelligent surface (RIS) prototypes have been developed, whose electromagnetic properties have been designed to efficiently reshape the wireless propagation environment to our advantage. Two extensive field measurement campaigns have been undertaken. A series of measurements obtained within RISaided wireless communication setups throughout an indoor environment reveal that substantial increases in channel gain are possible through strategic placement and configuration of these smart reflectors. Furthermore, frequency domain measurements obtained throughout an existing multi-antenna urban macrocell reveal the potential for contemporary networks to benefit from the SRE concept. The benefits RISs can bring to multiple-input multiple-output (MIMO) outdoor networks are revealed, alongside potentially detrimental impacts in the form of a reduced effective rank and increased interference. This works sheds a light on a number of practical issues, from design and implementation, to real-world deployment of RISs

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression