Item level characterization of mm-wave indoor propagation

According to the current prospect of allocating next generation wireless systems in the underutilized millimeter frequency bands, a thorough characterization of mm-wave propagation represents a pressing necessity. In this work, an “item level” characterization of radiowave propagation at 70 GHz is carried out. The scattering properties of several, different objects commonly present in indoor environment are investigated by means of measurements carried out in an anechoic chamber. The measured data have been also exploited to tune some parameters of a 3D ray tracing model

Evaluating Capacity Development in Planning, Monitoring, and Evaluation: A Case from Agricultural Research

Capacity development has moved to center stage on the agendas of development organizations. As technologies and institutions are changing fast and budgets for overseas development assistance are declining, strengthening the capabilities of individuals, organizations, and institutions is essential to ensure that development efforts are sustainable and poverty is eradicated. Substantial sums are being invested in the development of organizational and institutional capacities. Yet, the design and management of capacity development efforts leaves much to be desired. Few capacity development programs have been systematically and thoroughly evaluated to test their underlying theories and assumptions, document their results, and draw lessons for improving future programs. This report describes the concepts and methods used to evaluate a regional capacity development project in Latin America. The project under study aims to strengthen planning, monitoring, and evaluation (PM&E) in agricultural research organizations in the region. The report outlines the procedures employed in five evaluation studies and summarizes the results of each study. It then presents consolidated findings in response to three evaluation questions: What were the main contributions of the project to agricultural research management? What lessons can be learned to improve the design of future capacity development programs? What lessons can be learned to improve future evaluations of capacity development

Analysis of In-Room mm-Wave Propagation: Directional Channel Measurements and Ray Tracing Simulations

open11siFrequency bands above 6 GHz are being considered for future 5G wireless systems because of the larger bandwidth availability and of the smaller wavelength, which can ease the implementation of high-throughput massive MIMO schemes. However, great challenges are around the corner at each implementation level, including the achievement of a thorough multi-dimensional characterization of the mm-wave radio channel, which represents the base for the realization of reliable and high-performance radio interfaces and system architectures. The main properties of the indoor radio channel at 70 GHz, including angular and temporal dispersion as well as an assessment of the major interaction mechanisms, are investigated in this study by means of UWB directional measurements and ray tracing simulations in a reference, small-indoor office environment.openFuschini, F.; Häfner, S.; Zoli, M.; Müller, R.; Vitucci, E. M.; Dupleich, D.; Barbiroli, M.; Luo, J.; Schulz, E.; Degli-Esposti, V.; Thomä, R. S.Fuschini, F.; Häfner, S.; Zoli, M.; Müller, R.; Vitucci, E. M.; Dupleich, D.; Barbiroli, M.; Luo, J.; Schulz, E.; Degli-Esposti, V.; Thomä, R. S

Directional characterization of the 60 GHz indoor-office channel

Directional, dual-link, quad-polarized 60 GHz channel measurements have been carried out in a small-office environment. Purpose of the measurements is to study the directional properties of the channel in view of future multi-gigabit system adopting beam-forming or macro-diversity solutions. The impact of polarization on the characteristics of the channel is also addressed in the study

Interference mitigation in mm-wave backhaul networks with limited channel-state information

Our goal is to identify if limited channel-state information is sufficient to mitigate interferences between the stations of a wireless mobile backhaul network, which is especially of great importance if the network employs full-duplex operation or terrestrial and satellite links sharing the same spectrum. We analyze and compare the signal-to-interference-and-noise ratio of plain beam steering and zero-forcing beam steering for a millimeter-wave backhaul network with limited channel-state information where only the positions of the stations are known, while buildings and other possible sources of multipath components are unknown. Numerical analyses based on raytracing in a realistic urban scenario reveal that zero-forcing beam steering outperforms plain beam steering by about 12 dB. Furthermore, we compare the steering approaches to block diagonalization with full channel-state information as a reference. For situations with low signal-to-noise ratio as in wide-band communications, zero-forcing beam steering can achieve a similar signal-to-noise-and-interference ratio to block diagonalization. We conclude that knowing the positions of wireless backhaul stations obviates the need for expensive channel estimation

MDD-Enabled Two-Tier Terahertz Fronthaul in Indoor Industrial Cell-Free Massive MIMO

To liberate indoor industrial cell-free mas-sive multiple-input multiple-output (CF-mMIMO) net-works from wired fronthaul, this paper proposes amulticarrier-division duplex (MDD)-enabled two-tierterahertz (THz) fronthaul scheme. In our scheme, twolayers of fronthaul links rely on the mutually orthogonalsubcarrier sets in the same THz band, while accesslinks are implemented over sub-6G band. However, theproposed scheme leads to a complicated mixed-integernonconvex optimization problem incorporating accesspoint (AP) clustering, device selection, the assignmentof subcarrier sets and the resource allocation at boththe central processing unit (CPU) and APs. Hence, inorder to address the formulated problem, we first resortto the low-complexity but efficient heuristic methodsthereby relaxing the involved binary variables. Then,the overall end-to-end optimization is implementedby iteratively optimizing the assignment of subcarriersets and the number of AP clusters. Furthermore, anadvanced MDD frame structure consisting of three par-allel data streams is tailored for the proposed scheme.Simulation results demonstrate the effectiveness of theproposed dynamic AP clustering approach in dealingwith the networks of varying sizes. Moreover, benefit-ing from the well-designed frame structure, MDD iscapable of outperforming TDD in the two-tier fronthaulnetworks. Additionally, the effect of the THz band-width on system performance is analyzed, and it isshown that empowered by sufficient bandwidth, ourproposed two-tier fully-wireless fronthaul scheme canachieve a comparable performance to the fiber-opticbased systems. Finally, the superiority of the proposedMDD-enabled fronthaul scheme is verified in a practicalscenario with realistic ray-tracing simulations.</p

Polarimetric Analysis of mm-Wave Propagation for Advanced Beamforming Applications

Pencil-beam forming techniques based on large antenna arrays are becoming a crucial asset to cope with the very high throughput density requirements and high path-loss constraints of future millimeter-wave gigabit-wireless applications. Directional, polarimetric 60 GHz indoor measurements are used in the present work to modify and calibrate a 3D ray tracing model and in particular to tune the embedded effective-roughness diffuse scattering model. The potential of polarimetric beamforming is then evaluated through system simulation in simple, reference cases using the ray tracing model as a propagation-prediction engine

Millimeter-Wave Propagation: Characterization and modeling toward fifth-generation systems. [Wireless Corner]

The World Radiocommunication Conference 2015 (WRC-15) identified a number of frequency bands between 24 and 86 GHz as candidate frequencies for future cellular networks. In this article, an extensive review of propagation characteristics and challenges related to the use of millimeter wave (mm-wave) in future wireless systems is presented. Reference to existing path-loss models including atmospheric and material attenuation in recommendations of the International Telecommunication Union (ITU) in Geneva, Switzerland, is given, and the need for new multidimensional models and measurements is identified. A description of state-of-the-art mm-wave channel sounders for single and multiple antenna measurements is followed by a discussion of the most recent deterministic, semideterministic, and stochastic propagation and channel models. Finally, standardization issues are outlined with recommendations for future research