Towards Environmental RF-EMF Assessment of mmWave High-Node Density Complex Heterogeneous Environments

The densification of multiple wireless communication systems that coexist nowadays, as well as the 5G new generation cellular systems advent towards the millimeter wave (mmWave) frequency range, give rise to complex context-aware scenarios with high-node density heterogeneous networks. In this work, a radiofrequency electromagnetic field (RF-EMF) exposure assessment from an empirical and modeling approach for a large, complex indoor setting with high node density and traffic is presented. For that purpose, an intensive and comprehensive in-depth RF-EMF E-field characterization study is provided in a public library study case, considering dense personal mobile communications (5G FR2 @28 GHz) and wireless 802.11ay (@60 GHz) data access services on the mmWave frequency range. By means of an enhanced in-house deterministic 3D ray launching (3D-RL) simulation tool for RF-EMF exposure assessment, different complex heterogenous scenarios of high complexity are assessed in realistic operation conditions, considering different user distributions and densities. The use of directive antennas and MIMO beamforming techniques, as well as all the corresponding features in terms of radio wave propagation, such as the body shielding effect, dispersive material properties of obstacles, the impact of the distribution of scatterers and the associated electromagnetic propagation phenomena, are considered for simulation. Discussion regarding the contribution and impact of the coexistence of multiple heterogeneous networks and services is presented, verifying compliance with the current established international regulation limits with exposure levels far below the aforementioned limits. Finally, the proposed simulation technique is validated with a complete empirical campaign of measurements, showing good agreement. In consequence, the obtained datasets and simulation estimations, along with the proposed RF-EMF simulation tool, could be a reference approach for the design, deployment and exposure assessment of the current and future wireless communication technologies on the mmWave spectrum, where massive high-node density heterogeneous networks are expected.

Small batteryless wireless solar powered GPS receivers for subcentimeter land deformation monitoring

<p>We design, implement, and validate a unique permanently deployed land deformation monitoring system using small (brick sized), cheap (approximately $100 USD), batteryless, solar powered singleband GPS wireless sensor nodes. Both hardware and software were designed, implemented, and validated by us. Constraints by our hardware and application prompted us to design a unique distributed relative static positioning algorithm designed for intermittent poor quality phase observable measurements, for sites with high multipath and high node densities requiring good solution accuracies; the static solutions were calculated on a daily basis. Our algorithm used a quarter of the bandwidth that would typically be required for an RF link used for a comparable application. GPS on time was observed to vary greatly from as little as 0.5 hours a day in winter to over 8 hours a day and summer in one of our tests. Typical solution precision was 4 mm 2DRMS. Simulations predicted an undesirable slowly changing solution bias that would repeat every year.</p>

Small batteryless wireless solar powered GPS receivers for subcentimeter land deformation monitoring

<p>We design, implement, and validate a unique permanently deployed land deformation monitoring system using small (brick sized), cheap (approximately $100 USD), batteryless, solar powered singleband GPS wireless sensor nodes. Both hardware and software were designed, implemented, and validated by us. Constraints by our hardware and application prompted us to design a unique distributed relative static positioning algorithm designed for intermittent poor quality phase observable measurements, for sites with high multipath and high node densities requiring good solution accuracies; the static solutions were calculated on a daily basis. Our algorithm used a quarter of the bandwidth that would typically be required for an RF link used for a comparable application. GPS on time was observed to vary greatly from as little as 0.5 hours a day in winter to over 8 hours a day and summer in one of our tests. Typical solution precision was 4 mm 2DRMS. Simulations predicted an undesirable slowly changing solution bias that would repeat every year.</p>

On the node reliability of Harary graphs: an analysis through real-world topologies

The literature on network reliability shows that Harary networks are designed so that the link reliability is maximum in many cases. The following question: ``what are the best topology networks in maximizing node reliability?'' is still open. In this paper, we performed computational experiments with eleven real-world networks and their corresponding Harary graphs. The node reliability of both sets of networks was computed. Computational results point out that the Harary network has a topology with high node reliability if compared to the real-world networks studied.

On the node reliability of Harary graphs: an analysis through real-world topologies

The literature on network reliability shows that Harary networks are designed so that the link reliability is maximum in many cases. The following question: ``what are the best topology networks in maximizing node reliability?'' is still open. In this paper, we performed computational experiments with eleven real-world networks and their corresponding Harary graphs. The node reliability of both sets of networks was computed. Computational results point out that the Harary network has a topology with high node reliability if compared to the real-world networks studied.

Analisis Performa Protokol GPSR Dan GPSR-HLS Pada Jaringan Vehicular Ad hoc Network (VANET)

Salah satu karakteristik utama jaringan VANET yaitu kecepatan node yang tinggi sehingga menyebabkan topologi jaringan berubah secara cepat. Hal ini menjadi sebuah kendala dalam pengiriman paket data antara satu node dengan node lainnya. Tantangan yang dihadapi dalam VANET adalah pemilihan protokol routing yang tepat sesuai dengan skenario yang ada. Jenis protoko routing VANET dapat dikategorikan menjadi beberapa jenis yaitu protokol berbasis topologi, geografis, cluster, broadcast, dan geocast. Greedy Perimeter Stateless Routing (GPSR) adalah contoh protokol routing geografis yang menggunakan posisi node secara geografis untuk menentukan tujuan. Performa yang ditunjukkan protokol GPSR pada penelitian sebelumnya menunjukkkan performa yang cukup baik, tetapi masih ada kelemahan dalam mekanisme recovery pengiriman paket data. Metode yang bisa digunakan untuk menangani permasalahan tersebut adalah menggunakan Hierarchical Location Service (HLS) yaitu sebuah layanan untuk menentukan posisi node berdasarkan hierarki. Pengujian dengan skenario urban di Kota Malang berdasarkan kecepatan maksimal node, jumlah node, dan ukuran paket data menunjukkan performa protokol GPSR-HLS mengalami peningkatan dalam jumlah paket data yang diterima di node penerima hingga di atas 95% pada ketiga skenario.One of the main characteristics of VANET networks is the high node speed, which causes the network topology to change rapidly. This becomes an obstacle in sending data packets between one node and another node. The challenge faced in VANET is choosing the right routing protocol in accordance with the existing scenario. Types of VANET routing protocols can be categorized into several types, namely topology, geographic, cluster, broadcast and geocast based protocols. Greedy Perimeter Stateless Routing (GPSR) is an example of a geographical routing protocol that uses the position of a node geographically to determine its destination. The performance shown by the GPSR protocol in previous studies shows a fairly good performance, but there are still weaknesses in the recovery mechanism of sending data packets. The method that can be used to deal with these problems is to use Hierarchical Location Service (HLS), which is a service to determine the position of a node based on a hierarchy. Testing with urban scenarios in Malang based on the maximum node speed, number of nodes, and data packet size shows the performance of the GPSR-HLS protocol has increased in the number of data packets received at the receiving node to above 95% in all three scenarios.

Performance Evaluation and Interference Characterization of Wireless Sensor Networks for Complex High-Node Density Scenarios

The uncontainable future development of smart regions, as a set of smart cities’ networks assembled, is directly associated with a growing demand of full interactive and connected ubiquitous smart environments. To achieve this global connection goal, large numbers of transceivers and multiple wireless systems will be involved to provide user services and applications anytime and anyplace, regardless the devices, networks, or systems they use. Adequate, efficient and effective radio wave propagation tools, methodologies, and analyses in complex indoor and outdoor environments are crucially required to prevent communication limitations such as coverage, capacity, speed, or channel interferences due to high-node density or channel restrictions. In this work, radio wave propagation characterization in an urban indoor and outdoor wireless sensor network environment has been assessed, at ISM 2.4 GHz and 5 GHz frequency bands. The selected scenario is an auditorium placed in an open free city area surrounded by inhomogeneous vegetation. User density within the scenario, in terms of inherent transceivers density, poses challenges in overall system operation, given by multiple node operation which increases overall interference levels. By means of an in-house developed 3D ray launching (3D-RL) algorithm with hybrid code operation, the impact of variable density wireless sensor network operation is presented, providing coverage/capacity estimations, interference estimation, device level performance and precise characterization of multipath propagation components in terms of received power levels and time domain characteristics. This analysis and the proposed simulation methodology, can lead in an adequate interference characterization extensible to a wide range of scenarios, considering conventional transceivers as well as wearables, which provide suitable information for the overall network performance in crowded indoor and outdoor complex heterogeneous environments.

Genetic and morphological variability among the populations assigned to the genus Tropiocolotes Peters, 1880 (Squamata: Gekkonidae) in south Iran

Geckos of the genus Tropiocolotes are known from Africa through the Middle East to Iran and currently include ten recognized species. Recently Tropiocolotes naybandensis was described from Iran based on morphological data. Here, we confirm the taxonomic status of this species using both molecular and morphological data, and compare it with other populations of Tropiocolotes from Iran. A distinct new clade with high node support from southern Iran shows high genetic divergence from the clade of T. naybandensis and T. steudneri from Africa. Based on morphological examinations, three meristic characters differentiate the two clades: (1) number of gulars; (2) number of subdigital lamellae under first toe; (3) number of postmental scales. Data from two mtDNA genes (16S rRNA and COI) indicate mean genetic divergences for 16S and COI between T. naybandensis and a population from Bandar-e Lengeh of 3.8% and 6.2%, respectively. In addition, the genetic divergences between these two groups and a sample of T. steudneri from Egypt are 10.8% and 10.1% for 16S and 18% and 16.7% for COI, respectively. We thus confirm the specific status of T. naybandensis and present evidence for the existence of a new species level taxon of Tropiocolotes in south Iran.