1,721,207 research outputs found
Analytical Description of Access Probability and RRA strategy for UAV-Aided Vehicular Applications
No full textML-Based Channel Parameters Estimation For Sensing Applications in Industrial IoT Scenarios
No full textThis paper analyses an Industrial IoT scenario with sensing capabilities where a set of base stations (BS) is deployed to provide connectivity to devices located over industry assets. The objective of this study is to propose a machine learning (ML)-based channel propagation model which can be applied to sub-6 GHz, mmWaves, and THz frequencies for the purpose of sensing the surrounding environment. The dataset, generated with the 3DScat ray tracing tool and made publicly available, is initially processed by a ML classifier to identify line-of-sight (LoS) and non-LoS (NLoS) links, achieving an accuracy of over 99.1%. Subsequently, the best fit line for both types is derived through regression and it is employed to construct the channel model by extrapolating channel parameters such as the path loss exponent and the standard deviation of shadowing. Finally, we investigate the impact of the industrial layout on channel propagation and network performance, to determine the optimal BS height
L-CSMA: A MAC Protocol for Multihop Linear Wireless (Sensor) Networks
Full text linkWe consider a multi-hop wireless linear network, where multiple nodes are evenly spaced over a straight line. Two scenarios are addressed: a network where only one source generates traffic to be transmitted via multiple hops to the destination, and the case of linear sensor networks, where all nodes in the line generate data. A novel contention-based Medium Access Control (MAC) protocol, L-CSMA, specifically devised for linear topologies, is proposed. CSMA (Carrier Sensing Multiple Access) suffers from the well known hidden/exposed node problems: the scope of L-CSMA is to reduce their impact, while minimising the protocol overhead. L-CSMA assigns different levels of priority to nodes, depending on their positions in the line: nodes closer to destination have higher priority when accessing the channel. The priority is managed by assigning to nodes different durations of the carrier sensing phase. This mechanism speeds up the transmission of packets which are already in the path, making the transmission flow more efficient. Results show that L-CSMA outperforms existing contention-based MAC protocols. A mathematical model to derive the performance in terms of packet success probability and throughput is provided. The key idea of the model is the definition of the generic state at network-level, instead of node-level, and its representation through a set of bits indicating the status (activity or not) of the corresponding link. The model is validated through comparison with simulations
Channel Parameters Extraction: A Comparison Between Reference And Real Industrial Scenarios
No full textThis paper assesses the channel characteristics in an industrial setting for Industrial IoT (IIoT) applications, comparing elementary reference scenarios with real plants, like those of Robopac-Aetna Group and the Bi-Rex pilot line in Italy. Signal propagation inside the facilities is simulated using 3DScat, a ray tracing (RT) tool. The work focuses on the extrapolation of the major large-scale channel parameters, such as the path loss exponent (PLE) and the standard deviation of shadowing, for base station (BS)-to-node and node-to-node communications at sub-6 GHz, mmWaves, and THz frequencies. Results prove that, despite their differing characteristics, the investigated scenarios exhibit similar trends in terms of PLE and shadowing standard deviation as the operating frequency and transmitter height are varied
Body-to-Body Indoor Channel Modeling at 2.45 GHz
No full textThis paper presents an indoor Body-to-Body narrowband channel model based on experimental data, acquired through a real-time dynamic measurement campaign at 2.45 GHz. The radio channel was investigated under different communication conditions, according to the movement performed by some human subjects and to their mutual position. Several node locations were considered, and two antenna types were used to assess the impact of their radiation characteristics on channel properties. For each investigated link, the channel power transfer function was modeled as composed by a channel gain and a small-scale fading contribution, the latter arising from the multipaths due to the environment and the human's motion. The shadowing effect of the body was also evaluated considering that the body itself can act as an obstacle to the communication, according to its spatial orientation. Every model component was characterized for each scenario, highlighting how a specific movement results in different effects on channel dynamic properties
Modeling Query-Based Wireless CSMA Networks Through Stochastic Geometry
No full textA mathematical model to characterise the performance of wireless access networks based on a Carrier Sense Multiple Access (CSMA) mechanism is derived. The model is developed through a statistical description of the interference power coming from stochastic geometry and taking into account the hidden node problem. As an example of specific application of the model, IEEE 802.15.4 standard is considered. Nodes are assumed to be uniformly distributed according to a Poisson point process in a two-dimensional infinite plane. They have to communicate to the network coordinator through direct links (star topology), following a query-based application. The total interference power is modeled considering the actual density of nodes that are simultaneously transmitting. This takes into account the operation of the CSMA with Collision Avoidance algorithm used by nodes to access the channel, according to the IEEE 802.15.4. Results show the impact of nodes density, packets length, and sensing range on the system performance, evaluated in terms of success probability in transmitting packets from nodes to the coordinator
A multi-service wireless lamp post backbone for smart cities - centralized vs distributed control
No full textThis paper proposes an empirically-based methodology
for spatial down-scaling of wireless sensor networks (WSNs).
WSNs are often deployed in environments not easily accessible,
highly unpredictable and where running experiments is generally
very expensive and time consuming. The latter calls for the
need to develop down-scaled testbeds, deployed in a controlled
environment, where tests can be conducted under predictable and
replicable conditions. In this paper we present a methodology
to realise the down-scaling of a real testbed on an experimental
platform developed at the University of Bologna in the framework
of the ”European Laboratory of Wireless Communications for
the Future Internet” (EuWIn). The real testbed we refer to is
composed of 24 devices, deployed on the lamp posts of the small
town of Casalgrande (Italy), running a smart city application.
The proposed procedure for the down-scaling is implemented
and results achieved on the real testbed and those achieved on
EuWIn are compared. The comparison is performed in terms of
network topologies and packet error rate. Results demonstrate
the utility of EuWIn for down-scaling purposes and the efficacy
of the proposed methodology
Monitoring Soil Water Content via Wireless Underground Communication Networks: the Impact of Uncertainty in Soil Textural Parameters
No full textOn the Performance Improvement of a Cellular Network Supported by an Unmanned Aerial Base Station
No full textThis paper studies a cellular network, where base stations move according to traffic/service needs; cov- erage and capacity offered are adaptive to the time-spatial variations of user demand. In particular, we analyze the performance of a network, where a base station is carried by a UAV (Unmanned Aerial Vehicle, sometimes also denoted as drone). The Unmanned Aerial Base Station (UABS) flies over an urban area, offering coverage and capacity to users that are not served by the Terrestrial Base Stations (TBSs); in our scenario we consider in particular video users with stringent requirements in terms of downlink throughput. The paper proposes an approach to design the trajectory of the drone, that accounts for the actual position of users that are unsatisfied by the TBSs. The approach is based on the identification of clusters made of nearby users to be served, and a simple Nearest Neighbor algorithm. The potential improvements in terms of network capacity (sum throughput) and user satisfaction are estimated, in a scenario where the UABS uses a separate band with respect to the TBSs. This performance increase can be seen as an upper bound to the improvements that would be achieved by using the same band, where the UABS would actually interfere with the TBSs
- …
