35 research outputs found
Performance Evaluation of Adaptive Cooperative NOMA Protocol at Road Junctions
Vehicular communications (VCs) protocols offer useful contributions in the
context of accident prevention thanks to the transmission of alert messages.
This is even truer at road intersections since these areas exhibit higher
collision risks and accidents rate. On the other hand, non-orthogonal multiple
access (NOMA) has been show to be a suitable candidate for five generation (5G)
of wireless systems. In this paper, we propose and evaluate the performance of
VCs protocol at road intersections, named adaptive cooperative NOMA (ACN)
protocol. The transmission occurs between a source and two destinations. The
transmission is subject to interference originated from vehicles located on the
roads. The positions of the interfering vehicles follow a Poison point process
(PPP). First, we calculate the outage probability related to ACN protocol, and
closed form expressions are obtained. Then we compare it with other existing
protocols in the literature. We show that ACN protocol offers a significant
improvement over the existing protocols in terms of outage probability,
especially at the intersection. We show that the performance of ACN protocol
increases compared to other existing protocols for high data rates. The
theoretical results are verified with Monte-Carlo simulations
Interference modeling of wireless cooperative systems
The main goal of this thesis is to study the impact of interference on cooperative vehicular communications (VCs) with the aid of stochastic geometry tools. This thesis also proposes a framework to model interference in cooperative VCs. First, we study the effects of interference dependence on the received node for several transmission schemes, different channel models, and two mobility models. The performance in terms of outage probability is investigated. Second, we investigate the improvement of using non-orthogonal multiple access (NOMA) in the performance in terms of outage probability and average achievable rate for several transmission schemes. The results show that NOMA improves significantly the performance. We also investigate conditions in which NOMA outperforms OMA. Finally, studies are conducted: 1) an adaptive cooperative NOMA protocol is proposed, 2) an analysis of millimeter waves (mmWave) vehicular networks is carried out, 3) extension scenarios are investigated such as multiple relays, multiple hops, or multiples lanes
Technological Trends and Key Communication Enablers for eVTOLs
The world is looking for a new exciting form of transportation that will cut
our travel times considerably. In 2021, the time has come for flying cars to
become the new transportation system of this century. Electric vertical
take-off and landing (eVTOL) vehicles, which are a type of flying cars, are
predicted to be used for passenger and package transportation in dense cities.
In order to fly safely and reliably, wireless communications for eVTOLs must be
developed with stringent eVTOL communication requirements. Indeed, their
communication needs to be ultra-reliable, secure with ultra-high data rate and
low latency to fulfill various tasks such as autonomous driving, sharing a
massive amount of data in a short amount of time, and high-level communication
security. In this paper, we propose major key communication enablers for eVTOLs
ranging from the architecture, air-interface, networking, frequencies,
security, and computing. To show the relevance and the impact of one of the key
enablers, we carried out comparative simulations to show the superiority
compared to the current technology. We compared the usage of an air-based
communication infrastructure with a tower mast in a realistic scenario
involving eVTOLs, delivery drones, pedestrians, and vehicles.Comment: 8 pages, 10 figure
Signalling Design in Sensor-Assisted mmWave Communications for Cooperative Driving
Millimeter-Wave (mmWave) Vehicle-To-Vehicle (V2V) communications are a key enabler for connected and automated vehicles, as they support the low-latency exchange of control signals and high-resolution imaging data for maneuvering coordination.
The employment of mmWave V2V communications calls for Beam Alignment and Tracking (BAT) procedures to ensure that the antenna beams are properly steered during motion. The conventional beam sweeping approach is known to be unsuited for the high vehicular mobility and its large overhead reduces transmission efficiency. A promising solution to reduce BAT signalling foresees the integration of V2V communication systems with on-board vehicle sensors. We focus on a cooperative sensor-assisted architecture for mmWave V2V communications in line of sight, where vehicles exchange the estimate of antenna position and its uncertainty to compute the optimal beam direction and dimension.
We analyze and compare different signalling strategies for sharing the information on antenna estimate, evaluating the tradeoff between signalling overhead and performance loss for different position and uncertainty encoding strategies. Main attention is given to differential quantization on both the antenna position and uncertainty. Analyses over realistic urban mobility trajectories suggest that differential approaches introduce a negligible performance loss while significantly reducing the BAT signalling communication overhead