6,290 research outputs found
V2X Meets NOMA: Non-Orthogonal Multiple Access for 5G Enabled Vehicular Networks
Benefited from the widely deployed infrastructure, the LTE network has
recently been considered as a promising candidate to support the
vehicle-to-everything (V2X) services. However, with a massive number of devices
accessing the V2X network in the future, the conventional OFDM-based LTE
network faces the congestion issues due to its low efficiency of orthogonal
access, resulting in significant access delay and posing a great challenge
especially to safety-critical applications. The non-orthogonal multiple access
(NOMA) technique has been well recognized as an effective solution for the
future 5G cellular networks to provide broadband communications and massive
connectivity. In this article, we investigate the applicability of NOMA in
supporting cellular V2X services to achieve low latency and high reliability.
Starting with a basic V2X unicast system, a novel NOMA-based scheme is proposed
to tackle the technical hurdles in designing high spectral efficient scheduling
and resource allocation schemes in the ultra dense topology. We then extend it
to a more general V2X broadcasting system. Other NOMA-based extended V2X
applications and some open issues are also discussed.Comment: Accepted by IEEE Wireless Communications Magazin
Ultra-Reliable Low-Latency Vehicular Networks: Taming the Age of Information Tail
While the notion of age of information (AoI) has recently emerged as an
important concept for analyzing ultra-reliable low-latency communications
(URLLC), the majority of the existing works have focused on the average AoI
measure. However, an average AoI based design falls short in properly
characterizing the performance of URLLC systems as it cannot account for
extreme events that occur with very low probabilities. In contrast, in this
paper, the main objective is to go beyond the traditional notion of average AoI
by characterizing and optimizing a URLLC system while capturing the AoI tail
distribution. In particular, the problem of vehicles' power minimization while
ensuring stringent latency and reliability constraints in terms of
probabilistic AoI is studied. To this end, a novel and efficient mapping
between both AoI and queue length distributions is proposed. Subsequently,
extreme value theory (EVT) and Lyapunov optimization techniques are adopted to
formulate and solve the problem. Simulation results shows a nearly two-fold
improvement in terms of shortening the tail of the AoI distribution compared to
a baseline whose design is based on the maximum queue length among vehicles,
when the number of vehicular user equipment (VUE) pairs is 80. The results also
show that this performance gain increases significantly as the number of VUE
pairs increases.Comment: Accepted in IEEE GLOBECOM 2018 with 7 pages, 6 figure
A Two-Stage Allocation Scheme for Delay-Sensitive Services in Dense Vehicular Networks
Driven by the rapid development of wireless communication system, more and
more vehicular services can be efficiently supported via vehicle-to-everything
(V2X) communications. In order to allocate radio resource with the reasonable
implementation complexity in dense urban intersection, a two-stage allocation
algorithm is proposed in this paper, whose main objective is to minimize delay
and ensure reliability. In particular, as for the first stage, the allocation
policy is based on traffic density information (TDI), which is different from
utilizing channel state information (CSI) and queue state information (QSI) in
the second stage. Moreover, in order to reflect the influence of TDI on delay,
a macroscopic vehicular mobility model is employed in this paper. Simulation
results show that the proposed algorithm can acquire an asymptotically optimal
performance with the acceptable complexity
Performance Analysis of Unsupervised LTE Device-to-Device (D2D) Communication
Cellular network technology based device-to-device communication attracts
increasing attention for use cases such as the control of autonomous vehicles
on the ground and in the air. LTE provides device-to-device communication
options, however, the configuration options are manifold (leading to 150+
possible combinations) and therefore the ideal combination of parameters is
hard to find. Depending on the use case, either throughput, reliability or
latency constraints may be the primary concern of the service provider. In this
work we analyze the impact of different configuration settings of unsupervised
LTE device-to-device (sidelink) communication on the system performance. Using
a simulative approach we vary the length of the PSCCH period and the number of
PSCCH subframes and determine the impact of different combinations of those
parameters on the resulting latency, reliability and the interarrival times of
the received packets. Furthermore we examine the system limitations by a
scalability analysis. In this context, we propose a modified HARQ process to
mitigate scalability constraints. Our results show that the proposed reduced
HARQ retransmission probability can increase the system performance regarding
latency and interarrival times as well as the packet transmission reliability
for higher channel utilization
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