236 research outputs found
Reducing Message Collisions in Sensing-based Semi-Persistent Scheduling (SPS) by Using Reselection Lookaheads in Cellular V2X
In the C-V2X sidelink Mode 4 communication, the sensing-based semi-persistent
scheduling (SPS) implements a message collision avoidance algorithm to cope
with the undesirable effects of wireless channel congestion. Still, the current
standard mechanism produces high number of packet collisions, which may hinder
the high-reliability communications required in future C-V2X applications such
as autonomous driving. In this paper, we show that by drastically reducing the
uncertainties in the choice of the resource to use for SPS, we can
significantly reduce the message collisions in the C-V2X sidelink Mode 4.
Specifically, we propose the use of the "lookahead," which contains the next
starting resource location in the time-frequency plane. By exchanging the
lookahead information piggybacked on the periodic safety message, vehicular
user equipments (UEs) can eliminate most message collisions arising from the
ignorance of other UEs' internal decisions. Although the proposed scheme would
require the inclusion of the lookahead in the control part of the packet, the
benefit may outweigh the bandwidth cost, considering the stringent reliability
requirement in future C-V2X applications.Comment: Submitted to MDPI Sensor
Analytical Models of the Performance of C-V2X Mode 4 Vehicular Communications
The C-V2X or LTE-V standard has been designed to support V2X (Vehicle to
Everything) communications. The standard is an evolution of LTE, and it has
been published by the 3GPP in Release 14. This new standard introduces the
C-V2X or LTE-V Mode 4 that is specifically designed for V2V communications
using the PC5 sidelink interface without any cellular infrastructure support.
In Mode 4, vehicles autonomously select and manage their radio resources. Mode
4 is highly relevant since V2V safety applications cannot depend on the
availability of infrastructure-based cellular coverage. This paper presents the
first analytical models of the communication performance of C-V2X or LTE-V Mode
4. In particular, the paper presents analytical models for the average PDR
(Packet Delivery Ratio) as a function of the distance between transmitter and
receiver, and for the four different types of transmission errors that can be
encountered in C-V2X Mode 4. The models are validated for a wide range of
transmission parameters and traffic densities. To this aim, this study compares
the results obtained with the analytical models to those obtained with a C-V2X
Mode 4 simulator implemented over Veins
Adaptive RRI Selection Algorithms for Improved Cooperative Awareness in Decentralized NR-V2X
Decentralized vehicle-to-everything (V2X) networks (i.e., C-V2X Mode-4 and
NR-V2X Mode-2) utilize sensing-based semi-persistent scheduling (SPS) where
vehicles sense and reserve suitable radio resources for Basic Safety Message
(BSM) transmissions at prespecified periodic intervals termed as Resource
Reservation Interval (RRI). Vehicles rely on these received periodic BSMs to
localize nearby (transmitting) vehicles and infrastructure, referred to as
cooperative awareness. Cooperative awareness enables line of sight and non-line
of sight localization, extending a vehicle's sensing and perception range. In
this work, we first show that under high vehicle density scenarios, existing
SPS (with prespecified RRIs) suffer from poor cooperative awareness, quantified
as tracking error. Decentralized vehicle-to-everything (V2X) networks (i.e.,
C-V2X Mode-4 and NR-V2X Mode-2) utilize sensing-based semi-persistent
scheduling (SPS) where vehicles sense and reserve suitable radio resources for
Basic Safety Message (BSM) transmissions at prespecified periodic intervals
termed as Resource Reservation Interval (RRI). Vehicles rely on these received
periodic BSMs to localize nearby (transmitting) vehicles and infrastructure,
referred to as cooperative awareness. Cooperative awareness enables line of
sight and non-line of sight localization, extending a vehicle's sensing and
perception range. In this work, we first show that under high vehicle density
scenarios, existing SPS (with prespecified RRIs) suffer from poor cooperative
awareness, quantified as tracking error
- …