Efficient Message Composition and Coding for Cooperative Vehicular Safety Applications

Abstract-Emerging applications rely on wireless broadcast to disseminate time-critical information. For example, vehicular networks may exchange vehicle position and velocity information to enable safety applications. The number of nodes in one-hop communication range in such networks can be very large, leading to congestion and undesirable levels of packet collisions. Earlier work has examined such broadcasting protocols primarily from a MAC perspective and focused on selective aspects such as packet error rate. In this work, we propose a more comprehensive metric, the average system information age, which captures the requirement of such applications to maintain current state information from all other nearby nodes. We show that information age is minimized at an optimal operating point that lies between the extremes of maximum throughput and minimum delay. Also, via simulations we show that it cannot be achieved in 802.11 networks through pure MAC techniques such as contention window adaptation. This motivates our design of an applicationlayer broadcast rate adaptation algorithm. It uses local decisions at nodes in the network to adapt their messaging rate to keep the system age to a minimum. Our simulations and experiments with 300 ORBIT nodes show that the algorithm effectively adapts the messaging rates and minimizes the system age.

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“…In [23], the authors propose prediction and efficient messaging to keep the number of transmitted messages in a vehicular network to a minimum.…”

Section: Related Workmentioning

confidence: 99%

Minimizing age of information in vehicular networks

Kaul

Gruteser

Rai

et al. 2011

2011 8th Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks

767

561

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“…The message composition and coding scheme in [10] reduced the bandwidth requirement by merging the packets broadcasted in different VANET applications and by eliminating redundant DEs. On the basis of the analysis of real-time traffic environments or channel status, the adaptive broadcast rate control methods proposed in [11,12] improved channel utilization by reducing the frequency of BSM dissemination.…”

Section: Improving the Channel Utilization Of Basic Safety Message Inmentioning

confidence: 99%

Improving the Channel Utilization of Basic Safety Message in VANETs with Superposition Coded Modulation

Wang

Liu

et al. 2016

TELKOMNIKA

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In this paper, we propose a broadcast scheme to effectively utilize the scarce and shared wireless medium for vehicular ad-hoc networks (VANETs). By using superposition coded modulation (SCM) Keywords: Vehicular ad hoc networks, Superimposed coded modulation, Hierarchical quadrature amplitude modulationCopyright © 2016 Universitas Ahmad Dahlan. All rights reserved. IntroductionAs a promising wireless communication technology for future intelligent transportation systems, vehicular ad-hoc networks (VANETs) [1] have attracted significant attention. By providing high speed and low-latency data links among vehicles, VANETs enable a broad range of applications to enhance driving safety and transportation efficiency [2]. VANETs have been standardized by IEEE 802.11p [3]. However, given the high mobility of vehicles and the timevarying requirements of quality-of-service (QoS), 802.11p-based vehicular communications still suffer from a few open challenges. One of the most important problems is medium access congestion [4]. To enable versatile applications, moving vehicles in VANETs need to periodically broadcast their own status information, i.e., the so-called basic safety message (BSM), which is composed of several data elements (DEs), e.g., position, acceleration, heading, and velocity. The BSM packet has a typical length of 300-400 bytes, is disseminated at a data rate of 6 Mbps, has single-hop coverage of 300-500 m, and has a message rate of 1-10 Hz [5]. The bandwidth of the shared wireless medium is limited, and guaranteeing the required delivery rate and transmission delay of the BSM dissemination of all vehicles is difficult, particularly in dense traffic scenarios. This problem significantly reduces the validity of VANETs in aiding driving. In the current paper, we aim to reduce the bandwidth requirement of BSM broadcast by improving channel utilization.Several studies have addressed this problem in the context of VANETs and have used media-access-control (MAC) methods and information compression methods in the application layer. On one hand, given that the random access scheme employed by the MAC layer of the IEEE 802.11p standard is the main inducement of packet collisions and medium access congestion [6,7], numerous studies have focused on improving channel utilization by novel access schemes [4]. In [8], instead of the random media access, a time-slotted-based MAC scheme was proposed to reduce packet collisions. By dividing the entire service period into the collision detection and collision avoidance phases, a content-based MAC scheme was proposed in [9] to improve the reliability of BSM delivery. On the other hand, considering that the BSM is

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“…Therefore, the latter one is more a network congestion problem. In fact, this congestion problem is well-known and addressed in many works, e.g., [5], [7], and [21]. The main approaches are …”

Section: Summary Of the Evaluationmentioning

confidence: 99%

“…A lane change advisor and a forward collision warning application [1] are two typical examples that rely on this oPBC. These applications require a frequency of 10 messages per second with a maximum no message interval (or a tolerance time window) of [0.3sec,1.0sec] [1,4,5]. In addition, these applications pose a strict fairness requirement on oPBC [6,7], where each vehicle should have equal opportunity for using the shared channel.…”

Section: Introductionmentioning

confidence: 99%