Minimizing age of information in vehicular networks

Abstract

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.

LUPMAC: A cross-layer MAC technique to improve the age of information over dense WLANs

“…The Age of Information in IEEE 802.11 systems was first addressed in [1]. The authors study the age of information in a vehicular network (VANET) via simulation and with a VANET testbed.…”

“…We extend the work in [1] and [9] with a more practical implementation of their algorithm, in order to apply a more advanced cross layer approach in an IEEE 802.11 MAC. The procedure is summarized in Algorithm 1.…”

“…The concept of the Age of Information (AoI) was first introduced in [1], and then formalized in [2]. This new metric answers the question: how fresh is that particular information stored at the receiver?…”

“…In this paper, we extend the work in [1], [9] with a more practical implementation by introducing a new cross layer approach between the application layer and the MAC layer, called Latest UPdate MAC (LUPMAC), aimed at modifying the existing IEEE 802.11 in order to minimize the average AoI at the receiver end. We let the MAC know about the "freshness" of a packet received from the application layer, along with the particular application that generated it, in order to develop a strategy to minimize the AoI at the receiver.…”

An Efficient Message Dissemination Technique in Platooning Applications

“…The communications requirements of event-driven messages are typically quite different, as jitter is of no interest, but instead a low dissemination delay. Kaul et al [9] identifies the age of periodic beacons in vehicular networks as an important performance metric and propose a rate control algorithm to improve its properties. In [10] several information dissemination protocols for VANETs in general are reviewed and in [11], the dissemination delay in platooning is specifically considered.…”