Event-Based Adaptive Power Control in Vehicular Networked Systems With State-Dependent Bursty Fading Channels

Abstract

Vehicular Networked Systems (VNS) are mobile ad hoc networks where vehicles exchange information over wireless communication networks to ensure safe and efficient operation. It is, however, challenging to ensure system safety and efficiency as the wireless channels in VNS are often subject to state-dependent deep fades where the data rate suffers a severe drop and changes as a function of vehicle states. Such couplings between vehicle states and channel states in VNS thereby invalidate the use of separation principle to design event-based control strategies. By adopting a state-dependent fading channel model that was proposed to capture the interaction between vehicle and channel states, this paper presents a novel self-triggered scheme under which the VNS ensures efficient use of communication bandwidth while preserving stochastic stability. The novelty of the proposed scheme lies in its use of the state-dependent fading channel model in the event design that enables an adaptive and effective adjustment on transmission frequency in response to dynamic variations on channel and vehicle states. Under the proposed self-triggered scheme, this paper presents a novel source coding scheme that tracks vehicle's states with performance guarantee in the presence of state-dependent fading channels. The efficacy and advantages of the proposed scheme over other event-based strategies are verified through both simulation and experimental results of a leader-follower example. I. INTRODUCTION A. Background and MotivationVehicular Networked Systems (VNS) consist of numerous vehicles coordinating their operations by exchanging information over a wireless radio communication network. VNS represents one type of mobile ad hoc networks that have been deployed in a variety of safety-critical applications, such as intelligent transportation systems with Vehicle to Vehicle (V2V) communication [1], [2], [3], air transportation systems with Automatic Dependent Surveillance-Broadcast (ADS-B) [4], [5] and underwater autonomous vehicles with optic or acoustic communication [6], [7].These vehicular networks, however, are often subject to deep fades where the data rate drops precipitously and remains low over a contiguous period of time. Such deep fades functionally depend on the vehicles' physical states (e.g. intervehicle distance, velocities and heading angles) [8], [3]. Deep fades inevitably cause a significant degradation in the overall vehicular system performance and result in undesirable safety issues, such as vehicle collisions. To maintain system safety and quality performance, VNS may require a large amount of communication resources, such as channel bandwidth, to [30].Another challenge of using the event-based strategies under unreliable communication is that a strictly positive minimum inter-event time (MIET) may not be guaranteed if packet loss or delay is present. As discussed in [31], the loss of MIET inevitably leads to Zeno phenomenon that generates infinite transmissions or samplings with a finite time interval and seriously...