Redundant data transmission in control/estimation over wireless networks

Abstract

Abstract-In wireless networks the probability of successful communication can be significantly increased by transmitting multiple copies of a same packet. Communication protocols that exploit this by dynamically assigning the number of transmitted copies of the same data can significantly improve the control performance in a networked control system with only a modest increase in the total number of transmissions. In this paper we develop techniques to design communication protocols that exploit multiple packets transmissions while seeking a balance between stability/estimation performance and communication rate. An average cost optimality criterion is employed to obtain optimal protocols. Optimal protocols are also obtained for networks whose nodes are subject to limited computation.

Optimal Redundant Transmission for State Estimation with Packet Drops

“…For reasons of space and to enable comparisons, we consider only the scalar system that was solved by value iteration in Mesquita et al (2009).…”

“…This optimisation problem was first posed in Mesquita et al (2009), where it was formulated in terms of a Markov decision process (MDP). By placing a bound on N t and using value iteration, a numerical procedure for finding the optimal stationary redundant transmission policy was proposed and studied.…”

“…As described in Mesquita et al (2009), this is a Markov chain with dynamics that are independent of the noise process W ∞ 0 and the initial system state X 0 . There are two possible transitions from each possible state of the Markov chain: if transmission were to succeed at time t then the number of past consecutive failures would be reset to 0; otherwise it would increment by 1.…”

“…The number N t = ν(L t ) of packets transmitted at time t is a positive integer and the MDP-based optimisation method studied in Mesquita et al (2009) accomodates this constraint quite easily. However, the explicit cost representation (19) reveals a smooth dependence on ν(0), ν(1), .…”

“…The recent paper Mesquita et al (2009), explored the possibility of transmitting multiple packets per sampling interval, e.g. by use of an orthogonal scheme such as time-or frequencydivision multiplexing (TDM/FDM).…”