Showing papers by "Gam D. Nguyen published in 2016"
TL;DR: A system in which a sensor sends random status updates over a dynamic network to a monitor is studied, and an approximation that is shown to be close to the simulated age of the status age is provided.
Abstract: This paper focuses on status age, which is a metric for measuring the freshness of a continually updated piece of information (i.e., status) as observed at a remote monitor. In paper, we study a system in which a sensor sends random status updates over a dynamic network to a monitor. For this system, we consider the impact of having messages take different routes through the network on the status age. First, we consider a network with plentiful resources (i.e., many nodes that can provide numerous alternate paths), so that packets need not wait in queues at each node in a multihop path. This system is modeled as a single queue with an infinite number of servers, specifically as an $M/M/\infty $ queue. Packets routed over a dynamic network may arrive at the monitor out of order, which we account for in our analysis for the $M/M/\infty $ model. We then consider a network with somewhat limited resources, so that packets can arrive out of order but also must wait in a queue. This is modeled as a single queue with two servers, specifically an $M/M/2$ queue. We present the exact approach to computing the analytical status age, and we provide an approximation that is shown to be close to the simulated age. We also compare both models with $M/M/1$ , which corresponds to severely limited network resources, and we demonstrate the tradeoff between the status age and the unnecessary network resource consumption.
221 citations
10 Jul 2016
TL;DR: This work introduces a packet deadline as a control mechanism and study its impact on the average age of information for an M/M/1/2 queuing system, analyzing the system for a fixed deadline and derive a mathematical expression for theaverage age.
Abstract: We study the age of information, which is a recently introduced metric for measuring the freshness of a continually updated piece of information as observed at a remote monitor. The age of information metric has been studied for a variety of different queuing systems. In this work, we introduce a packet deadline as a control mechanism and study its impact on the average age of information for an M/M/1/2 queuing system. We analyze the system for a fixed deadline and derive a mathematical expression for the average age. We numerically evaluate the expression and show the relationship of the age performance to that of the M/M/1/1 and M/M/1/2 systems. We show that the system with a deadline constraint can outperform both the M/M/1/1 and M/M/1/2 without such a deadline.
85 citations
01 Nov 2016
TL;DR: This work models a wide variety of queuing systems and control mechanisms in simulation and computed the average age of information, which is a recently introduced metric for measuring the freshness of a continually updated piece of information as observed at a remote monitor.
Abstract: We study the age of information, which is a recently introduced metric for measuring the freshness of a continually updated piece of information as observed at a remote monitor. The age of information metric has been studied for a variety of different queuing systems, and in this work, we consider the impact of buffer sizes, packet deadlines, and packet replacement on the average age of information for queuing systems. We conduct a simulation-based study in which we modeled a wide variety of queuing systems and control mechanisms in simulation and computed the average age of information. We first study the buffer size alone to see how it affects the average age, and then we look at adding a packet deadline for such a system. We consider packet deadline control in the buffer only and in both the buffer and server, and we also compare the performance with a random deadline. We observe how the buffer size and deadline are optimized for the age, and we identify general trends for how to choose values of control mechanisms under different conditions of the packet generation rate. Lastly, we study the ability to replace packets in the buffer with newly arriving packets, and we are particularly interested in whether we can achieve the performance of such a system by controlling buffer size and deadline alone, for systems in which we do not have the ability to do packet replacement.
70 citations
09 May 2016
TL;DR: It is shown that, while a Stackelberg equilibrium always exists, a Nash equilibrium exists only when the wireless channel is affected by fading, and for the case of Rayleigh channel fading, both players have the same power cost at Nash equilibrium.
Abstract: We formulate the interaction between communication and hostile interference in wireless systems as a non-zero-sum two-player game. One player is the transmitter aiming to establish or maintain the communication to its receivers, and the other player is the interferer aiming to prevent or disrupt the communication. The strategy of the transmitter is a transmission power level, while the strategy of the interferer is an interfering power level. We provide closed-form equilibria for both Nash and Stackelberg models. We show that, while a Stackelberg equilibrium always exists, a Nash equilibrium exists only when the wireless channel is affected by fading. In addition, for the case of Rayleigh channel fading, we show that both players have the same power cost at Nash equilibrium.
4 citations