Abstract-Existing solutions to the sensor placement problem are based on sensor selection, in which the best subset of available sampling locations is chosen such that a desired estimation accuracy is achieved. However, the achievable estimation accuracy of sensor placement via sensor selection is limited to the initial set of sampling locations, which are typically obtained by gridding the continuous sampling domain. To circumvent this issue, we propose a framework of continuous sensor placement. A continuous variable is augmented to the grid-based model, which allows for off-the-grid sensor placement. The proposed offline design problem can be solved using readily available convex optimization solvers.Index Terms-Convex optimization, joint sparsity, sensor placement, sensor selection, sparse sensing, sparsity.
I. PROBLEM STATEMENT
SENSOR networks are widely used in a variety of applications like environmental monitoring, security and safety, to list a few. Sensors are devices capable of sensing a certain physical phenomenon, processing data, and communicating information to a central unit. Sensors are geographically deployed, and the data acquired by such distributed sensors are often used to solve statistical inference problems like field (e.g., heat, sound) estimation, target localization, and so on.The number of sensors available are often limited due to various factors like availability of physical or data storage space, economical constraints, or due to energy-efficiency reasons. Such a restriction on the number of sensors naturally limits the estimation accuracy. Moreover, selecting different sampling locations for the sensors generally leads to different values of the mean-squared-error. In this article, we are interested in finding the best placement of the sensors such that a desired estimation accuracy is ensured and the number of sensors are as low as possible. In other words, the focus will be on designing a sparse sensing technique to capture only informative data, thereby reducing the costs associated with sensing, data storage, and communication overheads.Let denote the observation signal with a continuousdomain argument, where without loss of generality (w.l.o.g.) denotes the sampling domain. We will restrict ourselves to the one-dimensional spatial domain, but the ideas presented can be applied directly to higher dimensions and even to temporal or spatio-temporal domains 1 . Assume that represents the measured physical field over a continuous one-dimensional space , and it satisfies the linear model (1) where collects the parameters to be estimated, is the known linear model representing the mapping between the parameters and the measurements, and is the noise. For example, in field estimation, might contain the source location and its field intensity. Furthermore, we assume for and . In other words, is completely described by its variation in the interval where we can place the sensors.The fundamental question of interest is-where to place the sensors such that the estimation error is as lo...