On the Displacement for Covering a $d-$dimensional Cube with Randomly Placed Sensors

TL;DR

This paper investigates the optimal movement of randomly placed sensors in a d-dimensional cube to achieve full coverage with minimal total displacement, revealing a tradeoff between sensing radius, number of sensors, and movement cost.

Contribution

It introduces algorithms that optimize sensor repositioning with respect to total movement, demonstrating bounds based on sensing radius and number of sensors in high-dimensional spaces.

Findings

Expected movement scales as $O(n^{1-rac{a}{2d}})$ for certain sensing radii.

Expected movement scales as $O(n^{1-rac{a}{2d}}(rac{ ext{ln} n}{n})^{a/2d})$ for larger sensing radii.

Simulation results support the theoretical bounds and algorithm effectiveness.

Abstract

Consider $n$ sensors placed randomly and independently with the uniform distribution in a $d-$dimensional unit cube ($d\ge 2$). The sensors have identical sensing range equal to $r$, for some $r >0$. We are interested in moving the sensors from their initial positions to new positions so as to ensure that the $d-$dimensional unit cube is completely covered, i.e., every point in the $d-$dimensional cube is within the range of a sensor. If the $i$-th sensor is displaced a distance $d_i$, what is a displacement of minimum cost? As cost measure for the displacement of the team of sensors we consider the $a$-total movement defined as the sum $M_a:= \sum_{i=1}^n d_i^a$, for some constant $a>0$. We assume that $r$ and $n$ are chosen so as to allow full coverage of the $d-$dimensional unit cube and $a > 0$. The main contribution of the paper is to show the existence of a tradeoff between the $d-$dimensional cube, sensing radius and $a$-total movement. The main results can be summarized as follows for the case of the $d-$dimensional cube. If the $d-$dimensional cube sensing radius is $\frac{1}{2n^{1/d}}$ and $n=m^d$, for some $m\in N$, then we present an algorithm that uses $O\left(n^{1-\frac{a}{2d}}\right)$ total expected movement (see Algorithm 2 and Theorem 5). If the $d-$dimensional cube sensing radius is greater than $\frac{3^{3/d}}{(3^{1/d}-1)(3^{1/d}-1)}\frac{1}{2n^{1/d}}$ and $n$ is a natural number then the total expected movement is $O\left(n^{1-\frac{a}{2d}}\left(\frac{\ln n}{n}\right)^{\frac{a}{2d}}\right)$ (see Algorithm 3 and Theorem 7). In addition, we simulate Algorithm 2 and discuss the results of our simulations.