This paper presents a tractable analytical framework for the exact calculation of the probability of node isolation and the minimum node degree distribution when N sensor nodes are independently and uniformly distributed inside a finite square region. The proposed framework can accurately account for the boundary effects by partitioning the square into subregions, based on the transmission range and the node location. We show that for each subregion, the probability that a random node falls inside a disk centered at an arbitrary node located in that subregion can be expressed analytically in closed-form.Using the results for the different subregions, we obtain the exact probability of node isolation and minimum node degree distribution that serves as an upper bound for the probability of k-connectivity.Our theoretical framework is validated by comparison with the simulation results and shows that the minimum node degree distribution serves as a tight upper bound for probability of k-connectivity. The proposed framework provides a very useful tool to accurately account for the boundary effects in the design of finite wireless networks.
Index TermsWireless multi-hop networks, sensor networks, probability of node isolation, node degree distribution, probability of connectivity, k-connectivity.Wireless multi-hop networks, also refereed to as wireless sensor networks and wireless ad hoc networks, consist of a group of sensor nodes deployed over a finite region [1]- [5]. The nodes operate in a decentralized manner without the need of any fixed infrastructure, i.e., the nodes communicate with each other via a single-hop wireless path (if they are in range) or via a multi-hop wireless path. In most of the applications, such wireless networks are formed by distributing a finite (small) number of nodes in a finite area, which is typically assumed to be a square region [6]- [9].Connectivity is a basic requirement for the planning and effective operation of wireless multi-hop networks [10], [11]. The k-connectivity is a most general notion of connectivity and an important characteristic of wireless multi-hop networks [9], [12], [13]. The network being k-connected ensures that there exists at least k independent multi-hop paths between any two nodes. In other words, k-connected network would still be 1-connected if (k − 1) nodes forming the network fail. The probability of node isolation, defined as the probability that a randomly selected node has no connections to any other nodes, plays a key role in determining the overall network connectivity (1-connectivity) [12], [14]. The minimum node degree distribution, which is the probability that each node in the network has at least k neighbours, is crucial in determining the k-connectivity of the network [12].For large-scale wireless sensor networks, assuming Poisson distributed nodes in an infinite area, the connectivity properties such as probability of isolation, average node degree, k-connectivity have been well studied [12], [15]- [21]. When the node locations follow an inf...