Relay Node Placement in Wireless Sensor Networks

Abstract

A wireless sensor network consists of many low-cost, low-power sensor nodes, which can perform sensing, simple computation, and transmission of sensed information. Long distance transmission by sensor nodes is not energy efficient, since energy consumption is a superlinear function of the transmission distance. One approach to prolong network lifetime while preserving network connectivity is to deploy a small number of costly, but more powerful, relay nodes whose main task is communication with other sensor or relay nodes. In this paper, we assume that sensor nodes have communication range r > 0 while relay nodes have communication range R ≥ r, and study two versions of relay node placement problems. In the first version, we want to deploy the minimum number of relay nodes so that between each pair of sensor nodes, there is a connecting path consisting of relay and/or sensor nodes. In the second version, we want to deploy the minimum number of relay nodes so that between each pair of sensor nodes, there is a connecting path consisting solely of relay nodes. We present a polynomial time 7-approximation algorithm for the first problem, and a polynomial time (5 +)-approximation algorithm for the second problem, where > 0 can be any given constant.

State-of-the-Art Review of Railway Track Resilience Monitoring

“…On the other hand, for transmitting the data from the base station to the server at the control centre, long-range communication such as GPRS, EDGE, UMTS, LTE or satellite can be used. Due to the short transmission range, communications from sensor nodes may not reach the base station, a problem that can be overcome by adopting relay nodes to pass the data from the sensor nodes to the base station [48]. Some of the transmission data techniques available are as follows:…”

PSH: A Pruning and Substitution Based Heuristic Algorithm for Relay Node Placement in Two-Tiered Wireless Sensor Networks

“…Lloyd et al [16] proposed a 7-approximation algorithm for single-tiered WSNs and a (5 þ e)-approximation algorithm for two-tiered WSNs, where e can be any positive constant. Srinivas et al [17] studied the problem of constructing and maintaining the wireless backbone network for the WSNs.…”

“…However, different from the RNP problem that has been extensively studied [8][9][10][11][12][13][14][15][16][17][18][19][20], the works on the DCRNP problem are very limited [21][22][23][24][25]. Moreover, published works only concentrate on the DCRNP problem in single-tiered WSNs.…”

“…Similar to the traditional two-tiered RNP algorithms [16][17][18][19], PSH solves this problem in two phases, i.e., the covering phase and the connecting phase, in which the shortest-path-based algorithm (SPA) and the tree-based connecting algorithm (TCA) are employed, respectively. In the covering phase, SPA deploys RNs to fully cover SNs with respect to delay constraints, and the deployment locations are carefully selected so as to further save RNs deployed in the next phase.…”

Energy Optimisation Schemes for Wireless Sensor Network

“…To prolong network lifetime while meeting certain network specifications, one proposed direction is to deploy a small number of relay nodes (RNs) in the WSN such that they can communicate with the SNs and other RNs [2], [3], [4], [5], [6], [7], [8], [9], [10]. Relay node placement problems can be classified into either single-tiered or two-tiered based on the routing structures [5], [6], [9], [14] and into either connected or survivable based on the connectivity requirements [13], [5], [7], [15]. In single-tiered relay node placement, a SN also forwards packets received from other nodes.…”