Location Discovery and Error Analysis of Wireless Sensor Networks Based on Difference of Arrival Time of Beacon Signals

Nodes of wireless sensor networks are characterized with energy constraint, difficult to implement time synchronization, random deployment etc. Range measurement and location discovery principle of several methods, such as RSSI, ToA, TDoA and AoA are briefly introduced. Afterwards, a novel location discovery algorithm which is based on difference of arrival time of beacon signals is proposed. There is no requirement of time synchronization among anchor nodes and target nodes. Also, no additional equipment or circuit is needed. Particularly, error of location discovery is analyzed when anchor nodes are placed in the form of equidistant right-angled triangle. According to the expression of error, accuracy of location discovery can be improved through enlarging the distance between anchor nodes and enhancing clock precision of target node.

I. Introduction

Node location discovery is a critical research area of wireless sensor networks from at least two aspects [1]. The location of nodes should be known as a prior in wireless sensor networks used for event detection to obtain the global estimation of detected area [2]. For example, in battle field environment, location of soldiers that carried with wireless sensor nodes should be detected to provide both command center and alliances with accurate position information to perform joint warfare and precision rescue [3]. From another aspect, some routing protocols14'5a, [4], [5] clustering' [6] [7] and data aggregation algorithms[8] are highly depended on the location of nodes; while in real applications nodes are always deployed by airplane or artillery, which indicates that node location, can not be fixed when the network is firstly deployed[9]. Consequently, to fully make use of wireless sensor networks, affiliated location discovery equipment as well as algorithms is needed in the self-organization phase of networks.