Indoor Positioning Algorithm of Wireless Sensor Based on RSSI Ranging Correction

Abstract

With the growing popularity of the application of wireless sensor network, the demand to the accuracy of wireless network is increasingly strict, the traditional location algorithm has been difficult to fulfill the needs of practicable applications. This paper proposes a new RSSI positioning algorithm based on the triangle positioning algorithm in accordance with the character of received signal strength and by modifying the proportion between path length and path loss to improve the ranging accuracy, and then uses the triangle centroid algorithm to estimate the coordinate position. Though simulation experiment, it turned out that the accuracy of algorithm has improved compared with triangle centroid positioning algorithm on the basis of RSSI. With the popularization and development of internet of things technology, the application of positiontechnology is becoming wider and wider, and the requirement of the position accuracy is higher. The application of traditional GPS positioning technology can be found everywhere in the life, however, GPS position technology consumes too much current and can hardly be used in poor GSM signal environment. Therefore, it can hardly realize in the real-time m onitoring in indoor environment. The wireless network can make up for the shortcomings of GPS. When researchers are monitoring and tracking by wireless sensor node, the accuracy of sensor node location information will cause the effectiveness of the sensor to collect data(1). Therefore, how to improve the positional accuracy is the key point. Currently, sensor network localization can be divided into two main types: positioning algorithm based on distance and positioning algorithm irrelevant to distance. Location- based positioning technology through inter-node point of measuring distance of angle information, using trilateration or maximum likelihood estimation method of position to calculate the node position. Irrelevant to distance method is not necessary distance and angle information can be realized only based on network connectivity and other information. RSSI positioning technology is a kind of positioning algorithm with based on distance, it has advantages of easy to implement, low cost and has board prospects in application. Many scholars have done research on it, and put forward improved algorithm. For example, article 7 put forward a RSSI-similarity positioning algorithm(7), it is estimate the location of unknown node by establishing anchor node matrix manner, this method improved the positioning accuracy, and average error between 0.21- 1.6(m).Nonetheless with the increase number of node the calculate energy consumption changed a lot, so it is difficult to use in case of massive deployment of nodes. Paper 8 process a method of positioning, using TSK fuzzy neighboring anchor nodes weighted centroid algorithm(8), determining the fuzzy membership function, genetic algorithm to optimize fuzzy membership function to get the right value, improve positioning accuracy by weighting range accuracy. For RSSI-based wireless sensor networks vulnerable to interference and fluctuation, paper 9 improved indoor multidimensional scaling RSSI location algorithm(9), using the node signal strength to establish dissimilarity matrices and multidimensional scaling method to solve the node relative coordinates. According to the actual coordinates of the reference node coordinate conversion flat four-parameter model by using particle swarm optimization parameters to estimate position of unknown nodes. In the wireless sensor network technology, the greater the density of anchor nodes, the higher the accuracy of the positioning is, otherwise the opposite(4). Under the condition of indoor positioning, if more positioning anchor nodes are deployed, the signal interference between sensors will make the RSSI measured value bring more error. In that case, in order to acquire higher indoor positioning accuracy, less anchor nodes shall be deployed. This paper aims at the condition of indoor positioning, ameliorated the triangle centroid algorithm based on RSSI, brought in a method based on attenuation factor correction to improve ranging accuracy of RSSI. Compared with triangle centroid algorithm, the improved algorithm has an increased accuracy of ranging of RSSI as well as positioning.