[Paper Review] An RSSI-based Wireless Sensor Node Localisation using Trilateration and Multilateration Methods for Outdoor Environment

Mohd Ismifaizul Mohd Ismail, Rudzidatul Akmam Dzyauddin+5 more|arXiv (Cornell University)|Dec 16, 2019

Indoor and Outdoor Localization Technologies20 citations

TL;DR

This study evaluates RSSI-based trilateration and multilateration for outdoor wireless sensor node localization using LoRa at 868 MHz. With three and four receiver nodes respectively, multilateration achieved a lower General Error Localization (1.83m) than trilateration (2.30m), demonstrating that increased receiver nodes improve localization accuracy in outdoor environments.

ABSTRACT

Localisation can be defined as estimating or finding a position of the node. There are two techniques in localisation, which are range-based and range-free techniques. This paper focusses on the Received Signal Strength Indicator (RSSI) localisation method, which is categorised in a range-based technique along with the time of arrival, time difference of arrival and angle of arrival. Therefore, this study aims to compare the trilateration and multilateration method for RSSI-based technique for localising the transmitted (Tx) node. The wireless sensor module in the work used LOng-RAnge radio (LoRa) with 868MHz frequency. Nowadays, wireless networks have been a key technology for smart environments, monitoring, and object tracking due to low power consumption with long-range connectivity. The number of received (Rx) nodes are three and four for trilateration and multilateration methods, respectively. The transmitted node is placed at 32 different coordinates within the 10x10 meter outdoor area. The results show that error localisation obtained for General Error Localisation (GER) for multilateration and trilateration is 1.83m and 2.30m, respectively. An additional, the maximum and minimum error for multilateration and trilateration from 1.00 to 5.28m and 0.5 to 3.61m. The study concludes that the multilateration method more accurate than trilateration. Therefore, with the increasing number of Rx node, the accuracy of localisation of the Tx node increases.

Motivation & Objective

• To evaluate and compare trilateration and multilateration techniques for RSSI-based localization in outdoor environments.
• To assess the impact of increasing receiver node count on localization accuracy using RSSI measurements.
• To implement and test a low-power, long-range wireless sensor network using LoRa for real-world outdoor node localization.
• To determine the optimal method for minimizing localization error in practical outdoor deployments.

Proposed method

• RSSI-based ranging was used to estimate distance between the transmitted (Tx) node and multiple receiver (Rx) nodes.
• Trilateration used three Rx nodes to estimate the Tx node's position using multilateration geometry.
• Multilateration used four Rx nodes to improve position estimation accuracy through overdetermined system solving.
• LoRa transceivers operating at 868 MHz were used for long-range, low-power communication in outdoor conditions.
• The Tx node was placed at 32 predefined coordinates within a 10×10 meter area to collect RSSI data.
• Position estimates were computed using trilateration and multilateration algorithms, with error calculated as the Euclidean distance from true to estimated position.

Experimental results

Research questions

• RQ1 How does multilateration compare to trilateration in terms of localization accuracy using RSSI in outdoor environments?
• RQ2 What is the effect of increasing the number of receiver nodes on RSSI-based localization error?
• RQ3 Can LoRa-based RSSI ranging achieve reliable and accurate node localization in real outdoor settings?
• RQ4 What are the maximum and minimum localization errors observed for trilateration and multilateration methods?

Key findings

• Multilateration achieved a General Error Localization (GER) of 1.83 meters, outperforming trilateration’s 2.30 meters.
• The minimum localization error for multilateration was 1.00 meter, while the maximum reached 5.28 meters.
• For trilateration, the error ranged from 0.50 to 3.61 meters, indicating higher variability.
• The study confirms that increasing the number of receiver nodes reduces localization error and improves accuracy.
• RSSI-based localization using LoRa is feasible in outdoor environments, though subject to environmental signal fading and multipath effects.