International Journal of Bioelectronics

Study of Power of Received Signal Strength Indicator (RSSI) for the Distance Between Nodes, Based on Freakduino for Wireless Sensor Networks (WSN)

Abstract

Wireless Sensor Networks (WSN) are composed of autonomous electronic nodes that can collect data from various sensors and transmit information to other nodes. This research studies the RSSI power versus the coverage distance of a Freakduino board in an outdoor environment with obstacles. Three types of sensors were used at different distances between nodes to evaluate performance using transmitter and receiver nodes. Programs were developed in Arduino open-source software to observe node behavior. Results indicate that increasing RSSI signal power by adjusting programming parameters nearly doubles signal strength; however, the communication range did not exceed 180 meters.

Keywords: Wireless Sensor Networks, Received Signal Strength Indicator (RSSI), Freakduino, Nodes, Distance.

Introduction

Wireless sensor networks (WSN) have advanced to support numerous scientific and engineering applications thanks to their small size, low cost, and easy installation compared with wired systems. They are deployed for environmental monitoring, agriculture, and health. Nodes (or motes) integrate sensors, RF communication, data processing, and power modules, forming flexible topologies for various domains. Power efficiency and autonomy are key challenges in WSN design, motivating optimization of consumption through parameter tuning and duty cycling.

Methodology

The study used Freakduino-900 MHz boards (v2.1a and v3.0a) for transmitter and receiver nodes. Node configuration involved PAN ID assignment (0x1234), addressing, and 900 MHz channel selection. Tests were conducted at the Venustiano Carranza Forest, Torreón, Coahuila, with obstacles present. Distances tested: 0, 30, 50, 100, 120, 150, 180, and 200 m. Sensors employed: LM35dz (temperature), DHT11 (temperature & humidity), and FC-28 (soil moisture).

Results

Three stages of testing were performed using the LM35dz, DHT11, and FC-28 sensors. Initial results with LM35dz indicated RSSI values decreasing from 84 (0 m) to 1 (200 m). The DHT11 sensor yielded similar results with a minimum of 6 (200 m). Reconfiguration of Freakduino library parameters (OQPSK modulation) using FC-28 increased RSSI by nearly twofold while maintaining stable readings, though the range still did not surpass 180 m.